HP 10500 series User manual
HP 10500 Switch Series
Layer 3 - IP Services
Configuration Guide
Part number: 5998-2209
Software version: Release 1201 and later
Document version: 6W102-20130530
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Contents
Configuring ARP··························································································································································· 1
Overview············································································································································································1
ARP message format ················································································································································1
ARP operation···························································································································································1
ARP table···································································································································································2
Configuring a static ARP entry·········································································································································3
Configuring the maximum number of dynamic ARP entries for an interface ·····························································4
Setting the aging timer for dynamic ARP entries ···········································································································4
Enabling dynamic ARP entry check ································································································································4
Configuring ARP quick update ········································································································································5
Enabling natural mask support for ARP requests···········································································································5
Configuring multicast ARP················································································································································6
Displaying and maintaining ARP ····································································································································7
ARP configuration examples············································································································································8
Static ARP entry configuration example·················································································································8
Multicast ARP configuration example (in standalone mode) ···············································································9
Multicast ARP configuration example (in IRF mode)·························································································· 10
Configuring gratuitous ARP·······································································································································12
Overview········································································································································································· 12
Enabling learning of gratuitous ARP packets ····································································································· 12
Configuring periodic sending of gratuitous ARP packets ················································································· 12
Configuration procedure··············································································································································· 13
Enabling IP conflict notification ···································································································································· 13
Configuring proxy ARP··············································································································································15
Overview········································································································································································· 15
Common proxy ARP·············································································································································· 15
Local proxy ARP ···················································································································································· 15
Enabling common proxy ARP ······································································································································· 16
Enabling local proxy ARP ············································································································································· 16
Displaying and maintaining proxy ARP ······················································································································ 17
Common proxy ARP configuration example··············································································································· 17
Network requirements··········································································································································· 17
Configuration procedure ······································································································································ 17
Local proxy ARP configuration example in case of port isolation ············································································ 18
Network requirements··········································································································································· 18
Configuration procedure ······································································································································ 19
Local proxy ARP configuration example in super VLAN···························································································· 20
Network requirements··········································································································································· 20
Configuration procedure ······································································································································ 20
Local proxy ARP configuration example in isolate-user-VLAN ·················································································· 21
Network requirements··········································································································································· 21
Configuration procedure ······································································································································ 21
Configuring ARP snooping········································································································································23
Overview········································································································································································· 23
Configuration procedure··············································································································································· 23
Displaying and maintaining ARP snooping ················································································································ 23
Configuring IP addressing·········································································································································24
Overview········································································································································································· 24
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IP address classes·················································································································································· 24
Special IP addresses ············································································································································· 25
Subnetting and masking ······································································································································· 25
Assigning an IP address to an interface······················································································································ 26
Configuration guidelines ······································································································································ 26
Configuration procedure ······································································································································ 26
Configuration example ········································································································································· 26
Displaying and maintaining IP addressing ················································································································· 28
DHCP overview ··························································································································································29
DHCP address allocation ·············································································································································· 29
Dynamic IP address allocation process ·············································································································· 30
IP address lease extension ··································································································································· 30
DHCP message format ·················································································································································· 31
DHCP options ································································································································································· 32
Common DHCP options········································································································································ 32
Custom DHCP options··········································································································································· 32
Protocols and standards ················································································································································ 35
Configuring the DHCP server····································································································································36
Overview········································································································································································· 36
DHCP address pool··············································································································································· 36
IP address allocation sequence···························································································································· 37
DHCP server configuration task list······························································································································ 38
Configuring an address pool on the DHCP server····································································································· 38
Configuration task list ··········································································································································· 38
Creating a DHCP address pool··························································································································· 39
Configuring address allocation mode for a common address pool ································································ 39
Configuring dynamic address allocation for an extended address pool························································ 41
Configuring a domain name suffix for the client ······························································································· 42
Configuring DNS servers for the client ··············································································································· 42
Configuring WINS servers and NetBIOS node type for the client ·································································· 42
Configuring BIMS server information for the client···························································································· 43
Configuring gateways for the client ···················································································································· 43
Configuring Option 184 parameters for the client with voice service ···························································· 43
Configuring the TFTP server and bootfile name for the client··········································································· 44
Specifying a server's IP address for the DHCP client ························································································ 45
Configuring self-defined DHCP options ·············································································································· 45
Enabling DHCP ······························································································································································ 46
Enabling the DHCP server on an interface·················································································································· 46
Configuration guidelines ······································································································································ 47
Configuration procedure ······································································································································ 47
Applying an extended address pool on an interface ································································································ 47
Configuring the DHCP server security functions ········································································································· 48
Configuration prerequisites ·································································································································· 48
Enabling unauthorized DHCP server detection·································································································· 48
Configuring IP address conflict detection ··········································································································· 48
Enabling client offline detection ··································································································································· 49
Enabling handling of Option 82·································································································································· 49
Configuration prerequisites ·································································································································· 49
Configuration procedure ······································································································································ 49
Specifying the threshold for sending trap messages·································································································· 50
Configuration prerequisites ·································································································································· 50
Configuration procedure ······································································································································ 50
Setting the DSCP value for DHCP packets ·················································································································· 50
Displaying and maintaining the DHCP server ············································································································ 50
DHCP server configuration examples ·························································································································· 51
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Static IP address assignment configuration example ························································································ 51
Dynamic IP address assignment configuration example··················································································· 53
Self-defined option configuration example········································································································· 54
Troubleshooting DHCP server configuration ··············································································································· 55
Configuring the DHCP relay agent···························································································································56
Overview········································································································································································· 56
Fundamentals························································································································································· 56
DHCP relay agent support for Option 82 ·········································································································· 57
DHCP relay agent configuration task list····················································································································· 58
Enabling DHCP ······························································································································································ 58
Enabling the DHCP relay agent on an interface ········································································································ 58
Correlating a DHCP server group with a relay agent interface ··············································································· 59
Configuration guidelines ······································································································································ 59
Configuration procedure ······································································································································ 59
Configuring the DHCP relay agent security functions································································································ 60
Configuring address check ·································································································································· 60
Configuring periodic refresh of dynamic client entries ····················································································· 60
Enabling unauthorized DHCP server detection·································································································· 61
Enabling DHCP starvation attack protection ······································································································ 61
Enabling client offline detection ··································································································································· 62
Configuring the DHCP relay agent to release an IP address···················································································· 62
Configuring the DHCP relay agent to handle Option 82·························································································· 63
Configuration prerequisites ·································································································································· 63
Configuration procedure ······································································································································ 63
Setting the DSCP value for DHCP packets ·················································································································· 64
Displaying and maintaining the DHCP relay agent ··································································································· 64
DHCP relay agent configuration examples················································································································· 65
DHCP relay agent configuration example·········································································································· 65
DHCP relay agent Option 82 support configuration example········································································· 66
Troubleshooting DHCP relay agent configuration······································································································ 67
Configuring DHCP client ···········································································································································68
Configuration restrictions ·············································································································································· 68
Enabling the DHCP client on an interface··················································································································· 68
Setting the DSCP value for DHCP packets ·················································································································· 68
Displaying and maintaining the DHCP client·············································································································· 69
DHCP client configuration example ····························································································································· 69
Network requirements··········································································································································· 69
Configuration procedure ······································································································································ 69
Verifying the configuration··································································································································· 70
Configuring DHCP snooping·····································································································································72
DHCP snooping functions·············································································································································· 72
Guaranteeing that DHCP clients obtain IP addresses from authorized DHCP servers ·································· 72
Recording IP-to-MAC mappings of DHCP clients······························································································· 72
Application environment of trusted ports····················································································································· 73
Configuring a trusted port connected to a DHCP server··················································································· 73
Configuring trusted ports in a cascaded network······························································································ 73
DHCP snooping support for Option 82······················································································································· 74
DHCP snooping configuration task list ························································································································ 75
Configuring DHCP snooping basic functions·············································································································· 75
Configuration guidelines ······································································································································ 75
Configuration procedure ······································································································································ 76
Configuring DHCP snooping to support Option 82··································································································· 76
Configuration guidelines ······································································································································ 76
Configuration procedure ······································································································································ 77
iv
Configuring DHCP snooping entries backup·············································································································· 78
Enabling DHCP starvation attack protection ··············································································································· 79
Enabling DHCP-REQUEST message attack protection ······························································································· 80
Configuring DHCP packet rate limit····························································································································· 80
Displaying and maintaining DHCP snooping············································································································· 81
DHCP snooping configuration examples····················································································································· 82
DHCP snooping configuration example ············································································································· 82
DHCP snooping Option 82 support configuration example ············································································ 82
Configuring IPv4 DNS ···············································································································································84
Overview········································································································································································· 84
Static domain name resolution····························································································································· 84
Dynamic domain name resolution······················································································································· 84
Configuring the IPv4 DNS client ·································································································································· 85
Configuring static domain name resolution········································································································ 85
Configuring dynamic domain name resolution·································································································· 86
Setting the DSCP value for DNS packets····················································································································· 86
Displaying and maintaining IPv4 DNS························································································································ 87
IPv4 DNS configuration examples ······························································································································· 87
Static domain name resolution configuration example····················································································· 87
Dynamic domain name resolution configuration example ··············································································· 88
Troubleshooting IPv4 DNS configuration ···················································································································· 91
Symptom································································································································································· 91
Solution··································································································································································· 91
Configuring IP forwarding basics ·····························································································································92
FIB table ·········································································································································································· 92
Displaying and maintaining the FIB table ··················································································································· 92
Configuring IP performance optimization ················································································································94
Enabling receiving and forwarding of directed broadcasts to a directly connected network······························· 94
Enabling receiving of directed broadcasts········································································································· 94
Enabling forwarding of directed broadcasts······································································································ 94
Configuration example ········································································································································· 95
Configuring TCP attributes ············································································································································ 95
Configuring TCP path MTU discovery ················································································································ 95
Configuring the TCP send/receive buffer size ··································································································· 96
Configuring TCP timers········································································································································· 97
Configuring ICMP to send error packets····················································································································· 97
Advantages of sending ICMP error packets······································································································· 97
Disadvantages of sending ICMP error packets·································································································· 98
Configuration procedure ······································································································································ 99
Enabling support for ICMP extensions························································································································· 99
ICMP extensions for MPLS···································································································································· 99
Handling ICMP messages ···································································································································· 99
Configuration procedure ····································································································································100
Displaying and maintaining IP performance optimization ······················································································100
Configuring UDP helper ········································································································································· 102
Configuration restrictions and guidelines··················································································································102
Configuration procedure·············································································································································102
Displaying and maintaining UDP helper ···················································································································103
UDP helper configuration example ····························································································································103
Network requirements·········································································································································103
Configuration procedure ····································································································································103
Configuring IPv6 basics·········································································································································· 105
Overview·······································································································································································105
v
IPv6 features·························································································································································105
IPv6 addresses·····················································································································································106
IPv6 neighbor discovery protocol······················································································································109
IPv6 path MTU discovery····································································································································112
IPv6 transition technologies································································································································112
Protocols and standards ·····································································································································113
IPv6 basics configuration task list·······························································································································113
Configuring basic IPv6 functions································································································································114
Enabling IPv6·······················································································································································114
Configuring an IPv6 global unicast address ····································································································114
Configuring an IPv6 link-local address ·············································································································116
Configure an IPv6 anycast address ··················································································································117
Configuring IPv6 ND ···················································································································································118
Configuring a static neighbor entry ··················································································································118
Configuring the maximum number of neighbors dynamically learned ·························································118
Setting the age timer for ND entries in stale state ···························································································119
Configuring parameters related to RA messages ····························································································119
Configuring the maximum number of attempts to send an NS message for DAD·······································122
Configuring path MTU discovery ·······························································································································123
Configuring a static path MTU for a specified IPv6 address ·········································································123
Configuring the aging time for dynamic path MTUs·······················································································123
Configuring IPv6 TCP properties ································································································································123
Configuring ICMPv6 packet sending·························································································································124
Configuring the maximum ICMPv6 error packets sent in an interval ····························································124
Enabling replying to multicast echo requests ···································································································124
Enabling sending ICMPv6 time exceeded messages······················································································125
Enabling sending ICMPv6 destination unreachable messages······································································125
Displaying and maintaining IPv6 basics configuration····························································································126
IPv6 basics configuration example ····························································································································128
Network requirements·········································································································································128
Configuration procedure ····································································································································128
Verifying the configuration·································································································································129
Troubleshooting IPv6 basics configuration················································································································133
Symptom·······························································································································································133
Solution·································································································································································133
DHCPv6 overview··················································································································································· 134
Concepts ·······································································································································································134
Multicast addresses used by DHCPv6 ··············································································································134
DUID ·····································································································································································134
IA···········································································································································································135
IAID·······································································································································································135
Binding ·································································································································································135
PD··········································································································································································135
DHCPv6 address/prefix assignment··························································································································135
Rapid assignment involving two messages ······································································································135
Assignment involving four messages·················································································································136
Address/prefix lease renewal ····································································································································136
Stateless DHCPv6 configuration·································································································································137
About stateless DHCPv6 ·····································································································································137
Operation·····························································································································································137
Protocols and standards ··············································································································································138
Configuring DHCPv6 relay agent·························································································································· 139
DHCPv6 relay agent operation ··································································································································139
Configuration prerequisites·········································································································································140
Configuration guidelines ·············································································································································140
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Configuration procedure·············································································································································140
Setting the DSCP value for DHCPv6 packets ···································································································140
Displaying and maintaining the DHCPv6 relay agent·····························································································141
DHCPv6 relay agent configuration example ············································································································141
Network requirements·········································································································································141
Configuration procedure ····································································································································142
Verifying the configuration·································································································································142
Configuring DHCPv6 client ···································································································································· 144
Configuration prerequisites·········································································································································144
Configuration procedure·············································································································································144
Setting the DSCP value for DHCPv6 packets ···································································································144
Displaying and maintaining the DHCPv6 client ·······································································································144
Stateless DHCPv6 configuration example ·················································································································145
Network requirements·········································································································································145
Configuration procedure ····································································································································145
Verifying the configuration·································································································································146
Configuring IPv6 DNS ············································································································································ 147
Configuring the IPv6 DNS client ································································································································147
Configuring static domain name resolution······································································································147
Configuring dynamic domain name resolution································································································147
Setting the DSCP value for IPv6 DNS packets ··········································································································148
Displaying and maintaining IPv6 DNS······················································································································148
IPv6 DNS configuration examples ·····························································································································149
Static domain name resolution configuration example···················································································149
Dynamic domain name resolution configuration example ·············································································150
Configuring tunneling ············································································································································· 155
Overview·······································································································································································155
IPv6 over IPv4 tunneling ·····································································································································155
IPv4 over IPv4 tunneling ·····································································································································157
IPv4 over IPv6 tunneling ·····································································································································158
IPv6 over IPv6 tunneling ·····································································································································159
Protocols and standards ·····································································································································159
Tunneling configuration task list ·································································································································160
Configuring a tunnel interface····································································································································160
Configuration prerequisites ································································································································160
Configuration guidelines ····································································································································160
Configuration procedure ····································································································································161
Configuring an IPv6 manual tunnel····························································································································162
Configuration prerequisites ································································································································162
Configuration guidelines ····································································································································162
Configuration procedure ····································································································································162
Configuration example ·······································································································································163
Configuring a 6to4 tunnel···········································································································································166
Configuration prerequisites ································································································································166
Configuration guidelines ····································································································································166
Configuration procedure ····································································································································166
Configuration example ·······································································································································167
Configuring an ISATAP tunnel····································································································································170
Configuration prerequisites ································································································································170
Configuration guidelines ····································································································································170
Configuration procedure ····································································································································170
Configuration example ·······································································································································171
Configuring an IPv4 over IPv4 tunnel ························································································································174
Configuration prerequisites ································································································································174
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Configuration guidelines ····································································································································174
Configuration procedure ····································································································································174
Configuration example ·······································································································································175
Configuring an IPv4 over IPv6 tunnel ························································································································178
Configuration prerequisites ································································································································178
Configuration guidelines ····································································································································178
Configuration procedure ····································································································································178
Configuration example ·······································································································································179
Configuring an IPv6 over IPv6 tunnel ························································································································182
Configuration prerequisites ································································································································182
Configuration guidelines ····································································································································182
Configuration procedure ····································································································································183
Configuration example ·······································································································································184
Displaying and maintaining tunneling configuration ·······························································································187
Troubleshooting tunneling configuration ···················································································································187
Configuring GRE····················································································································································· 189
Overview·······································································································································································189
GRE encapsulation format··································································································································189
GRE encapsulation and de-encapsulation processes ······················································································190
Protocols and standards ·····································································································································190
Configuring a GRE over IPv4 tunnel ··························································································································191
Configuration restrictions and guidelines ·········································································································191
Configuration prerequisites ································································································································191
Configuration procedure ····································································································································191
Configuring a GRE over IPv6 tunnel ··························································································································192
Configuration restrictions and guidelines ·········································································································192
Configuration prerequisites ································································································································193
Configuration procedure ····································································································································193
Displaying and maintaining GRE·······························································································································194
GRE over IPv4 tunnel configuration example············································································································194
GRE over IPv6 tunnel configuration example············································································································197
Troubleshooting GRE ···················································································································································201
Support and other resources ·································································································································· 202
Contacting HP ······························································································································································202
Subscription service ············································································································································202
Related information······················································································································································202
Documents····························································································································································202
Websites ······························································································································································202
Conventions ··································································································································································203
Index ········································································································································································ 205
1
Configuring ARP
This chapter describes how to configure the Address Resolution Protocol (ARP).
Overview
ARP resolves IP addresses into physical addresses such as MAC addresses. On an Ethernet LAN, a
device uses ARP to get the MAC address of the target device for a packet.
NOTE:
You can set an Ethernet port as a Layer 3 interface by using the port link-mode route command (see
Laye
r
2—LAN Switching Configuration Guide
).
ARP message format
ARP uses two types of messages, ARP request and ARP reply. Figure 1 shows the format of the ARP
request/reply. Numbers in the figure refer to field lengths.
Figure 1 ARP message format
•Hardware type—Hardware address type. The value 1 represents Ethernet.
•Protocol type—Type of the protocol address to be mapped. The hexadecimal value 0x0800
represents IP.
•Hardware address length and protocol address length—Length, in bytes, of a hardware address
and a protocol address. For an Ethernet address, the value of the hardware address length field is
6. For an IPv4 address, the value of the protocol address length field is 4.
•OP—Operation code, which describes type of the ARP message. Value 1 represents an ARP
request, and value 2 represents an ARP reply.
•Sender hardware address—Hardware address of the device sending the message.
•Sender protocol address—Protocol address of the device sending the message.
•Target hardware address—Hardware address of the device to which the message is being sent.
•Target protocol address—Protocol address of the device to which the message is being sent.
ARP operation
As shown in Figure 2, Host A and Host B are on the same subnet. Host A sends a packet to Host B as
follows:
2
1. Host A looks through its ARP table for an ARP entry for Host B. If an entry is found, Host A uses the
MAC address in the entry to encapsulate the IP packet into a data link layer frame and sends the
frame to Host B.
2. If Host A finds no entry for Host B, Host A buffers the packet and broadcasts an ARP request. The
payload of the ARP request comprises the following information:
{Sender IP address and sender MAC address—Host A's IP address and MAC address
{Target IP address—Host B's IP address
{Target MAC address—An all-zero MAC address
All hosts on this subnet can receive the broadcast request, but only the requested host (Host B)
processes the request.
3. Host B compares its own IP address with the target IP address in the ARP request. If they are the
same, Host B performs the following:
a. Adds the sender IP address and sender MAC address into its ARP table.
b. Encapsulates its MAC address into an ARP reply.
c. Unicasts the ARP reply to Host A.
4. After receiving the ARP reply, Host A performs the following:
a. Adds the MAC address of Host B into its ARP table.
b. Encapsulates the MAC address into the packet and sends the packet to Host B.
Figure 2 ARP address resolution process
If Host A and Host B are on different subnets, the resolution process is as follows:
1. Host A sends an ARP request to the gateway. The target IP address in the ARP request is the IP
address of the gateway.
2. The gateway responds with its MAC address in an ARP reply to Host A.
3. Host A uses the gateway MAC address to encapsulate the packet and sends the packet to the
gateway.
4. If the gateway has the ARP entry for Host B, it forwards the packet to Host B directly. If not, it
broadcasts an ARP request, in which the target IP address is the IP address of Host B.
5. After obtaining the MAC address of Host B, the gateway sends the packet to Host B.
ARP table
An ARP table stores dynamic and static ARP entries.
3
Dynamic ARP entry
ARP automatically creates and updates dynamic entries. A dynamic ARP entry is removed when its aging
timer expires or the output interface goes down, and it can be overwritten by a static ARP entry.
Static ARP entry
A static ARP entry is manually configured and maintained. It does not age out, and cannot be
overwritten by a dynamic ARP entry.
Static ARP entries protect communication between devices, because attack packets cannot modify the
IP-to-MAC mapping in a static ARP entry.
Static ARP entries can be classified into long and short ARP entries.
•To configure a long static ARP entry, specify the IP address, MAC address, VLAN, and output
interface. A long static ARP entry is directly used for forwarding matching packets. To communicate
with a host by using a fixed IP-to-MAC mapping through a specific interface in a specific VLAN,
configure a long static ARP entry on the device.
•To configure a short static ARP entry, you only need to specify the IP address and MAC address.
{If the output interface is a Layer 3 Ethernet interface, the short ARP entry can be directly used
to forward matching packets.
{If the output interface is a VLAN interface, the device first sends an ARP request whose target
IP address is the IP address of the short entry. If the sender IP and MAC addresses in the
received ARP reply match the IP and MAC addresses of the short static ARP entry, the device
adds the interface receiving the ARP reply to the short static ARP entry, and then uses the
resolved entry to forward the matching IP packets.
To communicate with a host by using a fixed IP-to-MAC mapping, configure a short static ARP
entry on the device.
Configuring a static ARP entry
A static ARP entry is effective when the device works normally. If a VLAN or VLAN interface is deleted,
all long static ARP entries in the VLAN are deleted, and all resolved short static ARP entries in the VLAN
becomes unresolved.
Follow these guidelines when you configure a long static ARP entry:
•The vlan-id argument must be the ID of an existing VLAN where the ARP entry resides. The specified
Ethernet interface must belong to that VLAN. The VLAN interface of the VLAN must be created.
•The IP address of the VLAN interface of the VLAN specified by the vlan-id argument must belong to
the same subnet as the IP address specified by the ip-address argument.
To configure a static ARP entry:
Step Command Remarks
1. Enter system view. system-view N/A
2. Configure a static
ARP entry.
•Configure a long static ARP entry:
arp static ip-address mac-address vlan-id
interface-type interface-number [ vpn-instance
vpn-instance-name ]
•Configure a short static ARP entry:
arp static ip-address mac-address
[ vpn-instance vpn-instance-name ]
Use either command.
4
Configuring the maximum number of dynamic ARP
entries for an interface
An interface can dynamically learn ARP entries, so it may hold too many ARP entries. To solve this
problem, you can set the maximum number of dynamic ARP entries that an interface can learn. When the
maximum number is reached, the interface stops learning ARP entries.
A Layer 2 interface can learn an ARP entry only when both its maximum number and the VLAN
interface's maximum number are not reached.
To set the maximum number of dynamic ARP entries that an interface can learn:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter interface view. interface interface-type
interface-number N/A
3. Set the maximum number of dynamic
ARP entries that the interface can
learn.
arp max-learning-num
number
Optional.
By default, a Layer 2 interface does
not limit the number of dynamic ARP
entries. The maximum number of
dynamic ARP entries that a Layer 3
interface can learn is 8192.
If the value of the number argument is
set to 0, the interface is disabled from
learning dynamic ARP entries.
Setting the aging timer for dynamic ARP entries
Each dynamic ARP entry in the ARP table has a limited lifetime, called aging timer. The aging timer of a
dynamic ARP entry is reset each time the dynamic ARP entry is updated. Dynamic ARP entries that are not
updated before their aging timers expire are deleted from the ARP table.
To set the aging timer for dynamic ARP entries:
Step Command Remarks
1. Enter system view. system-view N/A
2. Set the aging timer for
dynamic ARP entries. arp timer aging aging-time Optional.
20 minutes by default.
Enabling dynamic ARP entry check
The dynamic ARP entry check function controls whether the device supports dynamic ARP entries with
multicast MAC addresses.
When dynamic ARP entry check is enabled, the device cannot learn dynamic ARP entries containing
multicast MAC addresses.
When dynamic ARP entry check is disabled, the device can learn dynamic ARP entries containing
multicast MAC addresses.
5
To enable dynamic ARP entry check:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enable dynamic ARP entry
check. arp check enable Optional.
Enabled by default.
Configuring ARP quick update
HP recommends enabling ARP quick update in WLANs only.
As shown in Figure 3, the laptop frequently roams between AP 1 and AP 2. This affects the mapping
between its MAC address and outbound interface on the switch. If the switch does not update its ARP
table immediately after the outbound interface changes, it may fail to communicate with the laptop.
Figure 3 ARP quick update application scenario
With ARP quick update enabled, the switch updates the corresponding ARP entry immediately after the
change of the mapping between a MAC address and an outbound interface to ensure nonstop data
forwarding.
To enable ARP quick update:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enable ARP quick
update.
mac-address station-move
quick-notify enable
Optional.
Disabled by default.
Enabling natural mask support for ARP requests
This feature enables the device to learn the sender IP and MAC addresses in a received ARP request
whose sender IP address is on the same classful network as but a different subnet from the IP address of
the receiving interface. A classful network refers to a class A, B, or C network.
For example, VLAN-interface 10 with IP address 10.10.10.5/24 receives an ARP request from
10.11.11.1/8. Because the subnet address calculated by the AND operation of 10.11.11.1 and the 24-bit
6
subnet mask of the receiving interface is not in the subnet 10.10.10.5/24, VLAN-interface 10 cannot
process the ARP packet.
With this feature enabled, the device calculates the subnet address by using the default mask of the class
A network where 10.10.10.5/24 resides. Because 10.10.10.5/24 is on the same class A network as
10.11.11.1/8, VLAN-interface 10 can learn the sender IP and MAC addresses in the request.
To enable natural mask support for ARP requests:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enable natural mask support
for ARP requests. naturemask-arp enable Disabled by default.
Configuring multicast ARP
Microsoft NLB is a load balancing technology for server clustering developed on Windows Server.
NLB supports load sharing and redundancy among servers within a cluster. To implement fast failover,
NLB requires that the switch forwards network traffic to all servers or specified servers in the cluster, and
each server filters out unexpected traffic. In a medium or small data center that uses the Windows Server
operating system, the proper cooperation of the switch and NLB is very important. For more information
about NLB, see the related documents for Windows Server.
Microsoft NLB provides the following packet sending modes to make the switch forward network traffic
to all servers or specified servers:
•Unicast mode—NLB assigns each cluster member a common MAC address, which is the cluster
MAC address, and changes the source MAC address of each sent packet. The switch cannot add
the cluster MAC address to its MAC table. In addition, because the cluster MAC address is
unknown to the switch, packets destined to it are forwarded on all ports of the switch.
•Multicast mode—NLB uses a multicast MAC address that is a virtual MAC address for network
communication (for example 0300-5e11-1111).
•IGMP multicast mode—The switch sends packets only out of the ports that connect to the cluster
members rather than all ports.
NOTE:
Multicast ARP is applicable to only multicast-mode NLB.
To configure multicast ARP:
Step Command Remarks
1. Disable the ARP entry check
function. undo arp check enable
Required when the device learns
dynamic ARP entries that contain
multicast MAC addresses.
2. Configure a static ARP entry.
arp static ip-address mac-address
vlan-id interface-type interface-number
[ vpn-instance vpn-instance-name ]
Optional.
3. Configure a static multicast
MAC address entry.
mac-address multicast mac-address
interface interface-list vlan vlan-id
For more information about the
mac-address multicast
command, see IP Multicast
Command Reference.
7
NOTE:
W
hen confi
g
urin
g
multicast ARP, use the interfaces on the EB, EA, SE, or SF card of the switch to connect
to hosts and servers.
Displaying and maintaining ARP
CAUTION:
Clearing ARP entries from the ARP table might cause communication failures.
Task Command Remarks
Display ARP entries in the ARP
table. (In standalone mode.)
display arp [ [ all | dynamic | static ] [ slot
slot-number ] | vlan vlan-id | interface
interface-type interface-number ] [ count |
verbose ] [ |{ begin | exclude | include }
regular-expression ]
Available in any view.
Display ARP entries in the ARP
table. (In IRF mode.)
display arp [ [ all | dynamic | static ] [ chassis
chassis-number slot slot-number ] | vlan
vlan-id | interface interface-type
interface-number ] [ count | verbose ] [ |
{ begin | exclude | include }
regular-expression ]
Available in any view.
Display the ARP entry for a
specified IP address. (In
standalone mode.)
display arp ip-address [slot slot-number ]
[verbose ] [ | {begin |exclude |include }
regular-expression ]
Available in any view.
Display the ARP entry for a
specified IP address. (In IRF
mode.)
display arp ip-address [ chassis
chassis-number slot slot-number ] [ verbose ]
[ |{ begin | exclude | include }
regular-expression ]
Available in any view.
Display the ARP entries for a
specified VPN instance.
display arp vpn-instance vpn-instance-name
[ count ] [ | {begin | exclude |include }
regular-expression ]
Available in any view.
Display the aging timer of
dynamic ARP entries.
display arp timer aging [ |{ begin | exclude |
include } regular-expression ] Available in any view.
Clear ARP entries from the ARP
table. (In standalone mode.)
reset arp { all | dynamic | static | slot
slot-number | interface interface-type
interface-number }
Available in user view.
Clear ARP entries from the ARP
table. (In IRF mode.)
reset arp { all | dynamic | static | chassis
chassis-number slot slot-number | interface
interface-type interface-number }
Available in user view.
8
ARP configuration examples
Static ARP entry configuration example
Network requirements
As shown in Figure 4, hosts are connected to the switch, which is connected to the router through
interface GigabitEthernet 1/0/1 in VLAN 10. The IP and MAC addresses of the router are
192.168.1.1/24 and 00e0-fc01-0000 respectively.
To prevent malicious users from attacking the switch and enhance security for communications between
the router and switch, configure a static ARP entry for the router on the switch.
Figure 4 Network diagram
Configuration procedure
# Create VLAN 10.
<Switch> system-view
[Switch] vlan 10
[Switch-vlan10] quit
# Add interface GigabitEthernet 1/0/1 to VLAN 10.
[Switch] interface GigabitEthernet 1/0/1
[Switch-GigabitEthernet1/0/1] port link-type trunk
[Switch-GigabitEthernet1/0/1] port trunk permit vlan 10
[Switch-GigabitEthernet1/0/1] quit
# Create interface VLAN-interface 10 and configure its IP address.
[Switch] interface vlan-interface 10
[Switch-vlan-interface10] ip address 192.168.1.2 24
[Switch-vlan-interface10] quit
# Configure a static ARP entry that has IP address 192.168.1.1, MAC address 00e0-fc01-0000, and
output interface GigabitEthernet 1/0/1 in VLAN 10.
[Switch] arp static 192.168.1.1 00e0-fc01-0000 10 GigabitEthernet 1/0/1
# Display information about static ARP entries.
[Switch] display arp static
Type: S-Static D-Dynamic A-Authorized
9
IP Address MAC Address VLAN ID Interface Aging Type
192.168.1.1 00e0-fc01-0000 10 GE1/0/1 N/A S
Multicast ARP configuration example (in standalone mode)
Network requirements
As shown in Figure 5, a small data center uses Microsoft multicast-mode NLB. To enable the switch to
cooperate with NLB, perform the following configurations:
•Use the interfaces on the EB, EA, SE, or SF card of the switch to connect to the hosts and servers.
•Add GigabitEthernet 4/0/2 and GigabitEthernet 4/0/3 into VLAN 10, and specify IP address
16 .1.1.1 / 2 4 f o r V L A N - i n t e r f a c e 10 .
•Add GigabitEthernet 3/0/4 and GigabitEthernet 3/0/1 into VLAN 20, and specify IP address
10.0.0.1/24 for VLAN-interface 20.
•Disable the ARP entry check function so that the switch can learn dynamic ARP entries containing
multicast MAC addresses.
•Configure a static multicast MAC address entry so that only interfaces GigabitEthernet 4/0/2 and
GigabitEthernet 4/0/3 can receive multicast information.
•Specify 10.0.0.1/24 as the default gateway of Host A and Host B.
•S p e c i f y 16 .1.1.1 / 2 4 a s t h e d e f a u l t g a t e wa y o f S e r v e r A a n d S e r v e r B .
Figure 5 Network diagram
Configuration procedure
This example only gives the configurations on the switch. For the NLB configuration on the servers, see
related documents for Windows Server.
# Specify an IP address for VLAN-interface 10.
<Switch> system-view
[Switch] vlan 10
[Switch-vlan10] port GigabitEthernet 4/0/2
[Switch-vlan10] port GigabitEthernet 4/0/3
[Switch-vlan10] quit
[Switch] interface vlan-interface 10
[Switch-Vlan-interface10] ip address 16.1.1.1 255.255.255.0
[Switch-Vlan-interface10] quit
# Specify an IP address for VLAN-interface 20.
[Switch] vlan 20
10
[Switch-vlan20] port GigabitEthernet 3/0/1
[Switch-vlan20] port GigabitEthernet 3/0/4
[Switch-vlan20] quit
[Switch] interface vlan-interface 20
[Switch-Vlan-interface20] ip address 10.0.0.1 255.255.255.0
[Switch-Vlan-interface20] quit
# Disable the ARP entry check function.
[Switch] undo arp check enable
# Configure a static multicast MAC address entry.
[Switch] mac-address multicast 03bf-1001-0164 interface GigabitEthernet 4/0/2
GigabitEthernet 4/0/3 vlan 10
Verifying the configuration
•NLB load sharing—Enables the FTP server function of Server A and Server B. Host A and Host B
send requests to the virtual IP address, and each of them logs in to a different server.
•NLB redundancy—Disables the network interface card of Server A. Host A and Host B send
requests to the virtual IP address, and both log in to the FTP server on Server B.
Multicast ARP configuration example (in IRF mode)
Network requirements
As shown in Figure 6, a small data center uses Microsoft multicast-mode NLB. Two HP 10500 switches
form an IRF fabric. To enable the switches to cooperate with NLB, perform the following configurations:
•Use the interfaces on the EB, EA, SE, or SF card of the switch to connect to the hosts and servers.
•Add GigabitEthernet 1/4/0/2 and GigabitEthernet 2/4/0/3 into VLAN 10, and specify IP
address 16.1.1.1/24 for VLAN-interface 10.
•Add GigabitEthernet 1/3/0/4 and GigabitEthernet 2/3/0/1 into VLAN 20, and specify IP
address 10.0.0.1/24 for VLAN-interface 20.
•Disable the ARP entry check function so that the switch can learn dynamic ARP entries containing
multicast MAC addresses.
•Configure a static multicast MAC address entry so that only interfaces GigabitEthernet 1/4/0/2
and GigabitEthernet 2/4/0/3 can receive multicast information.
•Specify 10.0.0.1/24 as the default gateway of Host A and Host B.
•S p e c i f y 16 .1.1.1 / 2 4 a s t h e d e f a u l t g a t e wa y o f S e r v e r A a n d S e r v e r B .
Figure 6 Network diagram
11
Configuration procedure
This example only describes multicast ARP configuration. For more information about IRF, see the IRF
configuration guide for switches. For NLB configuration on the servers, see the related documents for
Windows Server.
# Specify an IP address for VLAN-interface 10.
<Switch> system-view
[Switch] vlan 10
[Switch-vlan10] port GigabitEthernet 1/4/0/2
[Switch-vlan10] port GigabitEthernet 2/4/0/3
[Switch-vlan10] quit
[Switch] interface vlan-interface 10
[Switch-Vlan-interface10] ip address 16.1.1.1 255.255.255.0
[Switch-Vlan-interface10] quit
# Specify an IP address for VLAN-interface 20.
[Switch] vlan 20
[Switch-vlan20] port GigabitEthernet 2/3/0/1
[Switch-vlan20] port GigabitEthernet 1/3/0/4
[Switch-vlan20] quit
[Switch] interface vlan-interface 20
[Switch-Vlan-interface20] ip address 10.0.0.1 255.255.255.0
[Switch-Vlan-interface20] quit
# Disable the ARP entry check function.
[Switch] undo arp check enable
# Configure a static multicast MAC address entry.
[Switch] mac-address multicast 03bf-1001-0164 interface GigabitEthernet 1/4/0/2
GigabitEthernet 2/4/0/3 vlan 10
Verifying the configuration
•NLB load sharing—Enables the FTP server function of Server A and Server B. Host A and Host B
send requests to the virtual IP address, and each of them logs in to a different server.
•NLB redundancy—Disables the network interface card of Server A. Host A and Host B send
requests to the virtual IP address, and both log in to the FTP server on Server B.
Other manuals for 10500 series
13
Table of contents
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