H3C S9500 Series User manual

Operation Manual – IP Performance
H3C S9500 Series Routing Switches Table of Contents
i
Table of Contents
Chapter 1 IP Performance Configuration....................................................................................1-1
1.1 Configuring IP Performance ..............................................................................................1-1
1.1.1 Configuring TCP Attributes .....................................................................................1-1
1.1.2 Configuring the Switch Whether to Send a Time Exceeded ICMP Packet.............1-2
1.2 Displaying and Maintaining IP Performance......................................................................1-2
1.3 Troubleshooting IP Performance.......................................................................................1-4

Operation Manual – IP Performance
H3C S9500 Series Routing Switches Chapter 1 IP Performance Configuration
1-1
Chapter 1 IP Performance Configuration
When configuring IP performance, go to these sections for information you are
interested in:
zConfiguring IP Performance
zDisplaying and Maintaining IP Performance
zTroubleshooting IP Performance
1.1 Configuring IP Performance
IP performance configuration includes:
zConfiguring TCP Attributes
zConfiguring the Switch Whether to Send a Time Exceeded ICMP Packet
1.1.1 Configuring TCP Attributes
TCP attributes include:
zsynwait timer: When sending the syn packets, TCP starts the synwait timer. If
response packets are not received before synwait timeout, the TCP connection is
terminated. The timeout of synwait timer ranges from 2 to 600 seconds and it is 75
seconds by default.
zfinwait timer: When the TCP connection state turns from FIN_WAIT_1 to
FIN_WAIT_2, finwait timer is started. If FIN packets are not received before finwait
timer timeout, the TCP connection is terminated. The timeout of finwait timer
ranges from 76 to 3600 seconds and it is 675 seconds by default.
zThe receiving/sending buffer size of the connection-oriented socket is in the range
from 1 to 32 KB and is 8 KB by default.
Perform the following configuration in system view to configure TCP attributes:
To do… Use the command…
Configure timeout time for the synwait
timer in TCP tcp timer syn-timeout time-value
Restore the default timeout time of the
synwait timer undo tcp timer syn-timeout
Configure timeout time for the
FIN_WAIT_2 timer in TCP tcp timer fin-timeout time-value
Restore the default timeout time of the
FIN_WAIT_2 timer undo tcp timer fin-timeout
Configure the socket receiving/sending
buffer size of TCP tcp window window-size

Operation Manual – IP Performance
H3C S9500 Series Routing Switches Chapter 1 IP Performance Configuration
1-2
To do… Use the command…
Restore the socket receiving/sending
buffer size of TCP to default value undo tcp window
1.1.2 Configuring the Switch Whether to Send a Time Exceeded ICMP Packet
The switch will return a destination unreachable packet to the sender when receiving a
packet whose TTL is "1”. But if an attacker continuously sends IP packets whoseTTL is
“1”, the switch will reply to this attacker with a destination unreachable packet
ceaselessly. As a result, the CPU of the switch is attacked.
When the switch receives IP packets whose TTL is “1”, if the switch sends a “time
exceeded" ICMP error packet, instead of with a destination unreachable packet to the
network management system, such an attack can be avoided.
Follow these steps to configure the switch whether to send a destination unreachable
packet:
To do… Use the command… Remarks
Enter system view system-view —
Configure the switch to send a
“time exceeded” ICMP error
packet to the IP packet sender
when the switch receives a
packet whose TTL is “1”
ip icmp-time-exceed
enable
By default, the switch
sends a "time
exceeded” ICMP error
packet to the network
management system.
Configure the switch to return a
destination unreachable packet
to the sender when the switch
receives a packet whose TTL is
“1”
undo ip
icmp-time-exceed
enable —
1.2 Displaying and Maintaining IP Performance
Displaying IP performance:
To do… Use the command… Remarks
Display the states of all the TCP
connections display tcp status
Display TCP connection statistics data display tcp statistics
Display UDP statistics information display udp statistics
Display IP statistics information display ip statistics
Available in
any view

Operation Manual – IP Performance
H3C S9500 Series Routing Switches Chapter 1 IP Performance Configuration
1-3
To do… Use the command… Remarks
Display ICMP statistics information display icmp statistics
Display the current socket information
of the system
display ip socket
[socktype sock-type ]
[task-id socket-id ]
Display the summary of the
Forwarding Information Base (FIB) display fib [ all ]
Display the FIB entries matching the
specified destination IP address
display fib [ all ]
[ip-address [ mask |
mask-length ] [ longer ] ]
Display the FIB entries matching the
specified destination IP address range
display fib [ all ]
ip-address1 {mask1 |
mask-length1 }
ip-address2 {mask2 |
mask-length2 }
Display the FIB entries permitted by a
specific ACL display fib [ all ]acl { number | name }
Display the FIB entries in the buffer
which begin with, include or exclude
the specified character string
display fib [ all ]|
{ { begin | include |
exclude } text }
Display the FIB entries permitted by a
specific prefix list display fib [ all ]
ip-prefix listname
Display the total number of the FIB
entries display fib [ all ]
statistics
Available in
any view
Debuging IP performance
To do… Use the command… Remarks
Reset IP statistics information reset ip statistics
Reset TCP statistics information reset tcp statistics
Reset UDP statistics information reset udp statistics
Available in
user view
Enable the debugging of IP packets debugging ip packet [ acl
acl-number ] Available in user view

Operation Manual – IP Performance
H3C S9500 Series Routing Switches Chapter 1 IP Performance Configuration
1-4
To do… Use the command… Remarks
Disable the debugging of IP
packets undo debugging ip packet
Enable the debugging of ICMP
packets debugging ip icmp
Disable the debugging of ICMP
packets undo debugging ip icmp
Enable the debugging of UDP
connections debugging udp packet [task-id socket-id ]
Disable the debugging of UDP
connections undo debugging udp packet [task-id socket-id ]
Enable the debugging of TCP
connections debugging tcp packet [task-id socket-id ]
Disable the debugging of TCP
connections undo debugging tcp packet [task-id socket-id ]
Enable the debugging of TCP
events debugging tcp event [task-id socket-id ]
Disable the debugging of TCP
events undo debugging tcp event [task-id socket-id ]
Enable the debugging of the MD5
authentication debugging tcp md5
Disable the debugging of the MD5
authentication undo debugging md5
Available in
user view
1.3 Troubleshooting IP Performance
Fault: IP layer protocol works normally but TCP and UDP cannot work normally.
Troubleshoot: In the event of such a fault, you can enable the corresponding debugging
information output to view the debugging information.
zUse the display command to view the running information of IP performance and
make sure that the PCs used by the user is running normally.
zUse the terminal debugging command to output the debugging information to the
console.
zUse the debugging udp packet command to enable the UDP debugging to trace
the UDP packet.
The following are the UDP packet formats:
UDP output packet:
Source IP address:202.38.160.1
Source port:1024
Destination IP Address 202.38.160.1

Operation Manual – IP Performance
H3C S9500 Series Routing Switches Chapter 1 IP Performance Configuration
1-5
Destination port: 4296
task = ROUT(15)
socketid = 6,
src = 192.168.1.1:520,
dst = 255.255.255.255:520,
datalen = 24
zUse the debugging tcp packet command to enable the TCP debugging to trace
the TCP packets.
Operations include:
<H3C> terminal debugging
<H3C> debugging tcp packet
Then the TCP packets received or sent can be checked in real time. Specific packet
formats include:
TCP output packet:
Source IP address:202.38.160.1
Source port:1024
Destination IP Address 202.38.160.1
Destination port: 4296
Sequence number :4195089
Ack number: 0
Flag :SYN
Packet length :60
Data offset: 10
task = ROUT(15)
socketid = 5
state = Established
src = 172.16.1.2
Source port:1025
dst = 172.16.1.1
Destination port: 4296
seq = 1921836502
ack = 4192768493
flag = ACK
window = 16079