H3C S3100-52P User manual

Operation Manual – QoS
H3C S3100-52P Ethernet Switch Table of Contents
i
Table of Contents
Chapter 1 QoS Configuration.......................................................................................................1-1
1.1 Overview............................................................................................................................1-1
1.1.1 Traffic ......................................................................................................................1-1
1.1.2 Traffic Classification................................................................................................ 1-1
1.1.3 Precedence.............................................................................................................1-1
1.1.4 Priority of Protocol Packets.....................................................................................1-5
1.1.5 Port Rate Limit.........................................................................................................1-5
1.1.6 Queue Scheduling Configuration Synchronization on Aggregated Ports............... 1-5
1.1.7 Queue Scheduling...................................................................................................1-6
1.2 QoS Supported by S3100-52P..........................................................................................1-7
1.3 Configuring the Mapping between 802.1p Priority and Queues........................................1-8
1.4 Setting to Use the Port Priority or Packet Priority..............................................................1-9
1.5 Setting the Precedence of Protocol Packet.....................................................................1-10
1.5.1 Configuration Prerequisites...................................................................................1-10
1.5.2 Configuration Procedure.......................................................................................1-10
1.5.3 Configuration Example.......................................................................................... 1-11
1.6 Configuring Port Rate Limit..............................................................................................1-11
1.6.1 Configuration Prerequisites...................................................................................1-11
1.6.2 Configuration Procedure.......................................................................................1-11
1.6.3 Configuration Example.......................................................................................... 1-12
1.7 Configuring Queue-Scheduling........................................................................................ 1-12
1.7.1 Configuration Prerequisites...................................................................................1-12
1.7.2 Configuration Procedure.......................................................................................1-13
1.7.3 Configuration Example.......................................................................................... 1-14
1.8 Displaying QOS Configuration.........................................................................................1-15

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Chapter 1 QoS Configuration
1.1 Overview
QoS (Quality of Service) is a concept generally existing in occasions with service
supply and demand. It evaluates the ability to meet the need of the customers in
service. Generally, the evaluation is not to grade precisely. Its purpose is to analyze the
conditions where the service is the best and the conditions where the service still needs
improvement and then to make improvements in the specified aspects.
In an internet, QoS evaluates the ability of the network to deliver packets. The
evaluation on QoS can be based on different aspects because the network provides
various services. Generally speaking, QoS is the evaluation on the service ability to
support the core requirements such as delay, jitter, and packet loss ratio in the packet
delivery.
1.1.1 Traffic
Traffic means service traffic; that is, all the packets passing the switch.
1.1.2 Traffic Classification
Traffic classification means identifying packets that conform to certain characteristics
according to certain rules.
Aclassification rule is a filter rule configured to meet your management requirements. It
can be very simple. For example, you can use a classification rule to identify traffic with
different priorities according to the ToS field in the IP packet header. It can be very
complicated too. For example, you can use a classification rule to identify the packets
according to the combination of link layer (Layer 2), network layer (Layer 3), and
transport layer (Layer 4) information including MAC addresses, IP protocols, source
addresses, destination addresses, port numbers of applications, and so on.
Classification is generally based on the information in the packet header and rarely
based on the packet contents.
1.1.3 Precedence
1) IP precedence, ToS precedence, and DSCP precedence

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Figure 1-1 DS field and TOS byte
The TOS field in an IP header contains eight bits:
zThe first three bits indicate IP precedence in the range of 0 to 7.
zBit 3 to bit 6 indicate ToS precedence in the range of 0 to 15.
zRFC2474 re-defines the ToS field in the IP packet header, which is called the DS
field. The first six (bit 0 to bit 5) bits of the DS field indicate DSCP precedence in
the range of 0 to 63. The first three bits in DSCP precedence are class selector
codepoints, bit 4 and bit 5 indicate drop precedence, and bit 6 is zero indicating
that the device sets the service class with the DS model. The last two bits (bit 6
and bit 7) are reserved bits.
The precedence values of the IP packet indicate eight different service classes.
Table 1-1 Description on IP Precedence
IP Precedence (decimal) IP Precedence (binary) Description
0 000 routine
1 001 priority
2 010 immediate
3 011 flash
4 100 flash-override
5 101 critical
6 110 internet
7 111 network
The Diff-Serv network defines four traffic classes:
zExpedited Forwarding (EF) class: In this class, packets can be forwarded
regardless of link share of other traffic. The class is suitable for preferential
services with low delay, low packet loss ratio, low jitter, and assured bandwidth
(such as virtual leased line);
zAssured forwarding (AF) class: This class is further divided into four subclasses
(AF1/2/3/4) and a subclass is further divided into three drop priorities, so the AF

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service level can be segmented. The QoS rank of the AF class is lower than that of
the EF class;
zClass selector (CS) class: This class comes from the IP TOS field and includes
eight classes;
zBest Effort (BE) class: This class is a special class without any assurance in the
CS class. The AF class can be degraded to the BE class if it exceeds the limit.
Current IP network traffic belongs to this class by default.
Table 1-2 Description on DSCP values
DSCP value (decimal) DSCP value (binary) Description
46 101110 ef
10 001010 af11
12 001100 af12
14 001110 af13
18 010010 af21
20 010100 af22
22 010110 af23
26 011010 af31
28 011100 af32
30 011110 af33
34 100010 af41
36 100100 af42
38 100110 af43
8 001000 cs1
16 010000 cs2
24 011000 cs3
32 100000 cs4
40 101000 cs5
48 110000 cs6
56 111000 cs7
0 000000 default (be)
2) 802.1p priority
802.1p priority lies in Layer 2 packet headers and is applicable to occasions where the
Layer 3 packet header does not need analysis but QoS must be assured at Layer 2.

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Figure 1-2 An Ethernet frame with an 802.1Q tag header
As shown in the figure above, each host supporting 802.1Q protocol adds a 4-byte
802.1Q tag header after the source address of the former Ethernet frame header when
sending packets.
The 4-byte 802.1Q tag header contains a 2-byte Tag Protocol Identifier (TPID) whose
value is 8100 and a 2-byte Tag Control Information (TCI). TPID is a new class defined
by IEEE to indicate a packet with an 802.1Q tag. Figure 1-3 describes the detailed
contents of an 802.1Q tag header.
Figure 1-3 802.1Q tag headers
In the figure above, the 3-bit priority field in TCI is 802.1p priority in the range of 0 to 7.
These three bits specify the precedence of the frame. Eight classes of precedence are
used to determine which packet is sent preferentially when congestion occurs.
Table 1-3 Description on 802.1p priority
CoS (decimal) CoS (binary) Description
0 000 best-effort
1 001 background
2 010 spare
3 011 excellent-effort
4 100 controlled-load
5 101 video
6 110 voice
7 111 network-management
The precedence is called 802.1p priority because the related applications of this
precedence are defined in detail in the 802.1p specifications.

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1.1.4 Priority of Protocol Packets
Protocol packets carry their own priority. You can perform QoS actions on protocol
packets by setting their priorities.
1.1.5 Port Rate Limit
Port rate limit is port-based rate limit. It limits the total rate of outbound packets on a
port.
1.1.6 Queue Scheduling Configuration Synchronization on Aggregated
Ports
The feature of queue scheduling configuration synchronization on aggregated ports
makes the queue scheduling configuration synchronous on each port of an aggregation
group.
zSupporting the feature of queue scheduling configuration synchronization on the
ports in an aggregation group
When you modify or delete the queue scheduling mode in Ethernet port view, the
queue scheduling modes of all the ports in the aggregation group are modified or
deleted if this port belongs to an aggregation group; only the queue scheduling mode of
this port is modified or deleted if this port does not belong to any aggregation group.
zDynamic aggregation supported by queue scheduling modes on ports
If the queue scheduling configuration information of some LACP-enabled ports in up
state is the same, these ports can be aggregated into the same aggregation group.
zStatic aggregation or manual aggregation supported by queue scheduling modes
on ports
You can add a queue-scheduling-enabled port into a specific static or manual
aggregation group. This operation can be performed not only on the local device but
also across devices in an intelligent resilient framework (IRF).
zYou can use the copy command to copy the queue scheduling configuration of a
port.
Note:
For the introduction to the copy command, refer to the Basic Port Configuration Module
in this manual.

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1.1.7 Queue Scheduling
When the network is congested, the problem that many packets compete for resources
must be solved, usually through queue scheduling.
In the following section, strict priority (SP) queueing and weighted round robin (WRR)
queueing are introduced.
1) SP queueing
Packets sent via this
interface
high priority
Low priority
Classify
Packets sent
Sending queueDequeue
queue 7
queue 6
queue 5
queue 4
queue 3
queue 2
queue 1
queue 0
Packets sent via this
interface
high priority
Low priority
Classify
Packets sent
Sending queueDequeue
queue 7
Packets sent via this
interface Packets sent
Sending queueDequeue
queue 7
queue 6
queue 5
queue 4
queue 3
queue 2
queue 1
queue 0
Packets sent via this
interface
high priority
Low priority
Classify
Packets sent
Sending queueDequeue
queue 7
Packets sent via this
interface
high priority
Low priority
Classify
Packets sent
Sending queueDequeue
queue 7
queue 6
queue 5
queue 4
queue 3
queue 2
queue 1
queue 0
Packets sent via this
interface
high priority
Low priority
Classify
Packets sent
Sending queueDequeue
queue 7
Packets sent via this
interface Packets sent
Sending queueDequeue
queue 7
queue 6
queue 5
queue 4
queue 3
queue 2
queue 1
queue 0
Figure 1-4 Diagram for SP queueing
SP queue-scheduling algorithm is specially designed for critical service applications.
An important feature of critical services is that they demand preferential service in
congestion in order to reduce the response delay. Assume that there are eight output
queues on the port and the preferential queue classifies the eight output queues on the
port into eight classes, which are queue7, queue6, queue5, queue4, queue3, queue2,
queue1, and queue0. Their priorities decrease in order.
In queue scheduling, SP sends packets in the queue with higher priority strictly
following the priority order from high to low. When the queue with higher priority is
empty, packets in the queue with lower priority are sent. You can put critical service
packets into the queueswith higher priority and put non-criticalservice (such as e-mail)
packets into the queues with lower priority. In this case, critical service packets are sent
preferentially and non-critical service packets are sent when critical service groups are
not sent.
The disadvantage of SP queue is that: if there are packets in the queues with higher
priority for a long time in congestion, thepackets in the queueswith lower priority will be
“starved” because they are not served.
2) WRR queueing

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Figure 1-5 Diagram for WRR
WRR queue-scheduling algorithm schedules all the queues in turn and every queue
can be assured of a certain service time. Assume there are eight priority queues on a
port. WRR configures a weight value for each queue, which is w7, w6, w5, w4, w3, w2,
w1, and w0. The weight value indicates the proportion of obtaining resources. On a 100
M port, configure the weight value of WRR queue-scheduling algorithm to 50, 50, 30,
30, 10, 10, 10, and 10 (corresponding to w7, w6, w5, w4, w3, w2, w1, and w0 in order).
In this way, the queue with the lowest priority can get 5 Mbps bandwidth at least, and
the disadvantage of SP queue-scheduling that the packets in queues with lower priority
may not get service for a long time is avoided. Another advantage of WRR queue is that:
though the queues are scheduled in order, the service time for each queue is not fixed;
that is to say, if a queue is empty, the next queue will be scheduled. In this way, the
bandwidth resources are made full use.
1.2 QoS Supported by S3100-52P
Table 1-4 QoS functions supported by S3100-52P and related commands
QoS Specification Related command
Priority mapping Support only the mapping
between 802.1p priority and
local queues
qos
cos-local-precedence-map
Port priority Supported priority priority-level
priority trust
Queue
scheduling
Support SP and WRR
Support queue scheduling
configuration synchronization
on aggregated ports
queue-scheduler

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QoS Specification Related command
Set the priority of
protocol packets Supported protocol-priority
Set port rate limit Supported line-rate
1.3 Configuring the Mapping between 802.1p Priority and
Queues
The mapping between the local precedence and the outbound queue is one-to-one.
You can modify the mapping between the 802.1p priority and the outbound queue by
modifying the mapping between the 802.1p priority and the local precedence.
I. Configuration prerequisites
You have understood the mapping between the 802.1p priority and the local
precedence and the default mapping table.
II. Configuration procedure
Table 1-5 Configure the mapping table
Operation Command Description
Enter system view system-view —
Configure the
COS-to-local-precedence
mapping table
qos
cos-local-precedence-map
cos0-map-local-prec
cos1-map-local-prec
cos2-map-local-prec
cos3-map-local-prec
cos4-map-local-prec
cos5-map-local-prec
cos6-map-local-prec
cos7-map-local-prec
Optional
Display the mapping table display qos
cos-local-precedence-map
Optional
You can execute the
display command in
any view
III. Configuration example
zConfigure the following 802.1p priority-to-local precedence mappings: 0 to 2, 1 to
3, 2 to 4, 3 to 1, 4 to 7, 5 to 0, 6 to 5, and 7 to 6.
zDisplay the configuration results.
Configuration procedure:
<H3C> system-view

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System View: return to User View with Ctrl+Z.
[H3C] qos cos-local-precedence-map 2 3 4 1 7 0 5 6
[H3C] dis qos cos-local-precedence-map
cos-local-precedence-map:
cos(802.1p) : 0 1 2 3 4 5 6 7
--------------------------------------------------------------------------
local precedence(queue) : 2 3 4 1 7 0 5 6
1.4 Setting to Use the Port Priority or Packet Priority
By default, the switch replaces the 802.1p priority of the received packet with the
priority of the inbound interface, and then assigns local precedence to the packet
according to the priority. In this case, you can set the port priority.
In addition, you can specify the switch to use the packet priority.
I. Configuration prerequisites
zThe priority trust mode is specified
zThe port whose priority is to be configured is specified
zThe priority value of the specified port is specified
II. Configuration procedure
Table 1-6 Set to use the port priority
Operation Command Description
Enter system view system-view —
Enter Ethernet port
view interface interface-type
interface-number —
Set the port priority priority priority-level Optional
By default, the port
priority is 0
Table 1-7 Set to use the packet priority
Operation Command Description
Enter system view system-view —
Enter Ethernet port
view interface interface-type
interface-number —
Set the switch to use
the packet priority priority trust
Through this
configuration, the switch
uses the packet priority
instead of the port priority

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III. Configuration example
zSet to use the port priority and specify the priority of Ethernet1/0/1 to 7.
Configuration procedure:
<H3C> system-view
System View: return to User View with Ctrl+Z.
[H3C] interface Ethernet1/0/1
[H3C-Ethernet1/0/1] undo priority
[H3C-Ethernet1/0/1] priority 7
zSet the switch to use the 802.1p priority carried in the packet on Ethernet1/0/1.
Configuration procedure:
<H3C> system-view
System View: return to User View with Ctrl+Z.
[H3C] interface Ethernet1/0/1
[H3C-Ethernet1/0/1] priority trust
1.5 Setting the Precedence of Protocol Packet
The protocol packet carries its own precedence. You can modify the precedence of the
protocol packet by setting its precedence. And then you can match the precedence with
the corresponding QoS action to perform the corresponding QoS operation on the
protocol packet.
1.5.1 Configuration Prerequisites
zThe type of protocol whose precedence needs modification is specified
zThe precedence value after modification is specified
1.5.2 Configuration Procedure
Table 1-8 Set the precedence of the protocol packet
Operation Command Description
Enter system
view system-view —
Set the
precedence of the
protocol packet
protocol-priority
protocol-type
protocol-type
{ip-precedence
ip-precedence | dscp
dscp-value }
Required
You can modify the IP precedence
or DSCP precedence of the
protocol packet
Only the precedence of TELNET,
OSPF, SNMP, and ICMP protocol
packets is supported currently

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Operation Command Description
Display the
precedence of the
protocol packet
display
protocol-priority
Optional
You can execute the display
command in any view
1.5.3 Configuration Example
zSet the IP precedence of ICMP protocol packets to 3.
zDisplay the configuration results.
Configuration procedure:
<H3C> system-view
System View: return to User View with Ctrl+Z.
[H3C] protocol-priority protocol-type icmp ip-precedence 3
[H3C] display protocol-priority
Protocol: icmp
IP-Precedence: flash(3)
1.6 Configuring Port Rate Limit
1.6.1 Configuration Prerequisites
zThe ports on which rate limit is to be performed is specified
zThe target rate is specified
zThe direction of rate limit is specified
1.6.2 Configuration Procedure
Table 1-9 Configure port rate limit
Operation Command Description
Enter system
view system-view —
Enter Ethernet
port view interface interface-type
interface-number —

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Operation Command Description
Configure
port-based rate
limit
line-rate {inbound |
outbound } target-rate
Required
ztarget-rate: Total rate to limit
packet sending and receiving
on the port, in Kbps. The
granularity of rate limit is 64
Kbps. If the number you input is
in the range of N*64 to
(N+1)*64 (N is a natural
number), the switch will set the
value to (N+1)*64 Kbps
automatically
zThe rate range of 100 M
Ethernet ports is from 64 to
99,968
zThe rate range of Gigabit
Ethernet ports is in from 64 to
1,000,000
1.6.3 Configuration Example
zSet rate limit in the outbound direction of Ethernet1/0/1 on the switch
zThe limit rate is 1 Mbps (1,024 Kbps)
Configuration procedure:
<H3C> system-view
System View: return to User View with Ctrl+Z.
[H3C] interface Ethernet1/0/1
[H3C-Ethernet1/0/1] line-rate outbound 1024
1.7 Configuring Queue-Scheduling
Refer to section 1.1.7 "Queue Scheduling" for the introduction to queue scheduling.
1.7.1 Configuration Prerequisites
The queue-scheduling algorithm is specified: which queues adopt the WRR
queue-scheduling algorithm, and which queues adopt the SP queue-scheduling
algorithm.

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1.7.2 Configuration Procedure
Table 1-10 Configure queue scheduling in system view
Operation Command Description
Enter system view system-view —
Configure the queue
scheduling mode
queue-scheduler
{strict-priority | wrr
queue0-weight
queue1-weight
queue2-weight
queue3-weight
queue4-weight
queue5-weight
queue6-weight
queue7-weight }
Required
In WRR mode, if the weight
value of one or more
queues is set to 0, SP
algorithm is used for this or
these queues
By default, all the outbound
queues on the port adopt
the WRR queue scheduling
algorithm and their default
weight values are
1:2:3:4:5:9:13:15.
Display the
queue-scheduling
mode and related
parameters on the
switch
display queue-scheduler
Optional
You can execute the
display command in any
view.
Table 1-11 Configure queue scheduling in Ethernet port view
Operation Command Description
Enter system view system-view —
Enter Ethernet
port view interface interface-type
interface-number —
Configure the
queue scheduling
mode
queue-scheduler wrr
queue0-weight queue1-weight
queue2-weight queue3-weight
queue4-weight queue5-weight
queue6-weight queue7-weight
Required
In WRR mode, if the weight
value of one or more
queues is set to 0, SP
algorithm is used for this or
these queues
By default, all the outbound
queues on the port adopt
the WRR queue scheduling
algorithm and their default
weight values are
1:2:3:4:5:9:13:15.

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Note:
zThe queue scheduling algorithm defined by executing the queue-scheduler
command in system view takes effect on all ports of the switch. The queue
scheduling algorithm defined by executing the queue-scheduler command in
Ethernet port view takes effect on the current port only. If the weight values of the
queues in the WRR queue scheduling algorithm defined globally cannot satisfy the
requirement of a port, you can modify the weight values of the queues in Ethernet
port view of this port. A new queue scheduling algorithm on this port will overwrite
the globally defined queue weight value. You cannot use the display
queue-scheduler command to display the queue weight defined in Ethernet port
view.
zIf you have configured link aggregation groups, the queue scheduling algorithm
defined on a port in an aggregation group will be synchronized to other ports in the
aggregation group automatically.
1.7.3 Configuration Example
zThe switch adopts the WRR queue scheduling algorithm, and the weight values of
outbound queues are 2, 2, 3, 3, 4, 4, 5, and 5, respectively;
zDisable the applied queue scheduling mode. By default, all outbound queues on
the port adopts the WRR queue scheduling algorithm and their default weight
values are 1:2:3:4:5:9:13:15;
zQuery the configuration information.
Configuration procedure:
<H3C> system-view
System View: return to User View with Ctrl+Z.
[H3C] queue-scheduler wrr 2 2 3 3 4 4 5 5
[H3C]display queue-scheduler
Queue scheduling mode: weighted round robin
weight of queue 0: 2
weight of queue 1: 2
weight of queue 2: 3
weight of queue 3: 3
weight of queue 4: 4
weight of queue 5: 4
weight of queue 6: 5
weight of queue 7: 5
[H3C] undo queue-scheduler
[H3C] display queue-scheduler
weight of queue 0: 1

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weight of queue 1: 2
weight of queue 2: 3
weight of queue 3: 4
weight of queue 4: 5
weight of queue 5: 9
weight of queue 6: 13
weight of queue 7: 15
1.8 Displaying QOS Configuration
After finishing the configurations mentioned above, you can execute the display
command in any view to check the running state of the QoS profile after the
configuration. You can verify the effect of the configuration by checking the information
on display.
Table 1-12 Display the QoS configuration
Operation Command Description
Display the
configuration of protocol
packet precedence display protocol-priority
Display the Mapping
between 802.1p Priority
and Queues
display qos
cos-local-precedence-map
Display all QoS
configurations on a port
or all ports
display qos-interface
{interface-type interface-number |
unit-id } all
Display the rate limit
configuration
display qos-interface
{ interface-type interface-number |
unit-id } line-rate
Display the global
queue scheduling
configuration display queue-scheduler
You can
execute the
display
command in any
view