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User Guide for FS models including: S3150-8T2FP, S3260-8T2FP, S3260-16T4FP, S3400-24T4FP, S3400-48T4SP, S3150-8T2FP PoE Series Switches, S3150-8T2FP, PoE Series Switches, Switches
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DocumentDocumentPoE+ Series Switches QoS Configuration Guide
Models: S3150-8T2FP S3260-8T2FP S3260-16T4FP S3400-24T4FP S3400-48T4SP
POE+ SERIES SWITCHES QOS CONFIGURATION GUIDE
Contents
1. QoS Configuration.................................................................................................................................................................................. 1 1.1 QoS Overview.......................................................................................................................................................................................1 1.1.1 QoS Concept............................................................................................................................................................................... 1 1.1.2 Terminal-To-Terminal QoS Model.............................................................................................................................................. 1 1.1.3 Queue Algorithm of QoS............................................................................................................................................................ 1 1.1.4 Weighted Random Early Detection............................................................................................................................................2 1.2 QoS Configuration Task List.................................................................................................................................................................2 1.3 QoS Configuration Tasks......................................................................................................................................................................3 1.3.1 Setting the Global CoS Priority Queue....................................................................................................................................... 3 1.3.2 Setting the Bandwidth of the CoS Priority Queue..................................................................................................................... 3 1.3.3 Setting the Schedule Policy of the CoS Priority Queue............................................................................................................. 4 1.3.4 Setting the Default CoS Value of a Port......................................................................................................................................4 1.3.5 Setting the CoS Priority Queue of a Port.................................................................................................................................... 4 1.3.6 Setting the CoS Priority Queue of a Port.................................................................................................................................... 5 1.3.7 Setting the Schedule Policy of the CoS Priority Queue of the Port........................................................................................... 5 1.3.8 Setting the CoS Priority Queue Based on DSCP......................................................................................................................... 6 1.3.9 Establishing the QoS Policy Mapping........................................................................................................................................ 6 1.3.10 Setting the Description of the QoS Policy Mapping................................................................................................................ 6 1.3.11 Setting the Matchup Data Flow of the QoS Policy Mapping................................................................................................... 7 1.3.12 Setting the Actions of the Matchup Data Flow of the QoS Policy Mapping........................................................................... 7 1.3.13 Applying the QoS Policy on a Port........................................................................................................................................... 8 1.3.14 Applying QoS Policy Globally................................................................................................................................................... 8 1.3.15 Setting the Trust Mode.............................................................................................................................................................9 1.3.16 Displaying the QoS Policy Mapping Table............................................................................................................................... 9 1.4 QoS Configuration Example................................................................................................................................................................ 9 1.4.1 Example for Applying the QoS Policy on a Port......................................................................................................................... 9
POE+ SERIES SWITCHES QOS CONFIGURATION GUIDE
1. QoS Configuration
If you care to use your bandwidth sufficiently and your network resources efficiently, you must pay attention to QoS configuration.
1.1 QoS Overview
1.1.1 QoS Concept
In general, the switch works in best-effort served mode in which the switch treats all flows equally and tries its best to deliver all flows. Thus, if congestion occurs all flows have the same chance to be discarded. However in a real network different flows have different significances, and the QoS function of the switch can provide different services to different flows based on their own significances, in which the important flows will receive a better service.
As to classify the importance of flows, there are two main ways on the current network:
The tag in the 802.1Q frame header has two bytes and 3 bits are used to present the priority of the packet. There are 8
priorities, among which 0 means the lowest priority and 7 means the highest priority.
The DSCP field in IP header of the IP packet uses the bottom 6 bits in the TOS domain of the IP header.
In real network application the edge switch distributes different priorities to different flows based on their significance and then different services will be provided to different flows based on their priorities, which is the way to realize the terminal-to-terminal QoS. Additionally, you can also configure a switch in a network, enabling the switch to process those packets with specific attributes (according to the MAC layer or the L3 information of packets) specially. This kind of behaviors are called as the one-leap behaviors.
The QoS function of the switch optimizes the usage of limited network bandwidth so that the entire performance of the network is greatly improved.
1.1.2 Terminal-To-Terminal QoS Model
The service model describes a group of terminal-to-terminal QoS abilities, that is, the abilities for a network to transmit specific network communication services from one terminal to another terminal. The QoS software supports two kinds of service models: Best-Effort service and Differentiated service.
1)
Best-effort service
The best-effort service is a singular service model. In this service model, an application can send any amount of data at any necessary time without application of permits or aforehand network notification. As to the best-effort service, if allowed, the network can transmit data without any guarantee of reliability, delay or throughput. The QoS of the switch on which the best-effort service is realized is in nature this kind of service, that is, first come and first served (FCFS).
2)
Differentiated Service
As to the differentiated service, if a special service is to be transmitted in a network, each packet should be specified with a corresponding QoS tag. This designation can be embodied in different modes, such as, use IP priority status setting in IP data packet. The switch uses this QoS rule to conduct classification and complete the intelligent queuing. The QoS of the switch provides Strict Priority (SP), Weighted Round Robin (WRR), Deficit Round Robin (DRR) and First-Come-First-Served (FCFS).
1.1.3 Queue Algorithm of QoS
Each queue algorithm is the important basis to realize QoS. The QoS of the switch provides the following algorithms: Strict Priority (SP), Weighted Round Robin (WRR), Weighted Fair Queuing (WFQ) and First-Come-First-Served (FCFS).
1)
Strict Priority
This algorithm means to first provide service to the flow with the highest priority and after the highest-priority flow comes the service for the next-to-highest flow. This algorithm provides a comparatively good service to those flows with relatively high priority, but its shortage is also explicit that the flows with low priority cannot get service and wait to die.
2)
Weighted Round Robin
Weighted Round Robin (WRR) is an effective solution to the defect of Strict Priority (SP), in which the low-priority queues always die out. WRR is an algorithm that brings each priority queue a certain bandwidth and provides service to each priority queue according to the order from high priority to low priority. After the queue with highest priority has used up all its bandwidth, the system automatically provides service to those queues with next highest priority.
3)
Weighted Fair Queuing
Weighted Fair Queuing (WFQ) classifies the packet according to the priority of the traffic. It sets the egress bandwidth based on the weight of each traffic. The bigger the weight, the greater the bandwidth. Thus, it gurantees the fairness of priority services and
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POE+ SERIES SWITCHES QOS CONFIGURATION GUIDE embodies the weight of different priority services.
4)
First come first served
The First-Come-First-Served queue algorithm, which is shortened as FCFS, provides service to those packets according to their sequence of arriving at a switch, and the packet that first arrives at the switch will be served first.
1.1.4 Weighted Random Early Detection
Congestion avoidance and traditional packet loss mechanism
Excessive congestion may inflict damage on network resources, so network congestion should be resolved through some measures. Congestion avoidance is a sort of flow control method of positively dropping packets and regulating network flows to solve network overload via network resource monitoring. Congestion prevention is a mechanism of traffic control, which monitors the network resource and drop the packet autonomously when the network is in overload. The traditional way of resolving network congestion is to drop all incoming packets when the queue length reaches its threshold. But for TCP packets, heavy packet loss may cause TCP timeout and lead to slow TCP startup and congestion avoidance, which is called as TCP global synchronization.
WRED
The SRED algorithm is adopted to prevent TCP global synchronization. SRED helps users to set the queue threshold. When the queue length is less than the configured threshold, the packets will not be dropped; otherwise, the packets will be dropped randomly. Because SRED drops packets randomly, it is avoided for multiple TCP connections to slow down the transmission speed at the same time, which is the reason why TCP global synchronization is avoided. SRED enables other TCP connections to maintain a relatively high transmission speed when the packets of a certain TCP connection begin to be dropped and their transmission speed is slowed down. No matter what time it is, there are always some TCP connections to transmit packets with a high speed, which ensures effective bandwidth usability.
SRED cooperation is conducted when packets enter the outgoing queue and are checked for their size and packets in different ranges get different treatments. The key parameters include Start, Slope and Drop priority. Parameters of each queue can be configured according to the requirement.
Pa ck ag e lo 100%ss ra te
0%
start
Average queue length
When the queue length is less than start, packets will not be dropped.
When the queue length is bigger than start, the incoming packets begin to be dropped randomly. The longer the queue, the
higher the drop rate.
The drop rate increases linearly with the queue length.
1.2 QoS Configuration Task List
In general, ONU will try its best to deliver each packet and when congestion occurs all packets have the same chance to be discarded. However, in reality different packets have different importance and the comparatively important packets should get the comparatively good service. QoS is a mechanism to provide different priority services to packets with different importance, in which the network can have its better performance and be used efficiently.
This chapter presents how to set QoS on ONU.
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POE+ SERIES SWITCHES QOS CONFIGURATION GUIDE
The following are QoS configuration tasks: Setting the GlobalCoSPriority Queue Setting the Bandwidth of theCoSPriority Queue Setting the Schedule Policy of theCoSPriority Queue To setthe minimum bandwidth or the maximum bandwidth of the port cos queue, run the previous commands. Setting Weighted SRED (Simple Random Early Detection) Setting the DefaultCoSValue of a Port Setting theCoSPriority Queue of a Port Setting the CoS Priority Queue based on dscp Establishing the QoS Policy Mapping Setting the Description of the QoS Policy Mapping Setting the Matchup Data Flow of the QoS Policy Mapping Setting the Actions of the Matchup Data Flow of the QoS Policy Mapping Applying the QoS Policy on a Port Displaying the QoS Policy Mapping Table Setting the trust mode.
1.3 QoS Configuration Tasks
1.3.1 Setting the Global CoS Priority Queue The task to set the QoS priority queue is to map 8 CoS values, which are defined by IEEE802.1p, to the priority queues in a switch. This series of switch has 8 priority queues. According to different queues, the switch will take different schedule policies to realize QoS. If a CoSpriority queue is set in global mode, the mapping of CoS priority queue on all ports will be affected. When priority queues are set on a L2 port, the priority queues can only work on this L2 port. Enter the following privileged mode and run the following commands as follows to set CoSpriority queue.
Command config
[no] cos map quid cos1..cosn exit
Purpose
Enters the global configuration mode.
Sets the CoS priority queue. quid stands for the ID of a CoS priority queue. cos1...cosn stands for the IEEE802.1p-defined CoS value.
Goes back to the EXEC mode.
write
Saves the settings.
1.3.2 Setting the Bandwidth of the CoS Priority Queue The bandwidth of priority queue means the bandwidth distribution ratio of each priority queue, which is set when the schedule policy of the CoS priority queue is set to wrr or wfq. This series of switches has 8 priority queues in total. If this command is run, the bandwidth of all priority queues on all interfaces are affected. This command validates only when the queue schedule mode is set to WRR/WFQ. This command decides the bandwidth weight value of the CoS priority queue when the WRR/WFQ schedule policy is used. Run the following commands as follows to set the bandwidth of theCoSpriority queue.
Command config
[no] scheduler weight bandwidth weight1...weightn exit
Purpose
Enters the global configuration mode.
Sets the bandwidth of the CoS priority queue.. weight1...weightn stand for the weights of 8 CoS priority queues of
WRR/DRR.
Goes back to the EXEC mode.
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POE+ SERIES SWITCHES QOS CONFIGURATION GUIDE write
Saves the settings.
1.3.3 Setting the Schedule Policy of the CoS Priority Queue
A switch has many output queues on each of its port. This series of switches has 8 priority queues. The output queues can adopt the following four schedule modes:
SP (Sheer Priority): In this algorithm, only when the high-priority queue is null can the packets in the low-priority queue be
forwarded, and if there are packets in the high-priority queue these packets will be unconditionally forwarded.
WRR (Weighted Round Robin) is an algorithm that brings each priority queue a certain bandwidth and provides service to
each priority queue according to the order from high priority to low priority.
WFQ (Weighted Fair Queuing) is an algorithm that brings each priority queue a certain bandwidth according to the priority
of the flow.
The First-Come-First-Served queue algorithm, which is shortened as FCFS, provides service to those packets according to
their sequence of arriving at a switch, and the packet that first arrives at the switch will be served first.
Enter the following EXEC configuration mode and set the schedule policy of CoSpriority queue.
Command config
[no] scheduler policy {sp | wrr|wfq|fcfs}
exit write
Purpose Enters the global configuration mode. Sets the schedule policy of the CoS priority queue. sp means to use the SP schedule policy. wrr means to use the WRR schedule policy. wfq means to use the WFQ schedule policy. fcfs means to use the FCFS schedule policy.
Goes back to the EXEC mode.
Saves the settings.
1.3.4 Setting the Default CoS Value of a Port If the port of a switch receives a data frame without tag, the switch will add a default CoSpriority to it. Setting the default cos value of a port is to set the untagged default CoSvalue, which is received by the port, to a designated value. Enter the EXEC mode and run the following commands to set the default CoSvalue of a port.
Command config
Purpose Enters the global configuration mode.
interface g0/1
Enters the to-be-configured port.
[no] cos default cos
Sets the CoS value of the received untagged frames. cos stands for the corresponding CoS value.
exit
Goes back to the global configuration mode.
exit
Goes back to the EXEC mode.
write
Saves the settings.
1.3.5 Setting the CoS Priority Queue of a Port
When a priority queue is set on a L2 port, the priority queue will be used by the L2 port; otherwise, you should conduct the configuration of a global CoSpriority queue.
Enter the privilege mode and run the following commands to set the default CoSvalue of a port:
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POE+ SERIES SWITCHES QOS CONFIGURATION GUIDE
Command config
interface g0/1
Purpose Enters the global configuration mode.
Enters the to-be-configured port.
[no] cos map quid cos1..cosn
Sets the CoS priority queue. quid stands for the ID of a CoS priority queue. cos1...cosn stands for the IEEE802.1p-defined CoS value.
exit
Goes back to the global configuration mode.
exit
Goes back to the EXEC mode.
1.3.6 Setting the CoS Priority Queue of a Port
When a bandwidth of the priority queue is set on a L2 port, the bandwidth of the priority queue will be used by the L2 port; otherwise, you should conduct the configuration of a global CoSpriority queue.
Run the following commands as follows to set the bandwidth of the CoSpriority queue.
Command
Purpose
config
Enters the global configuration mode.
interface g0/1
Enters the to-be-configured port.
[no] scheduler weight bandwidth weight1...weightn
Sets the bandwidth of the CoS priority queue.. weight1...weightn stand for the weights of 8 CoS priority queues of
WRR/DRR.
exit exit write
Goes back to the global configuration mode. Goes back to the EXEC mode. Saves the settings.
1.3.7 Setting the Schedule Policy of the CoS Priority Queue of the Port When a bandwidth of the priority queue is set on a L2 port, the schedule policy of the priority queue will be used by the L2 port; otherwise, you should conduct the configuration of a global CoSschedule policy. Enter the following EXEC configuration mode and set the schedule policy of CoSpriority queue.
Command config
Purpose Enters the global configuration mode.
interface g0/1 [no] scheduler policy {sp | wrr|wfq}
Enters the to-be-configured port. Sets the schedule policy of the CoS priority queue.
sp means to use the SP schedule policy. wrr means to use the WRR schedule policy. wfq means to use the WFQ schedule policy.
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POE+ SERIES SWITCHES QOS CONFIGURATION GUIDE exit exit write
Goes back to the global configuration mode. Goes back to the EXEC mode. Saves the settings.
1.3.8 Setting the CoS Priority Queue Based on DSCP Based on the DSCP value, the COS queue is mapped again, the DSCP value is modified and the congestion bit is changed. Enter the EXEC mode and run the following commands to set the defaultCoSvalue of a port.
Command
Purpose
config
Enters the global configuration mode.
[no] dscp map word {cos cos-value}
Word stands for the DSCP range table. Cos-value means to set the mapped priority CoS.
exit
Goes back to the global configuration mode.
exit
Goes back to the EXEC mode.
1.3.9 Establishing the QoS Policy Mapping Flow classification means to identify a class of packets with certain attributes by applying a certain regulation and take designated actions towards to these packets. Do as follows to set up a QoS policy. Enter the EXEC mode and then run the following commands to establish a new QoS policy mapping.
Command config
Purpose Enters the global configuration mode.
[no]policy-map name
Enters the configuration mode of the QoS policy map. Name stands for the name of the policy.
exit
Exits from the global configuration mode.
exit
Goes back to the EXEC mode.
1.3.10 Setting the Description of the QoS Policy Mapping Enter the EXEC mode and run the following commands to set the description of a QoS policy mapping. This setting will replace the previous settings.
Command config
Purpose Enters the global configuration mode.
[no] policy-map name
Entersthe configuration modeof the QoS policy map. namestands for the name of the policy.
description description-text
Sets the description of the QoS policy. description-text stands for the text to describe the policy.
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POE+ SERIES SWITCHES QOS CONFIGURATION GUIDE exit exit
Goes back to the global configuration mode. Goes back to the EXEC mode.
1.3.11 Setting the Matchup Data Flow of the QoS Policy Mapping The classification rule of the QoS data flow means the filtration rule configured by the administrator according to management requirements. It can be simple, for example, flows with different priorities can be identified by the ToS field of the IP packet's header, or complicated, for example, the packets can be classified according to the related information about the comprehensive link layer, the network layer and the transmission layer, such as the MAC address, the source address of IP, the destination address or the port ID of the application. In general, the classification standard is limited in the header of an encapsulated packet. It is rare to use the content of a packet as the classification standard. Enter the policy configuration mode, set the matchup data flow of policy and replace the previous settings with this data flow according to the following steps:
Command
Purpose
config
Enters the global configuration mode.
[no] policy-map name
Enters the configuration mode of the QoS policy map. name stands for the name of the policy.
description description-text
Sets the description of the QoS policy. description-text stands for the text to describe the policy.
Matches up with any packet.
Configures the matching COS value; the valid range is 0 to 7.
Configures the matching interior tag COS value; the valid range is 0
to 7.
vlanid stands for the matched VLAN, which ranges from 1 to 4094.
ivlanid stands for the matched inner VLAN, which ranges from 1 to
4094.
classify {any | cos cos | icos icos | vlan vlanid | ivlan ivlanid | ethernet-type ethernet-type | precedence precedence-value | dscp dscp-value | tos tos-value | diffserv diffserv-value | ip ip-
access-list | ipv6 ipv6-access-list | mac mac-access-list} no classify {cos | icos | vlan | ivlan | ethernet-type | precedence |
dscp | tos | diffserv | ip | ipv6 | mac}
ethernet-type stands for the matched packet type, which is between 0x0600 and 0xFFFF.
precedence-value stands for the priority field in tos of IP packet (5-7 of tos), which ranges from 0 to 7.
dscp-value stands for the dscp field in tos of IP packet (2-7 of tos), which ranges from 0 to 63.
tos-value stands for latency, throughput, reliability and cost fields in
tos of IP packet (1-4 of tos), which ranges from 0 to 15.
diffserv-value stands for the entire tos field: 8, 0-255.
Ip-access-list stands for the name of the matched IP access list. The
name has 1 to 20 characters.
Ipv6-access-list stands for the name of the matched IP access list. The
name has 1 to 20 characters.
Configures the name of the matched MAC access list. The name has
1 to 20 characters.
exit
Goes back to the global configuration mode.
exit
Goes back to the EXEC mode.
1.3.12 Setting the Actions of the Matchup Data Flow of the QoS Policy Mapping The actions to define the data flow mean to take corresponding actions to a data flow with compliance of the filtration rule, which include bandwidth limit, drop, update, etc. Enter the EXEC mode and run the following commands to set the action of a policy, matching up the data flow. The action will replace the previous settings.
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POE+ SERIES SWITCHES QOS CONFIGURATION GUIDE
Command
Purpose
config
Enters the global configuration mode.
[no] policy-map name
Enters the configuration mode of the QoS policy map. name stands for the name of the policy.
Max-band stands for the occupied maximum bandwidth: 1-65535.
Unit: 16Kbps
Configures policing.
Configures policing.
Sets the matched COS field to cos-value 0-7.
Action {bandwidth max-band |cos cos | drop | dscp dscp-value
drop means to drop the matched packets.
| precedence precedence-value | forward | icos icos | ivlanID
Sets the matched DSCP field to dscp-value 0~63.
{add addivlanid | ivlanid} | monitor session-value | quequ precedence-value stands for the priority field in tos of IP packet (5-7
quequ-value | redirect interface-id | stat-packet | stat-byte |
of tos), which ranges from 0 to 7.
vlanID {add addvlanid | vlanid} | copy-to-cpu}
forward Conducts no operations to the matched packets.
icos Sets the icos filed of matched flow, 0~7;
no action {bandwidth | cos | drop | dscp | precedence | forward ivlan ID Sets replacing or adding interior vlanid; the range is 1 to
| | icos | ivlanID | monitor | quequ | redirect | stat-packet | stat-
4094.
byte | vlanID | copy-to-cpu}
session-value Send the packets to monitor interface; the range is 1-4.
quequ-value Sets the queue mapping value 1-8.
Interface-id Redirects the egress port of the matched flow.
Stat-packet Calculates the number of packets.
Stat-byte Calculate the number of bytes.
vlan ID Sets replacing or adding exterior vlanid; the range is 1-4094.
copy-to-cpuSets forwarding the packet to CPU.
exit
Goes back to the global configuration mode.
exit
Goes back to the EXEC mode.
1.3.13 Applying the QoS Policy on a Port The QoS policy can be applied to a port; multiple QoS policies can be applied to the same port and the same QoS policy can also be applied to multiple ports. On the same port, the priorities of the policies which are earlier applied than those of the policies which are later applied. If a packet is set to have two policies and the actions are contradicted, the actions of the firstly matched policies. After a QoS policy is applied on a port, the switch adds a policy to this port by default to block other data flows, which are not allowed to pass through. When all policies on a port are deleted, the switch will automatically remove the default blockage policy from a port. Enter the following EXEC mode and run the following commands to apply the QoS policy.
Command config
Purpose Enters the global configuration mode.
interface g0/1
Enters the to-be-configured port.
[no] qos policy name ingress exit exit
Applies the QoS policy on a port. name stands for the name of QoS policy mapping. ingressingress means to exert an influence on the ingress.
Goes back to the global configuration mode. Goes back to the EXEC mode.
1.3.14 Applying QoS Policy Globally Enter EXEC mode and run the following commands to apply the QoS policy globally.
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POE+ SERIES SWITCHES QOS CONFIGURATION GUIDE
Command config
[no] qos policy name ingress exit
Purpose Enters the global configuration mode.
Applying the QoS Policy globally name stands for the name of QoS policy mapping. ingress means to exert an influence on the ingress.
Goes back to the EXEC mode.
1.3.15 Setting the Trust Mode
When configuring the trust mode under the global configuration mode, there are three options: cos, dscp or untrust. The data will be mapped to the queue in the option chosen above. If choosing the option: untrust, the priority of the packet will be mapped to the queque by default.
Configuring the trust mode in EXEC mode as follows:
Command config
[no] qos trust {cos | dscp | untrust} exit
Purpose Enters the global configuration mode. Configuring the trust mode in the global configuration mode. untrust means any mode is not trusted.
Goes back to the EXEC mode.
1.3.16 Displaying the QoS Policy Mapping Table You can run the show command to display all or some designated QoS policy maps. Run the following command in EXEC mode to display the QoS policy mapping table.
Command show policy-map [policy-map-name | interface | global]
Purpose Displays all or some designated QoS policy maps. policy-map-name stands for the name of QoS mapping table. Interface means to apply the QoS policy on a port;
Global means to apply QoS policy globally;
1.4 QoS Configuration Example
1.4.1 Example for Applying the QoS Policy on a Port
The following example shows how to configure a policy of dropping packets which meets IP access list on interface g0/2: ip access-list extended ipacl permit ip 192.168.20.2 255.255.255.255 192.168.20.210 255.255.255.255 policy-map pmap classify ip ipacl action drop interface g0/2 qos policy pmap ingress
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