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An AR router maintenance guide - FAQ (QoS)

Latest reply: Aug 30, 2017 06:35:53 3590 1 0 0 0

Hello, Community friends!

This post highlights an AR router maintenance guide - FAQ (QoS). Please see below to gain more knowledge on the topic.

2.16  QoS

2.16.1  What Is the Function of Interface Priorities?

The port priority command sets the interface priorities, that is, specifies the default priorities of incoming packets on the interface. AR series routers send packets to different queues based on the interface priority. By default, the AR interface does not trust packet priorities. Packets enter queues according to the interface priority.

If all packets enter queues according to the interface priority, all packets on an interface enter the same queue. Differentiated services cannot be provided. Using the trust command, you can specify the priority to be mapped for packets, that is, search for a priority mapping to the packet priority in the priority mapping table.
  • The AR100&AR120&AR150&AR160&AR200 series and AR1200 series send packets to different interface queues based on the mapped 802.1p priorities, and use the queue scheduling to provide services for packets with different priorities.

  • On AR2200 series,

    • From V200R001C00, the device sends packets to different interface queues based on the mapped 802.1p priorities, and use the queue scheduling to provide services for packets with different priorities.

    • From V200R003C00, the AR2204 or AR2220E sends packets to different interface queues based on the mapped 802.1p priorities, and use the queue scheduling to provide services for packets with different priorities. While the AR2201, AR2202, AR2220, AR2240C and AR2240 send packets to different interface queues based on the mapped local priorities, and use the queue scheduling to provide services for packets with different priorities.

  • The AR3200&AR3600 series send packets to different interface queues based on the mapped local priorities, and use the queue scheduling to provide services for packets with different priorities.


2.16.2  What Are the differences of Trust Command between AR100&AR120&AR150&AR160&AR200 series, AR1200 series, AR2200 series and AR3200&AR3600 series?

  • V200R001C00:
    • On the AR1200 series, the override keyword in the trust command cannot be set. By default, the priority field in a packet is modified.

    • On the AR2200 series and AR3200&AR3600 series, the override keyword in the trust command can be set. Users can determine whether to modify the priority field in a packet.

  • From V200R001C01:
    • When the override keyword is not set in the trust command on the AR1200 series, the DSCP value of a packet remains unchanged after the 802.1p value of the packet is set to the mapping value. When the override keyword is set in the trust command on the AR1200 series, the 802.1p value and DSCP value of a packet are changed to the mapping values.

    • The override keyword in the trust command can be set on the AR2200 series and AR3200&AR3600 series. Users can determine whether to modify the priority field in a packet.

  • From V200R002C00:
    • When the override keyword is not set in the trust command on the AR100&AR120& series, and AR1200 series, the DSCP value of a packet remains unchanged after the 802.1p value of the packet is set to the mapping value. When the override keyword is set in the trust command on the AR150, AR200, and AR1200 series, the 802.1p value and DSCP value of a packet are changed to the mapping values.

    • The override keyword in the trust command can be set on the AR2200 series and AR3200&AR3600 series. Users can determine whether to modify the priority field in a packet.

  • From V200R003C00:
    • When the override keyword is not set in the trust command on the AR100&AR120&AR150&AR160&AR200 series, AR1200 series, AR2204, and AR2200L, the DSCP value of a packet remains unchanged after the 802.1p value of the packet is set to the mapping value. When the override keyword is set in the trust command on the AR150, AR200, AR1200 series, and AR2204, the 802.1p value and DSCP value of a packet are changed to the mapping values.

    • The override keyword in the trust command can be set on the AR2201, AR2202, AR2220, AR2240C, AR2240, and AR3200&AR3600 series. Users can determine whether to modify the priority field in a packet.


2.16.3  How Do I Enable Packets with a Specific DSCP to Enter High-Priority Queues?

Use traffic classifiers to enable packets with high differentiated services code point (DSCP) values to enter expedited forwarding (EF) queues, and to ensure that the packets are transmitted preferentially. For example, to enable packets with a DSCP of 22 to enter EF queues, configure the following:

<Huawei> system-view
[Huawei] traffic classifier c1
[Huawei-classifier-c1] if-match dscp 22
[Huawei-classifier-c1] quit
[Huawei] traffic behavior b1
[Huawei-behavior-b1] queue ef bandwidth 100 cbs 2500
[Huawei-behavior-b1] quit
[Huawei] traffic policy p1
[Huawei-trafficpolicy-p1] classifier c1 behavior b1

2.16.4  How Can Packets Be Delivered to Queues with Different Priorities?

The AR delivers packets to different queues based on the priority. By default, the AR interfaces do not trust any packet priority. Packets received on the same interface are delivered to the same queue.

Packets enter queues of different priorities when the following requirements are met:
  • The trust command is used on the interface to map packets based on the priority.

  • Packets of different priorities exist in the service flows passing the interface.

6711c418de1945a6a6d6c41745fe9374 NOTE:
You can run the following commands to re-mark a priority of a packet.
  • remark 8021p: Re-marks the 802.1p priority of VLAN packets.

  • remark dscp: Re-marks the DSCP priority of IP packets.

  • remark local-precedence: Re-marks the internal priority of packets.


2.16.5  Why Is the CAR or GTS Sometimes Incorrect?

The committed access rate (CAR) or generic traffic shaping (GTS) is set by the AR main control board or interface board based on traffic volume. If the CAR or GTS is set by the interface board, the accuracy depends on the granularity of the rate limit. Within a specified granularity range, all CAR or GTS values are correct. In addition, different bearer links may trigger the protocol encapsulation correction.


2.16.6  What Are Experiential Values of CBS and PBS When CAR Is Configured on Interfaces?

In most cases:

  • If the peak information rate (PIR) is configured and the PIR and CIR are different, the committed burst size (CBS) is 125 times greater than the committed information rate (CIR), and the peak burst size (PBS) is 125 times greater than the PIR.

  • If the PIR is not configured or the PIR and CIR are the same, the CBS is 188 times greater than the CIR, and the PBS is 313 times greater than the CIR.

The CIR value is expressed in kbit/s, and the CBS and PBS values are expressed in Bytes.


2.16.7  Is the Priority of Packets Sent from Devices Affected, If the CAR Is Configured and the Priority Is Re-marked?

If the committed access rate (CAR) is configured on a device and the priority is re-marked, the priorities of packets sent from devices are modified according to the priority specified by the CAR and re-mark action.


2.16.8  What Are Differences Between the Outbound Traffic Policing and Traffic Shaping?

Both outbound traffic policing (TP) and traffic shaping (TS) limit the rate of outgoing traffic on an interface. Traffic policing and traffic shaping have the following differences:

  • Traffic policing directly discards packets with rates that are greater than the traffic policing rate. Traffic shaping, however, buffers packets with rates that are greater than the traffic shaping rate and sends the buffered packets at an even rate.

  • Traffic shaping increases the delay, whereas traffic policing does not.

2.16.9  Can the qos gts and qos car Commands Be Used Simultaneously for Outgoing Packets?

The qos car command affects the qos gts command effect. You are not advised to run these two commands at the same time.


2.16.10  The Interval at Which the Traffic Shaping Rate Increases Can Be Set, But the Interval at Which the Traffic Shaping Rate Decreases Cannot Be Set. Why?

When the NQA test instance detects that the packet loss ratio is greater than the upper threshold in the adaptive traffic profile, the upstream device reduces the traffic shaping rate. This ensures that the traffic shaping rate rapidly adapt to the network and prevents data loss.


2.16.11  Can the Adaptive Traffic Profile Be Bound to an NQA Test Instance?

The adaptive traffic profile can be bound to an NQA test instance. The upstream device uses the upper threshold for the traffic shaping rate in the adaptive traffic profile if the adaptive traffic profile is not bound to the NQA test instance.


2.16.12  Is the Upper or Lower Threshold for the Traffic Shaping Rate in the Adaptive Traffic Profile Used by Default?

The upper threshold for the traffic shaping rate is used by default. The system then dynamically adjust traffic shaping parameters based on the NQA result.


2.16.13  Which Scheduling Modes Do LAN-Side Boards and WAN-Side Boards Support?

Table 2-46  Scheduling modes supported by each interface
InterfaceScheduling Mode
LAN interface
  • PQ

  • DRR

  • WRR

  • PQ+DRR

  • PQ+WRR

NOTE:
  • Layer 2 FE interfaces on the AR150&AR200 series support only PQ, WRR, and PQ+WRR, but do not support DRR.

  • Layer 2 GE interfaces on the AR100&AR120&AR160(except AR161, AR161W, AR169, AR169W, AR169EW, AR169CVW, AR169CVW-4B4S, AR169EGW-L, AR161G-L, AR161EW, AR161EW-M1, AR161G-Lc, AR161G-U, AR169G-L, AR169W-P-M9, AR169RW-P-M9 and AR169-P-M9) series support only PQ, WRR, and PQ+WRR, but do not support DRR.

  • Layer 2 FE interfaces on the AR1200(except the AR1220E, AR1220EV, and AR1220EVW) series SRU support only PQ, WRR, and PQ+WRR, but do not support DRR.

  • V200R008C50 and later versions, layer 2 VE interfaces only support PQ, WFQ and PQ+WFQ.

WAN interface
  • PQ

  • WFQ

  • PQ+WFQ


2.16.14  Are There Any Requirements for Weights Assigned to Queues for WFQ Scheduling, and Do I Have to Ensure That the Sum of All Weights Is 100?

In weighted fair queuing (WFQ) scheduling, the value of the weight for each queue is 1–100. Generally, the sum of all weights is set to 100 to facilitate calculation. However, this is not mandatory.

The bandwidth ratio occupied by each queue = the weight of the queue/the sum of all weights.

For example: If the current interface has four queues, and the weights are 10, 10, 10, and 50 respectively, the bandwidth ratio is 10/80 when the weight value of the queue is 10, and the bandwidth ratio is 50/80 when the queue's weight value is 50.


2.16.15  What Impact Does the Queue Length Have?

A longer queue buffers more packets but introduces a longer delay.

If congestion intermittently occurs on a network, buffering more packets prevents unnecessary packet loss. If congestion constantly occurs on a network, increasing the queue length cannot solve this problem. You need to increase the bandwidth.


2.16.16  What Functions Do Drop Profiles Have?

Drop profiles have the following two functions:

  • By default, AR series routers use the tail drop method and discard data packets at the end of a queue when congestion occurs. The tail drop method causes global Transmission Control Protocol (TCP) synchronization and reduces link usage. Drop profiles and the Weighted Random Early Detection (WRED) can solve this problem.

  • By configuring different priority-based drop probabilities in drop profiles, you can ensure that packets with a low priority are dropped preferentially, and ensure the quality of high-priority and low-delay services.

2.16.17  In Which Situation Do EF Queues Preempt the Idle Bandwidth?

When traffic is not congested on a device interface and AF or BE queues have idle bandwidth, EF queues can preempt the idle bandwidth.

When the SRU80, SRU200, SRUX5, or SRU400 is used, Ethernet interfaces and POS interfaces do not support idle bandwidth preempted by EF queues.


2.16.18  What Is the Relationship Among the Enqueue, Queue pass, and Queue drop Fields in Traffic Policy Statistics? (V200R001C00 and V200R001C01)

  • Enqueue: the number of packets and the number of bytes that are allowed to enter a queue.

  • Queue pass: the number of packets and the number of bytes that are allowed to pass a queue.

  • Queue drop: the number of packets and the number of bytes that are discarded because the queue is full.

Enqueue = Queue pass + Queue drop


2.16.19  What Is the Relationship Among the Queue Matched, Enqueued, and Discarded Fields in Traffic Policy Statistics? (V200R002C00 and Later Versions)

  • Queue Matched: the number of packets and the number of bytes that are allowed to enter a queue.

  • Enqueued: the number of packets and the number of bytes that are allowed to pass a queue.

  • Discarded: the number of packets and the number of bytes that are discarded because the queue is full.

Queue Matched = Enqueued + Discarded


2.16.20  What Does Shaping Active in the Enqueue Field Mean?

If Shaping Active is in the Enqueue field, traffic shaping is configured in the traffic policy.
  • The value Shaping Active:NO indicates that traffic does not exceed the traffic shaping threshold. Traffic shaping is not performed.

  • The value Shaping Active:YES indicates that traffic has exceeded the traffic shaping threshold. Traffic shaping has been performed.

2.16.21  How Is the Bandwidth Calculated in the AF and EF Queues on a Tunnel Interface?

The tunnel interface is a virtual interface that cannot sense the bandwidth on the physical interface. Therefore, the following requirements are specified:
  • If the qos gts command is not executed on the tunnel interface, the available bandwidth is 1 Gbit/s.

  • If the qos gts command has been executed on the interface, the available bandwidth is the value of cir.

2.16.22  Why Does Not a Traffic Classifier Support the And Relationship Between ACL Rules?

ACL rules may cause conflicts when matching the same elements. For example, if two ACL rules defined in a traffic classifier match VLANs, the and relationship between ACL rules causes matching conflicts and leads to matching failure when VLAN IDs are different.


2.16.23  If a Traffic Behavior Contains Redirection, But the Redirection Route Is Not Found, Are Packets Dropped?

  • In V200R005 and later versions, packets will be dropped.

  • In earlier versions, packets will be forwarded based on the original router.

2.16.24  A Traffic Policy Is Bound to Multiple Pairs of Traffic Classifiers and Traffic Behaviors. What Is the Sequence in Which Traffic Classifiers and Traffic Behaviors Are Used?

If the classifier classifier-name behavior behavior-name command is executed for a traffic policy multiple times, the configured behaviors are executed in the order in which they are configured. For example, a traffic policy contains the following four behaviors:

classifier classifier1 behavior behavior1

classifier classifier2 behavior behavior2

classifier classifier3 behavior behavior3

classifier classifier4 behavior behavior4

The received packet is first checked against classifier1. If the packet matches classifier1, the packet is processed according to behavior1 and does not need to be checked against classifier2. If the packet does not match classifier1, the packet is checked against classifier2. If the packet matches classifier2, the packet is processed according to behavior2 and does not need to be checked against classifier3...


2.16.25  If a Traffic Policy Is Applied to Different Interfaces, Are the GAR and GTS Shared by These Interfaces?

If a stream policy is applied on different interfaces, the committed access rate (CAR) bandwidth and generic traffic shaping (GTS) bandwidth are independent for each interface. For example, if the behavior in a traffic policy sets the speed limit to 10 Mbit/s, and the traffic policy is applied to different interfaces, each interface can individually occupy a maximum bandwidth of 10 Mbit/s.


2.16.26  Which Preferential Transmission Assurances Do AR Series Routers Provide to User-Defined Traffic Classifiers?

AR series routers provide the following preferential transmission assurances to user-defined traffic classifiers:

  • Assured forwarding (AF): AF ensures the low probability of dropping packets when the rate of outgoing service traffic does not exceed the minimum bandwidth. It is used for services with heavy traffic that need to be ensured.

  • Expedited forwarding (EF): EF is used for services that require low delay, low drop probability, ensured bandwidth, and occupying low bandwidth, for example, voice packets.

    In addition to common EF queues, the device provides a special EF queue, LLQ queue with the shortest delay. LLQ provides good QoS assurance for delay-sensitive services such as VoIP services.

  • Best effort (BE): AR series routers allocate the remaining bandwidth that is not used by EF and AF queues to BE queues.

2.16.27  Which One Takes Effect First, the traffic-policy or traffic-filter Command?

The traffic-filter command is supported from V200R002C00.

When the traffic-policy and traffic-filter commands are simultaneously executed, the traffic-filter command takes effect first.


2.16.28  Upstream and Downstream Devices Are Connected Through the AR. How Do I Determine That Communication Packets Between Upstream and Downstream Devices Are Received and Sent by the AR?

Configure a traffic policy on the Router. Configure rules for the specified type of packets in a traffic classifier and enable traffic statistics in the traffic behavior.

Apply the traffic policy to the Router interface connected to upstream and downstream devices in the inbound and outbound directions, and check whether traffic statistics on the interface increase. If the traffic statistics increase, packets are sent and received.

As shown in Figure 2-15, ServerA connects to ServerB through the Router. Ping ServerA and ServerB and check whether ping packets are received and sent by the Router.

Figure 2-15  Connecting upstream and downstream devices through the AR
b36805c8a73a4bdaacf741030fd2cf67

The configuration is as follows:

...
#
acl number 3000  //Configure an ACL to match ICMP packets with the destination address as ServerB address 
                   and source address as ServerA address.
 rule 5 permit icmp source 192.168.4.0 0.0.0.255 destination 192.168.3.0 0.0.0.255
#
acl number 3001  //Configure an ACL to match ICMP packets with the destination address as ServerA address 
                   and source address as ServerB address.
 rule 5 permit icmp source 192.168.3.0 0.0.0.255 destination 192.168.4.0 0.0.0.255
#
traffic classifier atob operator or
 if-match acl 3000
traffic classifier btoa operator or
 if-match acl 3001
#
traffic behavior statistic  //Enable traffic statistics in the traffic behavior.
 statistic enable
#
traffic policy atob
 classifier atob behavior statistic
traffic policy btoa
 classifier btoa behavior statistic
#
interface GigabitEthernet1/0/0
 ip address 192.168.4.2 255.255.255.0
 traffic-policy atob inbound  //Collect traffic statistics on ping packets sent from ServerA to ServerB in 
                                the inbound direction.
 traffic-policy btoa outbound  //Collect traffic statistics on ping packets sent from ServerB to ServerA in 
                                 the outbound direction.
#
interface GigabitEthernet2/0/0
 ip address 192.168.3.2 255.255.255.0
 traffic-policy btoa inbound  //Collect traffic statistics on ping packets sent from ServerB to ServerA in 
                                the inbound direction.
 traffic-policy atob outbound  //Collect traffic statistics on ping packets sent from ServerA to ServerB in 
                                 the outbound direction.
#
...
  • Run the display traffic policy statistics interface gigabitethernet 1/0/0 inbound verbose rule-base command to check ping packets sent from ServerA to ServerB on GE1/0/0.

  • Run the display traffic policy statistics interface gigabitethernet 1/0/0 outbound verbose rule-base command to check ping packets sent from ServerB to ServerA on GE1/0/0.

  • Run the display traffic policy statistics interface gigabitethernet 2/0/0 inbound verbose rule-base command to check ping packets sent from ServerB to ServerA on GE2/0/0.

  • Run the display traffic policy statistics interface gigabitethernet 2/0/0 outbound verbose rule-base command to check ping packets sent from ServerA to ServerB on GE2/0/0.

If statistics of a flow exist in the inbound direction but there are no statistics of the flow in the outbound direction, packets are discarded by the Router. If there are statistics of the flow in both inbound and outbound direction, packets are forwarded by the Router.
The following information shows that ping packets sent from ServerA to ServerB are received by GE1/0/0 and sent out by GE2/0/0.
[Huawei] display traffic policy statistics interface gigabitethernet 1/0/0 inbound verbose rule-base

 Interface: GigabitEthernet1/0/0                                                
 Traffic policy inbound: atob                                                   
 Rule number: 1                                                                 
 Current status: OK!                                                            
 Classifier: atob operator or                                                   
 Behavior: statistic                                                            
 Board : 0                                                                      
 rule 5 permit icmp source 192.168.4.0 0.0.0.255 destination 192.168.3.0 0.0.0.255
Passed Packet                         5,Passed Bytes                       490  Dropped Packet                         0,Dropped Bytes                         0
[Huawei] display traffic policy statistics interface gigabitethernet 2/0/0 outbound verbose rule-base

 Interface: GigabitEthernet2/0/0                                                
 Traffic policy outbound: atob                                                   
 Rule number: 1                                                                 
 Current status: OK!                                                            
 Classifier: atob operator or                                                   
 Behavior: statistic                                                            
 Board : 0                                                                      
 rule 5 permit icmp source 192.168.4.0 0.0.0.255 destination 192.168.3.0 0.0.0.255
Passed Packet                         5,Passed Bytes                       490  Dropped Packet                         0,Dropped Bytes                         0

2.16.29  After NAT Is Configured, How Do I Configure the Device to Prevent PCs with Specified Internal IP Addresses from Accessing the Website?

A traffic policy is configured on the device connected to the internal network in the inbound direction. The traffic policy rejects packets with the source IP address as the specified network segment and destination IP address as the website address.

As shown in Figure 2-16, the IP address of GE0/0/1 (outbound interface) on the router is 200.100.1.2/24, and the IP address of Eth0/0/1 is 192.168.0.1/24. The remote IP address of GE0/0/1 is 200.100.1.1/24. The intranet user uses Easy IP to access the Internet through GE0/0/1.

Figure 2-16  Easy IP configuration on the outbound interface
f0a3e783856840d8bbf14483b78db6e2

The configuration is as follows:

#
 sysname Router  //Modify the device name.
#
acl number 2000  //Configure the internal address segment 192.168.0.0/24 that can be translated using NAT.
 rule 5 permit source 192.168.0.0 0.0.0.255
#
interface Ethernet0/0/1
 ip address 192.168.0.1 255.255.255.0  //Configure the internal gateway address.
#
interface GigabitEthernet0/0/1
 ip address 200.100.1.2 255.255.255.0
 nat outbound 2000  //Configure Easy IP on GE0/0/1.
#
ip route-static 0.0.0.0 0.0.0.0 200.100.1.1  //Configure a static route.
#

To prevent PCs with IP addresses 192.168.0.16 to 192.168.0.31 from accessing 211.1.1.6, perform the following operations:

[Router] acl 3000
[Router-acl-adv-3000] rule deny ip destination 211.1.1.6 0.0.0.0 source 192.168.0.16 0.0.0.15
[Router-acl-adv-3000] quit
[Router] traffic classifier c1
[Router-classifier-c1] if-match acl 3000
[Router-classifier-c1] quit
[Router] traffic behavior b1
[Router-behavior-b1] deny
[Router-behavior-b1] quit
[Router] traffic policy p1
[Router-trafficpolicy-p1] classifier c1 behavior b1
[Router-trafficpolicy-p1] quit
[Router] interface ethernet 0/0/1
[Router-Ethernet0/0/1] traffic-policy p1 inbound

2.16.30  When You Configure the set priority dscp and remark dscp Commands Simultaneously, Which One Takes Effect?

The set priority dscp command sets the DSCP priority of protocol packets sent by the device. To change the DSCP priority of protocol packets, you can also configure a traffic policy, define remark dscp for protocol packets in the traffic policy, and apply the traffic policy to the outbound direction of an interface.

If the ip soft-forward enhance enable command has been executed to enable the enhanced IP forwarding function, the remark dscp command takes effect. If the ip soft-forward enhance enable command is not used, the set priority command takes effect.


2.16.31  Does the Device Support Rate Limiting Based on IP Addresses ?

In later versions of V200R002C00, run the qos car command to set the rate limitint based on IP Addresses.


2.16.32  How Is Bandwidth of Different Types of Traffic Guaranteed?

Configure traffic classifiers to differentiate traffic, configure queue ef or queue af in traffic behaviors, bind the traffic classifiers and traffic behaviors to a traffic policy, and apply the traffic policy to an interface.


2.16.33  Why IP-based CAR Is Invalid on a WAN-side Interface?

Because NAT is configured on the WAN-side interface, the device cannot differentiate private IP addresses.

In V200R002C00 and later versions, to configure IP-based CAR on a WAN-side interface, create a VLANIF interface and configure IP-based CAR on the VLANIF interface.
  • To limit the download rate, configure IP-based CAR for a specified destination address in the outbound direction.

  • To limit the upload rate, configure IP-based CAR for a specified source address in the inbound direction.

2.16.34  Can IP-based Rate Limit Be Configured on a Layer 2 Interface?

IP-based rate limit cannot be configured on a Layer 2 interface. Create a VLANIF interface and configure IP-based CAR on the VLANIF interface.


2.16.35  How Is Redirection Configured on a PPPoE Link?

In V200R003C00 and later versions, run the redirect interface command and specify the dialer interface for redirection.


2.16.36  How Do I Set the Rate Limit Based on the Website Address

Assume that the AR router connects to users on private network segments of 192.168.0.2 and 192.168.0.100 and the rate limit needs to be set to 2 Mbit/s for each address in both inbound and outbound directions. Perform the following configurations:

Enter the view of the public network interface.

[Huawei] interface GigabitEthernet 0/0/0

Set the rate limit to 2 Mbit/s in the outbound direction so that traffic from the internal network to the public network is within 2 Mbit/s.

[Huawei-GigabitEthernet0/0/0] qos car outbound source-ip-address range 192.168.0.2 to 192.168.0.100 per-address cir 2000 //*If the rate limit needs to be set for each address, specifyper-address. If the rate limit is set for all addresses, you do not need to specifyper-address.*//

Set the rate limit to 2 Mbit/s in the inbound direction so that traffic from the public network to the internal network is within 2 Mbit/s.

[Huawei-GigabitEthernet0/0/0] qos car inbound destination-ip-address range 192.168.0.2 to 192.168.0.100 per-address cir 2000

2.16.37  What Is the Difference Between CAR and LR?

CAR is valid for only IP packets. CAR can limit the rate of incoming and outgoing packets.

LR is valid for all packets passing on a physical interface, but can only limit the rate of outgoing packets.


2.16.38  Are CoS Values 0-7 of the 802.1P Protocol in Descending Order of Priority?

802.1P is one of IEEE 802.1 protocols, and defines the priority (CoS value) of Ethernet frames. 802.1Q that defines VLAN information in Ethernet frames was also released with 802.1P. 802.1P and 802.1Q are often used together. They add a tag composed of 12-bit VLAN information and 3-bit CoS information to the Ethernet frame header.

When performing Layer 2 switching, an Ethernet switch use CoS values to differentiate priorities of Ethernet frames. When DiffServ is used, a Layer 3 switch or an edge router is often configured to map CoS values to ToS values in IP headers to achieve QoS guarantee. A ToS value identifies the priority of an IP packet.

CoS values 0-7 defined in 802.1P are in descending order of priority. The default value 0 is not the lowest to ensure compatibility.

CoS values 0-7 are as follows:

==========================

7(highest)....network management

6.............voice

5.............video

4.............controlled load

3.............excellent effort

2.............(undefined)

1(lowest).....background

0(default)....best effort

That is all I want to share with you! Thank you!

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  • convention:

WoodWood
Created Aug 30, 2017 06:35:53

An AR router maintenance guide - FAQ (QoS)-2430999-1
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