How prevent downstream congestion and drops ?

Created: Jul 16, 2019 11:53:52Latest reply: Jul 16, 2019 12:08:53 102 6 1 0
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In NE40E Router How to prevent drops in packets when the traffic volume on a network is heavy and the upstream router sends a large volume of data traffic so the downstream network congested and has a great number of dropped packets please any solution supported by NE40E-X8

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Admin Created Jul 16, 2019 12:03:30 Helpful(1) Helpful(1)

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Mr.Jack Created Jul 16, 2019 12:18:45
you're right Traffic shaping will be a solution for the outgoing traffic only but it isn't support incoming traffic  
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chenhui Admin Created Jul 16, 2019 12:03:30 Helpful(1) Helpful(1)

  • x
  • convention:

Mr.Jack Created Jul 16, 2019 12:18:45
you're right Traffic shaping will be a solution for the outgoing traffic only but it isn't support incoming traffic  
yogijain MVE Created Jul 16, 2019 12:08:36 Helpful(1) Helpful(1)


Hi,


I Hope Below Example will  support in configuration , related to your problem 


Example for Configuring Congestion Avoidance

This section provides an example for configuring congestion avoidance.The device monitors the usage of network resources and discards packets when congestion is intensifying.

Networking Requirements

As shown in Figure 3-2, devices Server, Telephone, PC1 and PC2 all send data to the network through Router A. The data sent from Server is of critical traffic class; the data sent from Telephone is of voice services; the data from PC1 and PC2 is of normal services. Because the rate of the inbound interface GE 1/0/0 on Router A is greater than that of the outbound interface POS 2/0/0, congestion may occur on POS 2/0/0.

When network congestion occurs, the data sent by Server and Telephone must be transmitted first. Users PC1 and PC2 allow a little delay to the transmission of their data but they also require bandwidth guarantee because they are VIP users. Therefore, Router A must discard packets based on the priority of the packets when the network congestion intensifies.

Therefore, WFQ and WRED must be both configured on Router A.

Figure 3-2  Networking diagram for configuring congestion avoidance 
imgDownload?uuid=5c2b9f5f860c4ba38d1a25b

Configuration Roadmap

The configuration roadmap is as follows:

  1. On GE 1/0/0 of Router A, mark the priority of different flows.

  2. Configure a WRED object to set the lower and upper percentage limits for discarding packets as well as the discarding probability.

  3. On POS 2/0/0, set the scheduling policy for the class queue and apply the WRED object in the scheduling policy.

Data Preparation

To complete the configuration, you need the following data:

  • ACL number, traffic classifier name, traffic behavior name, priority of the service to be re-marked and the traffic policy name

  • WRED object name, lower percentage limit and upper percentage limit, discarding probability and packet color in each queue

  • The interface where the packet discarding of WRED is applied and parameters for the class queue

Procedure

  1. Set ACL rules for packets that are sent from Server, Telephone, PC1 and PC2.

    <RouterA> system-view
    [RouterA] acl number 2001
    [RouterA-acl-basic-2001] rule permit source 10.1.1.3 0.0.0.0
    [RouterA-acl-basic-2001] quit
    [RouterA] acl number 2002
    [RouterA-acl-basic-2002] rule permit source 10.1.1.2 0.0.0.0
    [RouterA-acl-basic-2002] quit
    [RouterA] acl number 2003
    [RouterA-acl-basic-2003] rule permit source 10.1.1.4 0.0.0.0
    [RouterA-acl-basic-2003] quit
    [RouterA] acl number 2004
    [RouterA-acl-basic-2004] rule permit source 10.1.1.5 0.0.0.0
    [RouterA-acl-basic-2004] return

  2. On GE 1/0/0 of Router A, configure the complex traffic classification to mark the priority of services.

    <RouterA> system-view
    [RouterA] traffic classifier aa
    [RouterA-classifier-aa] if-match acl 2001
    [RouterA-classifier-aa] quit
    [RouterA] traffic classifier bb
    [RouterA-classifier-bb] if-match acl 2002
    [RouterA-classifier-bb] quit
    [RouterA] traffic classifier cc
    [RouterA-classifier-cc] if-match acl 2003
    [RouterA-classifier-cc] quit
    [RouterA] traffic classifier dd
    [RouterA-classifier-dd] if-match acl 2004
    [RouterA-classifier-dd] quit
    [RouterA] traffic behavior aa
    [RouterA-behavior-aa] remark ip-precedence 5
    [RouterA-behavior-aa] quit
    [RouterA] traffic behavior bb
    [RouterA-behavior-bb] remark ip-precedence 4
    [RouterA-behavior-bb] quit
    [RouterA] traffic behavior cc
    [RouterA-behavior-cc] remark ip-precedence 3
    [RouterA-behavior-cc] quit
    [RouterA] traffic behavior dd
    [RouterA-behavior-dd] remark ip-precedence 2
    [RouterA-behavior-dd] quit
    [RouterA] traffic policy ee
    [RouterA-trafficpolicy-ee] classifier aa behavior aa
    [RouterA-trafficpolicy-ee] classifier bb behavior bb
    [RouterA-trafficpolicy-ee] classifier cc behavior cc
    [RouterA-trafficpolicy-ee] classifier dd behavior dd
    [RouterA-trafficpolicy-ee] quit
    [RouterA] interface gigabiethernet1/0/0
    [RouterA-gigabitEthernet1/0/0]  undo shutdown
    [RouterA-gigabitEthernet1/0/0] traffic-policy ee inbound
    [RouterA-gigabitEthernet1/0/0] return

  3. Configure a WRED object on Router A.

    <RouterA> system-view
    [RouterA] port-wred pw
    [RouterA-port-wred-pw] color green low-limit 70 high-limit 100 discard-percentage 100
    [RouterA-port-wred-pw] color yellow low-limit 60 high-limit 90 discard-percentage 100
    [RouterA-port-wred-pw] color red low-limit 50 high-limit 80 discard-percentage 100
    [RouterA-port-wred-pw] return

    After the preceding configuration, run the display port-wred configuration verbose command to check the parameters set for the WRED object:

    <RouterA> display port-wred configuration verbose pw
    port-wred-name : pw
     color    low-limit    high-limit    discard-percent
     green    70           100            100
     yellow   60           90            100
     red      50           80            100
     reference relationships
      NULL                  

  4. On POS 2/0/0 of Router A, configure class queues and apply the WRED object pw.

    <RouterA> system-view
    [RouterA] interface pos2/0/0
    [RouterA-POS2/0/0]  undo shutdown
    [RouterA-POS2/0/0] port-queue ef pq port-wred pw outbound
    [RouterA-POS2/0/0] port-queue af4 wfq weight 15 shaping 100 port-wred pw outbound
    [RouterA-POS2/0/0] port-queue af3 wfq weight 10 shaping 50 port-wred pw outbound
    [RouterA-POS2/0/0] port-queue af2 wfq weight 10 shaping 50 port-wred pw outbound
    [RouterA-POS2/0/0] return

    After the preceding configuration, run the display port-queue configuration interface command to view the configuration of class queues:


  5. Check the configuration.

    When traffic transits the network, run the display port-queue statistics command on the outbound interface POS 2/0/0 of Router A. The output shows that the traffic volume of services EF, AF4, AF3, and AF2 increases rapidly.

    When the traffic volume increases rapidly in the network, the output shows that the discarded traffic of services EF, AF4, AF3, and AF2 is also increasing. The traffic of AF4, AF3, and AF2 is forwarded using the configured bandwidth.



Example for Configuring Queue Scheduling on Low-speed Links

This section provides an example for configuring queue scheduling on low-speed links. After queue scheduling is configured on low-speed links, queues with different priorities can be scheduled based on their CoSs when congestion occurs. In this manner, bandwidth is guaranteed for packets with a higher priority.

Networking Requirements

imgDownload?uuid=877157bb4bf0421eaacc1af NOTE:

This configuration example cannot be configured on the X1 and X2 models of the NE80E/40E.

As shown in Figure 3-3, Router A and Router B are located in two networks, and are joined through a low-speed link with limited bandwidth resources. To ensure that packets of different priorities are allocated bandwidth resources based on their CoS values in the case of congestion, PQ and WFQ need to be configured on the interfaces on Router A.

Figure 3-3  Networking diagram of configuring queue scheduling on low-speed links 
imgDownload?uuid=1d3714d4ab6f4f7d8516303

Configuration Roadmap

The configuration roadmap is as follows:

  1. Configure the interfaces of theRouter A and Router B to be UP.

  2. Configure IP addresses for interfaces on Router A and Router B.

  3. Configure PQ and WFQ on Router A.

Data Preparation

To complete the configuration, you need the following data.

  • IP addresses of interfaces

  • PIR and the traffic shaping rate in percentage of the total bandwidth for PQ

  • CIR, PIR, and the traffic shaping rate in percentage of the total bandwidth for WFQ

Procedure

  1. Create the serial interfaces on Router A and Router B.

    To be omitted. For details of the configuration, refer to the HUAWEI NetEngine80E/40E Router Configuration Guide WAN Access.

  2. Configure the interfaces of the Router A and Router B to be UP.

    <RouterA> system view
    [RouterA] interface serial 2/0/0:0
    [RouterA-serial2/0/0:0] undo shutdown
    [RouterA-serial2/0/0:0] return
    <RouterB> system view
    [RouterB] interface serial 2/0/0:0
    [RouterB-serial2/0/0:0] undo shutdown
    [RouterB-serial2/0/0:0] return

  3. Configure IP addresses for interfaces on Router A and Router B to ensure network connectivity.

    The configuration is omitted here. For detailed configuration, refer to the HUAWEI NetEngine80E/40E RouterConfiguration Guide - IP Routing.

  4. Configure PQ and WFQ on Serial 2/0/0:0 on Router A.

    <RouterA> system view
    [RouterA] interface serial 2/0/0:0
    [RouterA-serial2/0/0:0] port-queue ef pq shaping 60
    [RouterA-serial2/0/0:0] port-queue af4 wfq shaping 40
    [RouterA-serial2/0/0:0] port-queue af3 wfq shaping 40
    [RouterA-serial2/0/0:0] port-queue af2 wfq shaping 30
    [RouterA-serial2/0/0:0] return

    After the preceding configurations, run the display ls-port-queue configuration interface command to view the detailed configuration of class queues:


  5. Verify the configuration.

    When traffic is being transmitted in the network, run the display ls-port-queue statistics command on the outbound interface Serial 2/0/0:0 of RouterA. The output shows that the EF, AF4, AF3, AF2, and BE flows are increasing rapidly.

    When the traffic volume increases rapidly in the network, the output shows that a large number of the EF, AF4, AF3, AF2, and BE flows are discarded, and that the bandwidths are allocated to the AF4, AF3, and AF2 flows according to the configured weights.


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Mr.Jack Created Jul 16, 2019 12:29:08
applying QoS will be very useful but usually we avoid to change packets priority and we try to set the router ports on trust mode to pass the packet as it is.  
Yogendra%20Jain
chenhui Admin Created Jul 16, 2019 12:08:53 Helpful(1) Helpful(1)

Posted by chenhui at 2019-07-16 12:03 @Mr.Jack Hi,Traffic shaping could help to control the rate of outgoing packets to allow the traffic ...
But traffic shaping is a temporary solution, the permanent way is increase the downstream bandwidth.
Cause when the upstream traffic exceeds the upper limit of the traffic shaping processing, the other packets would still be dropped.
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Mr.Jack Created Jul 16, 2019 12:20:24
yes for sure it is temp solution and just for the light congestion cases  

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