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CX11x, CX31x, CX710 (Earlier Than V6.03), and CX91x Series Switch Modules V100R001C10 Configuration Guide 12

The documents describe the configuration of various services supported by the CX11x&CX31x&CX91x series switch modules The description covers configuration examples and function configurations.
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Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
Managing IP Routing Tables

Managing IP Routing Tables

This section describes how to manage IP routing tables.

Displaying and Maintaining a Routing Table

You can view routing tables to learn about the network topology and locate routing faults.

Context

You can view routing table information to locate routing faults. The following describes the commands used to display and maintain routing table information.

The display commands can be used in all views. The reset commands are used in the user view.

Procedure

  • Run the display ip routing-table command to check brief information about the active routes in the IPv4 routing table.
  • Run the display ip routing-table verbose command to check detailed information about the IPv4 routing table.
  • Run the display ip routing-table ip-address [ mask | mask-length ] [ longer-match ] [ verbose ] command to check detailed information about the routes with the specified destination address in the IPv4 routing table.
  • Run the display ip routing-table ip-address1 { mask1 | mask-length1 } ip-address2 { mask2 | mask-length2 } [ verbose ] command to check detailed information about the routes within the specified destination address range in the IPv4 routing table.
  • Run the display ip routing-table ip-prefix ip-prefix-name [ verbose ] command to check detailed information about the routes that match the specified IP prefix list in the IPv4 routing table.
  • Run the display ip routing-table protocol protocol [ inactive | verbose ] command to check detailed information about the routes discovered by the specified routing protocol in the IPv4 routing table.
  • Run the display ip routing-table statistics command to check route statistics in the IPv4 routing table.
  • Run the display ipv6 routing-table command to check brief information about the active routes in the IPv6 routing table.
  • Run the display ipv6 routing-table verbose command to check detailed information about the IPv6 routing table.
  • Run the display ipv6 routing-table protocol protocol [ inactive | verbose ] command to check detailed information about the routes discovered by the specified routing protocol in the IPv6 routing table.
  • Run the display ipv6 routing-table statistics command to check route statistics in the IPv6 routing table.
  • Run the reset ip routing-table statistics protocol { all | protocol } command to clear route statistics in the IPv4 routing table.
  • Run the reset ipv6 routing-table statistics protocol { all | protocol } command to clear route statistics in the IPv6 routing table.

Maintaining the Routing Management Module

Configuring maintenance of the routing management (RM) module includes the configuration of the device route prefix alarm threshold and public network route prefix restriction.

Context

The number of route prefixes that can be added to a routing table is limited. If the value exceeds the limit, new prefixes cannot be added to the routing table, which may interrupt services. To address this problem, configure an alarm threshold for the number of route prefixes.

If the device imports a large number of routes, system performance may be affected when services are being processed because the routes consume a lot of system resources. To improve system reliability, configure a limit on the number of public route prefixes. When the number of public route prefixes exceeds the limit, an alarm is generated, prompting you to check whether unnecessary public route prefixes exist.

Procedure

  • Configure two thresholds (one alarm threshold and one clear alarm threshold) for the number of route prefixes on a device.

    1. Run:

      system-view

      The system view is displayed.

    2. Run either of the following commands as required:
      • Run:

        ip prefix-limit system threshold-alarm upper-limit upper-limit-value lower-limit lower-limit-value

        Two thresholds (one alarm threshold and one clear alarm threshold) for the number of IPv4 route prefixes are configured on the device.

        By default, the alarm threshold for IPv4 route prefixes is 80%, and the clear alarm threshold for IPv4 route prefixes is 70%.

      • Run:

        ipv6 prefix-limit system threshold-alarm upper-limit upper-limit-value lower-limit lower-limit-value

        Two thresholds (one alarm threshold and one clear alarm threshold) for the number of IPv46 route prefixes are configured on the device.

        By default, the alarm threshold for IPv6 route prefixes is 80%, and the clear alarm threshold for IPv6 route prefixes is 70%.

      NOTE:
      When you configure upper-limit-value and lower-limit-value, note the following suggestions:
      • Set a value smaller than or equal to 95 for upper-limit-value.
      • lower-limit-value must be smaller than upper-limit-value. Set lower-limit-value to a value at least 10 smaller than upper-limit-value to prevent alarms from being frequently generated and cleared due to route flapping.
    3. Run:

      commit

      The configuration is committed.

  • Configure a limit on the number of public route prefixes.

    1. Run:

      system-view

      The system view is displayed.

    2. Run either of the following commands as required:
      • Run:

        ip prefix-limit number { alert-percent [ route-unchanged ] | simply-alert }

        A limit on the number of IPv4 public route prefixes is configured.

        By default, the maximum number of IPv4 public route prefixes is not limited.

      • Run:

        ipv6 prefix-limit number { alert-percent [ route-unchanged ] | simply-alert }

        A limit on the number of IPv6 public route prefixes is configured.

        By default, the maximum number of IPv6 public route prefixes is not limited.

      alert-percent indicates the percentage of the maximum number of public route prefixes that are supported. If you specify alert-percent in the command, an alarm is generated when the number of public route prefixes exceeds the value calculated by the following formula:

      (number x alert-percent)/100

      New public route prefixes can still be added to the routing table until the number of public route prefixes reaches the value of number. Subsequent route prefixes are then discarded.

      If you specify simply-alert in the command, new public route prefixes can still be added to the routing table and only an alarm is generated after the number of public route prefixes exceeds the value of number. However, when the total number of private and public route prefixes reaches the limit on the number of unicast route prefixes specified in the PAF file, subsequent public route prefixes are discarded.

      If you decrease the value of alert-percent after the number of public route prefixes exceeds the value of number, whether the routing table remains unchanged is determined by route-unchanged.
      • If you specify route-unchanged in the command, the routing table remains unchanged.

      • If you do not specify route-unchanged in the command, the system deletes all the routes from the routing table and re-adds routes.

      NOTE:
      After the number of public route prefixes exceeds the limit, note the following rules:
      • If you run the ip prefix-limit command to increase the value of number or run the undo ip prefix-limit command to delete the limit, the device relearns IPv4 public route prefixes.
      • If you run the ipv6 prefix-limit command to increase the value of number or run the undo ipv6 prefix-limit command to delete the limit, the device relearns IPv6 public route prefixes.
      • Direct and static routes can still be added to the IP routing table.
    3. Run:

      commit

      The configuration is committed.

Configuring IPv4 FRR

IPv4 FRR applies to the services that are very sensitive to delay and packet loss on IPv4 networks.

Applicable Environment

If a link failure occurs after FRR is enabled, the fault detection module reports the failure to the upper-layer routing system. The FRR module immediately uses a backup link to forward packets, minimizing the impact of the link failure on services.

IPv4 FRR implements route backup among routes of different routing protocols and may cause routing loops. Therefore, exercise caution when using IPv4 FRR.

Pre-configuration Tasks

Before configuring IPv4 FRR, complete the following task:

  • Configuring link layer protocol parameters and assigning IPv4 addresses to interfaces to ensure that the link layer protocol of the interfaces is Up

  • Configuring IPv4 routes destined for the same destination address but discovered by different routing protocols

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    ip frr

    IPv4 FRR is enabled.

    By default, IPv4 FRR is disabled.

    NOTE:

    When FRR is configured in both the system view and the routing protocol view, FRR configured in the routing protocol view is used for route backup.

  3. Run:

    commit

    The configuration is committed.

Checking the Configuration

After IPv4 FRR is configured, run the following command to check the configuration.

Run the display ip routing-table verbose command to check detailed information about the backup outbound interfaces and backup next hops of routes in the routing table.

Configuring IPv6 FRR

IPv6 FRR is applicable to services that are very sensitive to the delay and packet loss on an IPv6 network.

Applicable Environment

After IPv6 FRR is configured, if a link fault is detected at a lower layer (physical layer or link layer), the fault is reported to the upper-layer routing system. Meanwhile, packets are forwarded using a backup link to minimize the impact of the link fault on services.

IPv6 FRR enables routes generated by different routing protocols to back up each other, which may cause a loop. Therefore, exercise caution when configuring IPv6 FRR.

Pre-configuration Tasks

Before configuring IPv6 FRR, complete the following tasks:

  • Configuring link layer protocol parameters and assigning IPv6 addresses to interfaces to ensure that the link layer protocol on the interfaces is Up

  • Configuring IPv6 routes destined for the same destination address but discovered by different routing protocols

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    ipv6 frr

    IPv6 FRR is enabled.

    NOTE:

    When IPv6 FRR is configured in both the system view and the routing protocol view, the IPv6 FRR configuration in the routing protocol view takes effect.

  3. Run:

    commit

    The configuration is committed.

Checking the Configuration

Run the display ipv6 routing-table verbose command to check detailed information about backup outbound interfaces and backup next hops of routes in the routing table.

Configuring the ECMP Load Balancing Mode

Equal-Cost Multi-Path routing (ECMP) implements load balancing and link backup.

Context

ECMP applies to the network where multiple links to the same destination are available. In the traditional routing technology, packets are forwarded to the destination through one link only; the other links are in backup or inactive state; switching between these links requires a certain period when dynamic routes are used. Different from the traditional routing technology, ECMP can use multiple links to increase transmission bandwidth and transmit data on a faulty link without any delay or packet loss.

Table 7-57 lists load balancing modes of different packets.

Table 7-57 Load balancing modes for different packets

Packets (on the Inbound Interface)

Default Load Balancing Mode

Configurable Load Balancing Mode

IPv4 packets

src-ip, dst-ip, l4-src-port, and l4-dst-port

src-ip, dst-ip, l4-src-port, l4-dst-port, protocol, vlan, and src-interface

IPv6 packets

src-ip, dst-ip, l4-src-port, and l4-dst-port

src-ip, dst-ip, l4-src-port, l4-dst-port, protocol, vlan, and src-interface

TRILL packets

Ingress: src-mac, dst-mac, vlan, src-ip, dst-ip, l4-src-port, and l4-dst-port

src-ip, dst-ip, l4-src-port, l4-dst-port, protocol, vlan, and src-interface

Transit/Egress: Layer 2 packets are load balanced based on the inner src-mac, vlan, and dst-mac. Layer 3 packets are load balanced based on src-ip, dst-ip, l4-src-port, and l4-dst-port.

src-ip, dst-ip, l4-src-port, l4-dst-port

Procedure

  • Configure ECMP load balancing.
    1. Run:

      system-view

      The system view is displayed.

    2. Run:

      load-balance ecmp

      The ECMP view is displayed.

    3. Run:

      ipv4 { src-ip | dst-ip | vlan | l4-src-port | l4-dst-port | protocol | src-interface } *

      The ECMP load balancing mode of IPv4 packets, IPv6 packet, and TRILL packet is set.

    4. Run:

      commit

      The configuration is committed.

Checking the Configuration

Run the display port forwarding-path { src-ip src-ip-data | dst-ip dst-ip-data | src-mac src-mac-data | dst-mac dst-mac-data | protocol { protocol-number | gre | icmp | igmp | ip | ipinip | ospf | tcp [ l4-src-port src-port-data | l4-dst-port dst-port-data ]* | udp [ l4-src-port src-port-data | l4-dst-port dst-port-data ]* } } * command to displays the outbound interface of packets that contain specified 5-tuple information, source MAC address, and destination MAC address.

Configuring the Advertisement of IPv4 ARP Vlink Direct Routes

Advertising IPv4 Address Resolution Protocol (ARP) Vlink direct routes allows precise control of data traffic.

Applicable Environment

IP packets are forwarded through a specified physical interface, but cannot be forwarded through a VLANIF interface. If packets reach a VLANIF interface, the device obtains information about the layer-3 interfaces using IPv4 ARP and generates relevant routing entries. The routes recorded by the routing entries are called IPv4 ARP Vlink direct routes.

Before IPv4 ARP Vlink direct routes are advertised, a route-policy can be configured to filter the advertised routes and only routes that match the route-policy can be advertised. In this manner, data traffic can be precisely controlled.

Pre-configuration Tasks

Before advertising IPv4 ARP Vlink direct routes on the public network, complete the following task:

  • Configuring parameters of a link layer protocol and assigning an IP address to each interface to ensure that the link layer protocol on the interfaces is Up

Procedure

  1. Run:

    system-view

    The system view is displayed.

  2. Run:

    arp direct-route enable

    Advertising IPv4 ARP Vlink direct routes is enabled.

    By default, IPv4 ARP Vlink direct routes cannot be advertised.

  3. Run:

    commit

    The configuration is committed.

    After advertising IPv4 ARP Vlink direct routes is enabled, IPv4 ARP Vlink direct routes can be advertised only if they are imported to a dynamic routing protocol.

Checking the Configurations

Run the display ip routing-table verbose command to check information about advertised IPv4 ARP Vlink direct routes.

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Updated: 2019-08-09

Document ID: EDOC1000041694

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