Example for Configuring IS-IS Anycast FRR

IS-IS anycast FRR can be configured to enhance the reliability of an SR network.

Networking Requirements

As shown in Figure 1, CE1 can be reached through either PE2 and PE3. To enable PE2 and PE3 to protect each other, configure IS-IS anycast FRR. This improves network reliability.

Figure 1 IS-IS anycast FRR protection networking

Interfaces 1 and 2 in this example represent GE 0/1/0 and GE 0/1/8, respectively.


Configuration Roadmap

The configuration roadmap is as follows:

  1. Enable IS-IS on the backbone network to ensure that PEs interwork with each other.

  2. Enable MPLS on the backbone network, configure SR, and establish SR LSPs.

  3. Enable TI-LFA FRR on PE1 and configure the delayed switchback function.

Data Preparation

To complete the configuration, you need the following data:

  • MPLS LSR IDs of the PEs and P

  • SRGB ranges on the PEs

Procedure

  1. Assign an IP address to each interface.

    # Configure PE1.

    <HUAWEI> system-view
[~HUAWEI] sysname PE1
[*HUAWEI] commit
[~PE1] interface loopback 1
[*PE1-LoopBack1] ip address 1.1.1.9 32
[*PE1-LoopBack1] quit
[*PE1] interface gigabitethernet0/1/0
[*PE1-GigabitEthernet0/1/0] ip address 172.18.1.1 24
[*PE1-GigabitEthernet0/1/0] quit
[*PE1] interface gigabitethernet0/1/8
[*PE1-GigabitEthernet0/1/8] ip address 172.16.1.1 24
[*PE1-GigabitEthernet0/1/8] quit
[*PE1] commit

    # Configure PE2.

    <HUAWEI> system-view
[~HUAWEI] sysname PE2
[*HUAWEI] commit
[~PE2] interface loopback 1
[*PE2-LoopBack1] ip address 2.2.2.9 32
[*PE2-LoopBack1] quit
[*PE2] interface gigabitethernet0/1/0
[*PE2-GigabitEthernet0/1/0] ip address 172.16.1.2 24
[*PE2-GigabitEthernet0/1/0] quit
[*PE2] commit

    # Configure PE3.

    <HUAWEI> system-view
[~HUAWEI] sysname PE3
[*HUAWEI] commit
[~PE3] interface loopback 0
[*PE3-LoopBack0] ip address 4.4.4.9 32
[*PE3-LoopBack0] quit
[*PE3] interface loopback 1
[*PE3-LoopBack1] ip address 2.2.2.9 32
[*PE3-LoopBack1] quit
[*PE3] interface gigabitethernet0/1/0
[*PE3-GigabitEthernet0/1/0] ip address 172.18.1.2 24
[*PE3-GigabitEthernet0/1/0] quit
[*PE3] commit

  2. Configure an IGP on the backbone network to enable the PEs to communicate. IS-IS is used as an example.

    # Configure PE1.

    [~PE1] isis 1
[*PE1-isis-1] is-level level-1
[*PE1-isis-1] network-entity 10.0000.0000.0001.00
[*PE1-isis-1] quit
[*PE1] interface loopback 1
[*PE1-LoopBack1] isis enable 1
[*PE1-LoopBack1] quit
[*PE1] interface gigabitethernet0/1/0
[*PE1-GigabitEthernet0/1/0] isis enable 1
[*PE1-GigabitEthernet0/1/0] quit
[*PE1] interface gigabitethernet0/1/8
[*PE1-GigabitEthernet0/1/8] isis enable 1
[*PE1-GigabitEthernet0/1/8] quit
[*PE1] commit

    # Configure PE2.

    [~PE2] isis 1
[*PE2-isis-1] is-level level-1
[*PE2-isis-1] network-entity 10.0000.0000.0002.00
[*PE2-isis-1] quit
[*PE2] interface loopback 1
[*PE2-LoopBack1] isis enable 1
[*PE2-LoopBack1] quit
[*PE2] interface gigabitethernet0/1/0
[*PE2-GigabitEthernet0/1/0] isis enable 1
[*PE2-GigabitEthernet0/1/0] quit
[*PE2] commit

    # Configure PE3.

    [~PE3] isis 1
[*PE3-isis-1] is-level level-1
[*PE3-isis-1] network-entity 10.0000.0000.0004.00
[*PE3-isis-1] quit
[*PE3] interface loopback 1
[*PE3-LoopBack1] isis enable 1
[*PE3-LoopBack1] quit
[*PE3] interface gigabitethernet0/1/0
[*PE3-GigabitEthernet0/1/0] isis enable 1
[*PE3-GigabitEthernet0/1/0] quit
[*PE3] commit

  3. (Optional) Configure basic MPLS functions on the backbone network.

    MPLS is automatically enabled on the interface where IS-IS has been enabled. Therefore, you can skip this step.

    # Configure PE1.

    [~PE1] mpls lsr-id 1.1.1.9
[*PE1] mpls
[*PE1-mpls] commit
[~PE1-mpls] quit

    # Configure PE2.

    [~PE2] mpls lsr-id 2.2.2.9
[*PE2] mpls
[*PE2-mpls] commit
[~PE2-mpls] quit

    # Configure PE3.

    [~PE3] mpls lsr-id 4.4.4.9
[*PE3] mpls
[*PE3-mpls] commit
[~PE3-mpls] quit

  4. Configure SR, enable TI-LFA FRR, and configure microloop avoidance in traffic switchback scenarios on the backbone network.

    # Configure PE1.

    [~PE1] segment-routing
[*PE1-segment-routing] tunnel-prefer segment-routing
[*PE1-segment-routing] quit
[*PE1] isis 1
[*PE1-isis-1] cost-style wide
[*PE1-isis-1] segment-routing mpls
[*PE1-isis-1] segment-routing global-block 160000 161000

    The SRGB range various according to a live network. Set the range as needed. The SRGB setting here is an example.

    [*PE1-isis-1] frr
[*PE1-isis-1-frr] loop-free-alternate level-1
[*PE1-isis-1-frr] ti-lfa level-1
[*PE1-isis-1-frr] quit
[*PE1-isis-1] avoid-microloop segment-routing
[*PE1-isis-1] avoid-microloop segment-routing rib-update-delay 6000
[*PE1-isis-1] quit
[*PE1] interface loopback 1
[*PE1-LoopBack1] isis prefix-sid index 10
[*PE1-LoopBack1] quit
[*PE1] commit

    # Configure PE2.

    [~PE2] segment-routing
[*PE2-segment-routing] tunnel-prefer segment-routing
[*PE2-segment-routing] quit
[*PE2] isis 1
[*PE2-isis-1] cost-style wide
[*PE2-isis-1] segment-routing mpls
[*PE2-isis-1] segment-routing global-block 160000 161000

    The SRGB range varies according to the device. The configuration in this example is for reference only.

    [*PE2-isis-1] quit
[*PE2] interface loopback 1
[*PE2-LoopBack1] isis prefix-sid index 20
[*PE2-LoopBack1] quit
[*PE2] commit

    # Configure PE3.

    [~PE3] segment-routing
[*PE3-segment-routing] tunnel-prefer segment-routing
[*PE3-segment-routing] quit
[*PE3] isis 1
[*PE3-isis-1] cost-style wide
[*PE3-isis-1] segment-routing mpls
[*PE3-isis-1] segment-routing global-block 160000 161000

    The SRGB range varies according to the device. The configuration in this example is for reference only.

    [*PE3-isis-1] quit
[*PE3] interface loopback 1
[*PE3-LoopBack1] isis prefix-sid index 20
[*PE3-LoopBack1] quit
[*PE3] commit

  5. Checking the Configurations

    Run the display segment-routing prefix mpls forwarding verbose command on PE1 to check the SR label forwarding table. The command output shows FRR backup entry information.
    [~PE1] display segment-routing prefix mpls forwarding ip-prefix 2.2.2.9 32 verbose

                   Segment Routing Prefix MPLS Forwarding Information
             --------------------------------------------------------------
             Role : I-Ingress, T-Transit, E-Egress, I&T-Ingress And Transit

Prefix             Label      OutLabel   Interface         NextHop          Role  MPLSMtu   Mtu     State          
-----------------------------------------------------------------------------------------------------------------
2.2.2.9/32         160020     3          GE0/1/0           172.16.1.2       I&T   ---       1500    Active         
Protocol : ISIS          SubProtocol : Level-1       Process ID : 1         
Cost     : 10            Weight      : 0             UpdateTime : 2018-12-11 06:46:33.920       
BFD State: --            Favor       : Y
Label Stack (Top -> Bottom): { 3 }

Prefix             Label      OutLabel   Interface         NextHop          Role  MPLSMtu   Mtu     State          
-----------------------------------------------------------------------------------------------------------------
2.2.2.9/32         160020     3          GE0/1/8           172.18.1.2       I&T   ---       1500    Active          
Protocol : ISIS          SubProtocol : Level-1       Process ID : 1         
Cost     : 10            Weight      : 0             UpdateTime : 2018-12-11 06:47:21.478       
BFD State: --            Favor       : Y
Label Stack (Top -> Bottom): { 3 }

Total information(s): 2

Configuration Files

  • PE1 configuration file

    #
sysname PE1
#
mpls lsr-id 1.1.1.9
#               
mpls            
#               
segment-routing 
 tunnel-prefer segment-routing
#               
isis 1          
 is-level level-1
 cost-style wide
 network-entity 10.0000.0000.0001.00
 segment-routing mpls
 segment-routing global-block 160000 161000
 avoid-microloop segment-routing
 avoid-microloop segment-routing rib-update-delay 6000
 frr
  loop-free-alternate level-1
  ti-lfa level-1
#               
interface GigabitEthernet0/1/0
 undo shutdown  
 ip address 172.18.1.1 255.255.255.0
 isis enable 1  
#               
interface GigabitEthernet0/1/8
 undo shutdown  
 ip address 172.16.1.1 255.255.255.0
 isis enable 1  
#               
interface LoopBack1
 ip address 1.1.1.9 255.255.255.255
 isis enable 1  
 isis prefix-sid index 10
#
return

  • PE2 configuration file

    #
sysname PE2
#
mpls lsr-id 2.2.2.9
#               
mpls            
#               
segment-routing 
 tunnel-prefer segment-routing
#               
isis 1          
 is-level level-1
 cost-style wide
 network-entity 10.0000.0000.0002.00
 segment-routing mpls
 segment-routing global-block 160000 161000
#               
interface GigabitEthernet0/1/0
 undo shutdown  
 ip address 172.16.1.2 255.255.255.0
 isis enable 1  
#               
interface LoopBack1
 ip address 2.2.2.9 255.255.255.255
 isis enable 1  
 isis prefix-sid index 20
#
return

  • PE3 configuration file

    #
sysname PE3
#
mpls lsr-id 4.4.4.9
#               
mpls            
#               
segment-routing 
 tunnel-prefer segment-routing
#               
isis 1          
 is-level level-1
 cost-style wide
 network-entity 10.0000.0000.0004.00
 segment-routing mpls
 segment-routing global-block 160000 161000
#               
interface GigabitEthernet0/1/0
 undo shutdown  
 ip address 172.18.1.2 255.255.255.0
 isis enable 1  
#               
interface LoopBack0
 ip address 4.4.4.9 255.255.255.255
#               
interface LoopBack1
 ip address 2.2.2.9 255.255.255.255
 isis enable 1  
 isis prefix-sid index 20
#
return
Parent Topic: Configuring Examples for SR-MPLS BE
Copyright © Huawei Technologies Co., Ltd.
Copyright © Huawei Technologies Co., Ltd.
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