Example for Configuring IS-IS Auto FRR (IP Protecting IP)
Networking Requirements
As shown in Figure 7-39, four routers (RouterA, RouterB, RouterC, and RouterD) communicate using IS-IS. Reliability of data forwarding from RouterA to RouterD needs to be improved so that uninterrupted traffic transmission is ensured when a fault occurs on the network.
AR100&AR120&AR150&AR160&AR200 series do not support IS-IS Auto FRR.
Configuration Roadmap
The configuration roadmap is as follows:
Configure IP addresses for interfaces and enable IS-IS on each router to ensure reachable routes between the routers.
Set a larger link cost (in compliance with the traffic protection inequality of IS-IS Auto FRR) on GigabitEthernet2/0/0 of RouterA to ensure that Link T functions as the primary link to forward data from RouterA to RouterD.
Configure IS-IS Auto FRR on RouterA to allow traffic to be fast switched to the backup link without waiting for route convergence when a fault occurs on Link T. This ensures uninterrupted traffic transmission.
Procedure
- Configure IP addresses for interfaces on each router.
# Configure RouterA.
<Huawei> system-view[Huawei] sysname RouterA[RouterA] interface gigabitethernet 1/0/0[RouterA-GigabitEthernet1/0/0] ip address 10.1.0.1 24[RouterA-GigabitEthernet1/0/0] quit[RouterA] interface gigabitethernet 2/0/0[RouterA-GigabitEthernet2/0/0] ip address 10.2.0.1 24[RouterA-GigabitEthernet2/0/0] quitThe configurations of RouterB, RouterC, and RouterD are similar to the configuration of RouterA, and are not mentioned here.
- Configure basic IS-IS functions.
# Configure RouterA.
[RouterA] isis 1[RouterA-isis-1] is-level level-1-2[RouterA-isis-1] network-entity 10.0000.0000.0001.00[RouterA-isis-1] quit[RouterA] interface gigabitethernet 1/0/0[RouterA-GigabitEthernet1/0/0] isis enable 1[RouterA-GigabitEthernet1/0/0] quit[RouterA] interface gigabitethernet 2/0/0[RouterA-GigabitEthernet2/0/0] isis enable 1[RouterA-GigabitEthernet2/0/0] quit# Configure RouterB.
[RouterB] isis 1[RouterB-isis-1] is-level level-1-2[RouterB-isis-1] network-entity 10.0000.0000.0002.00[RouterB-isis-1] quit[RouterB] interface gigabitethernet 1/0/0[RouterB-GigabitEthernet1/0/0] isis enable 1[RouterB-GigabitEthernet1/0/0] quit[RouterB] interface gigabitethernet 2/0/0[RouterB-GigabitEthernet2/0/0] isis enable 1[RouterB-GigabitEthernet2/0/0] quit# Configure RouterC.
[RouterC] isis 1[RouterC-isis-1] is-level level-1-2[RouterC-isis-1] network-entity 10.0000.0000.0003.00[RouterC-isis-1] quit[RouterC] interface gigabitethernet 1/0/0[RouterC-GigabitEthernet1/0/0] isis enable 1[RouterC-GigabitEthernet1/0/0] quit[RouterC] interface gigabitethernet 2/0/0[RouterC-GigabitEthernet2/0/0] isis enable 1[RouterC-GigabitEthernet2/0/0] quit# Configure RouterD.
[RouterD] isis 1[RouterD-isis-1] is-level level-1-2[RouterD-isis-1] network-entity 10.0000.0000.0004.00[RouterD-isis-1] quit[RouterD] interface gigabitethernet 1/0/0[RouterD-GigabitEthernet1/0/0] isis enable 1[RouterD-GigabitEthernet1/0/0] quit[RouterD] interface gigabitethernet 2/0/0[RouterD-GigabitEthernet2/0/0] isis enable 1[RouterD-GigabitEthernet2/0/0] quit - Set the cost of GigabitEthernet2/0/0 on RouterA to 30, and check routing information.
# Set the cost of GigabitEthernet2/0/0 on RouterA to 30.
[RouterA] interface gigabitethernet 2/0/0[RouterA-GigabitEthernet2/0/0] isis cost 30[RouterA-GigabitEthernet2/0/0] quit# Check information about the link from RouterA to RouterD. Link T has a lower cost, and so IS-IS selects Link T to send traffic forwarded by RouterA.
<RouterA> display isis route 10.1.1.1 verbose Route information for ISIS(1) ----------------------------- ISIS(1) Level-1 Forwarding Table -------------------------------- IPV4 Dest : 10.1.1.0/24 Int. Cost : 30 Ext. Cost : NULL Admin Tag : - Src Count : 1 Flags : A/-/L/- Priority : Low NextHop : Interface : ExitIndex : 10.1.0.2 GE1/0/0 0x00000003 Flags: D-Direct, A-Added to URT, L-Advertised in LSPs, S-IGP Shortcut, U-Up/Down Bit Set ISIS(1) Level-2 Forwarding Table -------------------------------- IPV4 Dest : 10.1.1.0/24 Int. Cost : 30 Ext. Cost : NULL Admin Tag : - Src Count : 3 Flags : -/-/-/- Priority : Low Flags: D-Direct, A-Added to URT, L-Advertised in LSPs, S-IGP Shortcut, U-Up/Down Bit Set# Run the display fib 10.1.1.1 verbose command on RouterA to check the forwarding entry of traffic from RouterA to RouterD.
<RouterA> display fib 10.1.1.1 verbose Route Entry Count: 1 Destination: 10.1.1.0 Mask : 255.255.255.0 Nexthop : 10.1.0.2 OutIf : GigabitEthernet1/0/0 LocalAddr : 10.1.0.1 LocalMask: 0.0.0.0 Flags : DGU Age : 26sec ATIndex : 0 Slot : 0 LspFwdFlag : 0 LspToken : 0x0 InLabel : NULL OriginAs : 0 BGPNextHop : 0.0.0.0 PeerAs : 0 QosInfo : 0x0 OriginQos: 0x0 NexthopBak : 0.0.0.0 OutIfBak : [No Intf] LspTokenBak: 0x0 InLabelBak : NULL LspToken_ForInLabelBak : 0x0 EntryRefCount : 0 VlanId : 0x0 LspType : 0 Label_ForLspTokenBak : 0 MplsMtu : 0 Gateway_ForLspTokenBak : 0 NextToken : 0 IfIndex_ForLspTokenBak : 0 Label_NextToken : 0 Label : 0 LspBfdState : 0As shown in the command output, traffic from RouterA to RouterD is only forwarded through Link T.
- Enable IS-IS Auto FRR on RouterA, and check routing information.
# Enable IS-IS Auto FRR on RouterA.
[RouterA] isis [RouterA-isis-1] frr [RouterA-isis-1-frr]loop-free-alternate
# Check information about the routes from RouterA to RouterD. The information shows that IS-IS generates a backup link after IS-IS Auto FRR is enabled.
<RouterA> display isis route 10.1.1.1 verbose Route information for ISIS(1) ----------------------------- ISIS(1) Level-1 Forwarding Table -------------------------------- IPV4 Dest : 10.1.1.0/24 Int. Cost : 30 Ext. Cost : NULL Admin Tag : - Src Count : 1 Flags : A/-/L/- Priority : Low NextHop : Interface : ExitIndex : 10.1.0.2 GE1/0/0 0x00000003 (B)10.2.0.2 GE2/0/0 0x00000004 Flags: D-Direct, A-Added to URT, L-Advertised in LSPs, S-IGP Shortcut, U-Up/Down Bit Set ISIS(1) Level-2 Forwarding Table -------------------------------- IPV4 Dest : 10.1.1.0/24 Int. Cost : 30 Ext. Cost : NULL Admin Tag : - Src Count : 3 Flags : -/-/-/- Priority : Low Flags: D-Direct, A-Added to URT, L-Advertised in LSPs, S-IGP Shortcut, U-Up/Down Bit Set# Check the protection type for the traffic forwarded from RouterA to RouterD.
<RouterA> display isis spf-tree systemid 0000.0000.0004 verbose Shortest Path Tree for ISIS(1) ------------------------------ ISIS(1) Level-1 Shortest Path Tree ---------------------------------- 0000.0000.0004.00 Distance : 20 Distance-URT : 20 Flags : SPT/V6_Islt IPv4 Nexthops-URT : 1 (1) 10.1.0.2 IF:GE1/0/0 NBR:0000.0000.0003.00 (B) 10.2.0.2 IF:GE2/0/0 NBR:0000.0000.0002.00 TYPE:LOOP-FREE PROTECT:LINK-NODE IPv6 Nexthops : 0 Neighbors: 2 (Children:1 Parents:1 Others:0) (1) 0000.0000.0003.02 Cost : 10 Flags : Parent (2) 0000.0000.0004.03 Cost : 10 Flags : Child ISIS(1) Level-2 Shortest Path Tree ---------------------------------- 0000.0000.0004.00 Distance : 20 Distance-URT : 20 Flags : SPT/V6_Islt IPv4 Nexthops-URT : 1 (1) 10.1.0.2 IF:GE1/0/0 NBR:0000.0000.0003.00 (B) 10.2.0.2 IF:GE2/0/0 NBR:0000.0000.0002.00 TYPE:LOOP-FREE PROTECT:LINK-NODE IPv6 Nexthops : 0 Neighbors: 2 (Children:1 Parents:1 Others:0) (1) 0000.0000.0003.02 Cost : 10 Flags : Parent (2) 0000.0000.0004.03 Cost : 10 Flags : ChildAs shown in the preceding command output, link-node dual protection is performed on the traffic from RouterA to RouterD.
# Run the display fib 10.1.1.1 verbose command on RouterA to check the forwarding entry of traffic from RouterA to RouterD.
<RouterA> display fib 10.1.1.1 verbose Route Entry Count: 1 Destination: 10.1.1.0 Mask : 255.255.255.0 Nexthop : 10.1.0.2 OutIf : GigabitEthernet1/0/0 LocalAddr : 10.1.0.1 LocalMask: 0.0.0.0 Flags : DGU Age : 6sec ATIndex : 0 Slot : 0 LspFwdFlag : 0 LspToken : 0x0 InLabel : NULL OriginAs : 0 BGPNextHop : 0.0.0.0 PeerAs : 0 QosInfo : 0x0 OriginQos: 0x0 NexthopBak : 10.2.0.2 OutIfBak : GigabitEthernet2/0/0 LspTokenBak: 0x0 InLabelBak : NULL LspToken_ForInLabelBak : 0x0 EntryRefCount : 0 VlanId : 0x0 LspType : 0 Label_ForLspTokenBak : 0 MplsMtu : 0 Gateway_ForLspTokenBak : 0 NextToken : 0 IfIndex_ForLspTokenBak : 0 Label_NextToken : 0 Label : 0 LspBfdState : 0As shown in the command output, the primary link from RouterA to RouterD is Link T, the backup link follows the route with outbound interface GigabitEthernet2/0/0 and next hop 10.2.0.2.
- Verify the configuration.
# Run the shutdown command on GigabitEthernet2/0/0 of RouterC to shut down the link.
[RouterC] interface gigabitethernet 2/0/0[RouterC-GigabitEthernet2/0/0] shutdown# Run the display fib 10.1.1.1 verbose command on RouterA to check information about the route from RouterA to RouterD.
<RouterA> display fib 10.1.1.1 verbose Route Entry Count: 1 Destination: 10.1.1.0 Mask : 255.255.255.0 Nexthop : 10.2.0.2 OutIf : GigabitEthernet2/0/0 LocalAddr : 10.2.0.1 LocalMask: 0.0.0.0 Flags : DGU Age : 124sec ATIndex : 0 Slot : 0 LspFwdFlag : 0 LspToken : 0x0 InLabel : NULL OriginAs : 0 BGPNextHop : 0.0.0.0 PeerAs : 0 QosInfo : 0x0 OriginQos: 0x0 NexthopBak : 0.0.0.0 OutIfBak : [No Intf] LspTokenBak: 0x0 InLabelBak : NULL LspToken_ForInLabelBak : 0x0 EntryRefCount : 0 VlanId : 0x0 LspType : 0 Label_ForLspTokenBak : 0 MplsMtu : 0 Gateway_ForLspTokenBak : 0 NextToken : 0 IfIndex_ForLspTokenBak : 0 Label_NextToken : 0 Label : 0 LspBfdState : 0As shown in the command output, the traffic forwarded by the RouterA is switched to the backup link with outbound interface GigabitEthernet2/0/0 and next hop 10.2.0.2.
Configuration Files
Configuration file of RouterA
#
sysname RouterA#
isis 1
frr
loop-free-alternate level-1
loop-free-alternate level-2
network-entity 10.0000.0000.0001.00
#
interface GigabitEthernet 1/0/0
ip address 10.1.0.1 255.255.255.0
isis enable 1
#
interface GigabitEthernet 2/0/0
ip address 10.2.0.1 255.255.255.0
isis enable 1
isis cost 30
#
return
Configuration file of RouterB
#
sysname RouterB#
isis 1
network-entity 10.0000.0000.0002.00
#
interface GigabitEthernet 1/0/0
ip address 10.2.0.2 255.255.255.0
isis enable 1
#
interface GigabitEthernet 2/0/0
ip address 10.3.0.1 255.255.255.0
isis enable 1
#
return
Configuration file of RouterC
#
sysname RouterC#
isis 1
network-entity 10.0000.0000.0003.00
#
interface GigabitEthernet 1/0/0
ip address 10.1.0.2 255.255.255.0
isis enable 1
#
interface GigabitEthernet 2/0/0
shutdown
ip address 10.4.0.1 255.255.255.0
isis enable 1
#
return
Configuration file of RouterD
#
sysname RouterD#
isis 1
network-entity 10.0000.0000.0004.00
#
interface GigabitEthernet 1/0/0
ip address 10.4.0.2 255.255.255.0
isis enable 1
#
interface GigabitEthernet 2/0/0
ip address 10.3.0.2 255.255.255.0
isis enable 1
#
interface GigabitEthernet 3/0/0
ip address 10.1.1.1 255.255.255.0
isis enable 1
#
return
