2.15 Examples for Configuring of ISIS
2.15.6 Example for Configuring IS-IS Auto FRR (IP Protecting IP)
sysname RouterB
# bfd
# isis 1
is-level level-2
timer lsp-generation 1 1 120 level-1 timer lsp-generation 1 1 120 level-2 flash-flood level-1
flash-flood level-2
network-entity 10.0000.0000.0002.00 timer spf 1 20 100
#
interface GigabitEthernet1/0/0 ip address 100.1.1.2 255.255.255.0 isis enable 1
isis bfd static
#
bfd btoa bind peer-ip 100.1.1.1 interface GigabitEthernet1/0/0 discriminator local 2
discriminator remote 1 commit
# return
2.15.6 Example for Configuring IS-IS Auto FRR (IP Protecting IP)
Networking Requirements
As shown in Figure 2-15-6, 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.
Figure 2-15-6 Networking diagram of configuring IS-IS Auto FRR
Configuration Roadmap
The configuration roadmap is as follows:
1. Configure IP addresses for interfaces and enable IS-IS on each router to ensure reachable routes between the routers.
2. 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.
3. 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
1. Configure IP addresses for interfaces on each router.
# Configure RouterA.
[RouterA] interface gigabitethernet 1/0/0
[RouterA-GigabitEthernet1/0/0] ip address 1.0.0.1 24 [RouterA-GigabitEthernet1/0/0] quit
[RouterA] interface gigabitethernet 2/0/0
[RouterA-GigabitEthernet1/0/0] ip address 2.0.0.1 24
The configurations of RouterB, RouterC, and RouterD are similar to the configuration of RouterA, and are not mentioned here.
2016-1-11 Huawei Confidential Page 90 of 1210 2. 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
3. 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 100.1.1.1 verbose
Route information for ISIS(1) ---
ISIS(1) Level-1 Forwarding Table ---
IPV4 Dest : 100.1.1.0/24 Int. Cost : 30 Ext. Cost : NULL
Admin Tag : - Src Count : 1 Flags : A/-/L/- Priority : Low NextHop : Interface : ExitIndex : 1.0.0.2 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 : 100.1.1.0/24 Int. Cost : 30 Ext. Cost : NULL
Admin Tag : - Src Count : 3 Flags : -/-/-/-
2016-1-11 Huawei Confidential Page 92 of 1210 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 100.1.1.1 verbose command on RouterA to check the forwarding entry of traffic from RouterA to RouterD.
<RouterA> display fib 100.1.1.1 verbose
Route Entry Count: 1
Destination: 100.1.1.0 Mask : 255.255.255.0
Nexthop : 1.0.0.2 OutIf : GigabitEthernet1/0/0 LocalAddr : 1.0.0.1 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 : 0
As shown in the command output, traffic from RouterA to RouterD is only forwarded through Link T.
4. 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 100.1.1.1 verbose
Route information for ISIS(1) ---
ISIS(1) Level-1 Forwarding Table ---
IPV4 Dest : 100.1.1.0/24 Int. Cost : 30 Ext. Cost : NULL
Admin Tag : - Src Count : 1 Flags : A/-/L/- Priority : Low NextHop : Interface : ExitIndex : 1.0.0.2 GE1/0/0 0x00000003 (B)2.0.0.2 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 : 100.1.1.0/24 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
2016-1-11 Huawei Confidential Page 94 of 1210 As shown in the preceding command output, link-node dual protection is performed on the
traffic from RouterA to RouterD.
# Run the display fib 100.1.1.1 verbose command on RouterA to check the forwarding entry of traffic from RouterA to RouterD.
<RouterA> display fib 100.1.1.1 verbose Route Entry Count: 1
Destination: 100.1.1.0 Mask : 255.255.255.0
Nexthop : 1.0.0.2 OutIf : GigabitEthernet1/0/0 LocalAddr : 1.0.0.1 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 : 2.0.0.2 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 : 0
As 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 2.0.0.2.
5. 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 100.1.1.1 verbose command on RouterA to check information about the route from RouterA to RouterD.
<RouterA> display fib 100.1.1.1 verbose Route Entry Count: 1
Destination: 100.1.1.0 Mask : 255.255.255.0
Nexthop : 2.0.0.2 OutIf : GigabitEthernet2/0/0 LocalAddr : 2.0.0.1 LocalMask: 0.0.0.0
Flags : DGU Age : 124sec
2016-1-11 Huawei Confidential Page 96 of 1210 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 : 0
As 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 2.0.0.2.
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 1.0.0.1 255.255.255.0 isis enable 1
#
interface GigabitEthernet 2/0/0 ip address 2.0.0.1 255.255.255.0 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 2.0.0.2 255.255.255.0 isis enable 1
#
interface GigabitEthernet 2/0/0 ip address 3.0.0.1 255.255.255.0 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 1.0.0.2 255.255.255.0 isis enable 1
#
interface GigabitEthernet 2/0/0 shutdown
ip address 4.0.0.1 255.255.255.0 isis enable 1
# return
Configuration file of RouterD
#
sysname RouterD
2016-1-11 Huawei Confidential Page 98 of 1210
# isis 1
network-entity 10.0000.0000.0004.00
#
interface GigabitEthernet 1/0/0 ip address 4.0.0.2 255.255.255.0 isis enable 1
#
interface GigabitEthernet 2/0/0 ip address 3.0.0.2 255.255.255.0 isis enable 1
#
interface GigabitEthernet 3/0/0 ip address 100.1.1.1 255.255.255.0 isis enable 1
# return