Table of contents
Chapter 2 Features and Configuration of IS-IS Protocol
Experiment 2-1 IS-IS configuration experiment
Step 1. IP addressing and basic configuration
Step 2. Basic configuration of IS-IS protocol
Step 3. Modify the DIS priority
Step 4. Configure the IS-IS network type
Step 5. Configure IS-IS external route import
Step 6. Modify the Cost value of the IS-IS interface
Step 7. Configure IS-IS route penetration
Chapter 2 Features and Configuration of IS-IS Protocol
Experiment 2- 1 IS-IS configuration experiment
Experimental objectives
Master the basic configuration of IS-IS protocol
Master the IS-IS protocol DIS priority modification method
Master the modification method of IS-IS protocol network type
·Master IS-IS protocol to import external routes
Master the cost modification method of IS-IS interface
Master the IS-IS route penetration configuration method
Topology
Figure 2-1 IS-IS experimental topology
Scenes
Use IS-IS as the IGP of a network. R1 and R5 run in Level-2 area 49.0002. R2, R3, and R4 run in Area 49.0001. R4 is a Level-1 router, and R2 and R3 are Level-1-2 routers. Requirements: R4 can access the external routes imported by R5; the interface connecting R4 to S5 is used as DIS; R1 and R5 use a point-to-point link; the uplink and downlink traffic from R4 to R5 should be forwarded through the Ethernet interface, and route selection can be controlled through cost and route penetration; the switch does not perform additional configuration, only transparent forwarding.
Learning tasks
Step 1. IP addressing and basic configuration
Configure IP address information for all routers.
[R1]interface loopback 0
[R1-LoopBack0]ip address 10.0.1.1 32
[R1-LoopBack0]quit
[R1]interface GigabitEthernet 0/0/0
[R1-GigabitEthernet0/0/0]ip address 10.0.15.1 24
[R1-GigabitEthernet0/0/0]quit
[R1]interface GigabitEthernet 0/0/1
[R1-GigabitEthernet0/0/1]ip address 10.0.13.1 24
[R1-GigabitEthernet0/0/1]quit
[R1]interface interface Serial1/0/0
[R1-Serial1/0/0]ip address 10.0.12.1 24
[R1-Serial1/0/0]quit
[R2]interface LoopBack 0
[R2-LoopBack0]ip address 10.0.2.2 32
[R2-LoopBack0]quit
[R2]interface GigabitEthernet 0/0/0
[R2-GigabitEthernet0/0/0]ip address 10.0.234.2 24
[R2-GigabitEthernet0/0/0]quit
[R2]interface Serial1/0/0
[R2-Serial1/0/0]ip address 10.0.12.2 24
[R2-Serial1/0/0]quit
[R3]interface LoopBack 0
[R3-LoopBack0]ip address 10.0.3.3 32
[R3-LoopBack0]quit
[R3]interface GigabitEthernet 0/0/0
[R3-GigabitEthernet0/0/0]ip address 10.0.234.3 24
[R3-GigabitEthernet0/0/0]quit
[R3]interface GigabitEthernet 0/0/1
[R3-GigabitEthernet0/0/1]ip address 10.0.13.3 24
[R3-GigabitEthernet0/0/1]quit
[R4]interface LoopBack 0
[R4-LoopBack0]ip address 10.0.4.4 32
[R4-LoopBack0]quit
[R4]interface GigabitEthernet 0/0/0
[R4-GigabitEthernet0/0/0]ip address 10.0.234.4 24
[R4-GigabitEthernet0/0/0]quit
[R5]interface LoopBack 0
[R5-LoopBack0]ip address 10.0.5.5 32
[R5-LoopBack0]quit
[R5]interface GigabitEthernet 0/0/0
[R5-GigabitEthernet0/0/0]ip address 10.0.15.5 24
[R5-GigabitEthernet0/0/0]quit
After the configuration is complete, test the connectivity on R1 to the direct ports of R2, R3, and R5.
[R1]ping -c 1 10.0.13.3
PING 10.0.13.3: 56 data bytes, press CTRL_C to break
Reply from 10.0.13.3: bytes=56 Sequence=1 ttl=255 time=1 ms
--- 10.0.13.3 ping statistics ---
1 packet(s) transmitted
1 packet(s) received
0.00% packet loss
round-trip min/avg/max = 1/1/1 ms
[R1]ping -c 1 10.0.12.2
PING 10.0.12.2: 56 data bytes, press CTRL_C to break
Reply from 10.0.12.2: bytes=56 Sequence=1 ttl=255 time=26 ms
--- 10.0.12.2 ping statistics ---
1 packet(s) transmitted
1 packet(s) received
0.00% packet loss
round-trip min/avg/max = 26/26/26 ms
[R1]ping -c 1 10.0.15.5
PING 10.0.15.5: 56 data bytes, press CTRL_C to break
Reply from 10.0.15.5: bytes=56 Sequence=1 ttl=255 time=1 ms
--- 10.0.15.5 ping statistics ---
1 packet(s) transmitted
1 packet(s) received
0.00% packet loss
round-trip min/avg/max = 1/1/1 ms
Test the connectivity from R4 to the direct interface between R2 and R3.
[R4]ping -c 1 10.0.234.2
PING 10.0.234.2: 56 data bytes, press CTRL_C to break
Reply from 10.0.234.2: bytes=56 Sequence=1 ttl=255 time=1 ms
--- 10.0.234.2 ping statistics ---
1 packet(s) transmitted
1 packet(s) received
0.00% packet loss
round-trip min/avg/max = 1/1/1 ms
[R4]ping -c 1 10.0.234.3
PING 10.0.234.3: 56 data bytes, press CTRL_C to break
Reply from 10.0.234.3: bytes=56 Sequence=1 ttl=255 time=1 ms
--- 10.0.234.3 ping statistics ---
1 packet(s) transmitted
1 packet(s) received
0.00% packet loss
round-trip min/avg/max = 1/1/1 ms
Step 2. Basic configuration of IS-IS protocol
Configure the isis process of routers one by one according to the topology design. The process number is 1. Take R1 as an example:
Since R1 is in area 49.0002, use network-entity 49.0002.0000.0000.0001.
[R1]isis
[R1-isis-1]network-entity 49.0002.0000.0000.0001.00
By default, after the IS-IS process is enabled, the router works in Level-1-2 mode. According to the plan, R1 should be in L2 mode, so modify it:
[R1-isis-1]is-level level-2
[R1-isis-1]quit
Enable IS-IS on the corresponding interface, including the LoopBack interface. If the IS-IS process number is not specified, it will be enabled under process 1 by default:
[R1]interface LoopBack 0
[R1-LoopBack0]isis enable
[R1-LoopBack0]quit
[R1]interface GigabitEthernet 0/0/0
[R1-GigabitEthernet0/0/0]isis enable
[R1-GigabitEthernet0/0/0]quit
[R1]interface GigabitEthernet 0/0/1
[R1-GigabitEthernet0/0/1]isis enable
[R1-GigabitEthernet0/0/1]quit
[R1]interface Serial 1/0/0
[R1-Serial1/0/0]isis enable
[R1-Serial1/0/0]quit
Check the enabling status of IS-IS on the interface:
[R1]display isis interface
Interface information for ISIS(1)
---------------------------------
Interface Id IPV4.State IPV6.State MTU Type DIS
Loop0 001 Up Down 1500 L1/L2 --
GE0/0/0 001 Up Down 1497 L1/L2 No/No
GE0/0/1 002 Up Down 1497 L1/L2 No/No
S1/0/0 002 Up Down 1500 L1/L2 --
You can see that ISIS(1) has enabled 4 interfaces in total, and the status is Up under the IPV4 address.
Configure other routers in the same way, R2 and R3 work in Level-1-2 mode, so there is no need to modify is-level:
[R2]isis 1
[R2-isis-1]network-entity 49.0001.0000.0000.0002.00
[R2-isis-1]quit
[R2]interface LoopBack 0
[R2-LoopBack0]isis enable
[R2-LoopBack0]quit
[R2]interface GigabitEthernet 0/0/0
[R2-GigabitEthernet0/0/0]isis enable
[R2-GigabitEthernet0/0/0]quit
[R2]interface Serial 1/0/0
[R2-Serial1/0/0]isis enable
[R2-Serial1/0/0]quit
Check whether IS-IS is enabled on the interface on R2:
[R2]display isis interface
Interface information for ISIS(1)
---------------------------------
Interface Id IPV4.State IPV6.State MTU Type DIS
Loop0 002 Up Down 1500 L1/L2 --
GE0/0/0 001 Up Down 1497 L1/L2 No/No
S1/0/0 001 Up Down 1500 L1/L2 --
Configure IS-IS on R3:
[R3]isis 1
[R3-isis-1]network-entity 49.0001.0000.0000.0003.00
[R3-isis-1]quit
[R3]interface LoopBack 0
[R3-LoopBack0]isis enable
[R3-LoopBack0]quit
[R3]interface GigabitEthernet 0/0/0
[R3-GigabitEthernet0/0/0]isis enable
[R3-GigabitEthernet0/0/0]quit
[R3]interface GigabitEthernet 0/0/1
[R3-GigabitEthernet0/0/1]isis enable
[R3-GigabitEthernet0/0/1]quit
Check whether IS-IS is enabled on the interface on R3:
[R3]display isis interface
Interface information for ISIS(1)
---------------------------------
Interface Id IPV4.State IPV6.State MTU Type DIS
Loop0 001 Up Down 1500 L1/L2 --
GE0/0/0 002 Up Down 1497 L1/L2 No/No
GE0/0/1 001 Up Down 1497 L1/L2 No/No
Configure IS-IS on R4:
[R4]isis 1
[R4-isis-1]network-entity 49.0001.0000.0000.0004.00
[R4-isis-1]is-level level-1
[R4-isis-1] quit
[R4]interface LoopBack 0
[R4-LoopBack0]isis enable
[R4-LoopBack0]quit
[R4]interface GigabitEthernet 0/0/0
[R4-GigabitEthernet0/0/0]isis enable
[R4-GigabitEthernet0/0/0]quit
Check the enabling status of IS-IS on the interface on R4:
[R4]display isis interface
Interface information for ISIS(1)
---------------------------------
Interface Id IPV4.State IPV6.State MTU Type DIS
Loop0 001 Up Down 1500 L1/L2 --
GE0/0/0 001 Up Down 1497 L1/L2 No/No
Configure IS-IS on R5:
[R5]isis 1
[R5-isis-1]network-entity 49.0002.0000.0000.0005.00
[R5-isis-1]is-level level-2
[R5-isis-1]quit
[R5]interface LoopBack 0
[R5-LoopBack0]isis enable
[R5-LoopBack0]quit
[R5]interface GigabitEthernet 0/0/0
[R5-GigabitEthernet0/0/0]isis enable
[R5-GigabitEthernet0/0/0]quit
Check the enabling status of IS-IS on the interface on R5:
[R5]display isis interface
Interface information for ISIS(1)
---------------------------------
Interface Id IPV4.State IPV6.State MTU Type DIS
Loop0 001 Up Down 1500 L1/L2 --
GE0/0/0 001 Up Down 1497 L1/L2 No/No
After the configuration is complete, observe the neighbor status of each device. Taking R1 as an example, there should be 3 neighbors, namely R2, R3 and R5:
[R1]display isis peer
Peer information for ISIS(1)
System Id Interface Circuit Id State HoldTime Type PRI
----------------------------------------------------------------------------
0000.0000.0005 GE0/0/0 0000.0000.0005.01 Up 7s L2 64
0000.0000.0003 GE0/0/1 0000.0000.0001.02 Up 21s L2 64
0000.0000.0002 S1/0/0 0000000001 Up 28s L2 --
Total Peer(s): 3
The System Id here is similar to the Router Id of other protocols. You can see that the statuses of R2, R3, and R5 are all Up, and the status of the neighbors is normal.
Proceed to check the neighbor status of other devices:
[R2]display isis peer
Peer information for ISIS(1)
System Id Interface Circuit Id State HoldTime Type PRI
----------------------------------------------------------------------------
0000.0000.0001 S1/0/0 0000000001 Up 22s L2 --
0000.0000.0003 GE0/0/0 0000.0000.0004.01 Up 24s L1(L1L2) 64
0000.0000.0004 GE0/0/0 0000.0000.0004.01 Up 7s L1 64
0000.0000.0003 GE0/0/0 0000.0000.0002.01 Up 26s L2(L1L2) 64
Total Peer(s): 4
[R3]display isis peer
Peer information for ISIS(1)
System Id Interface Circuit Id State HoldTime Type PRI
----------------------------------------------------------------------------
0000.0000.0001 GE0/0/1 0000.0000.0001.02 Up 8s L2 64
0000.0000.0002 GE0/0/0 0000.0000.0004.01 Up 30s L1(L1L2) 64
0000.0000.0004 GE0/0/0 0000.0000.0004.01 Up 7s L1 64
0000.0000.0002 GE0/0/0 0000.0000.0002.01 Up 9s L2(L1L2) 64
Total Peer(s): 4
[R4]display isis peer
Peer information for ISIS(1)
System Id Interface Circuit Id State HoldTime Type PRI
----------------------------------------------------------------------------
0000.0000.0003 GE0/0/0 0000.0000.0004.01 Up 29s L1 64
0000.0000.0002 GE0/0/0 0000.0000.0004.01 Up 23s L1 64
Total Peer(s): 2
[R5]display isis peer
Peer information for ISIS(1)
System Id Interface Circuit Id State HoldTime Type PRI
----------------------------------------------------------------------------
0000.0000.0001 GE0/0/0 0000.0000.0005.01 Up 29s L2 64
Total Peer(s): 1
Step 3. Modify the DIS priority
R2, R3, and R4 establish neighbors under a broadcast network, so they need to elect a DIS. By default, the DIS priority is 64. If the interface with the same priority and a larger MAC address will become the DIS, we hope that the election will be clearer, so modify the DIS priority of R4 to ensure that it becomes the DIS.
[R4]interface GigabitEthernet 0/0/0
[R4-GigabitEthernet0/0/0]isis dis-priority 120
[R4-GigabitEthernet0/0/0]quit
[R4]display isis interface
Interface information for ISIS(1)
---------------------------------
Interface Id IPV4.State IPV6.State MTU Type DIS
GE0/0/0 001 Up Down 1497 L1/L2 Yes/No
Loop0 001 Up Down 1500 L1/L2 –
Check the neighbor's DIS priority on R2 and R3:
[R2]display isis peer
Peer information for ISIS(1)
System Id Interface Circuit Id State HoldTime Type PRI
----------------------------------------------------------------------------
0000.0000.0001 S1/0/0 0000000001 Up 29s L2 --
0000.0000.0003 GE0/0/0 0000.0000.0004.01 Up 25s L1(L1L2) 64
0000.0000.0004 GE0/0/0 0000.0000.0004.01 Up 8s L1 120
0000.0000.0003 GE0/0/0 0000.0000.0002.01 Up 20s L2(L1L2) 64
Total Peer(s): 4
[R3]display isis peer
Peer information for ISIS(1)
System Id Interface Circuit Id State HoldTime Type PRI
----------------------------------------------------------------------------
0000.0000.0001 GE0/0/1 0000.0000.0001.02 Up 8s L2 64
0000.0000.0002 GE0/0/0 0000.0000.0004.01 Up 22s L1(L1L2) 64
0000.0000.0004 GE0/0/0 0000.0000.0004.01 Up 7s L1 120
0000.0000.0002 GE0/0/0 0000.0000.0002.01 Up 8s L2(L1L2) 64
Total Peer(s): 4
Step 4. Configure the IS-IS network type
On a broadcast network, IS-IS sets the circuit-type of the interface to broadcast mode by default and participates in DIS election. However, there are only two routers in the Ethernet between R1 and R5 in the topology. We can set the interconnection interface between these two routers to point-to-point mode for optimization.
[R1]interface GigabitEthernet 0/0/0
[R1-GigabitEthernet0/0/0]isis circuit-type p2p
[R1-GigabitEthernet0/0/0]quit
[R5]interface GigabitEthernet 0/0/0
[R5-GigabitEthernet0/0/0]isis circuit-type p2p
[R5-GigabitEthernet0/0/0]quit
During the process of modifying the circuit-type, the neighbor will be re-established. Check the configuration effect, the format of the Circuit Id will be changed, and the detailed information of the interface will also display p2p. Take R1 as an example:
[R1]display isis peer
Peer information for ISIS(1)
System Id Interface Circuit Id State HoldTime Type PRI
----------------------------------------------------------------------------
0000.0000.0005 GE0/0/0 0000000002 Up 22s L2 --
0000.0000.0003 GE0/0/1 0000.0000.0001.02 Up 27s L2 64
0000.0000.0002 S1/0/0 0000000001 Up 22s L2 --
[R1]display isis interface GigabitEthernet 0/0/0 verbose
Interface information for ISIS(1)
---------------------------------
Interface Id IPV4.State IPV6.State MTU Type DIS
GE0/0/0 003 Up Down 1497 L1/L2 --
Circuit MT State : Standard
Circuit Parameters : p2p
Description : HUAWEI, AR Series, GigabitEthernet0/0/0 Interface
SNPA Address : d0d0-4b03-d3fc
IP Address : 10.0.15.1
IPV6 Link Local Address :
IPV6 Global Address(es) :
Csnp Timer Value : L12 10
Hello Timer Value : 10
DIS Hello Timer Value :
Hello Multiplier Value : 3
Cost : L1 10 L2 10
Ipv6 Cost : L1 10 L2 10
Retransmit Timer Value : L12 5
LSP-Throttle Timer : L12 50
Bandwidth-Value : Low 100000000 High 0
Static Bfd : NO
Dynamic Bfd : NO
Fast-Sense Rpr : NO
Extended-Circuit-Id Value : 0000000003
Step 5. Configure I S-IS external route import
Before importing routes, check the learning status of all current routes. The route from R1 to R4 is in a load-balanced state, and data packets will be evenly distributed between GE0/0/1 and S1/0/0:
[R1]display isis route
Route information for ISIS(1)
-----------------------------
ISIS(1) Level-2 Forwarding Table
--------------------------------
IPV4 Destination IntCost ExtCost ExitInterface NextHop Flags
----------------------------------------------------------------------------
10.0.4.4/32 20 NULL GE0/0/1 10.0.13.3 A/-/-/-
S1/0/0 10.0.12.2
10.0.5.5/32 10 NULL GE0/0/0 10.0.15.5 A/-/-/-
10.0.12.0/24 10 NULL S1/0/0 Direct D/-/L/-
10.0.13.0/24 10 NULL GE0/0/1 Direct D/-/L/-
10.0.234.0/24 20 NULL S1/0/0 10.0.12.2 A/-/-/-
GE0/0/1 10.0.13.3
10.0.15.0/24 10 NULL GE0/0/0 Direct D/-/L/-
10.0.1.1/32 0 NULL Loop0 Direct D/-/L/-
10.0.2.2/32 10 NULL S1/0/0 10.0.12.2 A/-/-/-
10.0.3.3/32 10 NULL GE0/0/1 10.0.13.3 A/-/-/-
Flags: D-Direct, A-Added to URT, L-Advertised in LSPs, S-IGP Shortcut,
U-Up/Down Bit Set
[R1]display ip routing-table protocol isis
Route Flags: R - relay, D - download to fib
----------------------------------------------------------------------------
Public routing table : ISIS
Destinations : 5 Routes : 7
ISIS routing table status : <Active>
Destinations : 5 Routes : 7
Destination/Mask Proto Pre Cost Flags NextHop Interface
10.0.2.2/32 ISIS-L2 15 10 D 10.0.12.2 Serial1/0/0
10.0.3.3/32 ISIS-L2 15 10 D 10.0.13.3 GigabitEthernet0/0/1
10.0.4.4/32 ISIS-L2 15 20 D 10.0.13.3 GigabitEthernet0/0/1
ISIS-L2 15 20 D 10.0.12.2 Serial1/0/0
10.0.5.5/32 ISIS-L2 15 10 D 10.0.15.5 GigabitEthernet0/0/0
10.0.234.0/24 ISIS-L2 15 20 D 10.0.12.2 Serial1/0/0
ISIS-L2 15 20 D 10.0.13.3 GigabitEthernet0/0/1
ISIS routing table status : <Inactive>
Destinations : 0 Routes : 0
Because R2 is a LEVEL-1-2 router, different routes are generated at the two levels. Note that there will be an entry for the default route at level1, which points to an empty interface. The situation of R3 and R2 is the same:
[R2]display isis route
Route information for ISIS(1)
-----------------------------
ISIS(1) Level-1 Forwarding Table
--------------------------------
IPV4 Destination IntCost ExtCost ExitInterface NextHop Flags
----------------------------------------------------------------------------
0.0.0.0/0 10 NULL
10.0.4.4/32 10 NULL GE0/0/0 10.0.234.4 A/-/L/-
10.0.12.0/24 10 NULL S1/0/0 Direct D/-/L/-
10.0.13.0/24 20 NULL GE0/0/0 10.0.234.3 A/-/L/-
10.0.234.0/24 10 NULL GE0/0/0 Direct D/-/L/-
10.0.2.2/32 0 NULL Loop0 Direct D/-/L/-
10.0.3.3/32 10 NULL GE0/0/0 10.0.234.3 A/-/L/-
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 Destination IntCost ExtCost ExitInterface NextHop Flags
----------------------------------------------------------------------------
10.0.4.4/32 20 NULL
10.0.5.5/32 20 NULL S1/0/0 10.0.12.1 A/-/-/-
10.0.12.0/24 10 NULL S1/0/0 Direct D/-/L/-
10.0.13.0/24 20 NULL
10.0.234.0/24 10 NULL GE0/0/0 Direct D/-/L/-
10.0.15.0/24 20 NULL S1/0/0 10.0.12.1 A/-/-/-
10.0.1.1/32 10 NULL S1/0/0 10.0.12.1 A/-/-/-
10.0.2.2/32 0 NULL Loop0 Direct D/-/L/-
10.0.3.3/32 10 NULL
Flags: D-Direct, A-Added to URT, L-Advertised in LSPs, S-IGP Shortcut,
U-Up/Down Bit Set
[R2]display ip routing-table protocol isis
Route Flags: R - relay, D - download to fib
----------------------------------------------------------------------------
Public routing table : ISIS
Destinations : 6 Routes : 6
ISIS routing table status : <Active>
Destinations : 6 Routes : 6
Destination/Mask Proto Pre Cost Flags NextHop Interface
10.0.1.1/32 ISIS-L2 15 10 D 10.0.12.1 Serial1/0/0
10.0.3.3/32 ISIS-L1 15 10 D 10.0.234.3 GigabitEthernet0/0/0
10.0.4.4/32 ISIS-L1 15 10 D 10.0.234.4 GigabitEthernet0/0/0
10.0.5.5/32 ISIS-L2 15 20 D 10.0.12.1 Serial1/0/0
10.0.13.0/24 ISIS-L1 5 20 D 10.0.234.3 GigabitEthernet0/0/0
10.0.15.0/24 ISIS-L2 15 20 D 10.0.12.1 Serial1/0/0
ISIS routing table status : <Inactive>
Destinations : 0 Routes : 0
[R3]display isis route
Route information for ISIS(1)
-----------------------------
ISIS(1) Level-1 Forwarding Table
--------------------------------
IPV4 Destination IntCost ExtCost ExitInterface NextHop Flags
----------------------------------------------------------------------------
0.0.0.0/0 10 NULL
10.0.4.4/32 10 NULL GE0/0/0 10.0.234.4 A/-/L/-
10.0.12.0/24 20 NULL GE0/0/0 10.0.234.2 A/-/L/-
10.0.13.0/24 10 NULL GE0/0/1 Direct D/-/L/-
10.0.234.0/24 10 NULL GE0/0/0 Direct D/-/L/-
10.0.2.2/32 10 NULL GE0/0/0 10.0.234.2 A/-/L/-
10.0.3.3/32 0 NULL Loop0 Direct D/-/L/-
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 Destination IntCost ExtCost ExitInterface NextHop Flags
----------------------------------------------------------------------------
10.0.4.4/32 20 NULL
10.0.5.5/32 20 NULL GE0/0/1 10.0.13.1 A/-/-/-
10.0.12.0/24 20 NULL
10.0.13.0/24 10 NULL GE0/0/1 Direct D/-/L/-
10.0.234.0/24 10 NULL GE0/0/0 Direct D/-/L/-
10.0.15.0/24 20 NULL GE0/0/1 10.0.13.1 A/-/-/-
10.0.1.1/32 10 NULL GE0/0/1 10.0.13.1 A/-/-/-
10.0.2.2/32 10 NULL
10.0.3.3/32 0 NULL Loop0 Direct D/-/L/-
Flags: D-Direct, A-Added to URT, L-Advertised in LSPs, S-IGP Shortcut,
U-Up/Down Bit Set
[R3]display ip routing-table protocol isis
Route Flags: R - relay, D - download to fib
----------------------------------------------------------------------------
Public routing table : ISIS
Destinations : 6 Routes : 6
ISIS routing table status : <Active>
Destinations : 6 Routes : 6
Destination/Mask Proto Pre Cost Flags NextHop Interface
10.0.1.1/32 ISIS-L2 15 10 D 10.0.13.1 GigabitEthernet0/0/1
10.0.2.2/32 ISIS-L1 15 10 D 10.0.234.2 GigabitEthernet0/0/0
10.0.4.4/32 ISIS-L1 15 10 D 10.0.234.4 GigabitEthernet0/0/0
10.0.5.5/32 ISIS-L2 15 20 D 10.0.13.1 GigabitEthernet0/0/1
10.0.12.0/24 ISIS-L1 15 20 D 10.0.234.2 GigabitEthernet0/0/0
10.0.15.0/24 ISIS-L2 15 20 D 10.0.13.1 GigabitEthernet0/0/1
ISIS routing table status : <Inactive>
Destinations : 0 Routes : 0
Since R4 is an L1 router, it can only establish neighbors with L1 or LEVEL-1-2 routers in the same area, and by default, the L1 router cannot learn the routing information of L2, and can only access the outside through the default route. R4 can see that the two default routes point to R2 and R3, showing load balancing.
[R4]display isis route
Route information for ISIS(1)
-----------------------------
ISIS(1) Level-1 Forwarding Table
--------------------------------
IPV4 Destination IntCost ExtCost ExitInterface NextHop Flags
----------------------------------------------------------------------------
0.0.0.0/0 10 NULL GE0/0/0 10.0.234.3 A/-/-/-
GE0/0/0 10.0.234.2
10.0.4.4/32 0 NULL Loop0 Direct D/-/L/-
10.0.12.0/24 20 NULL GE0/0/0 10.0.234.2 A/-/-/-
10.0.13.0/24 20 NULL GE0/0/0 10.0.234.3 A/-/-/-
10.0.234.0/24 10 NULL GE0/0/0 Direct D/-/L/-
10.0.2.2/32 10 NULL GE0/0/0 10.0.234.2 A/-/-/-
10.0.3.3/3 10 NULL GE0/0/0 10.0.234.3 A/-/-/-
Flags: D-Direct, A-Added to URT, L-Advertised in LSPs, S-IGP Shortcut,
U-Up/Down Bit Set
[R4]display ip routing protocol isis
Route Flags: R - relay, D - download to fib
----------------------------------------------------------------------------
Public routing table : ISIS
Destinations : 5 Routes : 6
ISIS routing table status : <Active>
Destinations : 5 Routes : 6
Destination/Mask Proto Pre Cost Flags NextHop Interface
0.0.0.0/0 ISIS-L1 15 10 D 10.0.234.3 GigabitEthernet0/0/0
ISIS-L1 15 10 D 10.0.234.2 GigabitEthernet0/0/0
10.0.2.2/32 ISIS-L1 15 10 D 10.0.234.2 GigabitEthernet0/0/0
10.0.3.3/32 ISIS-L1 15 10 D 10.0.234.3 GigabitEthernet0/0/0
10.0.12.0/24 ISIS-L1 15 20 D 10.0.234.2 GigabitEthernet0/0/0
10.0.13.0/24 ISIS-L1 15 20 D 10.0.234.3 GigabitEthernet0/0/0
ISIS routing table status : <Inactive>
Destinations : 0 Routes : 0
Before R5 imports external routes, the route learning situation:
[R5]display isis route
Route information for ISIS(1)
-----------------------------
ISIS(1) Level-2 Forwarding Table
--------------------------------
IPV4 Destination IntCost ExtCost ExitInterface NextHop Flags
10.0.4.4/32 30 NULL GE0/0/0 10.0.15.1 A/-/-/-
10.0.5.5/32 0 NULL Loop0 Direct D/-/L/-
10.0.12.0/24 20 NULL GE0/0/0 10.0.15.1 A/-/-/-
10.0.13.0/24 20 NULL GE0/0/0 10.0.15.1 A/-/-/-
10.0.234.0/24 30 NULL GE0/0/0 10.0.15.1 A/-/-/-
10.0.15.0/24 10 NULL GE0/0/0 Direct D/-/L/-
10.0.1.1/32 10 NULL GE0/0/0 10.0.15.1 A/-/-/-
10.0.2.2/32 20 NULL GE0/0/0 10.0.15.1 A/-/-/-
10.0.3.3/32 20 NULL GE0/0/0 10.0.15.1 A/-/-/-
Flags: D-Direct, A-Added to URT, L-Advertised in LSPs, S-IGP Shortcut,
U-Up/Down Bit Set
[R5]display ip routing-table protocol isis
Route Flags: R - relay, D - download to fib
----------------------------------------------------------------------------
Public routing table : ISIS
Destinations : 7 Routes : 7
ISIS routing table status : <Active>
Destinations : 7 Routes : 7
Destination/Mask Proto Pre Cost Flags NextHop Interface
10.0.1.1/32 ISIS-L2 15 10 D 10.0.15.1 GigabitEthernet0/0/0
10.0.2.2/32 ISIS-L2 15 20 D 10.0.15.1 GigabitEthernet0/0/0
10.0.3.3/32 ISIS-L2 15 20 D 10.0.15.1 GigabitEthernet0/0/0
10.0.4.4/32 ISIS-L2 15 30 D 10.0.15.1 GigabitEthernet0/0/0
10.0.12.0/24 ISIS-L2 15 20 D 10.0.15.1 GigabitEthernet0/0/0
10.0.13.0/24 ISIS-L2 15 20 D 10.0.15.1 GigabitEthernet0/0/0
10.0.234.0/24 ISIS-L2 15 30 D 10.0.15.1 GigabitEthernet0/0/0
ISIS routing table status : <Inactive>
Destinations : 0 Routes : 0
Create a new LoopBack port on R5 and introduce it to the isis process:
[R5]interface LoopBack 1
[R5-LoopBack1]ip address 192.168.1.1 24
[R5-LoopBack1]quit
[R5]interface LoopBack 2
[R5-LoopBack2]ip address 192.168.2.1 24
[R5-LoopBack2]quit
[R5]interface LoopBack 3
[R5-LoopBack3]ip address 192.168.3.1 24
[R5-LoopBack3]quit
[R5]isis
[R5-isis-1]import-route direct level-2
[R5-isis-1]quit
Import level-2 into the direct route on R5, and check the effect:
[R5]display isis route
Route information for ISIS(1)
-----------------------------
ISIS(1) Level-2 Forwarding Table
--------------------------------
IPV4 Destination IntCost ExtCost ExitInterface NextHop Flags
----------------------------------------------------------------------------
10.0.4.4/32 30 NULL GE0/0/0 10.0.15.1 A/-/-/-
10.0.5.5/32 0 NULL Loop0 Direct D/-/L/-
10.0.12.0/24 20 NULL GE0/0/0 10.0.15.1 A/-/-/-
10.0.13.0/24 20 NULL GE0/0/0 10.0.15.1 A/-/-/-
10.0.234.0/24 30 NULL GE0/0/0 10.0.15.1 A/-/-/-
10.0.15.0/24 10 NULL GE0/0/0 Direct D/-/L/-
10.0.1.1/32 10 NULL GE0/0/0 10.0.15.1 A/-/-/-
10.0.2.2/32 20 NULL GE0/0/0 10.0.15.1 A/-/-/-
10.0.3.3/32 20 NULL GE0/0/0 10.0.15.1 A/-/-/-
Flags: D-Direct, A-Added to URT, L-Advertised in LSPs, S-IGP Shortcut,
U-Up/Down Bit Set
ISIS(1) Level-2 Redistribute Table
----------------------------------
Type IPV4 Destination IntCost ExtCost Tag
----------------------------------------------------------------------------
D 192.168.1.0/24 0 0
D 192.168.2.0/24 0 0
D 192.168.3.0/24 0 0
Type: D-Direct, I-ISIS, S-Static, O-OSPF, B-BGP, R-RIP, U-UNR
At this time, check the routing table again on R4 and find that there is no change. The reason is that by default, the L2 route will not penetrate into the L1 router, but through the default route, R4 can access 192.168.1.0/24, 192.168.2.0/24 and 192.168.3.0/24.
[R4]display ip routing-table protocol isis
Route Flags: R - relay, D - download to fib
----------------------------------------------------------------------------
Public routing table : ISIS
Destinations : 5 Routes : 6
ISIS routing table status : <Active>
Destinations : 5 Routes : 6
Destination/Mask Proto Pre Cost Flags NextHop Interface
0.0.0.0/0 ISIS-L1 15 10 D 10.0.234.3 GigabitEthernet0/0/0
ISIS-L1 15 10 D 10.0.234.2 GigabitEthernet0/0/0
10.0.2.2/32 ISIS-L1 15 10 D 10.0.234.2 GigabitEthernet0/0/0
10.0.3.3/32 ISIS-L1 15 10 D 10.0.234.3 GigabitEthernet0/0/0
10.0.12.0/24 ISIS-L1 15 20 D 10.0.234.2 GigabitEthernet0/0/0
10.0.13.0/24 ISIS-L1 15 20 D 10.0.234.3 GigabitEthernet0/0/0
ISIS routing table status : <Inactive>
Destinations : 0 Routes : 0
[R4]ping -c 1 192.168.1.1
PING 192.168.1.1: 56 data bytes, press CTRL_C to break
Reply from 192.168.1.1: bytes=56 Sequence=1 ttl=253 time=14 ms
--- 192.168.1.1 ping statistics ---
1 packet(s) transmitted
1 packet(s) received
0.00% packet loss
round-trip min/avg/max = 14/14/14 ms
[R4]ping -c 1 192.168.2.1
PING 192.168.2.1: 56 data bytes, press CTRL_C to break
Reply from 192.168.2.1: bytes=56 Sequence=1 ttl=253 time=13 ms
--- 192.168.2.1 ping statistics ---
1 packet(s) transmitted
1 packet(s) received
0.00% packet loss
round-trip min/avg/max = 13/13/13 ms
[R4]ping -c 1 192.168.3.1
PING 192.168.3.1: 56 data bytes, press CTRL_C to break
Reply from 192.168.3.1: bytes=56 Sequence=1 ttl=253 time=1 ms
--- 192.168.3.1 ping statistics ---
1 packet(s) transmitted
1 packet(s) received
0.00% packet loss
round-trip min/avg/max = 1/1/1 ms
Step 6. Modify the Cost value of the IS-IS interface
By default, the cost value of the IS-IS interface is 10, which is not automatically calculated based on the bandwidth. For R1, the traffic destined for R4 will be load-balanced between R2 and R3. However, because the Series interface is used between R1 and R2, the bandwidth is small and bottlenecks are likely to occur. Therefore, you can control the route selection of R1 by modifying the corresponding cost value.
Increase the export cost value:
[R1]interface Serial 1/0/0
[R1-Serial1/0/0]isis cost 15
[R1-Serial1/0/0]quit
[R1]display isis route
Route information for ISIS(1)
-----------------------------
ISIS(1) Level-2 Forwarding Table
--------------------------------
IPV4 Destination IntCost ExtCost ExitInterface NextHop Flags
----------------------------------------------------------------------------
10.0.4.4/32 20 NULL GE0/0/1 10.0.13.3 A/-/-/-
10.0.5.5/32 10 NULL GE0/0/0 10.0.15.5 A/-/-/-
192.168.1.0/24 10 0 GE0/0/0 10.0.15.5 A/-/-/-
10.0.12.0/24 15 NULL S1/0/0 Direct D/-/L/-
192.168.2.0/24 10 0 GE0/0/0 10.0.15.5 A/-/-/-
10.0.13.0/24 10 NULL GE0/0/1 Direct D/-/L/-
192.168.3.0/24 10 0 GE0/0/0 10.0.15.5 A/-/-/-
10.0.234.0/24 20 NULL GE0/0/1 10.0.13.3 A/-/-/-
10.0.15.0/24 10 NULL GE0/0/0 Direct D/-/L/-
10.0.1.1/32 0 NULL Loop0 Direct D/-/L/-
10.0.2.2/32 15 NULL S1/0/0 10.0.12.2 A/-/-/-
10.0.3.3/32 10 NULL GE0/0/1 10.0.13.3 A/-/-/-
Flags: D-Direct, A-Added to URT, L-Advertised in LSPs, S-IGP Shortcut,
U-Up/Down Bit Set
It can be seen that the load balancing on R1 has disappeared, and the traffic destined for R4 will be forwarded from the Ethernet interface.
Step 7. Configure IS-IS route penetration
Observe the data forwarding of R4. Because R4 knows nothing about the Level-2 network status, it uses load balancing to forward data to R2 and R3. If we want R4 not to use the link between R2 and R1, we can introduce the Level-2 route to Level-1 through route penetration, and forward the data packet to R5 from R3 through the longest route matching route selection.
Before testing tracert, you need to enable the port unreachable response on R5. It is disabled by default. If it is not enabled, the last hop will time out.
Before opening:
[R4]tracert 192.168.1.1
traceroute to 192.168.1.1(192.168.1.1), max hops: 30 ,packet length: 40,press CTRL_C to break
1 10.0.234.2 2 ms 10.0.234.3 2 ms 10.0.234.2 2 ms
2 10.0.13.1 11 ms 10.0.12.1 9 ms 10.0.13.1 11 ms
3 * * *
After opening on R5:
[R5]icmp port-unreachable send
[R4]tracert 192.168.1.1
traceroute to 192.168.1.1(192.168.1.1), max hops: 30 ,packet length: 40,press CTRL_C to break
1 10.0.234.2 2 ms 10.0.234.3 2 ms 10.0.234.2 2 ms
2 10.0.13.1 2 ms 10.0.12.1 9 ms 10.0.13.1 1 ms
3 192.168.1.1 8 ms 1 ms 9 ms
It can be seen that the tracert packets sent each time will reach R5 in load balance between the two next-hop addresses. At this time, we enable route penetration in R3, making R3 a better next-hop:
[R3]isis
[R3-isis-1]import-route isis level-2 into level-1
[R3-isis-1]quit
[R4]display isis route
Route information for ISIS(1)
-----------------------------
ISIS(1) Level-1 Forwarding Table
--------------------------------
IPV4 Destination IntCost ExtCost ExitInterface NextHop Flags
----------------------------------------------------------------------------
0.0.0.0/0 10 NULL GE0/0/0 10.0.234.3 A/-/-/-
GE0/0/0 10.0.234.2
10.0.4.4/32 0 NULL Loop0 Direct D/-/L/-
10.0.5.5/32 30 NULL GE0/0/0 10.0.234.3 A/-/-/U
192.168.1.0/24 10 20 GE0/0/0 10.0.234.3 A/-/-/U
10.0.12.0/24 20 NULL GE0/0/0 10.0.234.2 A/-/-/-
192.168.2.0/24 10 20 GE0/0/0 10.0.234.3 A/-/-/U
10.0.13.0/24 20 NULL GE0/0/0 10.0.234 A/-/-/-
192.168.3.0/24 10 20 GE0/0/0 10.0.234.3 A/-/-/U
10.0.234.0/24 10 NULL GE0/0/0 Direct D/-/L/-
10.0.15.0/24 30 NULL GE0/0/0 10.0.234.3 A/-/-/U
10.0.1.1/32 20 NULL GE0/0/0 10.0.234.3 A/-/-/U
10.0.2.2/32 10 NULL GE0/0/0 10.0.234.2 A/-/-/-
10.0.3.3/32 10 NULL GE0/0/0 10.0.234.3 A/-/-/-
Flags: D-Direct, A-Added to URT, L-Advertised in LSPs, S-IGP Shortcut,
U-Up/Down Bit Set
[R4]display ip routing-table protocol isis
Route Flags: R - relay, D - download to fib
----------------------------------------------------------------------------
Public routing table : ISIS
Destinations : 11 Routes : 12
ISIS routing table status : <Active>
Destinations : 11 Routes : 12
Destination/Mask Proto Pre Cost Flags NextHop Interface
0.0.0.0/0 ISIS-L1 15 10 D 10.0.234.3 GigabitEthernet0/0/0
ISIS-L1 15 10 D 10.0.234.2 GigabitEthernet0/0/0
10.0.1.1/32 ISIS-L1 15 20 D 10.0.234.3 GigabitEthernet0/0/0
10.0.2.2/32 ISIS-L1 15 10 D 10.0.234.2 GigabitEthernet0/0/0
10.0.3.3/32 ISIS-L1 15 10 D 10.0.234.3 GigabitEthernet0/0/0
10.0.5.5/32 ISIS-L1 15 30 D 10.0.234.3 GigabitEthernet0/0/0
10.0.12.0/24 ISIS-L1 15 20 D 10.0.234.2 GigabitEthernet0/0/0
10.0.13.0/24 ISIS-L1 15 20 D 10.0.234.3 GigabitEthernet0/0/0
10.0.15.0/24 ISIS-L1 15 30 D 10.0.234.3 GigabitEthernet0/0/0
192.168.1.0/24 ISIS-L1 15 94 D 10.0.234.3 GigabitEthernet0/0/0
192.168.2.0/24 ISIS-L1 15 94 D 10.0.234.3 GigabitEthernet0/0/0
192.168.3.0/24 ISIS-L1 15 94 D 10.0.234.3 GigabitEthernet0/0/0
ISIS routing table status : <Inactive>
Destinations : 0 Routes : 0
[R4]tracert 192.168.1.1
traceroute to 192.168.1.1(192.168.1.1), max hops: 30 ,packet length: 40,press CTRL_C to break
1 10.0.234.3 2 ms 1 ms 1 ms
2 10.0.13.1 2 ms 2 ms 2 ms
3 192.168.1.1 1 ms 1 ms 2 ms
Finally, the influence of route penetration on IS-IS route selection is verified through the tracert test.
Configuration file reference
<R1>display current-configuration
[V200R007C00SPC600]
#
sysname R1
#
isis 1
is-level level-2
network-entity 49.0002.0000.0000.0001.00
#
interface Serial1/0/0
link-protocol ppp
ip address 10.0.12.1 255.255.255.0
isis enable 1
isis cost 15
#
interface GigabitEthernet0/0/0
ip address 10.0.15.1 255.255.255.0
isis enable 1
isis circuit-type p2p
#
interface GigabitEthernet0/0/1
ip address 10.0.13.1 255.255.255.0
isis enable 1
#
interface LoopBack0
ip address 10.0.1.1 255.255.255.255
isis enable 1
#
return
<R2>display current-configuration
[V200R007C00SPC600]
#
sysname R2
#
isis 1
network-entity 49.0001.0000.0000.0002.00
#
interface Serial1/0/0
link-protocol ppp
ip address 10.0.12.2 255.255.255.0
isis enable 1
#
interface GigabitEthernet0/0/0
ip address 10.0.234.2 255.255.255.0
isis enable 1
#
interface LoopBack0
ip address 10.0.2.2 255.255.255.255
isis enable 1
#
return
<R3>display current-configuration
[V200R007C00SPC600]
#
sysname R3
#
isis 1
network-entity 49.0001.0000.0000.0003.00
import-route isis level-2 into level-1
#
interface GigabitEthernet0/0/0
ip address 10.0.234.3 255.255.255.0
isis enable 1
#
interface GigabitEthernet0/0/1
ip address 10.0.13.3 255.255.255.0
isis enable 1
#
interface LoopBack0
ip address 10.0.3.3 255.255.255.255
isis enable 1
#
return
<R4>display current-configuration
[V200R007C00SPC600]
#
sysname R4
#
isis 1
is-level level-1
network-entity 49.0001.0000.0000.0004.00
#
interface GigabitEthernet0/0/0
ip address 10.0.234.4 255.255.255.0
isis enable 1
isis dis-priority 120
#
interface LoopBack0
ip address 10.0.4.4 255.255.255.255
isis enable 1
#
return
<R5>display current-configuration
[V200R007C00SPC600]
#
sysname R5
#
icmp port-unreachable send
#
isis 1
is-level level-2
network-entity 49.0002.0000.0000.0005.00
import-route direct
#
interface GigabitEthernet0/0/0
ip address 10.0.15.5 255.255.255.0
isis enable 1
isis circuit-type p2p
#
interface LoopBack0
ip address 10.0.5.5 255.255.255.255
isis enable 1
#
interface LoopBack1
ip address 192.168.1.1 255.255.255.0
#
interface LoopBack2
ip address 192.168.2.1 255.255.255.0
#
interface LoopBack3
ip address 192.168.3.1 255.255.255.0
#
return