Basic IS-IS configuration example
Network requirements
As shown in Figure 43, Switch A, Switch B, Switch C, and Switch D reside in an IS-IS AS.
Switch A and B are Level-1 switches, Switch D is a Level-2 switch, and Switch C is a Level-1-2 switch. Switch A, Switch B, and Switch C are in Area 10, and Switch D is in Area 20.
Figure 43: Network diagram
Configuration procedure
Configure IP addresses for interfaces. (Details not shown.)
Configure IS-IS:
# Configure Switch A.
<SwitchA> system-view [SwitchA] isis 1 [SwitchA-isis-1] is-level level-1 [SwitchA-isis-1] network-entity 10.0000.0000.0001.00 [SwitchA-isis-1] quit [SwitchA] interface vlan-interface 100 [SwitchA-Vlan-interface100] isis enable 1 [SwitchA-Vlan-interface100] quit
# Configure Switch B.
<SwitchB> system-view [SwitchB] isis 1 [SwitchB-isis-1] is-level level-1 [SwitchB-isis-1] network-entity 10.0000.0000.0002.00 [SwitchB-isis-1] quit [SwitchB] interface vlan-interface 200 [SwitchB-Vlan-interface200] isis enable 1 [SwitchB-Vlan-interface200] quit
# Configure Switch C.
<SwitchC> system-view [SwitchC] isis 1 [SwitchC-isis-1] network-entity 10.0000.0000.0003.00 [SwitchC-isis-1] quit [SwitchC] interface vlan-interface 100 [SwitchC-Vlan-interface100] isis enable 1 [SwitchC-Vlan-interface100] quit [SwitchC] interface vlan-interface 200 [SwitchC-Vlan-interface200] isis enable 1 [SwitchC-Vlan-interface200] quit [SwitchC] interface vlan-interface 300 [SwitchC-Vlan-interface300] isis enable 1 [SwitchC-Vlan-interface300] quit
# Configure Switch D.
<SwitchD> system-view [SwitchD] isis 1 [SwitchD-isis-1] is-level level-2 [SwitchD-isis-1] network-entity 20.0000.0000.0004.00 [SwitchD-isis-1] quit [SwitchD] interface vlan-interface 100 [SwitchD-Vlan-interface100] isis enable 1 [SwitchD-Vlan-interface100] quit [SwitchD] interface vlan-interface 300 [SwitchD-Vlan-interface300] isis enable 1 [SwitchD-Vlan-interface300] quit
Verifying the configuration
# Display the IS-IS LSDB on each switch to verify the LSPs.
[SwitchA] display isis lsdb
Database information for IS-IS(1)
---------------------------------
Level-1 Link State Database
---------------------------
LSPID Seq Num Checksum Holdtime Length ATT/P/OL
--------------------------------------------------------------------------
0000.0000.0001.00-00* 0x00000004 0xdf5e 1096 68 0/0/0
0000.0000.0002.00-00 0x00000004 0xee4d 1102 68 0/0/0
0000.0000.0002.01-00 0x00000001 0xdaaf 1102 55 0/0/0
0000.0000.0003.00-00 0x00000009 0xcaa3 1161 111 1/0/0
0000.0000.0003.01-00 0x00000001 0xadda 1112 55 0/0/0
*-Self LSP, +-Self LSP(Extended), ATT-Attached, P-Partition, OL-Overload
[SwitchB] display isis lsdb
Database information for IS-IS(1)
---------------------------------
Level-1 Link State Database
---------------------------
LSPID Seq Num Checksum Holdtime Length ATT/P/OL
--------------------------------------------------------------------------
0000.0000.0001.00-00 0x00000006 0xdb60 988 68 0/0/0
0000.0000.0002.00-00* 0x00000008 0xe651 1189 68 0/0/0
0000.0000.0002.01-00* 0x00000005 0xd2b3 1188 55 0/0/0
0000.0000.0003.00-00 0x00000014 0x194a 1190 111 1/0/0
0000.0000.0003.01-00 0x00000002 0xabdb 995 55 0/0/0
*-Self LSP, +-Self LSP(Extended), ATT-Attached, P-Partition, OL-Overload
[SwitchC] display isis lsdb
Database information for IS-IS(1)
---------------------------------
Level-1 Link State Database
---------------------------
LSPID Seq Num Checksum Holdtime Length ATT/P/OL
--------------------------------------------------------------------------
0000.0000.0001.00-00 0x00000006 0xdb60 847 68 0/0/0
0000.0000.0002.00-00 0x00000008 0xe651 1053 68 0/0/0
0000.0000.0002.01-00 0x00000005 0xd2b3 1052 55 0/0/0
0000.0000.0003.00-00* 0x00000014 0x194a 1051 111 1/0/0
0000.0000.0003.01-00* 0x00000002 0xabdb 854 55 0/0/0
*-Self LSP, +-Self LSP(Extended), ATT-Attached, P-Partition, OL-Overload
Level-2 Link State Database
---------------------------
LSPID Seq Num Checksum Holdtime Length ATT/P/OL
--------------------------------------------------------------------------
0000.0000.0003.00-00* 0x00000012 0xc93c 842 100 0/0/0
0000.0000.0004.00-00 0x00000026 0x331 1173 84 0/0/0
0000.0000.0004.01-00 0x00000001 0xee95 668 55 0/0/0
*-Self LSP, +-Self LSP(Extended), ATT-Attached, P-Partition, OL-Overload
[SwitchD] display isis lsdb
Database information for IS-IS(1)
---------------------------------
Level-2 Link State Database
---------------------------
LSPID Seq Num Checksum Holdtime Length ATT/P/OL
-------------------------------------------------------------------------------
0000.0000.0003.00-00 0x00000013 0xc73d 1003 100 0/0/0
0000.0000.0004.00-00* 0x0000003c 0xd647 1194 84 0/0/0
0000.0000.0004.01-00* 0x00000002 0xec96 1007 55 0/0/0
*-Self LSP, +-Self LSP(Extended), ATT-Attached, P-Partition, OL-Overload
# Display the IS-IS routing information on each switch.
[SwitchA] display isis route
Route information for IS-IS(1)
------------------------------
Level-1 IPv4 Forwarding Table
-----------------------------
IPv4 Destination IntCost ExtCost ExitInterface NextHop Flags
-------------------------------------------------------------------------------
10.1.1.0/24 10 NULL Vlan100 Direct D/L/-
10.1.2.0/24 20 NULL Vlan100 10.1.1.1 R/-/-
192.168.0.0/24 20 NULL Vlan100 10.1.1.1 R/-/-
0.0.0.0/0 10 NULL Vlan100 10.1.1.1 R/-/-
Flags: D-Direct, R-Added to Rib, L-Advertised in LSPs, U-Up/Down Bit Set
[SwitchC] display isis route
Route information for IS-IS(1)
------------------------------
Level-1 IPv4 Forwarding Table
-----------------------------
IPv4 Destination IntCost ExtCost ExitInterface NextHop Flags
-------------------------------------------------------------------------------
192.168.0.0/24 10 NULL Vlan300 Direct D/L/-
10.1.1.0/24 10 NULL Vlan100 Direct D/L/-
10.1.2.0/24 10 NULL Vlan200 Direct D/L/-
Flags: D-Direct, R-Added to Rib, L-Advertised in LSPs, U-Up/Down Bit Set
Level-2 IPv4 Forwarding Table
-----------------------------
IPv4 Destination IntCost ExtCost ExitInterface NextHop Flags
-------------------------------------------------------------------------------
192.168.0.0/24 10 NULL D/L/-
10.1.1.0/24 10 NULL D/L/-
10.1.2.0/24 10 NULL D/L/-
172.16.0.0/16 20 NULL Vlan300 192.168.0.2 R/-/-
Flags: D-Direct, R-Added to Rib, L-Advertised in LSPs, U-Up/Down Bit Set
[SwitchD] display isis route
Route information for IS-IS(1)
------------------------------
Level-2 IPv4 Forwarding Table
-----------------------------
IPv4 Destination IntCost ExtCost ExitInterface NextHop Flags
-------------------------------------------------------------------------------
192.168.0.0/24 10 NULL Vlan300 Direct D/L/-
10.1.1.0/24 20 NULL Vlan300 192.168.0.1 R/-/-
10.1.2.0/24 20 NULL Vlan300 192.168.0.1 R/-/-
172.16.0.0/16 10 NULL Vlan100 Direct D/L/-
Flags: D-Direct, R-Added to Rib, L-Advertised in LSPs, U-Up/Down Bit Set
The output shows that the routing table of Level-1 switches contains a default route with the next hop as the Level-1-2 switch. The routing table of Level-2 switch contains both routing information of Level-1 and Level-2.