161
192.168.0.0/24 10 NULL GE2/0 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
-------------------------------------------------------------------------------
10.1.1.0/24 10 NULL D/L/-
10.1.2.0/24 10 NULL D/L/-
192.168.0.0/24 10 NULL D/L/-
172.16.0.0/16 20 NULL GE2/0 192.168.0.2 R/-/-
Flags: D-Direct, R-Added to Rib, L-Advertised in LSPs, U-Up/Down Bit Set
[RouterD] 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 GE2/0 Direct D/L/-
10.1.1.0/24 20 NULL GE2/0 192.168.0.1 R/-/-
10.1.2.0/24 20 NULL GE2/0 192.168.0.1 R/-/-
172.16.0.0/16 10 NULL GE1/0 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 routers contains a default route with the next hop as the
Level-1-2 router, and the routing table of Level-2 router contains all Level-1 and Level-2 routes.
DIS election configuration example
Network requirements
As shown in
Figure 41
, on a broadcast network (Ethernet), Router A, Router B, Router C, and Router D
reside in IS-IS Area 10. Router A and Router B are Level-1-2 routers, Router C is a Level-1 router, and Router
D is a Level-2 router.
Change the DIS priority of Router A to make it elected as the Level-1-2 DIS router.