# 配置RouterA。
[RouterA] isis 1
[RouterA-isis-1] is-level level-1
[RouterA-isis-1] network-entity 10.0000.0000.0001.00
[RouterA-isis-1] quit
[RouterA] interface serial 1/0/0:0
[RouterA- serial 1/0/0:0] isis enable 1
[RouterA- serial 1/0/0:0] quit
# 配置RouterB。
[RouterB] isis 1
[RouterB-isis-1] is-level level-1
[RouterB-isis-1] network-entity 10.0000.0000.0002.00
[RouterB-isis-1] quit
[RouterB] interface serial 2/0/0:0
[RouterB- serial 2/0/0:0] isis enable 1
[RouterB- serial 2/0/0:0] quit
# 配置RouterC。
[RouterC] isis 1
[RouterC-isis-1] network-entity 10.0000.0000.0003.00
[RouterC-isis-1] quit
[RouterC] interface serial 1/0/0:0
[RouterC- serial 1/0/0:0] isis enable 1
[RouterC- serial 1/0/0:0] quit
[RouterC] interface serial 2/0/0:0
[RouterC- serial 2/0/0:0] isis enable 1
[RouterC- serial 2/0/0:0] quit
[RouterC] interface serial 3/0/0:0
[RouterC- serial 3/0/0:0] isis enable 1
[RouterC- serial 3/0/0:0] quit
# 配置RouterD。
[RouterD] isis 1
[RouterD-isis-1] is-level level-2
[RouterD-isis-1] network-entity 20.0000.0000.0004.00
[RouterD-isis-1] quit
[RouterD] interface ethernet 2/0/0
[RouterD-Ethernet2/0/0] isis enable 1
[RouterD-Ethernet2/0/0] quit
[RouterD] interface serial 3/0/0:0
[RouterD- serial 3/0/0:0] isis enable 1
[RouterD- serial 3/0/0:0] quit