IS-IS – Leaking Routes from Level 2

By default, level 2 routes are not distributed into level 1. There may be situations where you need a more specific route rather than the default route provided by the ABR.

https://www.juniper.net/documentation/us/en/software/junos/is-is/topics/concept/is-is-routing-overview.html#:~:text=Level%201%20routers%20share%20intra,with%20other%20Level%202%20routers.

The aim of this lab is to leak a route from level 2 so that level 1 devices have a more specific route to the loopback of vMX3. This is done with a policy on the ABR (vMX4)

vMX1

set interfaces ge-0/0/0 unit 0 family inet address 1.1.1.1/30
set interfaces ge-0/0/0 unit 0 family iso
set interfaces ge-0/0/1 unit 0 family inet address 1.2.2.1/30
set interfaces ge-0/0/1 unit 0 family iso
set interfaces ge-0/0/2 unit 0 family inet address 1.3.3.1/30
set interfaces ge-0/0/2 unit 0 family iso
set interfaces lo0 unit 0 family inet address 5.5.5.5/32
set interfaces lo0 unit 0 family iso address 49.0000.5555.5555.5555.00
set protocols isis interface ge-0/0/0.0 level 1 disable
set protocols isis interface ge-0/0/1.0 level 1 disable
set protocols isis interface ge-0/0/2.0 level 1 disable
set protocols isis interface lo0.0

vMX2

set interfaces ge-0/0/0 unit 0 family inet address 1.1.1.2/30
set interfaces ge-0/0/0 unit 0 family iso
set interfaces ge-0/0/1 unit 0 family inet address 2.2.2.1/30
set interfaces ge-0/0/1 unit 0 family iso
set interfaces lo0 unit 0 family inet address 6.6.6.6/32
set interfaces lo0 unit 0 family iso address 49.0000.6666.6666.6666.00
set protocols isis interface ge-0/0/0.0 level 1 disable
set protocols isis interface ge-0/0/1.0 level 1 disable
set protocols isis interface lo0.0

vMX3

set interfaces ge-0/0/0 unit 0 family inet address 2.2.2.2/30
set interfaces ge-0/0/0 unit 0 family iso
set interfaces ge-0/0/1 unit 0 family inet address 1.2.2.2/30
set interfaces ge-0/0/1 unit 0 family iso
set interfaces ge-0/0/2 unit 0 family inet address 3.3.3.1/30
set interfaces ge-0/0/2 unit 0 family iso
set interfaces lo0 unit 0 family inet address 7.7.7.7/32
set interfaces lo0 unit 0 family iso address 49.0000.7777.7777.7777.00
set protocols isis interface ge-0/0/0.0 level 1 disable
set protocols isis interface ge-0/0/1.0 level 1 disable
set protocols isis interface ge-0/0/2.0 level 1 disable
set protocols isis interface lo0.0

vMX4

set interfaces ge-0/0/0 unit 0 family inet address 1.3.3.2/30
set interfaces ge-0/0/0 unit 0 family iso
set interfaces ge-0/0/1 unit 0 family inet address 3.3.3.2/30
set interfaces ge-0/0/1 unit 0 family iso
set interfaces ge-0/0/2 unit 0 family inet address 4.4.4.1/30
set interfaces ge-0/0/2 unit 0 family iso
set interfaces ge-0/0/3 unit 0 family inet address 6.6.6.2/30
set interfaces ge-0/0/3 unit 0 family iso
set interfaces lo0 unit 0 family inet address 8.8.8.8/32
set interfaces lo0 unit 0 family iso address 49.0001.8888.8888.8888.00
set protocols isis export leak
set protocols isis interface ge-0/0/0.0
set protocols isis interface ge-0/0/1.0 level 1 disable
set protocols isis interface ge-0/0/2.0 level 2 disable
set protocols isis interface ge-0/0/3.0 level 2 disable
set protocols isis interface lo0.0
set policy-options policy-statement leak term 1 from protocol isis
set policy-options policy-statement leak term 1 from level 2
set policy-options policy-statement leak term 1 from route-filter 7.7.7.7/32 exact
set policy-options policy-statement leak term 1 to level 1
set policy-options policy-statement leak term 1 then accept

vMX5

set interfaces ge-0/0/0 unit 0 family inet address 4.4.4.2/30
set interfaces ge-0/0/0 unit 0 family iso
set interfaces ge-0/0/1 unit 0 family inet address 5.5.5.1/30
set interfaces ge-0/0/1 unit 0 family iso
set interfaces lo0 unit 0 family inet address 9.9.9.9/32
set interfaces lo0 unit 0 family iso address 49.0001.9999.9999.9999.00
set protocols isis interface ge-0/0/0.0 level 2 disable
set protocols isis interface ge-0/0/1.0 level 2 disable
set protocols isis interface lo0.0

vMX6

set interfaces ge-0/0/0 unit 0 family inet address 5.5.5.2/30
set interfaces ge-0/0/0 unit 0 family iso
set interfaces ge-0/0/1 unit 0 family inet address 6.6.6.1/30
set interfaces ge-0/0/1 unit 0 family iso
set interfaces lo0 unit 0 family inet address 10.10.10.10/32
set interfaces lo0 unit 0 family iso address 49.0001.1010.1010.1010.00
set protocols isis interface ge-0/0/0.0 level 2 disable
set protocols isis interface ge-0/0/1.0 level 2 disable

You will now have leaked route 7.7.7.7 into the level 1 route table so run ‘show route‘ on vMX5 or vMX6 to confirm.