Routing

Prior to any MPLS configuration, we need to set up routing in the network core. Configuration of interfaces and IGP is the core task explained in this section.

Interfaces#

Let's start with basic interfaces configuration following this diagram:

The below config snippets configure regular Ethernet-1/1, Ethernet-1/2 and a special loopback system0 interfaces.

srl1srl2srl3

enter candidate # (1)!

set / interface ethernet-1/1
set / interface ethernet-1/1 admin-state enable
set / interface ethernet-1/1 subinterface 0
set / interface ethernet-1/1 subinterface 0 admin-state enable
set / interface ethernet-1/1 subinterface 0 ipv4 admin-state enable
set / interface ethernet-1/1 subinterface 0 ipv4 address 10.1.2.1/30

set / interface system0
set / interface system0 admin-state enable
set / interface system0 subinterface 0
set / interface system0 subinterface 0 admin-state enable
set / interface system0 subinterface 0 ipv4 admin-state enable
set / interface system0 subinterface 0 ipv4 address 10.0.0.1/32

set / network-instance default
set / network-instance default interface ethernet-1/1.0
set / network-instance default interface system0.0

commit save

config snippets contain enter candidate command to switch to configuration context.
At the bottom of the snippet commit save command will perform a commit operation followed by saving the running config to a startup config file.

enter candidate

set / interface ethernet-1/1
set / interface ethernet-1/1 admin-state enable
set / interface ethernet-1/1 subinterface 0
set / interface ethernet-1/1 subinterface 0 admin-state enable
set / interface ethernet-1/1 subinterface 0 ipv4 admin-state enable
set / interface ethernet-1/1 subinterface 0 ipv4 address 10.1.2.2/30

set / interface ethernet-1/2
set / interface ethernet-1/2 admin-state enable
set / interface ethernet-1/2 subinterface 0
set / interface ethernet-1/2 subinterface 0 admin-state enable
set / interface ethernet-1/2 subinterface 0 ipv4 admin-state enable
set / interface ethernet-1/2 subinterface 0 ipv4 address 10.2.3.1/30

set / interface system0
set / interface system0 admin-state enable
set / interface system0 subinterface 0
set / interface system0 subinterface 0 admin-state enable
set / interface system0 subinterface 0 ipv4 admin-state enable
set / interface system0 subinterface 0 ipv4 address 10.0.0.2/32

set / network-instance default
set / network-instance default interface ethernet-1/1.0
set / network-instance default interface ethernet-1/2.0
set / network-instance default interface system0.0

commit save

enter candidate

set / interface ethernet-1/1
set / interface ethernet-1/1 admin-state enable
set / interface ethernet-1/1 subinterface 0
set / interface ethernet-1/1 subinterface 0 admin-state enable
set / interface ethernet-1/1 subinterface 0 ipv4 admin-state enable
set / interface ethernet-1/1 subinterface 0 ipv4 address 10.2.3.2/30

set / interface system0
set / interface system0 admin-state enable
set / interface system0 subinterface 0
set / interface system0 subinterface 0 admin-state enable
set / interface system0 subinterface 0 ipv4 admin-state enable
set / interface system0 subinterface 0 ipv4 address 10.0.0.3/32

set / network-instance default
set / network-instance default interface ethernet-1/1.0
set / network-instance default interface system0.0

commit save

When the interface config is committed¹, routers should be able to ping each neighbor's interface address.

srl1 pings srl2srl2 pings srl3

--{ running }--[  ]--
A:srl1# ping network-instance default 10.1.2.2
Using network instance default
PING 10.1.2.2 (10.1.2.2) 56(84) bytes of data.
64 bytes from 10.1.2.2: icmp_seq=1 ttl=64 time=49.7 ms

--{ running }--[  ]--
A:srl2# ping network-instance default 10.2.3.2
Using network instance default
PING 10.2.3.2 (10.2.3.2) 56(84) bytes of data.
64 bytes from 10.2.3.2: icmp_seq=1 ttl=64 time=0.033 ms

IGP#

With interfaces config done, proceed with configuring an IGP protocol to redistribute the loopback address information among all routers. In this tutorial, we will use IS-IS routing protocol to achieve this goal.

srl1srl2srl3

enter candidate

set / network-instance default protocols isis
set / network-instance default protocols isis instance ISIS
set / network-instance default protocols isis instance ISIS admin-state enable
set / network-instance default protocols isis instance ISIS level-capability L2
set / network-instance default protocols isis instance ISIS net [ 49.0001.0000.0000.0001.00 ]
set / network-instance default protocols isis instance ISIS ipv4-unicast
set / network-instance default protocols isis instance ISIS ipv4-unicast admin-state enable

set / network-instance default protocols isis instance ISIS interface ethernet-1/1.0
set / network-instance default protocols isis instance ISIS interface ethernet-1/1.0 circuit-type point-to-point
set / network-instance default protocols isis instance ISIS interface ethernet-1/1.0 ipv4-unicast
set / network-instance default protocols isis instance ISIS interface ethernet-1/1.0 ipv4-unicast admin-state enable
set / network-instance default protocols isis instance ISIS interface ethernet-1/1.0 level 2

set / network-instance default protocols isis instance ISIS interface system0.0
set / network-instance default protocols isis instance ISIS interface system0.0 admin-state enable
set / network-instance default protocols isis instance ISIS interface system0.0 passive true
set / network-instance default protocols isis instance ISIS interface system0.0 ipv4-unicast
set / network-instance default protocols isis instance ISIS interface system0.0 ipv4-unicast admin-state enable
set / network-instance default protocols isis instance ISIS interface system0.0 level 2

commit save

enter candidate

set / network-instance default protocols isis
set / network-instance default protocols isis instance ISIS
set / network-instance default protocols isis instance ISIS admin-state enable
set / network-instance default protocols isis instance ISIS level-capability L2
set / network-instance default protocols isis instance ISIS net [ 49.0001.0000.0000.0002.00 ]
set / network-instance default protocols isis instance ISIS ipv4-unicast
set / network-instance default protocols isis instance ISIS ipv4-unicast admin-state enable
set / network-instance default protocols isis instance ISIS interface ethernet-1/1.0
set / network-instance default protocols isis instance ISIS interface ethernet-1/1.0 circuit-type point-to-point
set / network-instance default protocols isis instance ISIS interface ethernet-1/1.0 ipv4-unicast
set / network-instance default protocols isis instance ISIS interface ethernet-1/1.0 ipv4-unicast admin-state enable
set / network-instance default protocols isis instance ISIS interface ethernet-1/1.0 level 2

set / network-instance default protocols isis instance ISIS interface ethernet-1/2.0
set / network-instance default protocols isis instance ISIS interface ethernet-1/2.0 circuit-type point-to-point
set / network-instance default protocols isis instance ISIS interface ethernet-1/2.0 ipv4-unicast
set / network-instance default protocols isis instance ISIS interface ethernet-1/2.0 ipv4-unicast admin-state enable
set / network-instance default protocols isis instance ISIS interface ethernet-1/2.0 level 2

set / network-instance default protocols isis instance ISIS interface system0.0
set / network-instance default protocols isis instance ISIS interface system0.0 admin-state enable
set / network-instance default protocols isis instance ISIS interface system0.0 passive true
set / network-instance default protocols isis instance ISIS interface system0.0 ipv4-unicast
set / network-instance default protocols isis instance ISIS interface system0.0 ipv4-unicast admin-state enable
set / network-instance default protocols isis instance ISIS interface system0.0 level 2

commit save

enter candidate

set / network-instance default protocols isis
set / network-instance default protocols isis instance ISIS
set / network-instance default protocols isis instance ISIS admin-state enable
set / network-instance default protocols isis instance ISIS level-capability L2
set / network-instance default protocols isis instance ISIS net [ 49.0001.0000.0000.0003.00 ]
set / network-instance default protocols isis instance ISIS ipv4-unicast
set / network-instance default protocols isis instance ISIS ipv4-unicast admin-state enable
set / network-instance default protocols isis instance ISIS interface ethernet-1/1.0
set / network-instance default protocols isis instance ISIS interface ethernet-1/1.0 circuit-type point-to-point
set / network-instance default protocols isis instance ISIS interface ethernet-1/1.0 ipv4-unicast
set / network-instance default protocols isis instance ISIS interface ethernet-1/1.0 ipv4-unicast admin-state enable
set / network-instance default protocols isis instance ISIS interface ethernet-1/1.0 level 2

set / network-instance default protocols isis instance ISIS interface system0.0
set / network-instance default protocols isis instance ISIS interface system0.0 admin-state enable
set / network-instance default protocols isis instance ISIS interface system0.0 passive true
set / network-instance default protocols isis instance ISIS interface system0.0 ipv4-unicast
set / network-instance default protocols isis instance ISIS interface system0.0 ipv4-unicast admin-state enable
set / network-instance default protocols isis instance ISIS interface system0.0 level 2

commit save

All routers now should have enabled IS-IS adjacency with their respective neighbors, and the routing table should contain respective system0.0 loopback addresses. A view from srl2 side:

AdjacencyRouting table

--{ running }--[  ]--
A:srl2# show  /network-instance default protocols isis adjacency
-----------------------------------------------------------------------------------------------------------------------
Network Instance: default
Instance        : ISIS
+----------------+----------------+---------------+------------+--------------+-------+---------------+---------------+
| Interface Name |    Neighbor    |   Adjacency   | Ip Address | Ipv6 Address | State |     Last      |   Remaining   |
|                |   System Id    |     Level     |            |              |       |  transition   |   holdtime    |
+================+================+===============+============+==============+=======+===============+===============+
| ethernet-1/1.0 | 0000.0000.0001 | L2            | 10.1.2.1   | ::           | up    | 2022-03-13T14 | 23            |
|                |                |               |            |              |       | :15:57.500Z   |               |
| ethernet-1/2.0 | 0000.0000.0003 | L2            | 10.2.3.2   | ::           | up    | 2022-03-13T14 | 21            |
|                |                |               |            |              |       | :25:50.100Z   |               |
+----------------+----------------+---------------+------------+--------------+-------+---------------+---------------+
Adjacency Count: 2
-----------------------------------------------------------------------------------------------------------------------

The below output verifies that srl2 has successfully received loopbacks prefixes from srl1/3 nodes.

--{ running }--[  ]--
A:srl2# /show network-instance default route-table all | grep isis
| 10.0.0.1/32 | 0    | isis      | isis_mgr            | True/success        | 10      | 18     | 10.1.2 | ethern |
| 10.0.0.3/32 | 0    | isis      | isis_mgr            | True/success        | 10      | 18     | 10.2.3 | ethern |

With IGP setup is done, we can proceed with LDP configuration.

for instance, with commit save command executed from within configuration context. ↩

Routing

Interfaces#

IGP#

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