Friday, February 27, 2026

Implementing Segment Routing Traffic Engineering using Explicit Path in Nokia 7750 SR

Most of the time we compare the features of one protocol with another newer version of protool.

My experience customer worked in Cisco Environment for longer always compare whether it is available in Juniper or Nokia routers even if they offer more flexible way of doing things. 

Same question here, Is it possible to mention the explicit path for SR-TE same like RSVP manually instead of controller pushing it? and Yes, it is possible to do the same but one need to make sure  number label and LSP pushed from the head-end router.  

We can configure the explicit path to the destination via strict or loose hop. Strict hop always point to adj sid and loose path point to Node SID.

We can configure the IP, but in SR-MPLS it will not work on ip so it will convert into the label stake. We can also use a label.

Topology:

 

Lets configure the SR-TE Path between PE5 to PE4 with strict and loose path combination.

Configuration is straight forward, Lets create Path 

PE5# configure router mpls

            path "explicit"

                hop 1 11.0.0.2 strict

                hop 2 11.0.0.4 loose

                no shutdown

            exit

 SR-TE LSP Configuration

            lsp "toPE4" sr-te

                to 1.0.0.4

                from 1.0.0.5

                max-sr-labels 7 additional-frr-labels 2

                primary "explicit"

                exit

                no shutdown

            exit

            no shutdown

 Lets check the LSP status

  

 lets explore why the LSP Path is down

 

Path is down, lets do some troubleshooting and fix the path error.


    path "explicit"

                hop 1 11.0.0.2 loose

                hop 2 11.0.0.4 loose

                no shutdown

            exit

when we provide Strict that means that hope 1 11.0.0.2 is not the next hop so it tried to find adj sid but not available to it was down after changing the configuration to loose the lsp path came up

 

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