Implementing BGP-Signaled SR Policy on Nokia 7750 SR

In the previous post, we discussed the SR-Static policy on the local router. Do we have the option to create a policy and advertise to other routers in the network? Then yes, it is possible to send the SR policy from the centralized controller or from the SR-OS routers within the network.

Let’s configure and advertise the SR policy from ASBR1 using BGP for PE3 to PE5.

It’s like the previous configuration, but the only difference is we mention the headend router ip address of PE3.

PE3 to PE5 SR policy

Enabling the sr-policy ipv4 in bgp family and importing the sr-policy, the sr-policy-import command in bgp allows the static policy to be advertised in BGP except for the local policy.

Enabling the sr-policy-ipv4 family under BGP neighbors

SR-policy advertisement from ASBR1

BGP advertisement of SR policy

PE3 to PE6 sr-policy verification

LSP trace confirms the traffic via the sr-policy path

SR-Policy Route installed in the tunnel table

PE5: Adding color to the route advertisement from PE5 to PE3

Add the policy in VPRN import/export policy

We can see the PE5 adding the color while advertising the routes to PE3

SR-policy applied for the route towards PE5 

Ping between PE3 and PE5 via SR policy

Steering Traffic via Local SR-Policy using BGP Color community on Nokia 7750 SR

SR-Policy can be used to steer traffic across a pre-determined path (similar to SR-TE strict hop)

SR-Policy can be configured locally aka Local SR-Policy or distributed via Central Controller aka BGP SR-Policy

SR Policy segment-list can be a complete list involving all nodes along the path to destination or listing only few intermediate nodes along the path (same like loose path in RSVP-TE or SR-TE)

 

 

Lets configure the Local SR-policy in PE5 router and bind the VPRN to the SR-policy.

Then we will configure the color on PE3 and attach the color to the VPRN route.

PE5 will check the color on received routes attach the SR-policy

First we need to configure the label block for Binding SID

PE5 Router configuration:

 

 There are total 6 hops between PE5 and PE3 router, I will use only 3 labels inside the SR_policy.

BGP Configuration:

 

 VPRN Configuration on PE5

 

VPRN configuration on PE3

 

Export policy to match the color on PE3:

 

VPRN route table installed route and pointing SR policy for Remote loopback

 

 Lets initiate the Ping to check the rechability between  PE5 vprn to PE3 vprn

  

Even we have the route installed in the respective route table ping is not successfully

Next, lets verify the LSP ping between PE5 and PE3 

 

 LSP ping is successfully completed

After performing trace observed the trace last reply from PE4 router which is before PE3

 

I did misunderstand that SR-policy no need to provide the Destination router Node-SID or ADJ SID in the SR-policy. So, configured the policy with the Node SID of PE3.

Its good making mistake so that we will not forget the concepts. also good to practice after reading the concepts.

 

 

After that we could see the Trace is completed from PE5 to PE3

 

Ping initiated between PE5 and PE3 VPRN is successful.

 

 Next blog will try to push the policy via BGP to other routers.