SR MPLS entries are not populated

1.Check if basic SR configuration is done and neighborship is up.

2.Routes are learnt properly. It can be verified by the command show ip route.

3. ISIS/OSPF database is properly populated with Self and Received LSPs/LSAs in levels they are configured. It can be verified by checking show isis/ospf database

4. If database is not populated correctly re-verify configuration

PHP Calculation for SR entries

In case PHP is not calculated properly, it's recommended to do clear ISIS or IP OSPF process.

 

PHP calculation is not supported for interfaces with no neighbor.

For loopback interface, IP address should be same as router ID.

SRGB allocation

Getting SRGB used by another process error:

 

Following is the priority thumb rule for SRGB allocation for protocol:

 

SRGB is allocated in first come first serve way. Once a particular block of SRGB is allocated to particular IGP or IGP process, same cannot be assigned/allocated to other IGP or other router process. They need to use corresponding ISIS/OSPF SRGB command to allocate non-overlapping blocks for themselves.

 

Mapping Server entries are not advertised

Check advertised-local command is configured and receive-disabled is not configured

SR-LSP stitching

SR and LDP entries are not getting stitched:

Make sure mpls lsp-sticthing is configured.

SR Policy is not coming up

Use this command:

Make sure color end-point key is configured and at least one candidate path is configured.

If SR Policy is not coming up with explicit path

Use the above command and "show mpls ilm-table" and make sure first SID of explicit segment-list is present in the ILM-table.

If SR Policy is not coming up with dynamic-path

Use this command:

 

It shows the CSPF computation related information.

If the state is compute, wait for next retry. In case next retry is also unsuccessful, Make sure end-to-end reachability is there, segment-routing is enabled in all the transit nodes, Prefix-SID is configured end-point.

If SR Policy is not coming up with dynamic-path and IP constraint

Use above command and make sure, Prefix-SID is configured for constraint, If the constraint is specified for Node constraint (loopback IP), make sure Node's router-id is same as loopback IP address.

 

To verify if Node-SID is present as an active entry, "show mpls forwarding-table" can be checked.

If SR Policy is not coming up with dynamic-path and affinity

Make sure above mentioned things are fine and mentioned affinities are correctly configured on all the transit nodes and respective interfaces.

If SR Policy is not coming up with dynamic PCE

Make sure the PCE entity attached to the policy is configured correctly in the PCE configuration mode.

Also ensure that the PCEP session is up with this entity.

PCEP session not coming up

Use this command:

"show pcep peer" to check the session state.

 

1. Make sure peer-address configured should be reachable and matches with the server IP.

2. Enable "debug pcep error" to see any error's received/sent for session establishment, based on error log, take appropriate action.

Ex: Capability mismatch.

3. Check any "Session Connect due" running in "show pcep peer". After this due we again retry for PCEP session.

Stateless/Passive stateful PCEP configured on SR/RSVP - Path not coming up.

1.This case can happen when controller send PcReply with NO-PATH object, so check the constraints configured on particular RSVP-TRUNK or SR-POLICY.

2.ERO Received in the PcReply not valid. "show rsvp session details" use this show command to check the error.

3.Similarly for SR check "show segment-routing policy detail" for CP state.(Valid/Invalid).

Active stateful PCEP configured on SR/RSVP - Path not coming up.

Use this command:

In case of SR-POLICY SR-ERO received in PcInitiate/PcUpdate not valid.

 

Use this command:

In case of RSVP the ERO received PcInitiate/PcUpdate not valid.

Traffic is not switching within 50msec on shutdown of a link. (when OSPF is used as IGP)

1. Check if TI-LFA is enabled. If not enabled, enable ti-lfa and check if the problem is resolved.

2. Check if Backup FTN and ILM entries are installed using "show mpls forwarding table" and "show mpls-ilm table" respectively for FTN and ILM table

3. Check output for "show ip ospf tilfa-backup-path" and "show ip ospf tilfa-repair-list" to see if P and Q node are calculated and repair tunnels are calculated

4. Use "debug ip ospf tilfa" to debug further as needed.

Traffic is not switching within 50msec on shutdown of a link. (when ISIS is used as IGP)

1. Check if TI-LFA is enabled. If not enabled, enable ti-lfa and check if the problem is resolved.

2. Check if Backup FTN and ILM entries are installed using "show mpls forwarding table" and "show mpls-ilm table" respectively for FTN and ILM table

3. Check output for "show isis tilfa pq" and "show ip isis route tilfa" to see if P and Q node are calculated and repair tunnels are calculated

4. Use "debug isis tilfa" to debug further as needed.

All the entries are correctly showing but traffic is not switching in 50 msec within 50 sec

Check total number of labels on backup path including labels on repair tunnel. Number of transport labels should not exceed 4 and service labels should not exceed 2.

SR ILM entry is not installed as ECMP in hardware

SR FTN entry is not installed as ECMP in hardware

Traffic is not load-balanced among the ECMP next-hops

Increase the number of flows, as load balancing depends on the internal hash computed by BCM. Note that lesser flows may lead to the same outgoing interface for different flows.