Segment Routing Application Design

Segment Routing Group Handling:

SR GroupKey data model

Segment Routing application interacts with the Group subsystem using the below SR specific GroupKey. So SR application associate a SRDefaultGroupKey or SRPolicyGroupKey for every group it creates. The SRGroupKey consists of collection of <PortNumber + Label Stack to be pushed on that port> where leftmost label representing the outermost label and rightmost label representing innermost label to be pushed.

For e.g. a ECMP group with two buckets pushing label L1 and output to two ports P1 and P2 respectively can be represented with a SRDefaultGroupKey {{P1, L1}, {P2, L1}}. 

SR GroupKey data model

Segment Routing application interacts with the Group subsystem using the below SR specific GroupKey. So SR application associate a SRDefaultGroupKey or SRPolicyGroupKey for every group it creates. The SRGroupKey consists of collection of <PortNumber + Label Stack to be pushed on that port> where leftmost label representing the outermost label and rightmost label representing innermost label to be pushed.

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• Default Group Handler & Recovery

• During Start-up:

• Create Segment Id database of all the nodes in the network

• Get all devices from Topology service

• Add to above list when DEVICE_ADDED event received

• For each switch that this instance is master,

• If the Group subsystem peforming Group AUDIT, then wait until AUDIT completes

• Create Neighbor list

• Get all outgoing links from Link service

• Update above list when LINK_ADDED event received

• Get all Groups from the Store

• Perform Audit using above Neighbor list

• Policy Group Handler & Recovery

• While creating the tunnel, ensure all the stitched groups are created before creating the Group chain in the ingress router

• Similarly, while deleting the tunnel, ensure the group is deleted at ingress router before deleting any stitched groups

• Group Event Handling