Support of BGP Extended Community Transitive Link Bandwidth attribute in BGP advertised routes and learned information.

[apratimmukherjee]

Feature Overview

• Related Issue: Fixes #456
• Brief Description:
• Supports advertisement of Transitive Extended Community with Link Bandwidth for IPv4 and IPv6 routes sent from BGP/BGP+ peers.
• Supports structured format of retrieval of Transitive Extended Community with Link Bandwidth in get_state for received IPv4 and IPv6 routes from BGP/BGP+ peers.

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Feature Details

• Redocli link for set_config

• Redocli link for get_states

• New Locations/Nomenclature:

1. config/devices/bgp/ipv[4|6]_interfaces/peers/v[4|6]_routes/extended_communities.
2. monitor/get_state/responses/200/bgp_prefixes/ipv[4|6]_unicast_prefixes/extended_communities

• Dev-Snappi branch reference
• Example command to fetch the dev-snappi branch:

  go get github.com/open-traffic-generator/snappi/gosnappi@bgp_ext_comm_trans_bw
  

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Code snippets

ext1.Transitive2OctetAsType().LinkBandwidthSubtype().
	SetGlobal2ByteAs(65000).
	SetBandwidth(1000)
	
...

req := gosnappi.NewStatesRequest()
 req.BgpPrefixes().SetBgpPeerNames(peerNames)
 res, err := client.GetStates(req)
 if err != nil {
 	return nil, err
 }
 
 learnedRoutes := res.BgpPrefixes()
 liFirstPeer := actualBGPv4Prefix.Items()[0]
 route := liFirstPeer.Ipv4UnicastPrefixes().Items()[0]
 extComm := route.ExtendedCommunities().Items()[0]
 if extComm.Structured() == nil ||
    extComm.Structured().Transitive2OctetAsType()== nil  ||
    extComm.Structured().Transitive2OctetAsType().LinkBandwidthSubtype() == nil {
       t.Fatal("Structured member expected and missing for Transitive Link Bandwidth Extended Community.")
 }
 if ( extComm.Structured().Transitive2OctetAsType().LinkBandwidthSubtype().Bandwidth()!= 1000.0 ||
        extComm.Structured().Transitive2OctetAsType().LinkBandwidthSubtype().Global2ByteAs() != 65000){
        t.Fatal("Bandwidth value / AS value not as expected.")
 }

---

Test Specification (Optional)

• Example test scenario:
  • Configuration details: Port1- DUT - Port2 with BGP routes on Port1 configured to send Transitive B/W Extended Community to DUT which should be configured to accept and forward the same to Port2.
  • GetStates can be used for presence of and exact check of Transitive2OctetAsType().LinkBandwidthSubtype().Bandwidth() in addition to DUT telemetry that DUT accepts and forwards the attribute as expected.

[SouravSinhaRoy]

Looks good for merge