Ipv6 srh no tlv

[anjan-keysight]

IPv6 Segment Routing Header Support

Redocly view of proposed model

Proposal is for IPv6 segment routing (Type 4) header, This is the first of the IPv6 routing extension header support in OTG model. This current PR is an abridged version of the original PR and does not have the SR TLVs.

The model is made generic to accommodate other IPv6 extension header types, hop-by-hop or fragment. Currently we will support routing extensions only. In routing also we will currently support Type 4 which is segment routing.

Note: The IPv6 next_header if set to AUTO, will be updated to reflect the correct next header type, which is 43 for IPv6 route.

RFC for reference

...
f1Ipv6 := f1.Packet().Add().Ipv6()
f1Ipv6.NextHeader().Auto()

f1ExtHdr := f1.Packet().Add().Ipv6ExtensionHeader()
f1ExtHdr.NextHeader().Auto()
f1ExtHdr.HdrExtLen().Auto()

f1SR := f1ExtHdr.Routing().SegmentRouting()
f1SR.SegmentsLeft().Auto()
f1SR.LastEntry().Auto()
f1SR.Flags().Protected().SetValue(1)
f1SR.Flags().Oam().SetValue(1)

f1SegList := f1SR.SegmentList()
f1SegList.Add().Segment().SetValue("2001:db8::1")
f1SegList.Add().Segment().SetValue("2001:cb7::1")
f1SegList.Add().Segment().SetValue("2001:4cd::1")
...

[apratimmukherjee]

Looks good , some comments on descriptions.

[SuryyaKrJana]

looks ok now.