VOQ Chassis with port type inband interface in KVM test bed does not establish iBGP connections

[vganesan-nokia]

Description

In KVM based test beds as decscribed in PR sonic-net/sonic-mgmt#3218 , in voq chassis with port type inband interface, iBGP sessions are not established

Steps to reproduce the issue:

1. Bring KVM t2 topology up with VOQ chassis configurations using configurations process as mentioned in PR Support for KVM based virtual T2 VoQ chassis sonic-mgmt#3218

Describe the results you received:

• iBGP connections among the asic's inband interfaces are not established

Describe the results you expected:

• With all the VOQ configurations, iBGP sessions among the asic's inband interface IPs must be established.

Additional information you deem important (e.g. issue happens only occasionally):

• This problem is specific to the VOQ chassis that use the port type inband interfaces. The problem is due to same mac is found in both src and dst of the packets generated by hosts destined to the voq neighbors. This is as per design (Refer: https://github.com/Azure/SONiC/blob/master/doc/voq/voq_hld.md) for port type inband interface. However for KVM test beds that use VS platform, since the forwarding happens in software, the linux ip stack drops the packet because both src mac and dst mac are same.
• This issue is fixed by PR Mac for kernel static neigh programmed for voq neighs in VOQ chassis with port type inband interface in VS platforms sonic-swss#1724