Why I did it
It was observed that on a multi-asic DUT bootup, the BGP internal sessions between ASIC's was taking more time to get ESTABLISHED than external BGP sessions. The internal sessions was coming up almost exactly 120 secs later.
In multi-asic platform the bgp dockers ( which is per ASIC ) on switch start are bring brought up around the same time and they try to make the bgp sessions with neighbors (in peer ASIC's) which may be not be completely up. This results in BGP connect fail and the retry happens after 120sec which is the default Connect Retry Timer
How I did it
Add the command to set the bgp neighboring session retry timer to 10sec for internal bgp neighbors.
1. Made the command next-hop-self force only applicable on back-end asic bgp. This is done so that BGPL iBGP session running on backend can send e-BGP learn nexthop. Back end asic FRR is able to recursively resolve the eBGP nexthop in its routing table since it knows about all the connected routes advertise from front end asic.
2. Made all front-end asic bgp use global loopback ip (Loopback0) as router id and back end asic bgp use Loopbacl4096 as ruter-id and originator id for Route-Reflector. This is done so that routes learnt by external peer do not see Loopback4096 as router id in show ip bgp <route-prerfix> output.
3. To handle above change need to pass Loopback4096 from BGP manager for jinja2 template generation. This was missing and this change/fix is needed for this also https://github.com/Azure/sonic-buildimage/blob/master/dockers/docker-fpm-frr/frr/bgpd/templates/dynamic/instance.conf.j2#L27
4. Enhancement to add mult_asic specific bgpd template generation unit test cases.
- Why I did it
Update the routine is_bgp_session_internal() by checking the BGP_INTERNAL_NEIGHBOR table.
Additionally to address the review comment #5520 (comment)
Add timer settings as will in the internal session templates and keep it minimal as these sessions which will always be up.
Updates to the internal tests data + add all of it to template tests.
- How I did it
Updated the APIs and the template files.
- How to verify it
Verified the internal BGP sessions are displayed correctly with show commands with this API is_bgp_session_internal()
* Initial commit for BGP internal neighbor table support.
> Add new template named "internal" for the internal BGP sessions
> Add a new table in database "BGP_INTERNAL_NEIGHBOR"
> The internal BGP sessions will be stored in this new table "BGP_INTERNAL_NEIGHBOR"
* Changes in template generation tests with the introduction of internal neighbor template files.
