What I did:
Added support when TSA is done on Line Card make sure it's completely
isolated from all e-BGP peer devices from this LC or remote LC
Why I did:
Currently when TSA is executed on LC routes are withdrawn from it's connected e-BGP peers only. e-BGP peers on remote LC can/will (via i-BGP) still have route pointing/attracting traffic towards this isolated LC.
How I did:
When TSA is applied on LC all the routes that are advertised via i-BGP are set with community tag of no-export so that when remote LC received these routes it does not send over to it's connected e-BGP peers.
Also once we receive the route with no-export over iBGP match on it and and set the local preference of that route to lower value (80) so that we remove that route from the forwarding database. Below scenario explains why we do this:
- LC1 advertise R1 to LC3
- LC2 advertise R1 to LC3
- On LC3 we have multi-path/ECMP over both LC1 and LC2
- On LC3 R1 received from LC1 is consider best route over R1 over received from LC2 and is send to LC3 e-BGP peers
- Now we do TSA on LC2
- LC3 will receive R1 from LC2 with community no-export and from LC1 same as earlier (no change)
- LC3 will still get traffic for R1 since it is still advertised to e-BGP peers (since R1 from LC1 is best route)
- LC3 will forward to both LC1 and LC2 (ecmp) and this causes issue as LC2 is in TSA mode and should not receive traffic
To fix above scenario we change the preference to lower value of R1 received from LC2 so that it is removed from Multi-path/ECMP group.
How I verfiy:
UT has been added to make sure Template generation is correct
Manual Verification of the functionality
sonic-mgmt test case will be updated accordingly.
Please note this PR is on top of this :#16714 which needs to be merged first.
Signed-off-by: Abhishek Dosi <abdosi@microsoft.com>
What I did:
In Chassis TSA mode Loopback0 Ip's of each LC's should be advertise through e-BGP peers of each remote LC's
How I did:
- Route-map policy to Advertise own/self Loopback IP to other internal iBGP peers with a community internal_community as define in constants.yml
- Route-map policy to match on above internal_community when route is received from internal iBGP peers and set a internal tag as define in constants.yml and also delete the internal_community so we don't send to any of e-BGP peers
- In TSA new route-map match on above internal tag and permit the route (Loopback0 IP's of remote LC's) and set the community to traffic_shift_community.
- In TSB delete the above new route-map.
How I verify:
Manual Verification
UT updated.
sonic-mgmt PR: sonic-net/sonic-mgmt#10239
Signed-off-by: Abhishek Dosi <abdosi@microsoft.com>
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.
* 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.
