What I did:
Make Sure for internal iBGP we are one-hop away (directly connected) by using Generic TTL security mechanism.
Why I did:
Without this change it's possible on packet chassis i-BGP can be established even if there no direct connection. Below is the example
- Let's say we have 3 LC's LC1/LC2/LC3 each having i-BGP session session with each other over Loopback4096
- Each LC's have static route towards other LC's Loopback4096 to establish i-BGP session
- LC1 learn default route 0.0.0.0/0 from it's e-BGP peers and send it over to LC2 and LC3 over i-BGP
- Now for some reason on LC2 static route towards LC3 is removed/not-present/some-issue we expect i-BGP session should go down between LC2 and LC3
- However i-BGP between LC2 and LC3 does not go down because of feature ip nht-resolve-via-default where LC2 will use default route to reach Loopback4096 of LC3. As it's using default route BGP packets from LC2 towards LC3 will first route to LC1 and then go to LC3 from there.
Above scenario can result in packet mis-forwarding on data plane
How I fixed it:-
To make sure BGP packets between i-BGP peers are not going with extra routing hop enable using GTSM feature
neighbor PEER ttl-security hops NUMBER
This command enforces Generalized TTL Security Mechanism (GTSM), as specified in RFC 5082. With this command, only neighbors that are the specified number of hops away will be allowed to become neighbors. This command is mutually exclusive with ebgp-multihop.
We set hop count as 1 which makes FRR to reject BGP connection if we receive BGP packets if it's TTL < 255. Also setting this attribute make sure i-BGP frames are originated with IP TTL of 255.
How I verify:
Manual Verification of above scenario. See blow BGP packets receive with IP TTL 254 (additional routing hop) we are seeing FIN TCP flags as BGP is rejecting the connection
Signed-off-by: Abhishek Dosi <abdosi@microsoft.com>
What I did:
Enable Sending BGP Community over internal neighbors over iBGP Session
Microsoft ADO: 25268695
Why I did:
Without this change BGP community send by e-BGP Peers are not carry-forward to other e-BGP peers.
str2-xxxx-lc1-2# show bgp ipv6 20c0:a801::/64
BGP routing table entry for 20c0:a801::/64, version 52141
Paths: (1 available, best #1, table default)
Not advertised to any peer
65000 65500
2603:10e2:400::6 from 2603:10e2:400::6 (3.3.3.6)
Origin IGP, localpref 100, valid, internal, best (First path received)
Last update: Tue Sep 26 16:08:26 2023
str2-xxxx-lc1-2# show ip bgp 192.168.35.128/25
BGP routing table entry for 192.168.35.128/25, version 52688
Paths: (1 available, best #1, table default)
Not advertised to any peer
65000 65502
3.3.3.6 from 3.3.3.6 (3.3.3.6)
Origin IGP, localpref 100, valid, internal, best (First path received)
Last update: Tue Sep 26 15:45:51 2023
After the change
str2-xxxx-lc2-2(config)# router bgp 65100
str2-xxxx-lc2-2(config-router)# address-family ipv4
str2-xxxx-lc2-2(config-router-af)# neighbor INTERNAL_PEER_V4 send-community
str2-xxxx-lc2-2(config-router-af)# exit
str2-xxxx-lc2-2(config-router)# address-family ipv6
str2-xxxx-lc2-2(config-router-af)# neighbor INTERNAL_PEER_V6 send-community
str2-xxxx-lc1-2# show bgp ipv6 20c0:a801::/64
BGP routing table entry for 20c0:a801::/64, version 52400
Paths: (1 available, best #1, table default)
Not advertised to any peer
65000 65500
2603:10e2:400::6 from 2603:10e2:400::6 (3.3.3.6)
Origin IGP, localpref 100, valid, internal, best (First path received)
**Community: 1111:1111**
Last update: Tue Sep 26 16:10:19 2023
str2-xxxx-lc1-2# show ip bgp 192.168.35.128/25
BGP routing table entry for 192.168.35.128/25, version 52947
Paths: (1 available, best #1, table default)
Not advertised to any peer
65000 65502
3.3.3.6 from 3.3.3.6 (3.3.3.6)
Origin IGP, localpref 100, valid, internal, best (First path received)
**Community: 1111:1111**
Last update: Tue Sep 26 16:10:09 2023
Signed-off-by: Abhishek Dosi <abdosi@microsoft.com>
Why I did it
In the recent minigraph changes we add separate BGP session configuration for V4 and V6 internal VoQ neighbors.
This PR is adding different Peer groups for V4 and V6 neighbors
How I did it
Add VOQ_CHASSIS_V4_PEER and VOQ_CHASSIS_V6_PEER groups
Add extra Unit tests
How to verify it
Signed-off-by: Arvindsrinivasan Lakshmi Narasimhan <arlakshm@microsoft.com>
The BGP_VOQ_CHASSIS_NEIGHBOR keepalive and holdtime timers are
configured similar to general neighbors. Changes are done to configure
BGP_VOQ_CHASSIS_NEIGHBOR timers similar to BGP_INTENAL_NEIGBOR since voq
chassis bgp neighbors are similar to bgp internal neighbors in
multi-asic. As it is done for bgp internal neighbors, the keepalive and
holdtime timers are set to 3 and 10 seconds respectively. Also similar
to bgp internal neighbors, connection retry timer is also configured for
voq chassis bgp neighbors.
Signed-off-by: vedganes <vedavinayagam.ganesan@nokia.com>
This commit has following changes:
* Add templates and code to support VoQ chassis iBGP peers
* Add support to convert a new VoQChassisInternal element in the
BGPSession element of the minigraph to a new BGP_VOQ_CHASSIS_NEIGHBOR
table in CONFIG_DB.
* Add a new set of "voq_chassis" templates to docker-fpm-frr
* Add a new BGP peer manager to bgpcfgd to add neighbors from the
BGP_VOQ_CHASSIS_NEIGHBOR table using the voq_chassis templates.
* Add a test case for minigraph.py, making sure the VoQChassisInternal
element creates a BGP_VOQ_CHASSIS_NEIGHBOR entry, but not if its
value is "false".
* Add a set of test cases for the new voq_chassis templates in
sonic-bgpcfgd tests.
Note that the templates expect the new
"bgp bestpath peer-type multipath-relax" bgpd configuration to be
available.
Signed-off-by: Joanne Mikkelson <jmmikkel@arista.com>
