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BGP BFD session things #17410

Merged
merged 5 commits into from
Nov 12, 2024
Merged

BGP BFD session things #17410

merged 5 commits into from
Nov 12, 2024

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ton31337
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Closes #17396
Closes #17408

@ton31337
bgpd: Do not use an existing peer pointer for ALL_LIST_ELEMENTS()
6e92e25 
Use a separate `member` in this case.

Signed-off-by: Donatas Abraitis <[email protected]>
@ton31337
bgpd: Do not try to uninstall BFD session if the peer is not established
29eafd3 
Having something like:

```
 neighbor 192.168.1.222 ebgp-multihop 32
 neighbor 192.168.1.222 update-source 192.168.1.5
 neighbor 192.168.1.222 bfd
```

Won't work and the result is (empty):

```
$ show bfd peers
BFD Peers:
```

bgp_stop() is called in BGP FSM multiple times (even at startup) that
causes intermediate session interruption when update-source/ebgp-multihop
is triggered.

With this fix, the ordering does not matter and the BFD session's parameters
are updated correctly.

Signed-off-by: Donatas Abraitis <[email protected]>
@ton31337
tests: Check if BGP BFD session is created correctly with multihop/up…
55dcbd3 
…date-source

Signed-off-by: Donatas Abraitis <[email protected]>
@frrbot frrbot bot added bgp tests Topotests, make check, etc labels Nov 11, 2024
@ton31337 ton31337 requested a review from rzalamena November 11, 2024 15:09
@tufeigunchu
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I tested the change but I couldn't get BFD session either when restarting frr, is it ready?

@ton31337
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I tested the change but I couldn't get BFD session either when restarting frr

Can you show show bfd peers, and show bgp neighbor?

Also, show the full config + logs. Because for me (and a topotest added confirms) it works.

@tufeigunchu
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Your topotest uses ip address in update-source, does it mean that using interface name is not supported?
I test with interface name and it failed.

@ton31337
bgpd: Update source address for BFD session
fcabeea 
If BFD is down, we should try to detect the source automatically from the given
interface.

Signed-off-by: Donatas Abraitis <[email protected]>
@ton31337
tests: Check if BFD session is created with update-source (interface)
2c08d9f 
Signed-off-by: Donatas Abraitis <[email protected]>
@ton31337
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@tufeigunchu could you retry with the latest changes (force pushed 1 commit)?

riw777
riw777 approved these changes Nov 12, 2024
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looks good

@riw777 riw777 merged commit fe56a65 into FRRouting:master Nov 12, 2024
11 checks passed
@ton31337 ton31337 deleted the fix/bgpd_ebgp_multihop_set_unset branch November 12, 2024 18:12
@triple-it
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Hi,
So I ran into this bug.

And I probably do not have the optimal configuration for this session-finding.

bgp
neighbor 10.64.2.2 description tun2
neighbor 10.64.2.2 bfd
neighbor 10.64.2.2 bfd profile BFDBGP
neighbor 10.64.2.2 bfd check-control-plane-failure
neighbor 10.64.2.2 update-source 10.64.2.1

bfd
peer 10.64.4.2 local-address 10.64.4.1
transmit-interval 200
receive-interval 200
echo-mode
echo transmit-interval 200
echo receive-interval 200
exit

I'm not configuring the dummy2 and vti2 (routed ipsec) configuration explicitly in the frr.conf but they are currently outside.
Dummy2 under control of netplan
vti2 under control of the ipsec software.

The BGP session does not go down when BFD goes down.

2024-12-17 11:47:23.781 [DEBG] bfdd: [SEY1D-NT8EQ] state-change: [mhop:no peer:10.64.2.2 local:10.64.2.1 vrf:default] up -> down reason:control-expired                                                                                                                                             
2024-12-17 11:47:23.781 [DEBG] bgpd: [Q4BCV-6FHZ5] zclient_bfd_session_update: 10.64.2.1/32 -> 10.64.2.2/32 (interface vti2) VRF default(0) (CPI bit no): Down                                                                                                                                      
2024-12-17 11:47:23.781 [DEBG] bgpd: [QFMSE-NPSNN] zclient_bfd_session_update:   sessions updated: 0                                              
2024-12-17 11:47:25.486 [DEBG] bfdd: [J1C6V-VMRW5] state-change: [mhop:no peer:10.64.2.2 local:10.64.2.1 vrf:default] down -> up                  
2024-12-17 11:47:25.486 [DEBG] bgpd: [Q4BCV-6FHZ5] zclient_bfd_session_update: 10.64.2.1/32 -> 10.64.2.2/32 (interface vti2) VRF default(0) (CPI bit no): Up                                                                                                                                        
2024-12-17 11:47:25.486 [DEBG] bgpd: [QFMSE-NPSNN] zclient_bfd_session_update:   sessions updated: 0                                              
2024-12-17 11:47:26.926 [DEBG] bfdd: [SEY1D-NT8EQ] state-change: [mhop:no peer:10.64.2.2 local:10.64.2.1 vrf:default] up -> down reason:control-expired                                                                                                                                             
2024-12-17 11:47:26.927 [DEBG] bgpd: [Q4BCV-6FHZ5] zclient_bfd_session_update: 10.64.2.1/32 -> 10.64.2.2/32 (interface vti2) VRF default(0) (CPI bit no): Down                                                                                                                                      
2024-12-17 11:47:26.927 [DEBG] bgpd: [QFMSE-NPSNN] zclient_bfd_session_update:   sessions updated: 0

What would be the best configuration to make this session matching happening now?

Should I change to interface configuration on the BFD ? Interface under update-source BGP?
Is interface configuration (of dummy2 or vti2) required in frr.conf?

If someone could give some pointers to get this session matching happening now, please let me know :)

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@riw777 riw777 riw777 approved these changes

@rzalamena rzalamena Awaiting requested review from rzalamena

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@ton31337 @tufeigunchu @triple-it @riw777