Wrong BGP NH metric
Hello, First I would like to thank you for this amazing software! I am running Bird 2.0.7 as RR for L3VPNs and on one RR the OSPF metric for the BGP NH is different than what's seen in BGP as shown below. BGP PREF/METRIC = (100/61580) , OSPF_METRIC = 61480. bird> sh route 10:10 94.207.96.0/19 all primary Table vpntab4: 10:10 94.207.96.0/19 unicast [ROUTER1 2022-09-28 00:10:09 from 10.100.186.1] * (100/61580) [AS15802i] Type: BGP univ BGP.origin: IGP BGP.as_path: 15802 BGP.next_hop: 10.100.184.8 bird> sh route 10.100.184.8/32 Table master4: 10.100.184.8/32 unicast [OSPF 2022-09-29 12:33:35] IA (150/61480) [10.100.186.5] After restarting the BIRD OSPF adjancency the BGP metric changed to 61480. Any help in understanding the issue would be much appreciated. Thank you!
Hello, The same issue on another RR, the BGP_Metric=60380 while the OSPF_Metric=60315. bird> sh route 10:10 202.81.16.0/24 all Table vpntab4: 10:10 202.81.16.0/24 unicast [ROUTER2 2022-09-29 15:21:18 from 10.100.186.6] * (100/60380) [AS4826i] Type: BGP univ BGP.origin: IGP BGP.as_path: 4826 BGP.next_hop: 10.100.186.6 bird> show route 10.100.186.6/32 Table master4: 10.100.186.6/32 unicast [OSPF 2022-09-30 15:01:51] IA (150/60315) [10.100.186.4] On 30/09/2022 09:08, Mihai wrote:
Hello,
First I would like to thank you for this amazing software!
I am running Bird 2.0.7 as RR for L3VPNs and on one RR the OSPF metric for the BGP NH is different than what's seen in BGP as shown below.
BGP PREF/METRIC = (100/61580) , OSPF_METRIC = 61480.
bird> sh route 10:10 94.207.96.0/19 all primary Table vpntab4: 10:10 94.207.96.0/19 unicast [ROUTER1 2022-09-28 00:10:09 from 10.100.186.1] * (100/61580) [AS15802i] Type: BGP univ BGP.origin: IGP BGP.as_path: 15802 BGP.next_hop: 10.100.184.8
bird> sh route 10.100.184.8/32 Table master4: 10.100.184.8/32 unicast [OSPF 2022-09-29 12:33:35] IA (150/61480) [10.100.186.5]
After restarting the BIRD OSPF adjancency the BGP metric changed to 61480.
Any help in understanding the issue would be much appreciated.
Thank you!
Hello! I'd suspect the internal nexthop resolving mechanisms of missing the OSPF route update. When working on the multithreaded version, I came across a similar kind of bug and I honestly don't know yet how exactly this may be broken. That said, is it possible that the metric is just an obsolete value from some previous route version? Thanks for your report. Maria On 9/30/22 17:10, Mihai via Bird-users wrote:
Hello,
The same issue on another RR, the BGP_Metric=60380 while the OSPF_Metric=60315.
bird> sh route 10:10 202.81.16.0/24 all Table vpntab4: 10:10 202.81.16.0/24 unicast [ROUTER2 2022-09-29 15:21:18 from 10.100.186.6] * (100/60380) [AS4826i] Type: BGP univ BGP.origin: IGP BGP.as_path: 4826 BGP.next_hop: 10.100.186.6
bird> show route 10.100.186.6/32 Table master4: 10.100.186.6/32 unicast [OSPF 2022-09-30 15:01:51] IA (150/60315) [10.100.186.4]
On 30/09/2022 09:08, Mihai wrote:
Hello,
First I would like to thank you for this amazing software!
I am running Bird 2.0.7 as RR for L3VPNs and on one RR the OSPF metric for the BGP NH is different than what's seen in BGP as shown below.
BGP PREF/METRIC = (100/61580) , OSPF_METRIC = 61480.
bird> sh route 10:10 94.207.96.0/19 all primary Table vpntab4: 10:10 94.207.96.0/19 unicast [ROUTER1 2022-09-28 00:10:09 from 10.100.186.1] * (100/61580) [AS15802i] Type: BGP univ BGP.origin: IGP BGP.as_path: 15802 BGP.next_hop: 10.100.184.8
bird> sh route 10.100.184.8/32 Table master4: 10.100.184.8/32 unicast [OSPF 2022-09-29 12:33:35] IA (150/61480) [10.100.186.5]
After restarting the BIRD OSPF adjancency the BGP metric changed to 61480.
Any help in understanding the issue would be much appreciated.
Thank you!
Hi Maria, Yes you are correct, the metric is not a random value but an old value, probably the first one after OSPF established. It looks like any subsequent change in the OSPF topology/metrics is not reflected in the BGP_NH metric. Best regards, Mihai On 03/10/2022 12:43, Maria Matejka via Bird-users wrote:
Hello!
I'd suspect the internal nexthop resolving mechanisms of missing the OSPF route update. When working on the multithreaded version, I came across a similar kind of bug and I honestly don't know yet how exactly this may be broken.
That said, is it possible that the metric is just an obsolete value from some previous route version?
Thanks for your report.
Maria
On 9/30/22 17:10, Mihai via Bird-users wrote:
Hello,
The same issue on another RR, the BGP_Metric=60380 while the OSPF_Metric=60315.
bird> sh route 10:10 202.81.16.0/24 all Table vpntab4: 10:10 202.81.16.0/24 unicast [ROUTER2 2022-09-29 15:21:18 from 10.100.186.6] * (100/60380) [AS4826i] Type: BGP univ BGP.origin: IGP BGP.as_path: 4826 BGP.next_hop: 10.100.186.6
bird> show route 10.100.186.6/32 Table master4: 10.100.186.6/32 unicast [OSPF 2022-09-30 15:01:51] IA (150/60315) [10.100.186.4]
On 30/09/2022 09:08, Mihai wrote:
Hello,
First I would like to thank you for this amazing software!
I am running Bird 2.0.7 as RR for L3VPNs and on one RR the OSPF metric for the BGP NH is different than what's seen in BGP as shown below.
BGP PREF/METRIC = (100/61580) , OSPF_METRIC = 61480.
bird> sh route 10:10 94.207.96.0/19 all primary Table vpntab4: 10:10 94.207.96.0/19 unicast [ROUTER1 2022-09-28 00:10:09 from 10.100.186.1] * (100/61580) [AS15802i] Type: BGP univ BGP.origin: IGP BGP.as_path: 15802 BGP.next_hop: 10.100.184.8
bird> sh route 10.100.184.8/32 Table master4: 10.100.184.8/32 unicast [OSPF 2022-09-29 12:33:35] IA (150/61480) [10.100.186.5]
After restarting the BIRD OSPF adjancency the BGP metric changed to 61480.
Any help in understanding the issue would be much appreciated.
Thank you!
Fine then! I was suspicious about some changes in thread-next (where this problem can be actually reproduced with a good probability) and now I know that I should assess the whole algorithm instead. Thanks a lot! Maria On October 7, 2022 11:29:09 AM UTC, Mihai <mihaigabriel@gmail.com> wrote:
Hi Maria,
Yes you are correct, the metric is not a random value but an old value, probably the first one after OSPF established. It looks like any subsequent change in the OSPF topology/metrics is not reflected in the BGP_NH metric.
Best regards, Mihai
On 03/10/2022 12:43, Maria Matejka via Bird-users wrote:
Hello!
I'd suspect the internal nexthop resolving mechanisms of missing the OSPF route update. When working on the multithreaded version, I came across a similar kind of bug and I honestly don't know yet how exactly this may be broken.
That said, is it possible that the metric is just an obsolete value from some previous route version?
Thanks for your report.
Maria
On 9/30/22 17:10, Mihai via Bird-users wrote:
Hello,
The same issue on another RR, the BGP_Metric=60380 while the OSPF_Metric=60315.
bird> sh route 10:10 202.81.16.0/24 all Table vpntab4: 10:10 202.81.16.0/24 unicast [ROUTER2 2022-09-29 15:21:18 from 10.100.186.6] * (100/60380) [AS4826i] Type: BGP univ BGP.origin: IGP BGP.as_path: 4826 BGP.next_hop: 10.100.186.6
bird> show route 10.100.186.6/32 Table master4: 10.100.186.6/32 unicast [OSPF 2022-09-30 15:01:51] IA (150/60315) [10.100.186.4]
On 30/09/2022 09:08, Mihai wrote:
Hello,
First I would like to thank you for this amazing software!
I am running Bird 2.0.7 as RR for L3VPNs and on one RR the OSPF metric for the BGP NH is different than what's seen in BGP as shown below.
BGP PREF/METRIC = (100/61580) , OSPF_METRIC = 61480.
bird> sh route 10:10 94.207.96.0/19 all primary Table vpntab4: 10:10 94.207.96.0/19 unicast [ROUTER1 2022-09-28 00:10:09 from 10.100.186.1] * (100/61580) [AS15802i] Type: BGP univ BGP.origin: IGP BGP.as_path: 15802 BGP.next_hop: 10.100.184.8
bird> sh route 10.100.184.8/32 Table master4: 10.100.184.8/32 unicast [OSPF 2022-09-29 12:33:35] IA (150/61480) [10.100.186.5]
After restarting the BIRD OSPF adjancency the BGP metric changed to 61480.
Any help in understanding the issue would be much appreciated.
Thank you!
-- Sent from my Android device with K-9 Mail. Please excuse my brevity.
participants (3)
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Maria Matejka -
Maria Matějka
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Mihai