Re: Sites unreachable while traversing Dallas IXP

[Tom Beecher via NANOG <nanog () lists nanog org>]

> Besides what others have mentioned,
> Another thing that changed moving from the physical interface to lacp
> is going to be the mac used on the ixp lan.
> I would check connectivity to all IPs on the peering lan as they may
> receive your routes from the route server but not be able to contact
> you directly.
> You may have already done this but as you mentioned removing the
> announcements to the route server, to solve the issue it rang the
> route server blackhole bell for me.
> It wouldn't be the first time I've seen this happen.

This is an excellent reminder. Many IXPs put a MAC filter on each port that
you have to have them change if you change your end.

I'm guessing this isn't the case here, since the OP stated his BGP sessions
came up and traffic was flowing, but it's possible and a good callout.

On Fri, Sep 26, 2025 at 11:14 AM Brian Turnbow via NANOG <
nanog () lists nanog org> wrote:

> Hi Andy,
>
>  Andy Cole via NANOG wrote on 26/09/2025 04:21:
>  > No
>  > configuration changes to routing policy at all.  After a few days we
>  > started to get customer complaints for certain sites/domains being
>  > unreachable. I worked around the issue by not announcing the customer
>  > blocks to the route servers and changed the return path to traverse
>  > transit. This solved the issue, but I'm perplexed as to what could've
>  > caused the issue, and where to look to resolve it.  If you guys could
>  > provide feedback and point me in the right direction I'd appreciate it.
> TIA.
>
> Besides what others have mentioned,
> Another thing that changed moving from the physical interface to lacp
> is going to be the mac used on the ixp lan.
> I would check connectivity to all IPs on the peering lan as they may
> receive your routes from the route server but not be able to contact
> you directly.
> You may have already done this but as you mentioned removing the
> announcements to the route server, to solve the issue it rang the
> route server blackhole bell for me.
> It wouldn't be the first time I've seen this happen.
>
> Brian
>
>
> Brian
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> NANOG mailing list
>
> https://lists.nanog.org/archives/list/nanog () lists nanog org/message/6CBYNULYVJ2ADUW7Y5VSYQ2A2WS6SODG/
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