Re: Sites unreachable while traversing Dallas IXP

[Brian Turnbow via NANOG <nanog () lists nanog org>]

HI,

On Fri, 26 Sept 2025 at 17:23, Tom Beecher <beecher () beecher cc> wrote:
> > 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.
Yes it is not an acl on his port, as no sessions would come up,  but
maybe a fabric forwarding issue.
I have no idea what they use if flat L2, evpn etc on the peering lan
but it would be something to check.
It could even be some crazy member that fixed static arp tables or L2
acls for "security purposes" ;-)

Brian
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