best practice for advertising peering fabric routes

William Herrin bill at
Wed Jan 15 16:43:11 UTC 2014

On Wed, Jan 15, 2014 at 10:57 AM, Patrick W. Gilmore <patrick at> wrote:
> On Jan 15, 2014, at 10:44 , William Herrin <bill at> wrote:
>> I have to disagree with you. If it appears in a traceroute to
>> somewhere else, I'd like to be able to ping and traceroute directly to
>> it. When I can't, that impairs my ability to troubleshoot the all too
>> common can't-get-there-from-here problems. The more you hide the
>> infrastructure, the more intractable problems become for your
>> customers.
>> The IXP LAN should be reachable from every device on the ASes which
>> connect to it, not just the immediate router.
> We disagree.
> Plus, you really can't type "ping" on the router connected to the IXP?

Not when I'm the downstream customer, no. It's jolly good that *you*
can test, but before the rest of us can get through the layers of
support which insulate you, we have to be able to convincingly test

> As I know 100% of ISPs (to at least one decimal place) cannot
> make such a guarantee, then doing so puts the IXP and all other
> members - whether peers of yours or not - at risk. Putting others
> at risk because you are lazy or because it makes your life easier
> is .. I believe I called it bad manners before.

That makes no sense. The IXP is at no more or less risk from your
customers than any other connection you have for Internet carriage.
Risk which you are responsible for managing either way.

> I said in an earlier post that if you carry a prefix I own,
> did not announce to you, and make it very clear I
> specifically do not want you to carry, I will ask you to
> stop or face possible disconnection. [...] That's not your prefix,
> you were not given it and told not to carry it, so Do Not Carry It.

Well yes, of course. If you participate in an IXP you follow the rules
of the IXP. I respectfully question the wisdom of such a rule and the
IXPs I deal with only ask that you not announce the IXP prefix
externally. But it's not OK to unilaterally break the IXP's rules,
however poorly conceived.

Bill Herrin

William D. Herrin ................ herrin at  bill at
3005 Crane Dr. ...................... Web: <>
Falls Church, VA 22042-3004

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