[165102] in North American Network Operators' Group
Re: BGP Route Issues
daemon@ATHENA.MIT.EDU (Randy)
Sun Aug 18 23:51:32 2013
Date: Sun, 18 Aug 2013 20:51:16 -0700 (PDT)
From: Randy <randy_94108@yahoo.com>
To: Blake Dunlap <ikiris@gmail.com>, Christopher Karel <chris.karel@gmail.com>
In-Reply-To: <CAJvB4tnTX=5s7iu8jQixZ58bDPoLVf=c5NkFEaQ36z6LsHYaWw@mail.gmail.com>
Cc: "nanog@nanog.org" <nanog@nanog.org>
Reply-To: Randy <randy_94108@yahoo.com>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
11 prepends is beyond-excessive besides being annoying.=0Afilter please _([=
0-9]+) _/1_/1_/1_=0A=0A=0A=0A=0A>________________________________=0A> From:=
Blake Dunlap <ikiris@gmail.com>=0A>To: Christopher Karel <chris.karel@gmai=
l.com> =0A>Cc: "nanog@nanog.org" <nanog@nanog.org> =0A>Sent: Sunday, August=
18, 2013 7:42 PM=0A>Subject: Re: BGP Route Issues=0A> =0A>=0A>Local Pref (=
which is common by the way to be set so customers > peers >=0A>transit). AS=
Path doesn't beat it.=0A>You can only request people follow the routes you=
want ingress, there's=0A>nothing you can do to force them to take a path t=
o you short of=0A>deaggregation, and that only works until they notice it, =
and it irratates=0A>the rest of the world as well by using additional route=
slots.=0A>=0A>Poor routing is purely a viewpoint problem, not necessarily =
in agreement=0A>between all parties.=0A>=0A>-Blake=0A>=0A>=0A>On Sun, Aug 1=
8, 2013 at 8:33 PM, Christopher Karel <chris.karel@gmail.com>wrote:=0A>=0A>=
>=A0 Good evening,=0A>>=0A>>=A0 =A0 I'm hoping you guys might be able to =
offer some advice or insight into=0A>> a BGP problem I've got.=A0 I've noti=
ced some strange routes between our=0A>> network, AS27270, and AS22943.=A0 =
It looks like both our networks are dual=0A>> homed.=A0 One ISP as the prim=
ary, and the other used as a backup, with path=0A>> prepending to prevent i=
t from actually being used except in an outage.=0A>>=A0 However, our route =
to 22943 appears to be using their backup link.=A0 (27270=0A>> 4323 7018 22=
943 22943 22943 22943 22943 22943 22943 22943 22943 22943=0A>> 22943)=A0 Wh=
ich is strange, because we can reach their primary ISP without=0A>> any suc=
h rigmarole.=0A>>=0A>>=A0 =A0 Playing around with Looking Glass servers in=
dicates that Cogent=0A>> (AS174) has a similar backup route to our network.=
=A0 (174 22402 27270 27270=0A>> 27270 27270 27270 27270)=A0 Everywhere else=
I check seems perfectly sane.=0A>>=A0 But since Cogent is essentially in-b=
etween the two networks I'm=0A>> troubleshooting, I would assume that the o=
ther network has a similar route.=0A>>=A0 But Cogent won't talk with me abo=
ut this, since I'm not a customer.=0A>>=0A>>=A0 =A0 So as far as advice go=
es, is there a common issue that might result in=0A>> such poor routes in b=
oth directions?=A0 Any further troubleshooting that I=0A>> should be doing?=
=A0 Or any ideas on how to help remedy things that appear to=0A>> be outsid=
e our network/ISP?=A0 Or are we doing something so wrong that this=0A>> is =
all my fault?=0A>>=0A>> I'd really appreciate any input on this.=0A>>=0A>>=
=0A>=0A>=0A>
