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----- Original Message -----
From: "Jason J. Roysdon"
To:
Sent: Saturday, April 14, 2001 12:44 PM
Subject: Re: Routing Performance Perspective [7:495]
> I use a CRON job and shell script to save logs from each night for a
weeks'
> worth, keep Sunday for the last 5 weeks, and the 1st & 15th of each month
> for the past 6 months. It's just interesting to me to see the changes
that
> occur from time to time (usually things get "closer" and have less hops
over
> time, as ISPs peer at more places).
>
> Anyway, the best thing to do is look up their ip space on one of the
looking
> bgp glasses and find out their ASN and how many different
directly-connected
> paths they're announcing out (how many ISPs they're connected to).
>
> route-server.cerf.net shows the best 3
> route-views.oregon-ix.net shows the best 22
>
> Use 'show ip bgp ' to find their ASN and such info. Here's an
> example with one of our netblocks:
> route-server>sh ip bgp 63.107.123.0
> BGP routing table entry for 63.107.123.0/24, version 294979
> Paths: (3 available, best #3)
> Advertised to non peer-group peers:
> 216.128.28.34
> 1740 1239 18506
> 134.24.88.55 from 134.24.88.55 (134.24.127.27)
> Origin IGP, metric 20, localpref 100, valid, external
> 1740 701 18506
> 192.157.69.5 from 192.157.69.5 (134.24.127.201)
> Origin IGP, metric 20, localpref 100, valid, external
> 1740 701 18506
> 198.32.176.25 from 198.32.176.25 (134.24.127.39)
> Origin IGP, metric 20, localpref 100, valid, external, best
>
>
> Our ASN is 18506, and 701 is UUNET and 1239 is Sprint, both of which are
our
> directly connected ISPs. If you compare on oregon-ix, you'll see that
we're
> only announced out those two ISPs in the 22 best routes it keeps. I would
> expect a good co-location place to be connected 3-5 of the top ISPs, but
> that's just a guess off the top of my head. I think I've seen a really
> high-end co-lo that boasted connections to the top 12 ISPs.
>
> Anyway, my guess is that your corp. ISP is either manipulating the BGP
> announcements (prepending or other means) and therefore influencing a
longer
> (but perhaps bigger/faster connection) route, whereas they're taking the
> shortest hop announcement from the co-lo.
>
> Again, look up your corp. netblock as well, and see how it's being
> announced.
>
> It could also be that the co-lo isn't taking full routes from all of their
> ISPs, which would result in the sub-optimal routing you fear.
>
> Just looking up the netblock of your MX, it does look like your ISP is
> prepending to influence routing far away from some of their links (Telstra
> AS16779) and their AT&T (AS7018) link, somewhat away from their UUNET
> (AS701) link and through the Sprint link (AS1239 has no prepending):
> 6395 7018 6993 6993 6993 6993
> 216.140.8.63 from 216.140.8.63 (216.140.8.63)
> Origin IGP, metric 483, localpref 100, valid, external
> Community: 6395:10
> 8297 6453 1239 6993
> 195.219.96.239 from 195.219.96.239 (195.219.96.239)
> Origin IGP, localpref 100, valid, external
> 1221 16779 3549 6993 6993 6993 6993 6993 6993 6993
> 203.62.248.4 from 203.62.248.4 (203.62.248.4)
> Origin IGP, localpref 100, valid, external
> 6066 701 6993 6993
> 204.29.239.1 from 204.29.239.1 (150.225.14.1)
> Origin IGP, localpref 100, valid, external
>
> I would guess that your ISP InterNAP knows what they're doing with all
these
> prepends and is purposely influencing return traffic toward their bigger
> pipes.
>
> --
> Jason Roysdon, CCNP+Security/CCDP, MCSE, CNA, Network+, A+
> List email: [EMAIL PROTECTED]
> Homepage: http://jason.artoo.net/
>
>
>
> wrote in message
> [EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> > I am hoping someone could provide me some experienced perspective for
the
> > following situation:
> >
> > We utilize a somewhat 'new on the block' co-location facility, and while
> > they otherwise provide fantastic service I have some questions about the
> > routing performance.
> > Over the past few weeks, I have noticed a degradation of service on our
> > colocator-provided connection. (significant latency, and loss of
packets)
> > As a result, I have been tracerouting our corporate offices from our
> > co-location facility (only 30 miles away) and it takes anywhere from 13
to
> > 16 hops to reach it's destination. I have been doing this on a
> > semi-scientific basis (whenever I remember) and the results are usually
> the
> > same, but closer to 16 hops than 13. When I traceroute from our
> corporate
> > offices to our co-location facility the results are usually 6 to seven
> hops
> > using the same semi-scientific methodology as stated above.
> >
> > My concerns are that end-user experience are being affected by apparent
> > sub-optimal routing.
> >
> > The question I ask of the Grand-Master BGP geniuses is: do I have a
valid
> > complaint regarding sub-optimal routing from our co-locator?
> >
> > Thanks!
> > Matthew
> > FAQ, list archives, and subscription info:
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