From: erik2@kuriosity.com
Date: Sun Mar 23 2003 - 18:51:07 GMT-3
I don't see this as being an issue. We did the same thing at my previous job, and there was no issue. There were some policies that each of our providers wanted us to use, but they really had no effect in regards to this scenario....
Erik Rudnick
------------------------------------------------
On Fri, 14 Mar 2003 12:14:37 -0800, "Anthony Pace" <anthonypace@fastmail.fm> wrote:
> My question is much simpler. Can I advertise the same route to 2
> providers and let the clients closer to provider 1 come in via provider 1
> and let the customers closer to provider 2 come in via 2.
>
> Can I get the whole BGP routing table from both providers and choose the
> best EGRESS path for any given network between the 2 providers?
>
> In the event of a failure everything will now INGRESS/EGRESS via the only
> provider getting my advertisement and sending me the BGP Internet routes?
>
> No prepends, meds or Local preference. Just a filter to make sure I'm not
> a transit AS. I can see nothing technically that would prevent this, is
> there an administrative policy between NAPS which would prohibit any of
> this? There would be asymetrical routing, but I don't see that as a big
> issue.
>
> Anthony Pace CCIE #10349
>
>
> On Fri, 14 Mar 2003 08:46:06 -0500, "OhioHondo"
> <ohiohondo@columbus.rr.com> said:
> > In addition to controlling load balancing, I prefer to have a
> > deterministic
> > traffic flow if at all possible. Knowing how the traffic is "supposed to"
> > egress the network always helps in troubleshooting.
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> > Voss, David
> > Sent: Thursday, March 13, 2003 10:19 PM
> > To: 'Anthony Pace'; ccielab@groupstudy.com
> > Subject: RE: BGP load balancing (via best path)
> >
> >
> > I have dual circuits at work. I think PREPEND is a very weak method in
> > to
> > try to dictate traffic mainly because it will not work in every scenario.
> > What if you prepend 5 5 5 5 5 to make one circuit less preffered but your
> > "customer" is:
> >
> > CUSTOMER 100 200 300 5 5 5 5 5
> > YOUR AS
> > CUSTOMER 100 200 300 400 500 600 700 800 9000 1000 1100 1200 1300 1400
> > YOUR AS
> >
> > The customer will still prefer the circuit that you prepend in this case.
> >
> > I have chosed to advertise one network out a T1 and one network out our
> > DS3.
> > I then use advertise-map / non-exist-map to advertise the network out the
> > other circuit should the router or circuit fail.
> >
> > The other obvious method is to play with MED's, but I had the luxery of 2
> > Class C network to play with.
> >
> > Regardless, AS-PATH prepend, I believe, is not a 100% reliable way to
> > dicate
> > traffic.
> >
> > -----Original Message-----
> > From: Anthony Pace [mailto:anthonypace@fastmail.fm]
> > Sent: Thursday, March 13, 2003 12:43 PM
> > To: ccielab@groupstudy.com
> > Subject: BGP load balancing (via best path)
> >
> >
> > All of the implementations I have seen, (as well as the examples in
> > Halabi's book) use a Primary/Failover method for both INGRESS and EGRESS
> > traffic when BGP is used. Outbound advertisements with AS-PREPEND'S to
> > the backup to cause the "world" to come in via the Primary; and perhaps
> > better local preference for routes learned on the PRimary to cause our
> > outbound traffic to use the primary.
> >
> > There are many flavors of this,but the principle remains consistant. For
> > any given route a primary and a failover.
> >
> > Here is my question:
> >
> > What is the detriment of taking in the all BGP routes from 2 providers
> > and choosing the best path for outbound traffic; What is the detriment of
> > advertising my own address space to 2 providers with no PREPENDS. Just
> > let the traffic come in and go out based on the "end systems" proximity
> > to either of my 2 providers?
> >
> > Without AS-PREPENDS to the BACKUP provider, I understand that if the
> > PRIMARY provider gave me a block of their address space, I would wind up
> > seeing the traffic all come in via the BACKUP link (as the backup
> > provider would advertise a more specific, route and the PRIMARY would
> > summarize my space into an aggrigate)
> >
> > Does that sound correct?
> >
> > If the address space belonged to neither provider, then couldn't I just
> > advertise it to both and let the traffic find me through both?
> >
> > Am I overlooking something very obvious?
> >
> > Anthony Pace CCIE#10349
> >
> >
> > --
> > Anthony Pace
> > anthonypace@fastmail.fm
> >
> > --
> > http://www.fastmail.fm - One of many happy users:
> > http://www.fastmail.fm/docs/quotes.html
> >
> >
> >
> --
> Anthony Pace
> anthonypace@fastmail.fm
>
> --
> http://www.fastmail.fm - Same, same, but different
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