/me swallows his pride and seconds the motion.
-Peter Slow, CCNBlah
----- Original Message -----
From: "Michael L. Williams"
To:
Sent: Tuesday, May 29, 2001 7:52 PM
Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
> I would have to agree....... Given that there are 2 European sites and
2
> US sites, I think the overhead of BGP would be negligible, while at the
same
> time providing a graceful solution to a sticky problem. I think you
stated
> your point very well that, even tho the network may seem "small", the fact
> there are multiple sites with redundant links makes the network more
complex
> like a "large" network, no matter how many actual routers, end PCs, etc.
> Using BGP (eBGP treating the 2 networks on each continent as a different
BGP
> AS) would definitely make things simpiler to manage while giving more
> control using routing policies and prefix lists. CCNP BSCN Question #1:
> When to use BGP? (two of the possible answers) 1) When the flow of
traffic
> entering and leaving an AS must be manipulated. 2) When the AS has
multiple
> connections to another AS. Breaking the 2 London routers into an AS and
the
> two US routers into an AS, it seems to me being able to maniuplate the
> routes between the 2 continents' ASes would be convenient and fits the
> purpose of BGP very nicely. But also consider: CCNP BSCN Question #2:
> When NOT to use BGP? (three of the possible answers) 1) Low bandwidth
> between ASes. 2) Lack of memory/CPU power on those routers 3) A limited
> understanding of BGP route filtering and selection. Kevin: What are the
> speed of the links between New York/London and San Jose/London? Can the
> routers at each site handle running BGP? Do you understand BGP and route
> filtering? If the links aren't too tiny, the routers can handle it, and
you
> understand how to implement BGP route filtering, this BGP solution doesn't
> sound bad to me........
>
> My 2 cents.
>
> Mike W.
>
> "W. Alan Robertson" wrote in message
> [EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> > Peter,
> >
> > OSPF has a distance of 110, and yes, iBGP has a distance of 200. By
> > having seperate routing domains for North America and Europe, he could
> > use eBGP (Distance - 20) between his two networks.
> >
> > Distance wouldn't really do anything in this case, though, because
> > European routes would not be learned via OSPF (Remember, we have
> > theoretically split OSPF into two seperate routing domains, never the
> > two shall meet).
> >
> > Instead, eBGP would be bridging the gap between the two OSPF networks.
> > This would afford the opportunity to really take control of what
> > routes were advertised between the two, and excercise strict control
> > of the routing metrics, manipulating them in such a way as to ensure
> > that the best path across the pond were utilized under all normal
> > circumstances, but providing the redundant "less preferred" path in
> > the event of some kind of outage.
> >
> > Can the same be accomplished via OSPF? Yes, but because we're dealing
> > with Intra-area, and Inter-area routes, it may be more complex than by
> > simply manipulating the link costs. Remember that OSPF chooses an
> > Intra-area route with a Cost of 4,000,000 over an Inter-area route
> > with a cost of 100. That's just one of the quirks of the protocol.
> >
> > As for "Why would you want to break up an AS that small into two
> > seperate private ASes?", it's called thinking outside the box. We
> > tend to think that a small network could not be better served by
> > applying the same principles that we might use for a larger
> > environment. Why is that? Instead of letting the number of devices
> > determine the right solution (Or more properly, a good solution),
> > let's form a solution based on the specific requirements.
> >
> > A network with a small number of devices, but consisting of multiple
> > sites, and redundant links, presents a unique challenge. Forget the
> > number of devices, and look at both the physical topology, and the
> > problem that needs solving. BGPs powerful policy routing tools make
> > it a good fit for this environment, when viewed from a requirements
> > perspective.
> >
> > It's not the only solution, but it is a valid solution, and in my
> > opinion, it's a good solution.
> >
> > Alan
> >
> > ----- Original Message -----
> > From: "Peter I. Slow, CCNP Voice Specialist"
> > To: "W. Alan Robertson" ;
> >
> > Sent: Tuesday, May 29, 2001 1:02 PM
> > Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
> >
> >
> > > Absolutely, but he has traffic going from one router to another,
> > it's not
> > > ever exiting the system.
> > > ...why would you want to break up an AS that small into two seperate
> > private
> > > ASes?
> > > besides... the OSPF routes are going to take precedence, not that
> > the admin
> > > dist. cant be changed, but ospf is 120, and BGP int routes are
> > 200....
> > > (right?)
> > >
> > > ----- Original Message -----
> > > From: "W. Alan Robertson"
> > > To: "Peter I. Slow, CCNP Voice Specialist" ;
> > >
> > > Sent: Tuesday, May 29, 2001 12:42 PM
> > > Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
> > >
> > >
> > > > Peter,
> > > >
> > > > With all due respect, he doesn't have an IGP problem... He has a
> > > > routing problem, and would like the ability to influence the flow
> > of
> > > > traffic under certain circumstances to provide for better network
> > > > performance.
> > > >
> > > > After hearing a better explanation of the real issue, path
> > selection
> > > > for an International site, the use of BGP might go a long way
> > toward
> > > > solving the issue.
> > > >
> > > > He could very simply address his issues by breaking his OSPF into
> > two
> > > > seperate routing domains, and utilizing BGP as a means of
> > > > interconnecting them. He could manipulate the traffic through the
> > use
> > > > of something as simple as AS-path prepending, or the other
> > mechanisms
> > > > Chuck mentioned (local preference, weight, or meds).
> > > >
> > > > Routing protocols are but tools, a simple means to an end. Like
> > all
> > > > tools, each has it's strengths and weaknesses. Most important is
> > that
> > > > you select the right one for a given situation. In the absence of
> > > > more information, the use of BGP sounds like a pretty good
> > solution to
> > > > the given problem.
> > > >
> > > > Alan
> > > >
> > > > ----- Original Message -----
> > > > From: "Peter I. Slow, CCNP Voice Specialist"
> >
> > > > To:
> > > > Sent: Tuesday, May 29, 2001 11:29 AM
> > > > Subject: Re: Wanna Be a CCIE? Try This One [7:6076]
> > > >
> > > >
> > > > > next time you recomend using bgp to fix an IGP problem, im going
> > > > to.., well,
> > > > > uh, just dont do it again.
> > FAQ, list archives, and subscription info:
> http://www.groupstudy.com/list/cisco.html
> > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
> FAQ, list archives, and subscription info:
http://www.groupstudy.com/list/cisco.html
> Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=6326&t=6076
--------------------------------------------------
FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
