From: Narbik Kocharians (narbikk@gmail.com)
Date: Fri Jun 27 2008 - 14:49:42 ART
Basically the cluster-ids should NOT match when you have redundant
route-reflectors, for the CCIE lab, you should make sure that they do, but
NOT in the real world scenario.
On Fri, Jun 27, 2008 at 10:30 AM, Brian McGahan <
bmcgahan@internetworkexpert.com> wrote:
> Hi Mohamed,
>
> The BGP router-id comes from the highest loopback address, or if
> there is no loopback, your highest interface IP address. The cluster-id
> comes from the router-id. In a real design you would always want to
> hard code at least the BGP router-id, and possibly the cluster-id
> depending on the design. There are certain designs that if your BGP
> router-id overlaps with someone else's there could be a problem, such as
> if you're doing Anycast RP for multicast. As a general rule OSPF,
> EIGRP, and BGP router-id's should always be hardcoded. In the lab exam
> if there isn't a requirement *not* to hardcode them, you should set it
> to a unique IP address configured on the router.
>
> HTH,
>
> Brian McGahan, CCIE #8593 (R&S/SP/Security)
> bmcgahan@internetworkexpert.com <mailto:bmcgahan@internetworkexpert.com>
>
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>
> Net Plus wrote:
> > Hi Brian,
> >
> > It means;
> >
> > Once you set the bgp Router-id, You don't need any Cluster-id, As per
> your
> > statement, bgp cluster-id is derived from Router-id.
> >
> > Regards,
> >
> > Mohamed.
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> > Brian McGahan
> > Sent: Friday, June 27, 2008 9:55 AM
> > To: cciestruggle; Cisco certification
> > Subject: Re: the relation between the route-reflector servers within the
> > same bgp cluster id?
> >
> >
> > You should statically set the BGP router ID to a globally significant
> > address on the router. The cluster-ID is inherited from router-id
> > regardless if you hardcode it or the router-id though.
> >
> > Brian McGahan, CCIE #8593 (R&S/SP/Security)
> > bmcgahan@internetworkexpert.com <mailto:bmcgahan@internetworkexpert.com>
> >
> > Internetwork Expert, Inc.
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> >
> > cciestruggle wrote:
> >
> >> Hello Brain,
> >>
> >> We do need to have the cluster id on the router reflectors to avoid
> >> loops ? right?
> >>
> >> And further more do we need to explicitly specify the cluster id? the
> >> command reference says that it is automatically set to the local
> >> router id (of which reflector ?)
> >>
> >>
> >>
> >
> http://www.cisco.com/en/US/docs/ios/iproute/command/reference/irp_bgp1.html#
> > wp1012377
> >
> >> Zealot
> >>
> >> On Fri, Jun 27, 2008 at 3:52 PM, Brian McGahan
> >> <bmcgahan@internetworkexpert.com
> >> <mailto:bmcgahan@internetworkexpert.com>> wrote:
> >>
> >> You can, but you don't necessarily have to. Most large scale route
> >> reflection designs include a full mesh of peerings between
> >> clusters via
> >> the route reflectors, but the route reflectors are not clients of
> each
> >> other. This means that if reflector A peers with reflector B, and
> >> reflector B peers with reflector C, reflector C cannot learn a route
> >> from reflector A's cluster through B's cluster, because if A is a
> >> non-client of B, B cannot advertise an iBGP route from A to C.
> >> However
> >> if these is a full mesh of non-client iBGP peerings between A, B,
> >> and C,
> >> reflector C wouldn't need to use B to get to A, since it has a
> direct
> >> peering.
> >>
> >> Ultimately for production it depends on your redundancy design.
> >> Technically you can have every single router be a router reflector
> >> with
> >> everyone else beings its clients. You won't cause any routing
> loops,
> >> since the cluster list prevents this, but instead you'll just have
> >> a lot
> >> of unnecessary route replication. However when we are talking about
> >> update messages in the order of 300,000 routes for the full BGP
> table,
> >> scalability from a resource management perspective is highly
> >> affected by
> >> route reflection design.
> >>
> >>
> >> HTH,
> >>
> >> Brian McGahan, CCIE #8593 (R&S/SP/Security)
> >> bmcgahan@internetworkexpert.com
> >> <mailto:bmcgahan@internetworkexpert.com>
> >> <mailto:bmcgahan@internetworkexpert.com
> >> <mailto:bmcgahan@internetworkexpert.com>>
> >>
> >> Internetwork Expert, Inc.
> >> http://www.InternetworkExpert.com
> >> Toll Free: 877-224-8987 x 705
> >> Outside US: 775-826-4344 x 705
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> >> Live Chat: http://www.internetworkexpert.com/chat/
> >>
> >>
> >> ccie wrote:
> >> > Hi experts,
> >> >
> >> > Assume I have 5 router within the same AS, and two of them will
> >> have IBGP
> >> > peer with the rest, So I configure these two with the same bgp
> >> cluster-id,
> >> > and configure the rest to be their route-reflector-clients. Should
> I
> >> > configure these two to be route-reflector-clients to each
> others!!!
> >> >
> >> > Thanks in advance
> >> >
> >> > Amin
> >> >
> >> >
> >> >
> >>
> >>
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-- Narbik Kocharians CCSI#30832, CCIE# 12410 (R&S, SP, Security) www.Net-Workbooks.com Sr. Technical Instructor
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