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Re: the relation between the route-reflector servers within the same bgp cluster id? posted 06/27/2008
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Narbik,

Why's that?

Marc

On Fri, Jun 27, 2008 at 7:49 PM, Narbik Kocharians <narbikk@xxxxxxxxx>
wrote:

> 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@xxxxxxxxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxxxxxxxxx <mailto:bmcgahan@xxxxxxxxxxxxxxxxxxxxxx>
> >
> > Internetwork Expert, Inc.
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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@xxxxxxxxxxxxxx [mailto:nobody@xxxxxxxxxxxxxx]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@xxxxxxxxxxxxxxxxxxxxxx <mailto:
> bmcgahan@xxxxxxxxxxxxxxxxxxxxxx>
> > >
> > > Internetwork Expert, Inc.
> > > http://www.InternetworkExpert.com <http://www.internetworkexpert.com/>
> > > Toll Free: 877-224-8987 x 705
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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@xxxxxxxxxxxxxxxxxxxxxx
> > >> <mailto:bmcgahan@xxxxxxxxxxxxxxxxxxxxxx>> 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@xxxxxxxxxxxxxxxxxxxxxx
> > >>     <mailto:bmcgahan@xxxxxxxxxxxxxxxxxxxxxx>
> > >>     <mailto:bmcgahan@xxxxxxxxxxxxxxxxxxxxxx
> > >>     <mailto:bmcgahan@xxxxxxxxxxxxxxxxxxxxxx>>
> > >>
> > >>     Internetwork Expert, Inc.
> > >>     http://www.InternetworkExpert.com<
> 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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> > >>
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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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