From: Michael Stewart (mstewart350@gmail.com)
Date: Sun Dec 23 2007 - 14:55:51 ART
It is my understanding if there was no RR, R1 would have received neither
route to "X", because R2 will not advertise out iBGP routes to other iBGP
peers... this is why RR is needed in this peering config, as there is no
full-mesh.
From that "directly-connected peering" config, if you create a full-mesh,
then R1 will see the 2 BGP entries for "X", but only one best one. (R2 will
still not send the update.. no surprise here.)
I would say that RR does remove some flexibility, but gives way easier
administration (compared to full-mesh peering configs).
Anyone have other trade-offs when choosing RR deployments?
Michael
On Dec 22, 2007 11:15 AM, Nambi Appachigounder <nambi_gct@yahoo.co.in>
wrote:
> Thanks Scott and others.Had there not been an RR, R1
> would have received both the routes.Can I say that RR
> took away some flexibility on R1.(I could have
> selected the other route on R1 with weight if there
> had been no RR).Is my understanding correct?
>
> Regards,
> -Nambi
> --- Scott Morris <smorris@ipexpert.com> wrote:
>
> > Disregard last e-mail. Lack of caffeine told me R1
> > was the RR. It's not.
> >
> > >R2< will have the notes below.
> >
> > R1, an RR client will only have ONE path.
> >
> >
> > Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service
> > Provider) #4713, JNCIE-M
> > #153, JNCIS-ER, CISSP, et al.
> > CCSI/JNCI-M/JNCI-ER
> > VP - Technical Training - IPexpert, Inc.
> > IPexpert Sr. Technical Instructor
> >
> > A Cisco Learning Partner - We Accept Learning
> > Credits!
> >
> > smorris@ipexpert.com
> >
> >
> >
> > Telephone: +1.810.326.1444
> > Fax: +1.810.454.0130
> > http://www.ipexpert.com
> >
> >
> >
> >
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com
> > [mailto:nobody@groupstudy.com] On Behalf Of
> > Scott Morris
> > Sent: Saturday, December 22, 2007 9:45 AM
> > To: 'Nambi Appachigounder'; 'groupstudy'
> > Subject: RE: BGP RR Question
> >
> > That will depend on what you have configured
> > (multipath or not?), but in a
> > generic configuration you'll get one "best" path
> > showing up on R1.
> >
> > "sh ip bgp" should indicate to you that there is
> > more than one valid path,
> > but only one best path.
> >
> > "sh ip ro b" will verify your routing table.
> >
> > HTH,
> >
> >
> > Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service
> > Provider) #4713, JNCIE-M
> > #153, JNCIS-ER, CISSP, et al.
> > CCSI/JNCI-M/JNCI-ER
> > VP - Technical Training - IPexpert, Inc.
> > IPexpert Sr. Technical Instructor
> >
> > A Cisco Learning Partner - We Accept Learning
> > Credits!
> >
> > smorris@ipexpert.com
> >
> >
> >
> > Telephone: +1.810.326.1444
> > Fax: +1.810.454.0130
> > http://www.ipexpert.com
> >
> >
> >
> >
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com
> > [mailto:nobody@groupstudy.com] On Behalf Of
> > Nambi Appachigounder
> > Sent: Saturday, December 22, 2007 8:36 AM
> > To: 'groupstudy'
> > Subject: BGP RR Question
> >
> > Hi All,
> >
> > I have a BGP question.Can someone please help me.
> >
> > 1) R1,R2,R3 and R4 are in AS 100.
> > 2) R2 is RR and R1,R3,R4 are RR clients.
> > 3) R5 is in AS 200.
> >
> >
> > R1
> > |
> > |
> > R2
> > / \
> > / \
> > / \
> > R3 R4
> > \ /
> > \ /
> > \ /
> > R5
> >
> > When R5 advertise advertises a network "X" to R3 and
> > R4, how many bgp
> > entries will we see on R1.(only the best or both?)
> >
> > Thanks,
> > Nambi
> >
> >
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