Re: Just shy of OT MPLS Question

I thought Rick had stated it before, although I may have just added
words for him in my mind. :)

You can run whatever protocol that you feel like running, including BGP
everyplace. However, if you ONLY run BGP, then you can NOT use LDP as
your label protocol because it simply will not work.

Can you exchange labels otherwise? Sure. BGP exchanges them. BGP
labels need to recurse to a next-hop path. You can use TE to set that
up. You simply CANNOT have LDP do it for you!

Now, I know we tend to take most technologies to their logical extremes
to study for the CCIE lab! But I think this may be a little too far!
:) Out of all the tracks, the SP one (IMHO) was the most "realistic".
Not perfect, mind you, but not off the deep end either. I think trying
to do a BGP-only core may be a little too far! If I ever saw someone
trying to do that in real life, I would ask them why they were spending
so much time and energy trying to fight the routers!

*Scott Morris*, CCIE/x4/ (R&S/ISP-Dial/Security/Service Provider) #4713,

JNCIE-M #153, JNCIS-ER, CISSP, et al.

JNCI-M, JNCI-ER

evil_at_ine.com

Internetwork Expert, Inc.

http://www.InternetworkExpert.com

Toll Free: 877-224-8987

Outside US: 775-826-4344

Knowledge is power.

Power corrupts.

Study hard and be Eeeeviiiil......

Keegan.Holley_at_sungard.com wrote:
> That's interesting. I think that was my original question whether you
> could build your base routing table using bgp and have LDP/RSVP base it's
> label assignments on it. I knew you could do it with statics (routes not
> labels sorry..) So just so I'm sure I understand you're saying that
> there's no way to replace your IGP with bgp even if the next-hop and other
> issues are taken care of? I was just curious since I've seen some of the
> smaller carriers where every router is a PE router so you cannot get away
> from doing BGP in the core. I was just curious if there was a way to keep
> from doing the IGP in the core and maybe save some resources that way even
> at the expense of TE.
>
>
>
> From:
> Rick Mur <rmur_at_ipexpert.com>
> To:
> <Keegan.Holley_at_sungard.com> <Keegan.Holley_at_sungard.com>
> Cc:
> ALL From_NJ <all.from.nj_at_gmail.com>, Cisco certification
> <ccielab_at_groupstudy.com>, nobody_at_groupstudy.com, Scott Morris
> <smorris_at_ine.com>, JR Garcia <ttuner_at_gmail.com>
> Date:
> 12/23/2009 03:00 AM
> Subject:
> Re: Just shy of OT MPLS Question
>
>
>
> The IGP label is usually the 'outer' label (unless another label get's
> attached in a CsC environment). Inner label is the VPN label, Outer label
> is the IGP label.
>
> A flat MPLS network with statics? I would never ever build a network with
> static label assignments :-) (doesn't even work on Cisco, it does on
> Juniper)
>
> You can't use BGP and LDP to assign labels. If you want BGP prefixes to
> get a label allocated, you do this within BGP and then BGP advertises and
> assigns labels for those prefixes. This will definitely work. So NO LDP
> then :-)

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Received on Wed Dec 23 2009 - 09:21:02 ART