From: Rick (rick@iptool.net)
Date: Sun Sep 11 2005 - 09:47:57 GMT-3
I see at least 3 post to this thread that said this is a "feature" of MPLS
"NOT" a Cisco feature and therefor since Alcatel and Juniper support the
MPLS standards they can have a BGP free core. I am not sure what you still
want answered.
Rick
Why is Juniper considered evil? Juniper has forced Cisco to finally build a
solid SP router in the CRS.
----- Original Message -----
From: "Richard Dumoulin" <Richard.Dumoulin@vanco.fr>
To: "'ccie 2005'" <cui666@gmail.com>; <ccielab@groupstudy.com>
Sent: Sunday, September 11, 2005 5:38 AM
Subject: RE : RE : Cisco MPLS
> Hi Pat,
>
> thx for the explanation but I already knew this. The question remains
> unanswered. I quote you " I would be REALLY surprised that
> Juniper, Alcatel or other vendors in this game would not see it" --> I
would
> just like the answer to this.
>
> Now let me correct some of your sentences below. In step 1 when the packet
> arrives at peer1, the router does not look at his routing table but at his
> CEF table. Then it imposes the label which also corresponds to peer2 BGP
ip
> address or BGP next hop.
>
> In steps 2,3 and 4 peer2 looks at its LFIB table in order to swap labels.
> Peer2 is supposed to not have any BGP table so how would it do a recursive
> BGP lookup? At least in a Cisco based network. The LFIB would is created
> from 2 tables: the LIB and the RIB (derived form an IGP).
>
> Finally, in step 6, the operation is such that peer2 will never have to
> perform 2 lookups. Either it will consult its CEF table because of PHP or
> its LFIB.
>
> All this started in my head because I did hear rumours that Juniper P
> routers needed a full routing table in order to label switch BGP
destination
> packets, that is all. Now this still remains unanswered.
>
> Also I did not say it was magic but just found the concept amazing and
> wonderful. I very much like MPLS and I am just starting to appreciate it
> although I did a lot of work with it when I was working for GlobalOne in
> Spain 5 years. It was the first MPLS network in the country by then!
>
> -- Richard
>
>
>
> -----Message d'origine-----
> De : ccie 2005 [mailto:cui666@gmail.com]
> Envoyi : dimanche 11 septembre 2005 05:46
> @ : ccielab@groupstudy.com
> Objet : Re: RE : Cisco MPLS
>
> let me try to explain this using packet walkthrough, imagine this;
>
> peer router1(igp/bgp/mpls) - p1(igp/mpls)-p2(igp/mpls)-peer
> router2(igp/bgp/mpls) - customer router(ebgp with peer2)
>
> peer router #1 and #2 have full bgp routing table, p1 and p2 only have
> isp's internal IGP routes and mpls lsp table based on igp. a packet
> trying to get to customer router from peer router 1, and here are the
> steps:
>
> 1. packet arrived at peer1 as ipv4 packet, looking at ip routing
> table, and a bgp route learned from peer2 indicates that the packet
> has to be delivered to peer2 router in order to reach the destination;
> 2. now peer1 started bgp recurisive lookup process, realized that in
> order to reach peer2, the packet need to go to p1;
> 3. because peer1 and p1 are running mpls in between, an mpls label
> imposition occurred. note that the packet's destination ip is still
> customer router's ip which p1 doesn't know;
> 4. packet arrived at p1, will p1 look at the destination ip of the
> packet? NO! (this is the key part), it will only look at the imposed
> label from peer1 and use mpls pre-learned lsp table to deliver the
> mpls packet to p2;
> 5. p2 will look at its lsp table and deliver the packet to peer2 as
> mpls packet or ip packet depends on whether you use PHP or not, to
> make it simple, let's say it still sent mpls to peer2;
> 6. peer2 receive the packet, as it's the last hop of the mpls lsp
> path, it performed 2 things: pop the label and do ip lookup. as it has
> the customer's route in its bgp routing table learnt via ebgp, it sent
> the packet to customer router. end of journey!
>
> like I mentioned, the key step is #4, and if you really understood
> this step, you will see there was no magic here: all because of you
> have used mpls as transport protocol instead of ip in the core
> network.
>
> And if I could see the "magic", I would be REALLY surprised that
> Juniper, Alcatel or other vendors in this game would not see it.
>
> and the similar steps goes to mpls/vpn,only one more label to deal
> with as the inner label is the indentity of the VPN, the edge PEs do
> all the work, P routers still see the outer label without knowledge of
> inner labels and ip info.
>
> to end this, MPLS is not only capable of transporting ipv4 packets,
> but also almost everything else - ATM cells, FR frames, IPv6, Ethernet
> frames, etc, other rfcs like martini-draft, vpls and cisco's ATOM(Any
> Transport Over MPLS) are based on the basic concept.
>
> HTH,
> Pat
>
>
>
>
> On 9/10/05, Richard Dumoulin <Richard.Dumoulin@vanco.fr> wrote:
> > Take the example of an ISP using an MPLS backbone. Will Juniper P
routers
> > need all the routes to create the LSP table? We all know that this is
not
> > the case with Cisco. What about the others?
> >
> > -- Richard
> >
> > -----Message d'origine-----
> > De : Scott Morris [mailto:swm@emanon.com]
> > Envoyi : dimanche 11 septembre 2005 04:05
> > @ : Richard Dumoulin; 'Joe Rinehart'; ccielab@groupstudy.com
> > Objet : RE: Cisco MPLS
> >
> > The LSP "routing table" is a different list all together. You CAN have
> BGP
> > routes present, but it's certainly not necessary to have your customer
> > routes present.
> >
> > Scott
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> > Richard Dumoulin
> > Sent: Saturday, September 10, 2005 9:19 PM
> > To: 'Joe Rinehart'; ccielab@groupstudy.com
> > Subject: RE : Cisco MPLS
> >
> > I heard that on a Juniper based MPLS network, the BGP networks needed to
> be
> > present on the P routing tables. Would be nice if anyone could confirm
or
> > not by having a look at the routing table...
> >
> > -- Richard
> >
> > -----Message d'origine-----
> > De : Joe Rinehart [mailto:jjrinehart@hotmail.com] Envoyi : dimanche 11
> > septembre 2005 02:12 @ : Richard Dumoulin; ccielab@groupstudy.com Objet
:
> > Re: Cisco MPLS
> >
> > Yes, I realize that but I was pointing out how the architecture works in
> > general, most notably the IGP vs. BGP functionality. Even if you do not
> > create MBGP VPNs the routing behavior is the same, with the IGP knowing
> ONLY
> > core routes and BGP just at the edges. Both protocols run separately
with
> > no real interaction...
> >
> > And as far as the AT&T network goes, yes there is a large Cisco
component,
> > particularly on the edges, but Avici routers are operating at the core.
> The
> > architecture is independent of the actual platforms....
> >
> > Joe Rinehart
> > CCIE #14256, CCNP, CCDP
> > Data Network Consultant
> > AT&T Pacific Northwest Enterprise Markets
> > ----- Original Message -----
> > From: "Richard Dumoulin" <Richard.Dumoulin@vanco.fr>
> > To: "'Joe Rinehart'" <jjrinehart@hotmail.com>; <ccielab@groupstudy.com>
> > Sent: Saturday, September 10, 2005 2:12 PM
> > Subject: RE : Cisco MPLS
> >
> >
> > > But AT&T are using Cisco routers I believe. Also please note that I am
> > > not talking about MPVPN but just about the way BGP network
> > > destinations are label switched,
> > >
> > > Regards
> > >
> > > -- Richard
> > >
> > > -----Message d'origine-----
> > > De : Joe Rinehart [mailto:jjrinehart@hotmail.com] Envoyi : samedi 10
> > > septembre 2005 01:07 @ : Richard Dumoulin; ccielab@groupstudy.com
> > > Objet : Re: Cisco MPLS
> > >
> > > Anyone feel free to jump in if I am way off base here...
> > >
> > > It's pretty much just a function of how the routing is set up...I
> > > created
> > a
> > > mini-MPLS network on my lab rack and really was surprised to see how
> > > the mechanics all work, especially as I tried to mimic how we have it
> > > set up
> > at
> > > AT&T. The feature you are referring to is sometimes called a
> > > route-free core. The label switched core itself doesn't have any
> > > knowledge of edge
> > (or
> > > MPLS VPN) routes at all, they are clueless of anything outside the
> > backbone
> > > itself. Usually an IGP like OSPF or ISIS is run between the P nodes
> > > in
> > the
> > > core and includes the PE devices too. I had one router get all buggy
> > > because of short memory so I verified just using static routing across
> > > the simulated backbone and that worked too. The core just uses IGP
> > > and
> > internal
> > > routes and does the label switching from PE to PE.
> > >
> > > The magic is at the PE, it's pretty much doing all the heavy lifting.
> > > The PE runs BGP at the edge only, peering with the CE (using eBGP) and
> > > other PE's (using iBGP), and it's also responsible for creating the
> > > MPLS VPN's using Route Distinguishers and Multiprotocol BGP. The core
> > > doesnt know, doesnt care and doesnt play with BGP or the VPN's, it
> > > just pushes
> > traffic...
> > >
> > > The same would apply to Internet routes, as the BGP on the edge/PE
> > > routers would know all of it, advertise routes, and such, but once
> > > passed to the core P routers it would be label switched....
> > >
> > > It really is cool fascinating stuff.....
> > >
> > > Joe Rinehart
> > > CCIE #14256, CCNP, CCDP
> > > Data Network Consultant
> > > AT&T Pacific Northwest Enterprise Markets
> > > ----- Original Message -----
> > > From: "Richard Dumoulin" <Richard.Dumoulin@vanco.fr>
> > > To: <ccielab@groupstudy.com>
> > > Sent: Friday, September 09, 2005 2:03 PM
> > > Subject: Cisco MPLS
> > >
> > >
> > > > There is a feature in MPLS that I find powerful and it is the
> > possibility
> > > of
> > > > building an Internet backbone with 160000 routes present only in the
> > > > PEs routing table. I was wondering if this was only a Cisco feature
> > > > or do
> > the
> > > Ps
> > > > of other vendors also support this like Juniper for example?
> > > >
> > > > Thx
> > > >
> > > > -- Richard
> > > >
> > > >
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