Yep, that's the way of thinking about it :) On Thu, Feb 11, 2010 at 3:28 PM, Mashburn, Vince <[email protected]>wrote:
> Ah, OK. It is the whole Control-Plane vs Data-Plane discussion. It is > much clearer now. The Route-Target is the control-plane route advertisement > and tells the PE routers how to get to a particular destination, per-vrf. > The VPN label is the data-plane and describes how the packet is actually > being forwarded. Thank you Bryan! > > > > Thanks, > > Vince Mashburn > > HP Americas Technology Services > > Account Services Manager > > FedEx On-site Office Phone: 901-263-6498 > > Mobile: 901-569-9734 > > > > > > *From:* Bryan Bartik [mailto:[email protected]] > *Sent:* Thursday, February 11, 2010 4:24 PM > > *To:* Mashburn, Vince > *Cc:* [email protected] > *Subject:* Re: [OSL | CCIE_RS] MPLS VPN Label > > > > You are talking about two things at once. Routing a packet is different > then advertising a route. When a router receives an advertisement, it looks > at the RT so it knows what VPN it belongs too. Then it stores it using the > RD, which uniquely identifies the route from all the other routes. When the > PE router receives a packet, it has 2 labels (actually 1 because of PHP). > The outer one (which has been popped) is for its own loopback. The last > label now corresponds to the VPN/interface to which the packet should be > forwarded. If this label did not exist, the router would not know which VPN > or interface the packet should be forwarded. > > On Thu, Feb 11, 2010 at 3:11 PM, Mashburn, Vince <[email protected]> > wrote: > > OK, so when the transport label is stripped off, the VPN label tells the > router which VRF table to inject the packet into. Once that is done, the > router looks at the RT to determine if the route is valid to export to the > customer. Is that correct? > > > > Thanks, > > Vince Mashburn > > HP Americas Technology Services > > Account Services Manager > > FedEx On-site Office Phone: 901-263-6498 > > Mobile: 901-569-9734 > > > > > > *From:* Bryan Bartik [mailto:[email protected]] > *Sent:* Thursday, February 11, 2010 4:06 PM > *To:* Mashburn, Vince > *Cc:* [email protected] > *Subject:* Re: [OSL | CCIE_RS] MPLS VPN Label > > > > Vince, > > The Route target identifies the route, but does not identify the packet > itself. Perhaps if there was an "RT" field in the IP header, you wouldn't > need the VPN label at all :) > > On Thu, Feb 11, 2010 at 2:48 PM, Mashburn, Vince <[email protected]> > wrote: > > OK. I am a little confused with the VPN label in MPLS. I completely > understand the Transport label, but I thought that all of the VPN > information was carried within the Route-Target extended BGP community. Why > do you also need a label to identify the VPN? > > > > > > Thanks, > > Vince Mashburn > > HP Americas Technology Services > > Account Services Manager > > FedEx On-site Office Phone: 901-263-6498 > > Mobile: 901-569-9734 > > > > > > > _______________________________________________ > For more information regarding industry leading CCIE Lab training, please > visit www.ipexpert.com > > > > > -- > Bryan Bartik > CCIE #23707 (R&S, SP), CCNP > Sr. Support Engineer - IPexpert, Inc. > URL: http://www.IPexpert.com > > > > > -- > Bryan Bartik > CCIE #23707 (R&S, SP), CCNP > Sr. Support Engineer - IPexpert, Inc. > URL: http://www.IPexpert.com > -- Bryan Bartik CCIE #23707 (R&S, SP), CCNP Sr. Support Engineer - IPexpert, Inc. URL: http://www.IPexpert.com
_______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com
