Hello Roy, Your answer is really simple, great and clarified my doubt in first reading :)
thanks so much!!. cheers Taq On Thu, Apr 28, 2011 at 3:31 PM, Roy Waterman <[email protected]>wrote: > Hi Taqdir > > Someone like Marko is going to be better equipped to answer this question, > but I'll throw in my 2p. > > Typically with MPLS VPNs, the penultimate (P) router performs the PHP > operation and pops the Egress PE label. As such, the Egress PE receives a > labelled packet with only a single label, the VPN Label, and, as it is > labelled, the Egress PE needs to consult the LFIB (i.e. mpls forwarding > table). > > After consulting the Local Label field of the mpls forwarding table to find > a match, the Egress PE sees the outgoing label as No Label (for routes > learned from CE), knows both the Outgoing Interface & Next Hop IP, & hence > removes label stack and forwards packet as an IP packet. > > So as you can see, there is no IP lookup here (for routes learned from > CE's). > Consider the situation whereby the Egress PE has 2 or more interfaces in > the same VRF. > If only a single VPN label was assigned to multiple routes learned from > CE's in the same vrf , the Egress PE would not know which Outgoing Interface > & Next Hop to use in order to forward the packet. > > For local routes on the Egress PE in the vrf, the aggregate label is > associated with them, and after a label pop operation, the cef vrf table IS > consulted. > > Hope this helps in some way. > > Regards > Roy > @routeleaker > > > > > > On 28 April 2011 05:00, Taqdir Singh <[email protected]> wrote: > >> Hello Team, >> >> >> As I understand vpn label is used to know which vrf that packet belongs >> to. >> >> But if VRF has 1000 of routes...why there would be 1000 of VPN labels ? >> >> should not there be only one VPN label per VRF for all routes into that >> VRF >> ? >> >> what is the concept behind this ? what is the benifit of having so many >> VPN >> labes per VRF >> >> >> -- >> >> >> -Taq >> _______________________________________________ >> For more information regarding industry leading CCIE Lab training, please >> visit www.ipexpert.com >> >> Are you a CCNP or CCIE and looking for a job? Check out >> www.PlatinumPlacement.com >> > > > > -- > Regards > Roy > -- -Taq _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com Are you a CCNP or CCIE and looking for a job? Check out www.PlatinumPlacement.com
