Happy to help, Taq :) Regards Roy @routeleaker
On 28 April 2011 15:17, Taqdir Singh <[email protected]> wrote: > 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 > > > > -- Regards Roy _______________________________________________ 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
