The MPLS WG Archive[Date Prev][Date Next][Thread Prev][Thread Next] [Date Index][Thread Index][Author Index][Subject Index] swap & push operation
hi robert thanks for the clarification, the slide had it clearly explained so if i want to establish an explicit path between 2 LSRs do I need to use swap&push always, or is it only in special case like this ? thanks sajith >One example can be the CSC (Carrier of Carriers) case. When the packet >from ISP CE router is received to the carrier network it is a labeled >packet. The label is ahead of time distributed from Carrier's PE to the >CE. > >At the PE based on the incomming label value the label is being swapped >+ new IGP label is being pushed on top of stack to get packets to the >other side PE of the carrier (the one which faces the other ISP). > >For more graphical picture of this take a look at page from the below >ppt url (sorry for this but I hate draw ascii pictures :). >ftp://ftp-eng.cisco.com/rraszuk/interas_csc/RR_CSC_InterAS.ppt > >R. > >> Sajith Kizhikkepurayil wrote: >> >> hi >> >> from rfc 3031: >> ---- >> c) replace the label at the top of the label stack with a >> specified new label, and then push one or more specified new >> labels onto the label stack. >> ---- >> >> could somebody give me an application scenario ? >> >> i understand that this is useful in ingress of an LSP >> i would like to know how exactly it works with respect >to deciding >> the next hop, and how is the label that swaped&pushed being >> is decided >> >> if this is already being discussed, please give me the >pointers. >> >> thanks >> sajith > |
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