The MPLS WG Archive[Date Prev][Date Next][Thread Prev][Thread Next] [Date Index][Thread Index][Author Index][Subject Index] How Egress ATM-LSR/FR-LSR distinguishes IPv4 and IPv6 packets?
David, It is as you describe for LDP. Generally, one key advantage to downstream allocation of labels is that the LSR doing the label allocation gets decides what labels to give out. Naturally, it makes sense to only give out labels for traffic the LSR knows how to forward... Eric W. Gray Systems Architect Celox Networks, Inc. egray@celoxnetworks.com 508 305 7214 -----Original Message----- From: David Charlap [mailto:David.Charlap@marconi.com] Sent: Friday, August 09, 2002 2:43 PM To: mpls@UU.NET Subject: Re: How Egress ATM-LSR/FR-LSR distinguishes IPv4 and IPv6 packets? Narendra Byrapuram wrote: > > How Egress ATM-LSR/FR-LSR distinguishes IPv4 and IPv6 packets? > > In the case of Generic Label, RFC 3032 "MPLS Label Stack Encoding" > specifies IPv4 Explicit NULL (0) and IPv6 Explicit NULL (2). > > RFC3034 (MPLS on FR) and RFC 3035 (MPLS using ATM VC Switching) doesn't > talk about the similarly to identify Network Layer. > > When Egress ATM-LSR receives an MPLS packet, how it can identify the packet > is IPv4 packet or IPv6? > > Could some one point me to the document/rfc where I can find the answer? I don't think you can tell, just by looking at the data-plane packets. But you can tell from signaling. If RSVP-TE is used to set up the LSP, the L3PID field in the LABEL_REQUEST object should contan the ethertype for IPv4 (0x0800) or IPv6 (0x86dd) For LDP, I'm not certain, but I would assume that labels that correspond to an IPv4 FEC would contain IPv4 payload, and labels correspoding to an IPv6 FEC would contain IPv6 payload. -- David |
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