Subject: How Egress ATM-LSR/FR-LSR distinguishes IPv4 and IPv6 packets?

From: "Narendra Byrapuram" <[email-masked]>
Date: Fri, 9 Aug 2002 13:21:18 -0400

Hello,

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?

Excuse me if this is a repeated question.
I checked in the archive, couldn't find the answer to the following
question.

Thanks in Advance
Naren

--------------------~~~~~-----------------------
Narendra Reddy Byrapuram
Mail: [email-masked]

---

From: David Charlap <[email-masked]>
Date: Fri, 09 Aug 2002 14:42:45 -0400

Narendra Byrapuram wrote:
> specifies IPv4 Explicit NULL (0) and IPv6 Explicit NULL (2).
> 

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