Re: [Softwires] IPv4 fragmentation and reassembly in DS-Lite

Except that, as the AFTR needs to NAT the packet back to the tunnel, it needs to reassemble the packet first..

   - Alain.

On May 28, 2010, at 8:49 AM, Lee, Yiu wrote:

Hi Taurn,

So the v4 packet is fragmented by the remote host before reaching AFTR? If so, the AFTR shouldn’t wait but pass the fragmented packet untouched with encapsulation. That said, the fragmented v4 packet could be fragmented one more time in the AFTR after adding the v6 header overhead. B4 must reassemble the v6 fragmented packets before sending to the host. It is the host responsible for reassembling the v4 fragmented packets.

Regards,
Yiu

On 5/28/10 2:23 AM, "Tarun Saxena" <tsaxena@juniper.net<x-msg://766/tsaxena@juniper.net>> wrote:

Hello Alain,

DS-Lite draft mentions that for big packets, v6 fragmentation must be performed after encapsulation both at the B4 and AFTR. What is the expected behaviour in case an already fragmented IPv4 packet is received at an end-point?

1)       Should the end-point wait for all the fragments to turn, reassemble the packet and then encapsulate.
2)       Or, it should just handle fragments as “normal” v4 packets and encapsulate them.
a.       What if the encapsulated fragment needs v6 fragmentation?

Is there a take from the standards point of view, or are these details left open for the implementation to do what it deems fit?

Regards
Tarun Saxena
Ph +91 80 41904390
Juniper Networks

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