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

From: Tarun Saxena <[email-masked]>
Date: Fri, 28 May 2010 11:53:44 +0530

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

---

From: "Lee, Yiu" <[email-masked]>
Date: Fri, 28 May 2010 08:49:43 -0400

Hi Taurn,

So the v4 packet is fragmented by the remote host before reaching AFTR? If
so, the AFTR shouldn¹t 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" <[email-masked]> wrote:

> 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 ³normal² v4 packets and
> encapsulate them.
> 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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> Softwires mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/softwires