Re: Fragment : 2nd Ques

Hi

        IP protocol itself doesnt guarantee that all the packets of a
particular flow will take the same path to reach the destination. In your
scenario it is easy to predict that there is only one path to the
destination. However what will happen if you have multiple paths to reach
the destinatioon. This means you will have multiple fragments arriving at a
router with different fragmentation offset and hence you just cant
reassemble it. Only at destination end you will have all pieces of
information to reassemble.

        I hope this helps you out.

Regards
Sundeep Sadhwani
CCIE#26228(RnS)

On Tue, Sep 21, 2010 at 11:03 AM, Happy Singh <
happynetworkingsingh_at_gmail.com> wrote:

> Hi
>
> Again ; trying to understand Fragmentation .
> Lets have following scenario :
>
> R1 --------R2 ------------R3 ----R4
>
> R1-R2 MTU = 3300 bytes
> R2-R3 MTU = 1300 bytes
> R3-R4 MTU = 3300 bytes
>
>
> Let pkt of 12000 byte came in R1 . It fragments and send on R1-R2 link
>
> R2 must fragment each of these into smaller fragments to send them over
> the
> 1,300-byte MTU link. Note that the R3 does *not* reassemble the
> 1,300-byte fragments, even though next link has an MTU of 3,300
> bytes.WHYYYYYY ????
>
> My question is that why is re-assembly done by end router ? Reasons ?
>
> Thnx
> Happy
>
>
> Blogs and organic groups at http://www.ccie.net
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html

Blogs and organic groups at http://www.ccie.net
Received on Tue Sep 21 2010 - 15:57:19 ART