Re: Fragment : 2nd Ques

Not efficient, not needed, and may be impossible.
If you have multiple paths, an intermediate router may not see all
fragments, so there is no way to do it!

shiran guez @ 22/09/2010 5:55 -0300 dixit:
> Well the answer is simple routers do not reassemble fragment along the path
> as it is not efficient and not needed, if each router along the path would
> look on the traffic and try to reassemble and fragment the routers would
> soon crash.
> in programming there is a formula that check how many bugs can happen in
> single line code a good code is considered if it is efficient and that
> usually mean the short's way to perform what you require to do.
>
> So the question is Why should you try to reassemble the packet if you are
> not the destination?!
>
> routers check only if the interface MTU they need to send the packet out
> is sufficient to send that packet.
>
>
> On Tue, Sep 21, 2010 at 7:33 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
>>
>>
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>
>

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Carlos G Mendioroz  <tron_at_huapi.ba.ar>  LW7 EQI  Argentina
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