Cell Relay Archive

["Rajagopalan K" <rajagopalan.kot@wipro.com>]

As u know, VPI.VCI fields in the header are protected by
CRC. There is a chance that transmission errors in the
ATM cell header could go unnoticed/undetectable. In this
case, a cell actually belonging to some other VPI.VCI
could get into this connection bcos of undetectable error
in VPI.VCI. This is called misinserted cell. Misinserted
cells at the receiving entity are ones which dont originate
from corresponding transmitting entity. Misinserted cell in
one connection could be the lost cell of another connection.

There could be other ways for misinsertion possible. But one
way is bcos of undetectable errors in ATM cell header.
Using the sequence number in the AAL1 header, u can detect
misinserted cells and lost cells.

Hope it helps,
Raj

Harsh wrote:

> Hi all,
> I am a newbie, and want to know more about cell-sequencing.
>
> As far as I know, it is used in AAL for detecting:
> 1. Lost cells
> 2. Mis-inserted cells.
>
> I am unable to imagine a scenario for the second case. Since ATM is
> basically connection oriented, all cells for a VC, will be delivered in
> the order they were sent. Right?
>
> TIA,
> harsh.
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.