Re: Relation /difference between MTU & MRU

MTU & MRU - (Maximum) Transmit & Receive (Unit)

The difference is transmit and receive - the relation is more protocol-
dependent.

Protocols generally define, negotiate, or otherwise assume how much
data they are able to transmit, but in some cases it is also
beneficial to let the other side of the connection know how much data
you can receive.

This was common in PPP (rfc1661), where there was some ability to
share this information. You could do it if you wanted to - even if the
other side did not choose to listen :)

Then PPPoE (rfc2516) came along and told us that we should not exceed
1500 octets (1492 + 8 overhead) to assure compatibility of PPP in a
'standard' Ethernet environment :(

Todays networks support larger MTUs/MRUs/paths and PPPoE data
transfers limited to 1500 octets (or less) can become suboptimal and/
or fragmented. Would you want to be limit your PPPoE connection to
1500 octets if your link supported jumbo frames? Add PPPoA to the mix
and on the other hand we have different fingers... We can use MRU in
these environments to help adjust, reducing fragmentation, and
optimizing connections.

rfc4638 can tell you more...

~M

On Jul 18, 2009, at 3:32 PM, Bhuvanesh Rajput wrote:

> Hi,
>
> Can anybody explain relation /difference between MTU & MRU??
>
> Brgds
> Bhuvanesh Rajput
>
>
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Received on Sat Jul 18 2009 - 16:54:33 ART