Re: Clarify SCTP max packet size.

 
> Prior sending e-mail I've already did your suggestions, but 
> vendor B is saying that they can not change MTU - they set 
> the MTU=1500 since is the minimum allowed value (they cannot 
> have a bigger MTU either).

The problem I see is that the MTU is usually a property of the
'ethernet' interface, not of the protocol. So the IP stack should
be able to process receive messages that are the size of the
largest MTU on the media - which is usually 1500 bytes from the
'ethertype' for ethernet networks.
(the mtu field for the interface itself may have to include the
mac addresses and ethertype - so would be 1516)

Setting the interface mtu to a smaller value is likely to cause
bigger interworking issues.

IIRC all SCTP packets are required to have the IP DNF (do not
fragment) bit set. So an ICMP error could be used at the IP
layer to force a smaller MTU - as is done to avoid PMTU blackholeing
when there is a PPPoE link.

	David

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