Subject: [Ipoverib] Ethertype field and IPoIB header format

From: Yaron Haviv <[email-masked]>
Date: Sun, 08 Sep 2002 22:55:27 +0300

Currently in the IPoIB spec the order of the datagram is:

16-bit Ethertype -> 16-bit reserved -> TCP/IP

In Ethernet the format is:

Src/dst MAC -> LLC/SNAP/VLAN/none -> Ethertype -> TCP/IP

So, in case of fast forwarding a packet between two environments the bridge
will need to
Crop the first part, and modify the packet to make room for the reserved (16
bit zero) field
This could also happen when you build Ethernet driver for IPoIB and you need
to change the header built by the TCP stack

I suggest we change (swap) the header definition from:
16-bit type -> 16-bit reserved

to:
16-bit reserved -> 16-bit Ethertype

this will simplify the packet manipulation in those cases
I hope it is not too late for that

Yaron

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