Subject: RE: [Ipoverib] MIB's ifPhysAddress needs to be updated

From: "Aditya Dube" <[email-masked]>
Date: Wed, 17 Apr 2002 11:19:24 -0700

As the Lid is an assigned address rather than a burned in address, as in
Ethernet, the chances of duplicate ifphysaddr's in a network spanning
multiple IB subnets are a lot higher. We should reduce this chance as
much as possible.

The ifphysaddr is also not in sync with what IpOverIB has decided to use
as the link address in ARPs.

IMHO the two, ifphysaddr and the link address is an arp packet, should
match.

Aditya Dube

-----Original Message-----
From: Vivek Kashyap [mailto:[email-masked]] 
Sent: Tuesday, April 16, 2002 12:18 PM
To: Aditya Dube
Cc: [email-masked]
Subject: Re: [Ipoverib] MIB's ifPhysAddress needs to be updated

The same question was addressed last october/november.
See the message:

http://www1.ietf.org/mail-archive/working-groups/ipoverib/current/msg000
87.html

Vivek

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> 
> In the MIB draft, the ifPhysAddress is specified as the LID. This is
out
> of sync with the IpOverIb draft. Can the ifPhysAddress in the MIB be
> changed to match  IPoverIB's physical address, i.e. the GID + QPN?
> 
> http://www.ietf.org/internet-drafts/draft-ietf-ipoib-ibif-mib-01.txt
> 
> Aditya Dube
> 
> 

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---

From: Bill Strahm <[email-masked]>
Date: Wed, 17 Apr 2002 11:34:21 -0700

The problem is that ifPhysAddr covers more than just IP, it is just
the layer 2 wire representation of address.  If you can show me an
IB format that includes GID+LID in a packet header, I might conceed
defeat here.

The address duplicating across multiple subnets is a red herring.  You
can assign identical Ethernet MAC addresses, so long as they are on
differing subnets as well.  

From RFC 2863...
            "The interface's address at its protocol sub-layer.  For
            example, for an 802.x interface, this object normally
            contains a MAC address.  The interface's media-specific MIB
            must define the bit and byte ordering and the format of the
            value of this object.  For interfaces which do not have such
            an address (e.g., a serial line), this object should contain
            an octet string of zero length."
Note that there is no mention of any Layer 3 semantics.  

We can bring the topic up for discussion, I don't know which of the MIB
authors are currently active right now though.

Bill