Subject: [Ipoverib] comments on the DHCP draft

From: "H.K. Jerry Chu" <[email-masked]>
Date: Wed, 11 Dec 2002 17:22:22 -0800 (PST)

"draft-ietf-ipoib-dhcp-over-infiniband-03.txt" contains the
following paragraph:

	The GID is associated with a particular hardware port. The GID
        and a QPN define an IPoIB interface at the port[IPOIB_ENCAP].
        Therefore an implementation could associate multiple IPoIB
        interfaces on the same port by utilising a common GID but
        different QPNs. It is up to the implementation to ensure a
        unique client-identifier when multiple IPoIB interfaces are
        defined over the same port and same GID. A unique, invariant
        value MUST be included in addition to the GID to achieve
        this.   

The paragraph may mislead people in believing they must include
a unique-value (e.g. QPN) in their Client-Identifier even when
multiple IPoIB "interfaces" defined over the same port/GID are on
different partitions. This is not the case because a Client-Identifier
needs to be unique only within the same IP subnet; and different
partitions constitute different IP links.

I'm aware an earlier paragraph has a statement to that fact:

	The DHCP protocol states that the 'client identifier' option
        may be used as the unique identifying value for the client.
        This value must be unique within the subnet the client is a
        member of.
        
But I think it is still worth clearing up to avoid any confusion.

BTW, I'm not sure how useful it is to have more than one IPoIB
interface attached to the same HCA port on the same partition
but differentiated only by the QPNs. This is the only case I can
think of where the Unique-value(4 octets) is needed.

Jerry

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From: "Larsen, Roy K" <[email-masked]>
Date: Thu, 12 Dec 2002 09:12:24 -0800

> -----Original Message-----
> From: H.K. Jerry Chu [mailto:[email-masked]]
> Sent: Wednesday, December 11, 2002 5:22 PM
> To: [email-masked]
> Cc: [email-masked]
> Subject: [Ipoverib] comments on the DHCP draft
>

<snip>

> think of where the Unique-value(4 octets) is needed.

Jerry,

How about link aggregation?

Roy

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From: "Larsen, Roy K" <[email-masked]>
Date: Thu, 12 Dec 2002 09:12:24 -0800

<snip>

Jerry,

Roy

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From: "H.K. Jerry Chu" <[email-masked]>
Date: Thu, 12 Dec 2002 13:02:21 -0800 (PST)

>How about link aggregation?

How useful is it to aggrevate multiple QPs if they are all attached
to the same physical link? (Did I misunderstand the question?)

Jerry

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From: "H.K. Jerry Chu" <[email-masked]>
Date: Thu, 12 Dec 2002 13:02:21 -0800 (PST)

Jerry

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From: "H.K. Jerry Chu" <[email-masked]>
Date: Fri, 13 Dec 2002 07:38:30 -0800 (PST)

>>
>>BTW, I'm not sure how useful it is to have more than one
>>IPoIB interface attached to the same HCA port on the same
>>partition but differentiated only by the QPNs. This is the
>>only case I can think of where the Unique-value(4 octets)
>>is needed.
>>
>>Jerry
>>
>
>Wouldn't it be just as legitimate as using two different
>client IDs from the same Ethernet NIC?
>
>The main reason I can think of is to establish a user or
>process specific identity that can be firewalled/shaped
>and/or tracked seperately based upon a distinct IP.

Strange use of client IDs. Note that each network interface
can have only one active client ID at a time. That means only
one IP address assigned by DHCP.

Jerry

>
>I would hope that nobody would waste a Public IPv4 address
>like that, but why not for Private addresses?
>
>
>Caitlin Bestler
>http://asomi.com/CaitlinBestler/

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From: "H.K. Jerry Chu" <[email-masked]>
Date: Fri, 13 Dec 2002 07:38:30 -0800 (PST)

Jerry