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

_______________________________________________
IPoverIB mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/ipoverib

---

From: Vivek Kashyap <[email-masked]>
Date: Thu, 12 Dec 2002 12:53:25 -0800 (Pacific Standard Time)

> But I think it is still worth clearing up to avoid any confusion.

Jerry,
	How about the following rephrasing of the section given below?
Vivek

	----

        Every IPoIB interface is associated with an identifier
        referred to as the GID [IPoIB_ARCH]. The GID is unique in the
        InfiniBand fabric. An invariant GID is formed by appending the
        port's EUI-64 identifier to the InfiniBand subnet prefix.

        The GID is associated with a particular hardware port. The GID
        and a QPN define an IPoIB interface on the port[IPOIB_ENCAP].
        Therefore an implementation could associate multiple IPoIB
        interfaces on the same port by utilising a common GID but
        different QPNs. In such a case the GID is shared between
        multiple interfaces, and therefore, the 'client identifier'
        formed from just the GID is no longer unique.

        This is not an issue if the IPoIB interfaces sharing the GID are in
        different InfiniBand partitions, and thereby on different
        IPoIB links, since the 'client identifier' need only be unique
        within a subnet. However, if the GID is shared by interfaces
        within the same partition the implementation MUST ensure a
        unique client-identifier. For example, a unique
        client-identifier may be formed by including the QPN
        associated with the relevant IPoIB interface if the
        implementation is designed to keep this association constant
        across boots. Some other value unique to the implementation
        may also be used for the same purpose.

        If, within a partition, there is only one IPoIB interface
	associated with a particular GID, then use of the GID is
        sufficient.

        Note: a port may be associated with multiple GIDs. Therefore,
        multiple IPoIB interfaces may exist on the same port while
        using a different GID from among the GIDs associated with the
        port.

        This document does not preclude the use of other 'client
        identifier' type, such as fully qualified domain name(FQDN) or
        the EUI-64 value associated with the interface.

---

From: Vivek Kashyap <[email-masked]>
Date: Thu, 12 Dec 2002 12:53:25 -0800 (Pacific Standard Time)

Jerry,

	----

---

From: Caitlin Bestler <[email-masked]>
Date: Thu, 12 Dec 2002 16:46:57 -0600

On 12/11/02, H.K. Jerry Chu wrote:

>
>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.

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/
_______________________________________________
IPoverIB mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/ipoverib

---

From: Caitlin Bestler <[email-masked]>
Date: Thu, 12 Dec 2002 16:46:57 -0600

Caitlin Bestler