[ewg] Re: [ofw] SC'09 BOF - Meeting notes

[Liran Liss]

The link local address that we are currently passing down from the
rdmacm encodes a MAC address that was obtained through neighbor
discovery; so we are safe. 

There are RDMAoE applications (some in the embedded space) that do not
use the rdmacm. Some of these rely on custom L2 address assignment and
would like to completely avoid the use of neighbor discovery. For these,
we can clearly state the requirement that the "Interface Identifier" in
the link local address that they pass down should be such that it
encodes a valid MAC address that the interface currently responds to.

In the future we also intend to allow the use of (non link local) IP
addresses encoded in the GIDs. And we will definitely use neighbor
discovery to translate those.
--Liran


-----Original Message-----
From: Roland Dreier [mailto:rdreier at cisco.com] 
Sent: Monday, November 30, 2009 7:34 AM
To: Liran Liss
Cc: Richard Frank; ofw at lists.openfabrics.org; OpenFabrics EWG
Subject: Re: [ewg] Re: [ofw] SC'09 BOF - Meeting notes


 > RFC 4291, Appendix A.

Thanks for the pointer.  As far as I can tell from reading some IPv6
stuff, it really is broken to try to go from a link-local IPv6 address
back to a L2 ethernet address.  For example, RFC 2464 (pointed to by RFC
4291) says:

    Ethernet Address
               The 48 bit Ethernet IEEE 802 address, in canonical bit
               order.  This is the address the interface currently
               responds to, and may be different from the built-in
               address used to derive the Interface Identifier.

It really seems to be setting ourselves up for trouble not to use
neighbor discovery to map IPv6 addresses to link-layer addresses.

 - R.