RE: Multi-address DNS name and SendTargets

[Black_David@emc.com]

I think the best advice here (admittedly on short notice) is "Send Draft".
We can decide later whether to publish as its own informational RFC vs.
rolling it and drafts like Mallikarjun's command ordering draft into
an informational "Implementer's Guide" RFC.

Thanks,
--David

----------------------------------------------------
David L. Black, Senior Technologist
EMC Corporation, 176 South St., Hopkinton, MA  01748
+1 (508) 293-7953             FAX: +1 (508) 293-7786
black_david@emc.com        Mobile: +1 (978) 394-7754
----------------------------------------------------

> -----Original Message-----
> From: wrstuden@wasabisystems.com [mailto:wrstuden@wasabisystems.com]
> Sent: Wednesday, February 26, 2003 11:06 AM
> To: ips@ece.cmu.edu
> Subject: Multi-address DNS name and SendTargets
> 
> 
> We recently noticed an oddity with SendTargets and hostnames with both
> IPv4 and v6 addresses.
> 
> Our config syntax for portals has a transport (tcp/tcp6, will have
> scpt/scpt6 some day), a host name, and all the portal parameters.
> 
> Recently we set up a target to listen on an interface with 
> both IPv4 and
> IPv6 sockets. Each socket/portal had different target portal 
> group tags.
> The two sockets were both on an interface that has a DNS name that has
> both an A and an AAAA record. Since we know exactly what 
> address family we
> want, we typed the same hostname into the config file.
> 
> The SendTargets code just prints hostnames (unless the "hostname" is a
> inet6 portal and looks like an IPv6 numeric address in which 
> case we add
> the bracketing brackets). :-)
> 
> The rub is that the output of SendTargets looked weird:
> 
> TargetName=iqn.XXXX
> TargetAddress=hostname,5	# this is the IPv4 portal
> TargetAddress=hostname,6	# this is the IPv6 portal
> 
> 
> I don't really see anything wrong done by the target, but I can see an
> initiator might get VERY confused.
> 
> I think the best resolution of this "issue" is to add a note to
> administrators to not configure portals with DNS names that resolve to
> both ipv4 and v6 records if the target listens on both 
> address families
> (well, tcp & tcp6) and the portals have different TPGTs. Wow, that's a
> mouthfull.
> 
> I guess the other thing to do is make initiators/discovery 
> agents aware of
> the fact that you can have a host name duplicated in TargetAddress
> responses for a given node, and that that would probably indicate that
> multiple address families are in use at once.
> 
> Take care,
> 
> Bill
>