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Re: [nfsv4] TSVDIR review of draft-ietf-nfsv4-federated-dns-srv-namespace

2011-09-13 09:38:58

On Sep 12, 2011, at 1:00 PM, Robert Thurlow wrote:

Joe Touch wrote:

Either this is an nfs service or it isn't.
If it is, then it should be using _nfs._tcp.example.com, etc. If it isn't, 
then:
   a) a new service name is required
   which then *requires*
   b) a new port number be assigned

This doesn't show any real understanding of what we're actually
trying to do.  To recap:

We don't want to enumerate all NFS servers in a domain.  That is
not an interesting enumeration.  We want to find certain ones that
are known to share a "domain root" (hence the syntax we chose).

When we find those servers, we will talk NFSv4 to them (not a new
service).  And we will talk NFSv4 on port 2049 (not a new port).

Your proposal above makes things worse in that it will no longer
be clear what the SRV record means.  It also ensures that we have a
problem if we ever want to enumerate other subsets of NFS servers
(none of which have been discussed).

Rob T

Hi Rob, 

Few inputs you can take with a huge grain of salt

1) some people on this list have suggest TXT records. Keep in mind this is 
totally the wrong group to tell you how to use DNS. Last time I discussed TXT 
records with the DNS directorate they certainly would not have recommended them 
for this use. I suspect the advice to use TXT is very bad but either way, if 
you want advice on that, go talk to the DNS Directorate not the transport guys. 

2) My understanding is that you have two types of service you want to be able 
to find using SRV. Now these two services both happen to use the same protocol 
to talk to them and both run on same default port so you don't need two ports 
allocated for them but you do need to be able to make separate DNS entries for 
the two because some servers offer one of the service and some don't. 

Using SRV and having one labels like _service1._tcp.example.com for one service 
and _service._tcp.example.com for the other service seem perfectly reasonable 
to me, but this is the TSV review and I don't know why the TSV directorate 
would be providing any comment on how you use DNS. Now the fact that both will 
likely point as the same port and same server in some times seems fine to me. 

3) Nothing to do with TSV but, your motivation for separating the 
_service1._tcp into _service1._foo._tcp seems like something you don't really 
need and is going to make this  harder for you to get this all approved. Unless 
you need this, I'd think carefully about how much you want it. Keep in mind if 
some other protocol wants the domain concept, they can just go allocate two 
tags for use in SRV DNS.

4) I have not seen a single transport issue raised in this thread 

Cullen

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