Capwap Mailing List: Re: Issue 156: Need more details on use of DNS for discovery

FWIW, Pasi's wording sounds good to me.  I also agree that we should  
ask for an IANA-assigned service name, which implies a related change  
to the IANA Considerations.
Margaret
On Aug 7, 2008, at 5:27 AM, <Pasi.Eronen [at] nokia.com>  
<Pasi.Eronen [at] nokia.com> wrote:
Hi Pat,
The 'DNS name "CAPWAP-AC-Address" MAY be resolvable' part still
isn't quite right; that DNS name won't be resolvable (which
is clear after reading the third sentence). Also, some more details
would be helpful for the SRV record part. Would something like this
match your intent?
  DNS: The WTP MAY support use of DNS SRV records [RFC2782] to
  discover the AC address(es).  In this case, the WTP first obtains
  (e.g., from local configuration) the correct domain name suffix
  (e.g., "example.com") and performs a SRV lookup with Service name
  "capwap-control" and Proto "udp". Thus, the name resolved in DNS
  would be, e.g., "_capwap-control._udp.example.com".  Note that the
  SRV record MAY specify a non-default port number for the control
  channel; the port number for the data channel is the next
  port number (control channel port + 1).
(I'm assuming the use of the IANA-assigned service name, instead of
non-registered "CAPWAP-AC-Address"; and with this text about SRV port
number handling, you might need small tweaking in Section 3.1, too.
Or you might want to handle port number in some other way.)
Best regards,
Pasi
-----Original Message-----
From: ext Pat Calhoun (pacalhou) [mailto:pcalhoun [at] cisco.com]
Sent: 31 July, 2008 01:38
To: Eronen Pasi (Nokia-NRC/Helsinki); capwap [at] frascone.com
Subject: RE: Issue 156: Need more details on use of DNS for discovery
My apologies, Pasi. I'm not sure what I was thinking when I wrote the
text.
What I should have sent was:
<text>
   DNS:  The DNS name "CAPWAP-AC-Address" MAY be resolvable to one or
      more AC addresses.  A WTP that wishes to make use of DNS SHOULD
      use the format described in [RFC2782].  The recommended
format for
      a lookup would be CAPWAP-AC-Address._udp.example.com.
</text>
Does that make more sense?
PatC
-----Original Message-----
From: Pasi.Eronen [at] nokia.com [mailto:Pasi.Eronen [at] nokia.com]
Sent: Wednesday, July 30, 2008 12:29 PM
To: Pat Calhoun (pacalhou); capwap [at] frascone.com
Subject: RE: Issue 156: Need more details on use of DNS for discovery
Pat Calhoun wrote:

Pasi's comment was:
   Section 3.3: there's a single sentence about DNS-based discovery;
   probably slightly more details would be useful.
Well... There's not much else we can say, but I am proposing the
following text In hopes that it will provide more clarity to the
implementor.
<new text>
3.3.  AC Discovery
[...]
      DNS: The DNS name "CAPWAP-AC-Address" MAY be resolvable to one
      or more AC addresses.  A WTP that wishes to make use of DNS
      SHOULD use the format described in [RFC2782].  The

recommended

      format for a lookup would be _capwap._udp.example.com.
</new text>

I have some trouble parsing the 'The DNS name
"CAPWAP-AC-Address" MAY be
resolvable...' part. It seems to be suggesting doing a DNS
query for DNS
name "CAPWAP-AC-Address" -- or in other words, defining a new
Top-Level
Domain. That probably isn't a good idea.
The two latter sentences are also leaving awfully lot of

details to the

implementor -- RFC2782 has specific requirements about the labels  
etc.

(E.g. RFC 3861 has much more text about using SRV records for another

purpose.)
Best regards,
Pasi
_________________________________________________________________
To unsubscribe or modify your subscription options, please visit:
http://lists.frascone.com/mailman/listinfo/capwap
Archives: http://lists.frascone.com/pipermail/capwap

Re: Issue 156: Need more details on use of DNS for discovery	<– Date –> <– Thread –>
From: Margaret Wasserman (margaretthingmagic.com)
Date: Thu, 7 Aug 2008 05:42:49 -0700 (PDT)