RE: [MIPSHOP-MIH-DT] DNS SRV records

Taking your comment more generically, I think you are asking for a
fallback mechanism, in case a NAPTR record does not exists for that
application tag. 

I thought it is implicit from the existing standards that in case you
know the application and the transport, you do not need to make a NAPTR
query, but only an SRV. So, this may not need to be explicitely
specified, but I need to doublecheck this.

- gabor

-----Original Message-----
From: ext Vijay Devarapalli [mailto:vijay.devarapalli@azairenet.com] 
Sent: Wednesday, December 05, 2007 11:03 PM
To: Bajko Gabor (Nokia-SIR/MtView)
Cc: mipshop-mih-dt@ietf.org
Subject: Re: [MIPSHOP-MIH-DT] DNS SRV records

Gabor,

Sure you can use NAPTR records for the mobile node to figure out the
FQDN on which it needs to perform a DNS lookup. But it could be as
simple as the mobile node being configured with either
_mih._udp.example.com or _mih._tcp.example.com. Or perhaps configured
with both. The mobile node will do a DNS lookup on the first FQDN and
then the second one.

If there is no MIH server available in a particular network, the mobile
node won't get any response.

Note that NAPTR is not that widely implemented. So you might want to
make sure that DNS lookup for the MIH server can work without using
NAPTR.

Vijay

Gabor.Bajko@nokia.com wrote:
> Vijay,
> 
> 
> NAPTR records provide a mapping from a domain to the SRV record for 
> contacting a server with the specific transport protocol in the NAPTR 
> services field.
> 
> The NAPTR record lets you to look at a specific service in a specific 
> domain. The response will tell you if whether that domain has a server

> or not, and if yes, what kind of transport protocol and the order of 
> preference. Once you have that information, you can construct an SRV 
> record to find the server which provides the service with the desired 
> transport.
> 
> In the example you gave you made the assumption that the domain hosts 
> an mih service using udp.
> 
> - gabor
> 
> -----Original Message-----
> From: ext Vijay Devarapalli [mailto:vijay.devarapalli@AzaireNet.com]
> Sent: Wednesday, December 05, 2007 11:17 AM
> To: Bajko Gabor (Nokia-SIR/MtView)
> Cc: mipshop-mih-dt@ietf.org
> Subject: Re: [MIPSHOP-MIH-DT] DNS SRV records
> 
> Gabor.Bajko@nokia.com wrote:
>> We are using NAPTR records, SRV record is not enough for the 
>> discovery, as we do not know the fqdn of the server(s).
> 
> I am probably missing some context then. I haven't really followed the

> discussions so far. Sorry about that.
> 
> But a question on SRV records. You would be creating a label, 
> something like "_mih._udp.example.com". You would then set aside a new

> SRV record for the above label. Then the mobile node would be 
> configured to do a DNS lookup based on the above label. example.com 
> can be translated into any realm.
> 
> Isn't this sufficient? Not clear why you need NAPTR records.
> 
> Vijay
> 
>> But thanks for the pointer.
>>
>> - gabor
>>  
>>
>> -----Original Message-----
>> From: ext Vijay Devarapalli [mailto:vijay.devarapalli@azairenet.com]
>> Sent: Wednesday, December 05, 2007 10:11 AM
>> To: mipshop-mih-dt@ietf.org
>> Subject: [MIPSHOP-MIH-DT] DNS SRV records
>>
>> I was chatting with Telemaco this morning and he told me that you 
>> guys
> 
>> are writing a draft on reserving a new DNS SRV record.
>> DNS SRV records are not maintained by the IANA (no IETF involvement).
>> The SRV records are maintained at
>>
>> http://www.dns-sd.org/ServiceTypes.html
>>
>> You just need to send an email to add a new SRV record.
>>
>> There is some discussion on using DNS SRV records for MIPv6 home 
>> agent
> 
>> lookup. See section 5.1.2 of RFC 5026.
>>
>> Vijay
>>
>> _______________________________________________
>> MIPSHOP-MIH-DT mailing list
>> MIPSHOP-MIH-DT@ietf.org
>> https://www1.ietf.org/mailman/listinfo/mipshop-mih-dt
> 

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