Subject: Re: [Hipsec] Rendezvous Server Concerns

From: Teemu Koponen <[email-masked]>
Date: Fri, 8 Apr 2005 23:52:53 +0300

On Feb 7, 2005, at 15:40, Kevin Grace wrote:

Kevin,

>>> Today, using readily available DNS implementations and without 
>>> Rendezvous Servers, one can create an A record in an authoritative 
>>> name server for a mobile host and assign it a time-to-live of 1 
>>> second. The longest the record could possibly be cached by 
>>> non-authoritative name servers then is 1 second.When the node moves 
>>> and changes IP addresses, it can successfully update its A record 
>>> within the authoritative name server in less than a second. The 
>>> total latency between when a node's address changes and when DNS is 
>>> properly updated need not exceed a couple seconds and could well be 
>>> closer to one second.
>>
>>
>> This is very good news indeed.  Would you care to share us with a 
>> reference?
>
> Sure. From the London Communications Symposium in 2002:
>    http://www.ee.ucl.ac.uk/lcs/papers2002/LCS072.pdf
>
> The authors in the referenced paper demonstrate empirically how fast 
> DNS can perform zone transfers and the maximum update rate it can 
> support for a given configuration. Note, they are using what today 
> would be considered slow platforms (650 MHz PIII) and even better 
> performance results can be obtained today. My own organization has 
> conducted similar tests using faster hardware and have been able to 
> support over 300 individual dynamic updates/sec where each mobile node 
> has a unique TSIG key; each individual update completes in well under 
> a second.

I just recalled this thread while reading a more recent paper about DNS 
TTL violations:

Pang et al., On the responsiveness of DNS-based network control,
http://www-2.cs.cmu.edu/~aditya/papers/imc04-resp.pdf

My interpretation of their DNS measurements is that pure DNS based 
mobility is simply not possible due to the current TTL violations in 
Internet even though DNS itself could handle the slight increase in 
load, which is by the way argued in more detail in the following paper:

Jung et al., DNS performance and the effectiveness of caching,
http://nms.lcs.mit.edu/papers/dns-ton2002.pdf

Teemu

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