Subject: [DNA] Host BCP Issue 1: Same link vs Link change

From: Sathya Narayanan <[email-masked]>
Date: Mon, 04 Apr 2005 14:13:26 -0400

Issue 1: Same link vs Link change
Should the BCP make recommedations to the host only to find if there is 
a link-change? If the host is on the same link - is it OK if the host 
doesn't find out that it is on the same link efficiently? This question 
I think shows up both on the BCP and on the solutions work.

 From the goals:
G1: DNA schemes should detect the identity of the currently attached  
link to ascertain the validity of the existing IP configuration. They 
should recognize and determine whether a link change has occurred and 
initiate the process of acquiring a new configuration  if necessary.

The first sentence makes it sound like the goal is to 'detect identity' 
irrespective of whether the link has changed or not. The second sentence 
makes it sound like our focus is only to detect 'link-change' and 
initiate the process of ...

FWIW, I think DNA should not differentiate between same-link and 
link-change. DNA should define efficient mechanisms (in BCP and Soln.) 
for the hosts to quickly identify its current link, whether it be the 
same or different link.

What do others think?

- Sathya

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From: JinHyeock Choi <[email-masked]>
Date: Tue, 05 Apr 2005 09:18:15 +0900

Dear Sathya

> initiate the process of ...

The first and second sentence are intended to mean the same.  
 
> for the hosts to quickly identify its current link, whether it be the

I agree that DNA should detect link identity EFFICIENTLY, whether
link change or not.

But I don't think that implies that a host needs to QUICKLY find out 
that it still remains at the same link. 

In case of a link change, it's important for a host to quickly check 
for link change lest there should be service disruption. 

But in case of no link change, I can't think of any harm from 
a little DNA delay.   

Best Regards

JinHyeock

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From: Greg Daley <[email-masked]>
Date: Tue, 05 Apr 2005 16:09:22 +1000

Hi JinHyeock,

JinHyeock Choi wrote:
[chop prior text]
> But in case of no link change, I can't think of any harm from 

Indeed.  In some networks, forwarding state will need to be updated
by transmitting MAC frames (with a matching MAC to that perviously
used) onto the medium.

This may need to be done, perhaps with an RS, but the response from
the router needn't arrive before packets start flowing.

Greg

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From: Yushun Wang <[email-masked]>
Date: Tue, 05 Apr 2005 12:00:34 -0700

Hi,

Some questions below...

<...>

>> But in case of no link change, I can't think of any harm from a little 
>> DNA delay.   

I am not sure I understand the above statement, so
here's the dumb question: how does a host know the link
has changed or not before finding out if the link has
changed or not?

 > for the hosts to quickly identify its current link, whether it be the

This is of course from the host's bcp perspective.

Regards,

yushun
-- 
Yu-Shun Wang <[email-masked]>  http://www.isi.edu/~yushunwa
USC Information Sciences Institute