Re: [DNA] [Issue X] LinkID v.s. Landmark Prefix

[Erik Nordmark <erik.nordmark@sun.com>]

JinHyeock Choi wrote:

> ok. From now on, I will use the term "flapping" only in the sense you 
> describes. 
> 
> For the more general case I presented, I will use the term 'LOS (Lack 
> of Synchronization). Is it ok? 

ok, but see below.
Also, I don't think "out of synch" can be determined in a distributed 
system, since there is always a non-zero delay. Hence if R1 sends a RA 
and R2 and R3 receives it, an observer can't tell which or R2 and R3 
updated the prefix list first (or whether they did it at exactly the 
same time).

> (The term "link" gave me enough trouble already. I don't want another 
> Jason problem arising from ambiguous terms.)  
> 
> 
>>Such flapping is unavoidable for the cases we are
>>interested in (an unknown and changeable set of routers on the link, and
>>a changeable set of prefixes being advertised.)
>>
>>I think it is important that the DNA solution cope gracefully with such
>>flapping.
> 
> 
> ok. I think it's also important that DNA solution cope gracefully with 
> more general case of  temporary LOS (Lack of Synchronization). If 
> DNA solution can deal with LOS, I think it can deal with flapping 
> automatically. 

I don't see using the LOS term as helpful here.
LOS captures the case when router1's list of prefixes is out of date 
with router2's two list of prefixes, even if only for a nanosecond.

What matters is the sequence of events that are observable.


>>>If the (solicited) RA carries 1) NO answer and 2) a known prefix,
>>>the host would not assume a link change.
>>>(So in effect, "known prefix" would overrule "NO".)
>>>
>>>Is this right?
>>
>>I think that makes sense.
> 
> 
> ok. I think the above is a non-trivial change for Link Identification 
> criteria, so needs to be reflected in the Landmark/ CompleteRA draft. 

Agreed.

    Erik