Re: [DNA] Scope of solutions discussion document

[Sathya Narayanan <sathya@research.panasonic.com>]

Brett -

<snip>
> The basic asssumptions that we made were that:
> - hints from layer 2 would be available to trigger router solicitations
I was thinking about this particular assumption we made while driving to work today. I checked 2461 and in section 6.3.7, the following statements are made:

"To obtain Router Advertisements quickly, a host SHOULD transmit up to MAX_RTR_SOLICITATIONS Router Solicitation messages each separated by at least RTR_SOLICITATION_INTERVAL seconds."

and
"
Before a host sends an initial solicitation, it SHOULD delay the transmission for a random amount of time between 0 and MAX_RTR_SOLICITATION_DELAY.  This serves to alleviate congestion when many hosts start up on a link at the same time, such as might happen   after recovery from a power failure."

What does 'initial solicitation' mean in ,'Before a host sends an initial solicitation ...'? - does this refer to the RS sent when 'The interface is initialized at system startup time' or 'The host re-attaches to a link after being detached for some time'?

The values for these three variables are:
MAX_RTR_SOLICITATION_DELAY        1 second
RTR_SOLICITATION_INTERVAL         4 seconds
MAX_RTR_SOLICITATIONS             3 transmissions

The MAX_RTR_SOLICITATIONS limit is alright. But, the requirment to delay between 0..1 seconds before sending RS, and maintain inter-RS delay of 4 seconds, I think, will have a negative impact on rapid DNA. BTW, both the restrictions are 'SHOULD's. 

Does it make sense to consider relaxing these conditions? 0..1 seconds delay restriction is useful though in avoiding congestion if many hosts change their points of attachment at the same time.

with regards,
Sathya