Re: [DNA] Issue 1: Use of 1.5 hours in the text

[Brett Pentland <brett.pentland@eng.monash.edu.au>]

Sathya Narayanan wrote:
> Issue: WiMAX is trying to increase the MaxRtrAdvInterval into hours or 
> days. Should we change 1.5 hours to 3 * MaxRtrAdvInterval?
> Agreement at the meeting: Yes. Lets make the change. We need to include 
> the MaxRtrAdvInterval in the RA so that the hosts can know about the 
> value. If different routers on the link use different values for 
> MaxRtrAdvInterval, host should use the minimum (Should it be maximum?) 
> value of MaxRtsAdvtInterval times three as the lifetime for prefixes in 
> the DNAHostPrefixList.
> 
> If you have any objection to the proposed change, please post your 
> objection on the list.

Hi Sathya,

JinHyeock is right about the 1.5 coming from the maximum value of 
MaxRtrAdvInterval.  If this maximum is to be increased to "hours or 
days" then I'd worry about just using 3 * that value.

The 1.5 hours is the time used to age out old prefix information.  It 
was picked because it was supposed to ensure that at least 3 router 
advertisements from each router would have been sent in that time.  The 
idea was to ensure that hosts have received an indication that the 
lifetime of a prefix has been changed if an operator wants to move a 
prefix to another link.

Section 5.1.11 recommends that operators wait for at least 1.5 hours 
after removing a prefix from a link before reassigning it to another 
link. (I don't know if any operators will read this, but I guess that's 
another issue)  I don't think it desirable to increase this to days.

Perhaps another approach might be to simply have some text that says 
that when changing the lifetime of a prefix, a router must send at least 
3 Router Advertisements with the new prefix lifetime before removing the 
prefix from a link.  Even if a router normally only sends Advertisements 
very infrequently, it doesn't seem unreasonable to make it send a few 
quick ones just during a period of prefix change.

Cheers,
Brett.