Subject: Preferred and Valid Lifetimes

From: "Sivaramakrishnan A" <[email-masked]>
Date: Tue, 21 Aug 2001 09:22:10 +0530

I have a doubt regarding Router Advertisement specified in RFC 2461
(Neighbor Discovery for IPv6).
Our implementation is purely a Router. The doubt is regarding the following:

AdvValidLifetime
	The value to be placed in the Valid Lifetime in the Prefix Information
option, in seconds. The designated value of all 1's (0xffffffff) represents
infinity. Implementations MUST allow AdvValidLifetime to be specified in two
ways: - a time that decrements in real time, that is, one that will result
in a Lifetime of zero at the specified time in the future, or - a fixed time
that stays the same in consecutive advertisements.
           Default: 2592000 seconds (30 days), fixed (i.e., stays the same
in consecutive advertisements).

AdvPreferredLifetime
            The value to be placed in the Preferred Lifetime in the Prefix
Information option, in seconds. The designated value of all 1's (0xffffffff)
represents infinity. See [ADDRCONF] for details on how this value is used.
Implementations MUST allow AdvPreferredLifetime to be specified in two
ways: - a time that decrements in real time, that is, one that will result
in a Lifetime of zero at a specified time in the future, or - a fixed time
that stays the same in consecutive advertisements.
          Default: 604800 seconds (7 days), fixed (i.e., stays the same in
consecutive advertisements).

When the ValidLifeTime and PreferredLifeTime are specified in two ways
given, there exists a conflict on when to set the
lifetime as fixed /decrementing. What is the condition under which the
LifeTime is set to be fixed and under which situation
is it to be set decrementing? Is there any way to configure them by SNMP
Manager.
If yes, what is the standard MIB to be used? (I couldn't find any relevant
object in standard MIB specified under RFC 2465!)

Thanks,
Sivarama Krishnan. A

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