[IPv6]Re: How are AdvReachableTime and AdvCurHopLimit in RFC4861 used?
Ted Lemon <mellon@fugue.com> Fri, 24 May 2024 21:44 UTC
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From: Ted Lemon <mellon@fugue.com>
Date: Fri, 24 May 2024 17:43:56 -0400
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To: David Farmer <farmer@umn.edu>
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Subject: [IPv6]Re: How are AdvReachableTime and AdvCurHopLimit in RFC4861 used?
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No, that says what it is, but not what specifically it is used for. I couldn’t find any normative language about that. Op vr 24 mei 2024 om 17:36 schreef David Farmer <farmer@umn.edu> > > > On Fri, May 24, 2024 at 3:58 PM Ted Lemon <mellon@fugue.com> wrote: > >> We've spent the past half hour in the SNAC interim trying to understand >> what these do, and we've come up empty. Are they in fact used? What do they >> do? We don't know what values to specify for them in SNAC router RAs. >> > > I believe AdvReachableTime = Advertised ReachableTime and AdvCurHopLimit = > Advertised CurHopLimit. ReachableTime and CurHopLimit are ND variables for > nodes and are set from values advertised in an RA. See the following; > > RFC4861 Section 6.3.4, Processing Received Router Advertisements, says; > > If the received Cur Hop Limit value is non-zero, the host SHOULD set > its CurHopLimit variable to the received value. > > If the received Reachable Time value is non-zero, the host SHOULD set > its BaseReachableTime variable to the received value. If the new > value differs from the previous value, the host SHOULD re-compute a > new random ReachableTime value. ReachableTime is computed as a > uniformly distributed random value between MIN_RANDOM_FACTOR and > MAX_RANDOM_FACTOR times the BaseReachableTime. Using a random > component eliminates the possibility that Neighbor Unreachability > Detection messages will synchronize with each other. > > In most cases, the advertised Reachable Time value will be the same > in consecutive Router Advertisements, and a host's BaseReachableTime > rarely changes. In such cases, an implementation SHOULD ensure that > a new random value gets re-computed at least once every few hours. > > The RetransTimer variable SHOULD be copied from the Retrans Timer > field, if the received value is non-zero. > > > I hope that helps. > -- > =============================================== > David Farmer Email:farmer@umn.edu > Networking & Telecommunication Services > Office of Information Technology > University of Minnesota > 2218 University Ave SE Phone: 612-626-0815 > Minneapolis, MN 55414-3029 Cell: 612-812-9952 > =============================================== >
- [IPv6]How are AdvReachableTime and AdvCurHopLimit… Ted Lemon
- [IPv6]Re: How are AdvReachableTime and AdvCurHopL… David Farmer
- [IPv6]Re: How are AdvReachableTime and AdvCurHopL… Ted Lemon
- [IPv6]Re: How are AdvReachableTime and AdvCurHopL… David Farmer
- [IPv6]Re: How are AdvReachableTime and AdvCurHopL… Ted Lemon
- [IPv6]Re: How are AdvReachableTime and AdvCurHopL… David Farmer
- [IPv6]Re: How are AdvReachableTime and AdvCurHopL… Ted Lemon
- [IPv6]Re: How are AdvReachableTime and AdvCurHopL… Timothy Winters
- [IPv6]Re: How are AdvReachableTime and AdvCurHopL… David Farmer
- [IPv6]Re: How are AdvReachableTime and AdvCurHopL… Erik Kline
- [IPv6]Re: How are AdvReachableTime and AdvCurHopL… Ted Lemon
- [IPv6]Re: How are AdvReachableTime and AdvCurHopL… Mark Smith
- [IPv6]Re: How are AdvReachableTime and AdvCurHopL… Ted Lemon
- [IPv6]Re: How are AdvReachableTime and AdvCurHopL… Ole Trøan
- [IPv6]Re: How are AdvReachableTime and AdvCurHopL… Timothy Winters
- [IPv6]Re: How are AdvReachableTime and AdvCurHopL… Ted Lemon