28 Jul
2019
28 Jul
'19
5:52 p.m.
The hello timer is essentially how long between the node sends out the
hello messages on a circuit. This in turn, is used to detect when a
circuit goes down.
The listen timer is on a per node basis for adjacent nodes, and is set
to two times the hello time, plus a few seconds. So the detection of a
circuit going down is when the listen time expires.
You cannot directly set the listen timer, but you can choose your own
hello timers, and having a longer time means the other end will take
longer before it detects a circuit going down.
All that said, I usually have long times, since I do not feel really
quick detection of a circuit down is that important, but I don't mind
reducing the traffic a load a little.
Other than that, everyone should feel free to make whatever choice they
feel most appropriate for their expectations.
Johnny
On 2019-07-28 16:41, Mark Matlock wrote:
Johnny,
I have one question I?ve been meaning to ask about hello timers and listen timers.
The default seems to to be 15 seconds hello and 40 seconds listen. But on MIM I have seen
some other combinations like Hello 300 secs but the Listen varies from 608 to the default
40 (at least on IP-0-10)
All the values seem to work ok, but on my 30.1 node which is a real PDP-11, I?d like to
use something closer to 300 and 600+ to reduce load and unneeded up and down messages due
to my flakey ISP?s internet.
What are your thoughts on this topic?
Thanks!
Mark
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt at softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
On Jul 28, 2019, at 8:31 AM, Johnny Billquist
<bqt at softjar.se> wrote:
People, I have written a page about DECnet costs and HECnet costs, which I would
recommend that anyone interested read through. It contains a bit of elaboration on how
DECnet does routing, and gives some suggestions on how costs could be set on HECnet to
make it perform better.
I have noticed over the years that sometimes we do get really silly routing decisions
just because of how people set, or do not set costs. The page I've written is by no
means perfect, nor are the suggestions in there. But feel free to come with feedback, or
ignore it. But I am going to try and use this myself more properly from now on, and that
means that if others don't, you probably are going to get more traffic through your
nodes. Traffic that probably do not make sense that it passes through you, but I just feel
that I prefer to try and make it work right from my point of view, and then just at least
tell people how I worked my numbers out. If someone have a different idea, I'm open to
changing my settings, but I will not try and do optimizations to achieve:
a) Same paths for packets in both directions - DECnet explicitly does not do this.
b) Specifically penalize one type of interface because of any subjective preference about
that type of interface in general.
Oh - and the link to my writeup: http://mim.update.uu.se/costs.htm
Johnny
--
Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt at softjar.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol