Possible explanations for a large hop in latency
warren at kumari.net
Fri Jun 27 09:06:20 CDT 2008
On Jun 26, 2008, at 11:36 PM, Randy Bush wrote:
> Frank Bulk - iNAME wrote:
>> Just google "tbr1.sl9mo.ip.att.net" and it's clear that high
>> latency through
>> that point has occurred before. And guess what kind of customer
>> to me about the latency? A gamer.
> you can pay a lot of money for the net propagation anomaly detection
> services that gamers give you for free.
Many years ago I worked for a small Mom-and-Pop type ISP in New York
state (I was the only network / technical person there) -- it was a
very free wheeling place and I built the network by doing whatever
made sense at the time.
One of my "favorite" customers (Joe somebody) was somehow related to
the owner of the ISP and was a gamer. This was back in the day when
the gaming magazines would give you useful tips like "Type 'tracert
$gameserver' and make sure that there are less than N hops". Joe
would call up tech support, me, the owner, etc and complain that there
was N+3 hops and most of them were in our network. I spent much time
explaining things about packet-loss, latency, etc but couldn't shake
his belief that hop count was the only metric that mattered.
Finally, one night he called me at home well after midnight (no, I
didn't give him my home phone number, he looked me up in the
phonebook!) to complain that his gaming was suffering because it was
"too many hops to get out of your network". I finally snapped and
built a static GRE tunnel from the RAS box that he connected to all
over the network -- it was a thing of beauty, it went through almost
every device that we owned and took the most convoluted path I could
come up with. "Yay!", I figured, "now I can demonstrate that latency
is more important than hop count" and I went to bed.
The next morning I get a call from him. He is ecstatic and wildly
impressed by how well the network is working for him now and how great
his gaming performance is. "Oh well", I think, "at least he is happy
and will leave me alone now". I don't document the purpose of this GRE
anywhere and after some time forget about it.
A few months later I am doing some routine cleanup work and stumble
across a weird looking tunnel -- its bizarre, it goes all over the
place and is all kinds of crufty -- there are static routes and policy
routing and bizarre things being done on the RADIUS server to make
sure some user always gets a certain IP... I look in my pile of notes
and old configs and then decide to just yank it out.
That night I get an enraged call (at home again) from Joe *screaming*
that the network is all broken again because it is now way too many
hops to get out of the network and that people keep shooting him...
What I learnt from this:
1: Make sure you document everything (and no, the network isn't
2: Gamers are weird.
3: Making changes to your network in anger provides short term
pleasure but long term pain.
Do not meddle in the affairs of dragons, for you are crunchy and taste
good with ketchup.
More information about the NANOG