[LARTC] Random ping jumps

[Artūras Šlajus]

R. Steve McKown wrote:

> What happens if you ping from the linux box to the linux box's default 
> gateway?  If the problem doesn't exhibit in this test nor in any test between 
> machines in your LAN, the problem is probably your providers: the DSL modem 
> or something 'downstream' from it.  You should consider doing tests #2 and #3 
> anyway as support for your position when you call your ISP to open a trouble 
> ticket.
It's not an ISP. Now it's morning and only 5 users online. The ping is flawless...
Well almost :)
Hostname                     Last  50 pings
  1. adsl-213-190-40-129.taka ..........>.......................................
  2. fe22-acc0-tai.kns.teleco ..........c......................................
  3. telecom-gw.is.lt         ..........b......................................
  4. litnet-gw.is.lt          .........3a......................................
  5. cat6506-p2-1.kttc.litnet .........b3...1a.................................
  6. ktu-lan.litnet.lt        .........c..........................1............
  7. diz.ktu.lt               .........>......1................................

Scale:  .:30 ms  1:46 ms  2:62 ms  3:99 ms  a:193 ms  b:283 ms  c:441 ms

> 2. plug a PC, configured as the linux router's eth0:1 interface (with proper 
> default gateway) and ping from the pc to the default gateway.  If the problem 
> goes away, its probably the linux router (hardware or software).
The problem goes away. I tried it here on my winxp box.

> * security note *
> 
> Running both your LAN and the internet provider subnets on the same ethernet 
> network puts you at a much greater security risk.  You should seriously 
> consider installing a third network interface into your linux box and moving 
> eth0:1's ip info to eth2.  Then plug the DSL modem into eth2 with a 
> cross-over cable with no computers attached.
Huh, would be great, but there is one but. Modem is at one house and server is at another :)
It's zyxel, maybe he has allow by mac or sth. I will look at his firmware setup.
Or maybe you have some thoughts how to connect server and modem? (about 200 m) :)

> I'm guessing your thirty users using Windows.  If they have windows network 
> enabled, they are all generating broadcast traffic.  That traffic will most 
> likely be crossing the DSL modem (since it is bridging).  Aside from security 
> implications, the local traffic that does get bridged is tying up your DSL 
> bandwidth.  It seems unlikely that 30 PC's could saturate your 128kbps 
> uplink, but I'm no expert on windows networking.  128kbps is not a huge pipe, 
> so perhaps it's possible.  If so, the solution to your security problem is 
> also the solution to the latency variability issue.  If this is the case, 
> both tests #2 and #3 will not show the variability, since your local LAN is 
> effectively removed from the test.

Yes, this may be true and solution. But is C class subnet traffic routed? I think it isn't.
It seems that when many users is browsing or doing normal day activities such as email checking
and irc download/upload? is saturated and it causes ping jumps. I will try to move ACKs into front
of queue and also prioritize some traffic. Bad that tc syntax is so unreadable.. Once it took 4 days
for me to write tc script ;-)

Also as roy mentioned, there is no such ip: 81.7.84.1
But if i set nexthop as my gw it says net unreachable... Maybe that gw has multiple addresses
or some magic is done on ISP side.

-- 
Sincerely, Artūras Šlajus
ICQ: 157929934
Jabber: arturaz@akl.lt

Oh, and please'o'please use UTF-8! :-)