Telnet connection timeouts

[masauso zimba]

We are experiencing problems telneting to our Alpha 4100 running Digital Unix 4.0E. Sometimes we are getting error message "Could not resolve host name", or "Connection timed out" and sometimes a connection is established.
What unix command can I use to diagnose the problem ? What parameters should I check for that will help determine cause and nature of problem

Thanking You in dvance.

Masauso.

[Ravi_8]

Hi,

Till what time do u have the licence, if the licence expires, if you will be facing these problems.
usually Compaq sends the licence(upon request, in the form of a script) which is valid for a year, each
year we need to get the licenece and run that script.

[David_246]

Hi,

This looks like an overloaded network issue to me. Is it true that the machines have different locations ? I mean not in the same room.
You can trace the delay of the hops using : $machine1:/usr/contrib/bin/traceroute $machine2

You will say the response time for each hop now. I'dd recommend you run this now and then to see if the numbers are high. Internal 5 ms is acceptable, external connection can have a 30 - 50 ms to be ok (bit slow).

You can of course also have a bad cable. You can test this using a "Fluke". But this would mean that users would have problems too, try-ing to connect the application.

Using netstat -s on both machines will tell you something about the network statistics. It will also tell you 2 important items :

- tcp: 341130624 packets sent
339425805 data packets (3514366717 bytes)
3916 data packets (3024207 bytes) retransmitted

The retransmit is never allowed to be more than 10% of the actual packets sent. If so, you have a broken cable, or you can have the awfull problem with f.e., running your server at 100 Full duplex, and your switch at 100 Half duplex. This will generate a lot of problems.

I know you can request the status of you device, but to be honest don't know how to do it on an HP box. Sun has it :
ndd -set instance 0 (for selecting hme0)
ndd -get link_mode /dev/hme
ndd -get link_speed /dev/hme

Good Luck !!

Regs David

[masauso zimba]

David, what would you make of our netstat -s output below ?

tcp:
139230 packets sent
124480 data packets (35968370 bytes)
3412 data packets (3833171 bytes) retransmitted

[Ron Kinner]

Your first error message indicates a possible problem with etc/hosts or your DNS server if you use one. Try
nslookup hostname
where hostname is the name of the device you are having problems talking to. Does that work?

ping ipAddress

is your next check. See if you get a good response. Do you get the same response with
ping hostname
?

Try pinging a device on the same LAN. Does that work?

If that fails:

If you are on an HP then you can run

linkloop -n 100 MAC

where MAC is the mac address of another device on the same LAN. This checks that you have a good LAN connection.

Also

lanadmin
lan
display

will tell you the state of your LAN connection and show you the presence of errors.

Non HP and HP can both use

netstat -s


If pinging the local device works but a distant device fails then you check your routing table:

netstat -rn

See if you have a default that makes sense.

then run a trace

traceroute ipaddress

or

tracert -d ipaddress
if you are working on a window box.

Ron

[Steven E. Protter]

You have a DNS problem more than likely.

I'm betting the output of more than one of your commands will show errors and a lack of resolution.

Its certainly possible you have a router that isn't cooperating, but the traceroute will help you figure it out.

Steve

[masauso zimba]

David, Steve, Ron,

Thanks for your suggestions. As it turned out the problem was with one of our gateway. The problem has since been resolved.

Thanks once again.

Masa.