Communication problems with certain IP addresses

[Koos Fourie]

Hi all

We recently upgraded from Tru64 v5.1 to Tru64 v5.1B-2 (Patchkit 4).

Since the upgrade we have servers and PC's that suddenly cannot connect to the server. One moment the can connect then suddely they cant. I can then still ping the IPs above and below the specific one. Other servers or PC's on the network can still ping the IP.

The only workaround is to reboot the server or chage the NIC in the PC.

I include a sys_check of the server.

Any help or suggestions will be welcome.

Regards

Koos

[Michael Schulte zur Sur]

Hi,

sys_check suggests:
Tuning Suggestion: Many interface drops ( 148 ) on network interface elan0
Packet drops can be avoided by raising ifqmaxlen to 2048.
Use the sysconfigdb command or the Kernel Tuner to add the following to /etc/sysconfigtab:
net:
ifqmaxlen=2048

hth,

Michael

[Koos Fourie]

I have implemented the suggestion and will monitor the situation. I will report back if this has cured the problem.

Thanks

Koos

[Ralf Puchner]

forget the "drop" issue sys_check always report this message if drop is greater than a number of pakets. If you check your hostnames and error files you will see the reasons:

Aug 16 16:04:32 BMS6 sshd2[379727]: WARNING: DNS lookup failed for "156.8.112.103".
Aug 16 16:04:32 BMS6 sshd2[379773]: Local disconnected: Connection closed by remote host.
Aug 16 16:04:32 BMS6 sshd2[379773]: connection lost: 'Connection closed by remote host.'
Aug 16 16:04:33 BMS6 sshd2[379727]: Remote host disconnected: Terminating connection
Aug 16 16:04:33 BMS6 sshd2[379727]: disconnected by application in remote: 'Terminating connection'

hostnames with "_" are not RFC compliant and so your configuration is unsupported. Also uppercase hostnames looks a little bit strange since hostnames are defined as lowercase on unix systems (look like UCX issue).

If checking all logs and messages you will come to the conclusion that hostname lookup will not properly work.

The reason could not be the upgrade from 5.1 to 5.1B-2 because ssh was not delivered with 5.1. You told us "connection" doesn't work, what else this means but could be also a problem due to ssh implementation within 5.1B.

So please correct your hostnames, have a look into the RFC's...