Networking issue.

[sudhapage]

Dear all,

Our HPUX server having two network interfaces, I have configured both interfaces as below.

eth0 - 192.168.1.56
eth1 - 192.168.1.57

If I telnet the server using eth0, server is connecting. That time If I remove eth1 networking cable. Still I am able to work on the server using eth0 connection.

But if I connect through eth1, server is connecting. That time If I remove eth0 networking cable. My connection getting hang, Once again if I connect eth0, then only its working.

What may the issue?

Regards,
Sudhakaran.K

[Jollyjet]

hey can post you server model.

normally one will be the management port that is mp we use to login via mp and collect log's and to get console login from network we use that ip you might have got confused. post the out put of ioscan -fnC lan and ifconfig lan0 and ifconfig lan1 we will explain you clearly.

[sudhapage]

hi,

I have checked both are two ethernet cards only.

MP port is different.

I have same issue in solaris server also.

Network card interface details.

eth0 - 192.168.1.56 - 255.255.255.0
eth1 - 192.168.1.57 - 255.255.255.0

I am able to login through both interfaces. The problem is if I connect through eth1, server is connecting. That time If I remove eth0 networking cable. My connection getting hang, Once again if I connect eth0, then only its working.

Regards,
Sudhakaran.K

[Steven Schweda]

Both interfaces are on the same subnetwork.
There's no particular reason for the system
to send data _to_ you on the same interface
where it gets the data _from_ you. If it
always sends on eth0, then pulling the cable
for eth0 would stop data from getting back to
you.

Why do you have two interfaces on the same
subnetwork? If you are looking for
reliability through redundancy, then you need
to do more than just install multiple
interfaces on the same subnet.

[sudhapage]

Hi steven,

This is user requirement, user project is symantec gateway security. So they want to test like this.

Is there any rules are there like,

Primary interface should be up?

Regards,
Sudhakaran.K

[Steven Schweda]

> This is user requirement [...]

_What_ is the user requirement? Two network
interfaces (where one must always work), or
some kind of redundant/fail-over network
connection which will keep working when one
of the pieces fails?

I assume that you want the second one, as
it's more useful. I don't know how to do it,
and a quick look at the HP-UX Web site didn't
tell me anything useful, but I'd be willing
to bet that it's possible -- but you can't
do it by just configuring two interfaces this
way.

A quick Google search for:
hp-ux redundant network
found this:

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=290477

Perhaps you can do better.

[Torsten.]

Hi,

you wrote:

"eth0 - 192.168.1.56
eth1 - 192.168.1.57"

"eth0" doesn't sound like HP-UX, I would expect something like "lan0".

Anyway, the IP addresses are in the same subnet (right?), if you want to do something like load balancing you should have a look at this:

(APA - auto port aggregation)

http://www.hp.com/products1/serverconnectivity/adapters/apa_overview.html?jumpid=reg_R1002_USEN

[SUDHEER M S]

Can you please provide
uname -a,
hostname
model
ioscan -fnC lan
lanscan
netstat -ni command outputs please.

[rick jones]

Unless other things are done, when one configures multiple physical NICs into the same IP subnet, under HP-UX, traffic will be accepted on both, but will only flow out one of them, and there is nothing inherent in the TCP/IP stack to cause it to switch from one to the other.

If one really _must_ have multiple physical NICs in the same IP subnet, and one cannot use Auto Port Aggregation, then you have to start doing some creative stuff with ndd settings like ip_strong_es_model and perhaps some judiciously selected static routes in the routing table.