Multiple IP addresses in same HP-UX server

[Subhash_5]

We are having HP-UX 11.23 server with 5 network cards.
I have configured 3 LAN cards with following IP & subnet masks
1LAN0 IP_address- 172.16.1.6 ,subnet mask-255.255.255.0
2.lan1- IP 10.10.12.46 subnet mask-255.255.192.0
3.Lan2 IP 10.10.10.63 subnet mask -255.255.248.0
&everything is working fine.
now i am configuring LAN3 with IP address 192.168.1.51 Subnet mask 255.255.255.0
its not working ,i checked cables/switch/Vlan configuration & everyting seems ok.
please advice is there any limitation of HP-UX??

Reagrds
SP.

[Ivan Ferreira]

I think that should work. Check the ouput of netstat -ni, you should get increasing input packets for that interface.

Post the ouput of netstat -nr.

Use lanadmin to check the status of your interface.

[Steven E. Protter]

Shalom SP,

It seems you have avoided the problem of having two NIC cards on the same network. This should be avoided for it would crash networking.

If the netstat and lanadmin tests show the interfaces are working, check with network administration. If the cable is plugged into the wrong switch, or is not configured for this network setup, it could explain the entire situation.

SEP

[rick jones · Accepted solution]

"crash networking" is a bit harsh IMO. "Might not result in the expected behaviour and/or loss of connectivity" is more accurate as there is no panic or anything - which I think is implied by "crash"

but then it might be my DC upbringing coming-through again :)

the suggestions to provide netstat -rn output are good ones.

you might also try link-loop rather than ping - assuming you have another UX system on the 192.168.1 network (or a Linux one with the linkloop package from sourceforge.net - or was that freshmeat? anyway a web search will find it) linkloop will do a "link-level" ping based on MAC address and so will be independent of any IP routing funnies in the system(s)

[Subhash_5]

Thanks lots for your reply's all.
actually when we enble LAN3 with IP 192.168.1.51 server stops communicating to 192.168.x.x network.
from 172.168.1.6 as of now we can ping to 192.168 network also. Whole idea is that we want to change IP from 172.16. to 192.168 but cant do it immediatly as lot of other devices are communicating to this server on 172 IP.
I just want to know can we have two IP's of same subnet MASK in HP-UX.

kindly advice.
regards
SP.

[freddy_21]

if you have 2 lancard, with same subnet. i think not allowed.

for your case it's not allowed. and make your server crash. I have bad experience to configure 2 lancard with same segment. server crash.

but you create virtual ip for one lancard with same subnet, it's ok.
ex:
lan 0 ---> 172.16.1.16, 255.255.255.0
lan 0:1 ---> 172.16.1.100 255.255.255.0

thanks
freddy

[Victor Fridyev]

Hi,

I think, the problem is with the routing table. Could you please answer with output of
#>netstat -rn

HTH

[Subhash_5]

HI thanks for yours reply,
r u sure that I cannot have 2 LAN cards on with same subnet mask IP's.
now i have unplumbed new LAN card & deleted routes related to this IP.
Please advice.

[Victor Fridyev]

Hi,

It's permitted gto have different IP on the same server, the same subnet masks with different subnets. You even can connect more than on IP-address in one subnet, with the same subnet mask to one NIC.
What is prohibit is to have more than on NIC in the same subnet, with different IP-addresses.

HTH

[Subhash_5]

Victor Thanks
so it means i cannot have IP address 192.168.1.51 & 172.16.16 with subnet mask 255.255.255.0.
is this true?please confirm. also if you have any link/doc mentioning the same please send it to me.
Many thanks for your time & help.

Regards
SP

[Yogeeraj_1]

hi SP,

>so it means i cannot have IP address >192.168.1.51 & 172.16.16 with subnet mask >255.255.255.0.
>is this true?

NO. You can have this configuration. All you need to do now is to define the appropriate route on the gateway/route.


should not be a problem.

You can even do a ping test from a PC on the lan.

You may first try to do:
route ADD 172.0.0.0 MASK 0.0.0.0 192.168.1.1
destination^ ^mask ^gateway

(sorry i could not test it here!)

kind regards
yogeeraj

[rick jones]

172.... and 192... are always going to be different subnets. It would be a question, as already stated of what might be happening with routing.

Also, one _is_ allowed to configure multiple physical NICs (physical from the point of view of the transport) in the same IP subnet. It is just that by default, the behaviour of HP-UX might not be what you expect. By default it assumes you have equal connectivity on each of the NICs configured in the same subnet. Also, while traffic will be accepted on all NICs, it will only go-out one of the NICs configured into the subnet.

So, if you do not have equal connectivity on each NIC in the same IP subnet, it will appear that some things cannot be reached.

One addresses this either with static routing, or by using ip_strong_es_model set to 1 or 2. That causes the source IP to be included in the route lookups so that in general, replies will go-out the same interface on which the requests were received.

Finally, the _best_ way to have multiple physical NICs in the same IP subnet is to aggregate them with Auto Port Aggregation. This then presents one "physical" interface to the transport, so no need of special routes or ip_strong_es_model and provides automagic failover etc.

[nanan]

Hi SP
your tyring seems not to be wrong.
you can configure two and more ip address on each LAN cards with the same mask
what you said subnet is MASK
it makes a classification of network

Can you give me the procedure of assigning ip address.
and outpus of netstat -rn, ifconfig all of LANxx.

[David de Beer]

Hey Subhash, can you mail us your /etc/rc.config.d/netconf file?

Maybe you numbered SUBNET_MASK or INTERFACE_NAME, or one of the other params wrong? Often happens if you "yyp" in vi. Are you adding the lan through SAM or doing a vi on netconf?

Tx!
David.