10.20 subnetting

[Bill Bryceland]

I was informed that I can't subnet with 10.20 because of a bug in the software. Can anybody verify if this is the case and if so is there a fix ?
Thanks,
Bill B.

[Patrick Wallek]

I think it depends on how exactly you are subnetting. You definitely can subnet with 10.20, but there are some configurations that aren't supported. As far as subnetting goes, HP has always gone by the RFC, I don't recall which one, for TCP/IP subnetting.

How are you trying to subnet? What subnet mask are you wanting to use?

[A. Clay Stephenson]

Hi Bill:

You need to be a bit more specific. I've run 10.20 boxes with multiple NIC's and ,of course, each had it own subnet.

[Darrell Allen · Accepted solution]

Hi Bill,

I believe you've been mis-informed. I have used subnetting on 10.20 systems without problem. Of course, just like for any other software, you want to load current, recommended patches either from the Support Plus CD or Custom Patch Manager.

Darrell

[Olav Baadsvik]

Hi,

This is not correct. There was at some
time a discussion on how to interprete
RFC-1122, and as far as I remember
HP in some early version of HP-UX 10.xx
interpreted this very strict and thus
said that certain subnetmasks were illegal.
This is no longer an issue.

Regards
Olav

[Bill Bryceland]

Thanks for replying,
I haven't tested my HP 10.20 machine yet, still in progress of loading. I have 2 subnets thus far.
both subnet masks are 255.255.255.192
first subnet is xxx.xxx.xxx.2 through .62
Second subnet is xxx.xxx.xxx.66 though .126
I need my Hp 10.20 box to talk to both subnets. I was told by a counter part that there is a bug in 10.20 that I can only use 255.255.255.0 as a subnet mask there for if I'm in the first subnet I won't be able to talk to the second ?????

[A. Clay Stephenson]

Hi Bill:

I think I see the problem now. If I understand, your are configuring 2 NIC's which share a common subnet mask. That is not allowed. The bad news is that it will almost work perfectly and drive you nuts. The following is an excerpt from 'Installing and Administering LAN/9000 Software':

-------------
Multiple LAN interfaces, intermittent failures: I have been having problems getting the two LAN interfaces on my system to operate at the same time. Occasionally the ethernet cards stop communicating with remote systems. When this happens, the remote system also cannot communicate with the local system.

Answer: Check that the two interfaces on your system do not have the same network number or, if you are subnetting, the same subnet address. If both LAN interfaces have the same value in the network (subnet) address portions of the IP address, the cards may not be enabled simultaneously (although they may both run separately.)

Related Documentation: Refer to chapter 6, "Network Addressing".
-------------

You can freely download the entire guide from:
http://docs.hp.com/hpux/onlinedocs/B2355-90748/B2355-90748.html

[Bill Bryceland]

Nope I'm not working with two Nic's. In setting up my network they created two subnets. I just want to make sure I can talk to machines on both subnets. If my counter part is right and I can only use 255.255.255.0 then I know I won't be able to talk to the second subnet that is using xxx.xxx.xxx.192 as a subnetmask because the broadcats addresses will be different.
Am I making any sense or am I just confusing everyone ?

[Steven Gillard_2]

Hopefully I've understood correctly... The only problem I see is with your configuration is the 'all zeroes' subnet address which was traditionally never supposed to be used according to the RFC.

You can use 'nettune' on 10.20 to turn this check off:

/usr/contrib/bin/nettune -s ip_check_subnet_addr 0

Once you've done that it should work with the 255.255.255.192 subnet mask.

The only way its going to work with the 255.255.255.0 subnet mask is if the router separating the two subnets is configured to do proxy ARP.

Regards,
Steve

[Kevin Wright]

How can you have 2 subnets bound to one NIC but using only one subnet mask?????? This makes absolutely no sense.

[Patrick Wallek]

Yes you can use the 255.255.255.192 subnet mask on your HP machine. You will just have to make sure that your default gateway is configured so that you can talk to whichever subnet you are not part of.

This should not be a problem at all.

[Kevin Wright]

you have to choose one subnet that you wish to be on, the router will take care of you communication to the other subnet. One Nic cannot be on two subnets at the same time. And by the way, how can you have two subnets with only one subnet mask?