10.20: A 10.0.0.0 will not subnet to a /24 Class C address.

[Trent Cameron]

Hi, Hopefully someone can help me with this..

I'm using HP-UX v10.20 and I am having trouble setting the IP Address of a NIC to 10.0.0.250 with a subnet mask of 255.255.255.0
If I leave the subnet mask 255.0.0.0, it accepts the settings and works perfectly.

I know this is an issue with HPUX v10.20 (RFC standards bla bla) and that in version 11 it has been resolved, but in this case I need to use 10.20.

Is there a workaround for this issue???
(I've heard there may be a way using nettune?)

Thanks in advance for all your help
Trent.

[John Bolene]

We use 10.1.160.0 subnet in 10.20 with mask 255.255.255.0 with no problems.

Also use 10.1.152.0 mask 255.255.252.0

[Bruce Regittko_1]

Hi,

Many routers do not like subnet portion of the IP address to contain all zero bits nor all one bits. A 10.0.0.0 network subnetted to 255.255.255.0 means that the middle two octets are the subnet bits and all 16 are zero with 10.0.0.250. You can use ndd(1m) to allow these addresses to be used:

ndd -set /dev/ip ip_check_subnet_addr 0

will allow the subnet bits to be all ones or zeros. Note that according to the man page for ndd, setting the ip_check_subnet_addr is not recommended and is not supported. While you may be able to set these addreses on the interface, they may not work correctly with other software/hardware.

--Bruce

[Trent Cameron]

Thanks Bruce, but I think the ndd command is HP-UX 11 specific and I need something to work under 10.20. When I try it under 10.20 I don't have the command, nor a device called "ip"

any other ideas??

Thanks
Trent.

[Vincent Stedema]

Trent,

Have you tried "nettune"? Issue "nettune -h" to get information about settings and objects.

Vincent