HP-UX 11i December 2004 Release Notes

Internet and Networking Services
Network Transport
Chapter 12
265
Network Transport
new at 11i
original release
Network Transport includes ifconfig, ndd, netstat, virtual IP address,
setsockopt, and t_optmgmt. All are discussed in more detail below.
ifconfig
The ifconfig subnet mask default now allows all 1’s or all 0’s in the masked part of the
subnet field. (The subnet field is that portion of an IP address that identifies the subnet
beyond the network portion of the address.) This provides up to twice as many IP
addresses as before. Even though the default behavior now allows more IP address and
subnet mask combinations, any addresses working before will continue working without
alteration.
In the following example, a class A IP address used with the mask 255.192.0.0
(0xffc000000) has a two-bit subnet field which is the 5th and 6th bits:
11111111 11 000000 00000000 00000000
Now, ifconfig can assign the following IP address and subnet mask to an interface,
even though the subnet field (subnet portion of the address) is all 1’s:
IP address: 15.192.1.1
Subnet mask: 255.192.0.0 (0xffc00000)
In binary:
00001111 11 000000 00000001 00000001
11111111 11 000000 00000000 00000000
Also, ifconfig can now assign the following IP address and subnet mask to an
interface, even though the subnet field is all 0’s:
IP address: 15.1.1.1
Subnet mask: 255.192.0.0 (0xffc00000)
In binary:
00001111 00 000001 00000001 00000001
11111111 11 000000 00000000 00000000
To disallow subnet fields with all ones or all zeroes, set the ndd parameter
ip_check_subnet_addr to 1 in the nddconf file.
ndd
The networking configuration tool, ndd, is used to customize the networking kernel. To
make an 11i system more Internet friendly and easier to run “out of the box,” some of the
ndd tunable parameters defaults have changed, some formerly unsupportable tunable
parameters are now supported, and some new tunable parameters have been added. In
part, these modifications reflect changes to networking industry standards.