Can HP9000 servers on 11X have two NICs with same subnet?
John Kutil
We're interested on doing a private network on lan1 for our customers
which have D,R,and L model servers. They currently have only the lan0
network interface installed.
Will sam allow me to set up the lan1 with 192.168.1.1 with
subnet 255.255.255.0 if lan0 is configured the same? In other word,
a potential overlapping subnet on lan0 that our customers might be
using.
Our software that we are writing will then open specifically the
lan1 network interface.
John Kutil
Rick Jones
Presumeably then your software is not using the host's TCP/IP stack?
If so, then why do you want/need to ifconfig the lan1 interface?
There is nothing in HP-UX 11 to preclude configuring multiple
interfaces into the same subnet. HOWEVER, it may or may not behave as
you desire. All else at defaults, traffic will be accepted on both
interfaces, however only one of them will be used for outbound
traffic. I can never remember if it is the first or the last
ifconfig'd.
Now, you may be able to coerce traffic to leave via the same interface
on which it arrived on 11.X if you set ip_strong_es_model to a value
of 1. This tells the routing code to consider source IP address when
making route selections. I have verified that it will do what most
folks want when a client connects to that dual-card server.
What I have not looked into is what will happen with a connection
initiated from the server. Ostensibly, if the server application
bind()'s to a specific local IP before calling connect() the route(s)
selected will be through the interface with that source IP. I at
present have no idea what will happen if that same app does not bind()
to a specific local IP first. To the best of my knowledge most if not
all of the network client apps under HP-UX 11 (eg ftp, telnet etc) do
_not_ bind to a specific local IP address when they connect to the
remote system.
It may be necessary/desireable to configure specific static routes for
the (presumably small) private network.
rick jones
A couple other things - you will probably want to disable IP
forwarding. When ip_strong_es_model is set to one, it also means
that the system will only accept inbound traffic to a given IP on the
interface with that IP address assigned. If it arrives on another
interface, it will be ignored. (Hence the "strong" in
ip_strong_es_model).
ftp://ftp.cup.hp.com/dist/networking/briefs/annotated_ndd.txt
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