<> IP on same NIC , possible ?
João Natal
Env.: OSR 5.0.5 + NE2000 NIC
Is it possible to have more then one IP adress on the same NIC ?
TIA.
Jean-Pierre Radley
| Hi there,
|
| Env.: OSR 5.0.5 + NE2000 NIC
|
| Is it possible to have more then one IP adress on the same NIC ?
man ifconfig. look for 'alias'.
--
Jean-Pierre Radley <j...@jpr.com> XC/XT Custodian Sysop, CompuServe SCOForum
phenom
well so that two mac addresses can co-exist on the server at the same
time. Otherwise you will keep getting Arp table overwritten errors.
John DuBois
>>
>> na...@mail.telepac.pt averred (on Mon, Apr 05, 1999 at 01:30:27PM +0000):
>> | Hi there,
>> |
>> | Env.: OSR 5.0.5 + NE2000 NIC
>> |
>> | Is it possible to have more then one IP adress on the same NIC ?
>>
>> man ifconfig. look for 'alias'.
In article <370D7B5A...@yugosucks.com>,
phenom <we...@yugosucks.com> wrote:
>Yes ifconfig is the tool, you will need to also run an arp statement as
>well so that two mac addresses can co-exist on the server at the same
>time. Otherwise you will keep getting Arp table overwritten errors.
Hmmm? He wants two IP addresses on the *same* NIC. That's one mac address.
John
--
John DuBois spc...@armory.com. KC6QKZ http://www.armory.com./~spcecdt/
Evan Hunt
Don't blame me, I voted for spc...@deeptht.armory.com. (John DuBois).
>>> man ifconfig. look for 'alias'.
>
>>well so that two mac addresses can co-exist on the server at the same
>>time. Otherwise you will keep getting Arp table overwritten errors.
>
>Hmmm? He wants two IP addresses on the *same* NIC. That's one mac address.
That's true; the reason given for running arp was incorrect... but
actually, it may still be necessary to run arp.
Suppose you're on a class C network, 1.2.3.xxx. Your system is named
1.2.3.4, and you want it to respond to another IP address as well.
If the new IP address is *also* going to be on the 1.2.3 subnet--
say 1.2.3.5--then you need to run arp to publish another IP address
for your existing mac address. However, if the new IP address is a
whole different set of numbers (say, 4.3.2.1), then you don't
need to run arp (but your router does need to know how to route
to that address, of course).
I don't know if that made any sense at all.
Fortunately, on 5.0.4 and 5.0.5, there's a handy-dandy little tool
that can save you from having to understand any of this. It's called
ipal, and all you have to do is type "/usr/internet/etc/ipal <ip address>"
and it will run ifconfig and (if necessary) arp *for* you. Later,
if you want to delete the alias, run "ipal -d <ip address>".
The -f flag tells it to handle a list of IP addresses taken from
standard input, one to a line. The -n flag tells it to print out the
commands it would normally have executed, without actually executing
them.
--
Evan Hunt - evanh at sco dot com
"The only thing better than normal, everyday spam is spam from the Lord."
- Jason Abbott
Jean-Pierre Radley
Could you go the extra kilometer, Evan, and spread around a man page for
ipal? :-)
John DuBois
>
>Don't blame me, I voted for spc...@deeptht.armory.com. (John DuBois).
>>Hmmm? He wants two IP addresses on the *same* NIC. That's one mac address.
>
>That's true; the reason given for running arp was incorrect... but
>actually, it may still be necessary to run arp.
>
>Suppose you're on a class C network, 1.2.3.xxx. Your system is named
>1.2.3.4, and you want it to respond to another IP address as well.
>
>If the new IP address is *also* going to be on the 1.2.3 subnet--
>say 1.2.3.5--then you need to run arp to publish another IP address
>for your existing mac address.
My understanding has always been that you only need to run arp if you want to
publish an IP address that *isn't* an address for an interface.
ifconfig -alias binds an IP address to an interface in such a way that it *is*
an address for the interface, so modification of the arp table with arp(ADMN)
isn't neccessary.
That understanding is borne out by my experience with IP aliases; I have a half
dozen IP aliases for addresses in the same class C network on my 5.0.0 system,
and have never done anything other than 'ifconfig alias' to establish them.
The other systems on the thinnet as well as the DSL router (and the ISDN bridge
that preceded it) have had no problem seeing all of the IP addresses.