Re: [WinMac] 2 IP addresses on Mac

Shawn Protsman(protsman[at]christianliving.net)
Sun, 28 Feb 1999 22:13:27 -0800

At 11:25 AM -0500, 2/28/99, thus spake Tim Scoff:
> > My client has 3 G3's and one 8600 all running OS 8.1 on a 100 BASE T
> > network attached to an NT 4sp3 server.
> > They use TCP/IP to attach to the server via DAVE.
> > They all have their own modems to dial the internet.
> > When the want to dial the internet they have to select another IP
> > configuration from the TCP/IP control panel. They find this too
> > cumbersome.
> > I was wondering if there was a simple inexpensive way to simplify this.
> > i.e. 2 active IP addresses on the Mac at the same time.
> >
> > Thanx in advance.
>
> Open Transport 2.0 supposedly supports what you are asking
> for. Unfortunately I can't find how to implement the Multi-homing
> feature anywhere in Apple's documentation, just a note that it is
> possible.
> Tim Scoff, MCSE
> casper@nb.net

Hi Tim,

This is from Apple's Tech Info Library #58138

http://til.info.apple.com/techinfo.nsf/artnum/n58138

Single Link Multi-homing System Setup

Open Transport 1.3 introduced Single Link Multi-homing, a mechanism by
which Open Transport can support multiple IP addresses on the same hardware
interface. Synonyms for this feature include IP Aliasing, Secondary IP
address Support, IP Masquerading, "Multihoming", IP Multinode support. This
is useful for sites like Internet Service Providers (ISPs), that want to
give each of their clients a distinct IP address, without requiring
separate computers for each address. Web server software packages, or
server plug-ins that utilize this feature can offer virtual domain support
that supports all web browsers. You will need to contact your application
developer to see if they are supporting this new feature of Open Transport.
This feature is only available with Open Transport 1.3 and later.

You configure a system to use multiple IP addresses as follows:

1. The TCP/IP Control Panel must be set for manual addressing.

2. You create a text file with the required name "IP Secondary Addresses"
and put it into the Preferences folder in the System Folder.

Each line of the IP Secondary Addresses file contains a secondary IP
address to be used by the system, and an optional subnet mask and router
address for the secondary IP address. If there is no subnet mask entry,
then a default subnet mask for the IP address class will be used. If there
is no router address entry, then the default router associated with the
primary address will be used.

Each secondary address entry must be prefixed by "ip=". Each subnet mask
entry must be prefixed by "sm=". Each router address entry must be prefixed
by "rt=". Lines proceeded by a ; are ignored.
An example of the contents of the IP Secondary Addresses file follows.

; 'ip=' for ip address, 'sm=' subnet mask, 'rt=' router address

; Note: no space in 'ip=192.168.22.200'

;

; IP address Subnet Mask router addresses

;----------- ----------- ----------------

ip=192.168.22.200 sm=255.255.255.0 rt=192.168.20.1

ip=192.168.22.201 rt=192.168.20.1

ip=192.168.22.202

The order of the entries is important. The "rt=" entry must follow the
"sm=" entry if used.

When Open Transport activates TCP/IP, the primary address will be obtained
from the TCP/IP Control Panel setting. Open Transport then looks for the IP
Secondary Addresses file in the Preferences folder to determine if
additional addresses should also be configured. If there are duplicate IP
address entries in the IP Secondary Addresses file, the duplicate addresses
will be ignored. When Open Transport binds a TCP/IP connection, if there is
an address conflict with either the primary or any secondary addresses with
another host, Open Transport will present an error message using a dialog
box and unload Open Transport/TCP from memory. The error dialog will
display the conflicting IP address, the hardware address of the conflicting
machine and note that your TCP/IP network interface has been shut down.

To resolve the conflict, quit all of the TCP/IP applications on both
conflicting machines, reconfigure TCP/IP on one of the machines so there is
no longer an address conflict, then relaunch your TCP/IP applications.

--------------------------------------------------------------------------------
----

Also check out artice 20378 for additional info regarding multihoming and
multinode setups.

http://til.info.apple.com/techinfo.nsf/artnum/n20378
Semper Fidelius,

Shawn
mailto:protsman@christianliving.net

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