Two PPP connections to the same ISP with same remote gateway

[Tom Jobbins]

Hi,

I have a FreeBSD 6.0-STABLE server running as my internet gateway.  It 
was newly installed to 6.0-RELEASE yesterday, and built to -STABLE from 
a cvsup early this morning.

I have two separate accounts at the same broadband ISP, with two 
separate PPPoE modems on two separate phone lines.  I need to connect 
both of these simultaneously thus providing me with two PPP connections 
to the same ISP.

The problem I am having is that both connections have the same remote 
gateway, and FreeBSD is preventing me from setting the IP address on the 
second connection because its gateway is the same.

This can be demonstrated from the command line with the following:
[root at magrathea:~]$ ifconfig tun0 1.2.3.6 1.2.3.250
[root at magrathea:~]$ ifconfig tun1 1.2.3.7 1.2.3.250  
ifconfig: ioctl (SIOCAIFADDR): File exists

What is strange is that I was speaking to an op on the Efnet IRC channel 
#FreeBSDHelp who said he was able to execute the above two commands on 
his 6.0 machine without problems.  So I am confused as to why it won't 
work for me.  Perhaps there is some kernel or other configuration option 
he has set but I don't, which would make this work?

If anyone could tell me a way to get this working I would be most 
grateful.  Ultimately what I need to achieve is two simulatenous PPP 
connections to the same ISP using the same remote gateway.  Once these 
are established I will be using ipfilter to do source-IP routing, i.e. 
LAN machine 192.168.0.100 will be routed via tun0, 192.168.0.200 will be 
routed via tun1, etc.

Thanks in advance

Tom

PS.  Mulilink connections or any other method of combining the two PPP 
connections will not work for me - I need them to be separate and 
distinct, with their own IP addresses.  If I had realised there would be 
this problem then I would have chosen a different broadband ISP for the 
second connection - but now I'm stuck into a minimum contract so I need 
to get it working.