Multiple ip addresses on a 2600 interface

[cro9uk]

Hi guys, new to cisco and my problem is this. at one of our sites there are 4 companies wanting internet access. they all have there own subnets (p2p) and i don't want to have the hassle of changing the ip address ranges on them all as i will then be called in at every small problem they have (these are seperate companies simply renting rooms). I thought about vlans but i am still left with only one interface on the router for their LAN. Can i configure multiple virtual ip addresses to the one interface?

[rsissons]

Yes, you can configure multiple IP addresses on an interface using the SECONDARY keyword. For example

int fast 1/0

ip address 10.1.1.1 255.255.255.0

ip address 10.1.2.1 255.255.255.0 secondary

but you might want to consider using VLANs and configuring the router interface as a trunk. The following URL has numerous examples of configuring trunking depending on what switch platform you are using.

http://www.cisco.com/cgi-bin/Support/browse/psp_view.pl?p=Technologies:Trunking&viewall=true

[cro9uk]

Thanks for the link (thats a lot of material!) so in a nutshell, i configure 4 vlans with ip addresses matching the ip address range of the clients. Then configure the ports on the switch that they are attached to to belong to their vlan. Then i configure the trunk ports on both the uplink from the switch and the router interface. is that right? (the switches are connected via fibre so i take it i configure all fiber interfaces on the switches as trunk ports) also, can these individual vlan ip addresses be completely different (vlan1 being 192.168.x.x vlan2 being 10.10.x.x and so on) to the router ethernet interface and still be routable to the outside world?

[Georg Pauwen]

Hello,

it is no problem if the IP addresses of your VLANs are completely different from each other, just configure the corresponding VLAN interface on the router and have the clients use that IP address as their default gateway. Then just add a static default route pointing to the interface connecting your router to the outside world, e.g.:

ip route 0.0.0.0 0.0.0.0 dialer1

Regards,

GP