Solved: Secondary IP addressing

rj.remien · ‎11-18-2002

Is adding a second IP address to a router with only one ethernet interface the best solution when more IP addresses are needed on a LAN and the other subnet being used has had all the IP addresses exhausted? Will there be a performance issue if I add 12 more hosts from a different subnet on the same switch where there are 35 other hosts from another subnet within the same VLAN? I cannot use subinterfaces and ISL trunking since the ethernet interface is not a fastethernet interface.

Thanks,

RJ

thisisshanky · ‎11-18-2002

Since you dont have a fast ethernet interface, the only option you have is to use secondary ip addresses.

Adding 1 more subnet to the router ethernet interface as secondary shouldnt be a problem.

One thing to be noticed is that, the bandwidth of the link between the switch and the router will be shared with 12 more additional hosts, during communication between the 2 subnets. ( this case arises when all hosts are communicating simult., which is less likely).

Obviously there is a small percentage of load on the router, because it has to route more packets, not only to the wan, but also between the subnets.

Sankar Nair
UC Solutions Architect
Pacific Northwest | CDW
CCIE Collaboration #17135 Emeritus

View solution in original post

thisisshanky · ‎11-18-2002

Since you dont have a fast ethernet interface, the only option you have is to use secondary ip addresses.

Adding 1 more subnet to the router ethernet interface as secondary shouldnt be a problem.

One thing to be noticed is that, the bandwidth of the link between the switch and the router will be shared with 12 more additional hosts, during communication between the 2 subnets. ( this case arises when all hosts are communicating simult., which is less likely).

Obviously there is a small percentage of load on the router, because it has to route more packets, not only to the wan, but also between the subnets.

Sankar Nair
UC Solutions Architect
Pacific Northwest | CDW
CCIE Collaboration #17135 Emeritus

rj.remien · ‎11-19-2002

Once again, thanks for your insight.

RJ

jeffrey.zhou · ‎11-20-2002

In some higher IOS version, you can configure the ethernet to trunk dot1q. I ever test the configuration, and it work well.