Routers with multiple links

Routers with multiple links
This is a perfectly workable solution for small networks, but it does not scale well when you
have more than a few VLANs. It depends on the type of router you have. For every VLAN, you
need to have a router interface (typically FastEthernet or Gigabit Ethernet), so a larger, more
expensive router can have more interfaces without being saturated. But sooner rather than later,
you will run out of physical interfaces.
The more VLANs you have, the more router interfaces you have to purchase with the router.
Also, you should have a fast router such as a high-end (at least a 4700 or 7200 series) router that
can route quickly so the router does not become a bottleneck. Cost then becomes the issue with
multiple links, and the possible requirement for multiple or redundant route processors doubles
the cost.

Using Legacy Equipment
Using multiple links is not a desirable thing to do in most cases, but there are times when it
might be the only solution. The alternate solutions—using a trunk, for example—require Fast
Ethernet at the least. Trunks do not run over 10Mbits/second Ethernet. So if you have some
routers with only slower Ethernet interfaces, such as the obsolete 2500 series, then you would
be able to effect inter-VLAN routing with one of those—albeit quite slowly.