Vlan Interface on a 2691 router

Question

Hi,
I am trying to create an vlan interface on a 2691 router but can't do it. What switch module do I need and what code. Argh!! I've searcehed all over cisco but I can't find it. What am I mmissing??
Thanks,
Lee

Answer 1

Can you give us more information about what is it that you're trying to do?
Your IOS is the latest and greatest in the 12.3 line as of the date of this posting. And your Feature Set is Advanced Enterprise Services, which is the fullest Feature Set you can get. (The "Plus" capabilities were folded into Enterprise Services when Cisco reorganized the Feature Sets they offer.)
Going back to your original situation. I may have misunderstood exactly what you are trying to do.
RE: "I am trying to create an vlan interface on a 2691 router but can't do it."
If by this you mean you are tring to create an "interface Vlan2" or "interface Vlan10" or "interface Vlan18" like you can do on the Cisco Catalyst switches, and then put interface-specific commands underneath it, then I don't think you can. Even though you can enter "interface ?" and it shows Vlan as one of the options, it is my understanding that you do it as I outlined above in my previous post.
If you are going to carry multiple VLANs on a single router port connected to an 802.1Q trunking switch port, then if you need IPX capabilities on a particular sub-interface, just add the IPX network address and IPX frame/encapsulation type under the sub-interface.
If you're just trying to dedicate one router LAN port to act as a default gateway for a particular VLAN, then connect the router to a switch port that is defined as an access port for that VLAN. Assign the appropriate IP and IPX addressing under the router's LAN interface and you're done. No need for sub-interfaces, or bothering to configure the router with any Layer 2 VLAN information, except maybe a description assigned to the port that tells you what VLAN on the switch you're connecting it to.
RE: "What switch module do I need and what code."
If you're trying to host multiple 10/100 switching ports within the router, then you are looking for some version of Cisco's 16-port EtherSwitch Network Module. The model number NM-16ESW-something, where the "something" designates support for inline power or an optional Gigabit Ethernet interface. This should run on the code you have.
The NM-16ESW supports 802.1Q, according to the documentation. But I have never worked with one, so I couldn't tell you how the interfaces are numbered (Fa1/0 through Fa1/15?). Also, I have no idea how the router communicates with the switching network module internally: are there 16 separate FastEthernet ports now, each one configurable as the router's own LAN ports are? Or is there some common, internal backplane-type connection between the network module and the router's CPU, configured like a Gigabit Ethernet VLAN trunk port when you implement multiple access VLANs on the 10/100 ports?
Rather than use an NM-16ESW in a router to handle multiple VLANs, I would just use a Cisco Layer 3 switch if it were only for routing IP. 3550 or 3750 would be fine. But if you need IPX routing, then in Cisco's line you either need routers or chassis switches running Enterprise code. Other manufacturers support IPX and IP in a stackable size: Foundry, HP, and Extreme Networks, for example. In fact, Foundry and HP (who OEMs some product from Foundry) use a CLI very much like Cisco's. I've even seen HP switches show up as CDP neighbors to a Cisco router.
There are times to use routers and times to use Layer 3 switches. And times when you need both. It all depends on what you're doing, and what you're trying to do it with...