Port based static routing on Catalyst 2948G Switch

[annointed3]

Hi,

I have a Catalyst 2948G Layer 3 Switch configured as a switch here at work. Currently, there are several hubs plugged into the switch, that are connected to a test network. All machines on the test network are on the 192.168.10.1 - 192.168.10.254 network.

Let's say for example, that my hub (test network) is plugged into port 20 of the switch. I would like to change the network of my test machines to be 192.168.20.1-192.168.20.254. Is it possible for me to modify the routing table on the switch in some way to be able to route traffic between the 2 networks? Could I say something like, any traffic that comes in on port 20 destined for the other network be routed to the other network appropriately? If this is possible, what commands do I type in to do this? I have tried to implement vlans, and I've had several issues.

Thanks in advance.

[Georg Pauwen]

Hello,

not sure if I fully understand your question, but in order to route between those two networks, you need to configure VLAN interfaces with IP addresses from the respective ranges, which will be the default gateway for the clients. In your case, for your two networks, the VLAN interfaces could be:

interface VLAN10

ip address 192.168.10.1 255.255.255.0

interface VLAN20

ip address 192.168.20.1 255.255.255.0

Your clients would use these IP addresses as respective gateways.

Makes sure you globally configure ´ip routing´ on your L3 switch.

Does that make sense ?

Regards,

Georg

[3cayers]

As far as I know, without digging around Cisco's site, the 2948G is not a Layer-3 capable switch. If I remember correctly, 2900 series switches are strictly access-layer and the 3550 Enterprise is the first L3 capable.

You can find out by entering "ip routing" in the switch configuration. If this works, you will need to put port 20 in routing mode using the command "no switchport" and then give the port an IP address ("ip address 192.168.20.1 255.255.255.0")

If the switch truly does not support routing, you must use VLANs and an external router.

[annointed3]

Hi,

I'm fairly new to Cisco hardware, so please excuse any incorrect terminology that is use. Here is some background information on the Catalyst 2948G-L3 switch from Cisco's website:

It is important to consider the following information about the Catalyst 2948G-L3 switch:

From a configuration standpoint, the Catalyst 2948G-L3 is a router that runs Cisco IOS, and all interfaces are routed interfaces by default.

The Catalyst 2948G-L3 does not extend your VLANs. Rather, it terminates them on a routed interface unless bridging is configured. Bridging interfaces allows you to extend VLANs on the routed interfaces.

The Catalyst 2948G-L3 does not support several Layer 2-oriented protocols, such as VTP, DTP, and PAgP, found on other Catalyst switches.

Release 12.0(7)W5(15d) and earlier the Catalyst 2948G-L3 does not support the following:

Data-plane (security) Access-Control Lists (ACLs) on any interfaces (in other words, user data traffic cannot be restricted using input or output access lists on the router interfaces) -- ACLs on the Gigabit Ethernet interfaces are now supported in release 12.0(10)W5(18e).

Bridging on 802.1q subinterfaces -- Bridging on 802.1q subinterfaces is now supported in release 12.0(10)W5(18e).

AppleTalk routing.

Port snooping (also known as SPAN, port mirroring, promiscuous mode).

Because the Catalyst 2948G-L3 switch does not support bridging on IEEE 802.1q subinterfaces in IOS release 12.0(7)W5(15d), we cannot bridge a single IP subnet across VLAN 1 in this example (as we did on ISL subinterfaces in Example 2). Therefore, management for the Catalyst 2948G-L3 will be through any IP interface on the switch, while management for the Catalyst 2948G switches will be on one of the user VLAN subnets rather than on VLAN 1.

In general, putting the sc0 management interface in a user VLAN is not recommended. However, an exception is made in this example because the Catalyst 2948G-L3 does not support bridging on 802.1q subinterfaces in the IOS release used in this example, and because the user subnets are relatively small (no more than 126 host addresses per subnet).

The configurations in this document were implemented in an isolated lab environment. Ensure that you understand the potential impact of any configuration or command on your network before using it. The configurations on all devices were cleared with the clear config all and write erase commands to ensure that they have a default configuration.

The normal vlan commands do not work on this switch. I think that bridging group are actually considered the vlan. For example, if you create bridge group 1 (that would be vlan 1) and bridge group 2 (would be vlan 2). If this is correct, how do I route traffic between the 2 groups?

[robhorniachek]

Hello again...

I seemed to have picked up this thread in another forum, just thought I would post here so others can see what's going on...

On the Layer-3 version of the 2948G, they don't use VLANs. You have to configure bridge-groups, then assign the ports to the bridge groups. You can then configure IP addresses directly on the interface, and routing will occur. Here's a sample config:

conf t

bridge irb

ip routing

bridge 100 protocol ieee (creates 'vlan' 100)

interface FastEthernet 1

ip address 1.1.1.1 255.255.255.0

bridge-group 100

This example will create VLAN 100, assign FAS48 to that VLAN (bridge group), and enable routing.

Hope that helps...