Accessing computers from different subnets with Dell Layer 2 switches possible?

Question

I have two separate networks, a 192.168.20.x and a 192.168.80.x each on their own Dell X1026 Switch in Layer 2 mode. I would like the ability to access shares, ping, etc from computers on the .20.x network to computers on the .80.x network. I have one network cable run from the .20.x switch to the .80.x switch currently and have them both setup with a subnet of 255.255.0.0 and I can see the other computers, I just can't access shares or ping anything. Each computer currently has the gateway set to the IP for its respective switch (192.168.20.1 and 192.168.80.1).

Is this feasible with the hardware that I have on hand? The Dell switches support VLANs and I can configure each port in the VLAN to Layer 2 or Layer 3.

Answer 1

You are in a very early stage in network knowledge ;).

Basicly, you need "someone" who make the L3 routing between these two networks. This someone can be the switch working in L3 mode. As far as I can remember, the X1000 series come in unmanaged mode and you need to do some trick with the front button to transform it in managed mode (and gain ability to create vlans an so on).

Ok, i'll try to summarize it the actions needed and the command associated.

• Create a VLAN 20 with IP address 192.168.20.1/24. This will be the gateway for first network.

interface vlan 20

ip address 192.168.20.1 255.255.255.0

• Idem with VLAN 80

interface vlan 80

ip address 192.168.80.1 255.255.255.0

• Assign ports for each of the vlan. The hosts in the 192.168.20.X should be assigned to VLAN 20 and same por VLAN 80.

interface g1/0/1 (port where the host is attached)

switchport access vlan 20 (or vlan 80)

That's all! Now you are able to communicate a host in the VLAN 20 with a host in the VLAN 80 (assuming you have set up correct ip, mask and gateway on the hosts).

Have fun playing with your enviroment.

Answer 2

When you connect two different layer-2 segments each on its own switch they become one. As you've found out, layer-2 connectivity is not the same as layer-3 connectivity required for ping, SMB, ...

Depending on your actual goal you've got several options.

1. Renumber one side's node to create a common L3 subnet.
2. Merge - decrease the netmask length so that the "supernet" encompasses all nodes (192.168.0.0/17 or shorter). Note that all nodes have to be updated to the shorter prefix length in order to talk to the formerly other subnet.
3. Route - Remove the interswitch link, install a router in between the switches and direct the nodes to route through it. You can either use a static route on each node or simply set the default gateway to the in-between router (note that the router needs to provide Internet access if its the default gateway). The router can be external to the switches or an L3 switch with VLANs set up.

VLANs on L2 switches are not exactly of much use here unless you want to keep the segments separate and conect your nodes to an arbitrary segment on both switches.

You've probably noticed that there's quite a bit of work when everything is set up statically. It might be a good idea to set up a DHCP server to get central address management.