1

I need to create a vlan on a dell switch. I'm brand new to vlans, and have a few simple questions.

  1. I have the MAC addresses for devices that are plugged into the switch, how can I figure out which devices map to which ports? From what I've seen 'show bridge address-list' should give the results, though some ip-addresses don't seem to be listed, so I was wondering if a) the MAC addresses I have would be incorrect b) there's another way to find the port-mac mapping.

  2. I have created the vlan, assigned the switch an IP address on it, and added a port I believe to refer to a device (let's call it device 1). Device 1 is not able to ping the switches ip, or vice versa, would could be the cause of this? (This could go back to question 1, that I have in fact added the wrong port.)

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Ethernet VLANs do nothing more than "partition" switches such that they act like multiple switches, with separate broadcast domains for each VLAN. (That is, broadcast traffic from one VLAN doesn't appear in another.)

If you're planning on doing port-based VLANs (that is, port X will be a member of VLAN 2, port Y will be a member of VLAN 3, etc) and you're looking to "map" the devices plugged-into the switch ports you can do that a few different ways. You're not going to see IP addresses in the show bridge address-list because you're asking the switch to give you its layer 2 adjacency / bridging table, which will only contain MAC addresses (and ports).

  • Obtain the MAC address from each device via OS mechanisms (ipconfig /all on Windows, ifconfig on Linux, for example). Locate the device's MAC in the output of the show bridge address-list command that you've already discovered.

  • From a computer in the same IP subnet of the subject devices, PING each device and look-up the MAC address in your ARP table (using arp -a on Windows, for example). Locate the device's MAC in the show bridge address-list output.

  • Pull cables and see who complains.

Presumably you're using a layer 3 switch (one the Dell PowerConnect 6200-series, 7000-series, or 8000-series) if you're assigning multiple IP addresses to VLAN interfaces. There's a chance you're not, though, and it's probably worth talking about.

If you're using a layer 2 switch (like the other PowerConnect models that I didn't list above) then the switch isn't capable of routing traffic between VLANs. The switch can be assigned a management VLAN and and IP address within the subnet you use in that VLAN, but the switch won't act as a router moving traffic between VLANs. If you're using a layer 2 switch you should still be able to PING it from a test device. Assign the switch's management VLAN number to the VLAN assigned to the port where the test device is plugged-in, assign a management IP address to the switch, and assign the test device an IP address in the same subnet. (I will caution that some of the lowest-end Powerconnect switches-- the 2000-series, I believe, don't allow you to change the management VLAN away from 1. These switches are best installed in dumpsters.)

A layer 3 switch is capable of acting as a router, receiving traffic from one VLAN and routing it to another. (You can think of a layer 3 switch as a layer 2 switch with a router that has a flexible number of interfaces hidden inside it.) If you're using a layer 3 switch you'll need to assign an IP address to a the VLAN interface for the VLAN where your test device is plugged-in and assign your test device an IP address within the subnet you used for the VLAN interface.

In my experience, the kind of scenario you're describing, with the inability to PING a switch, is typically caused by not having the test device and the switch configured for the same subnet (and not having a router that can move traffic between the subnets).

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