Is Switches have MAC address

[shacharmarkovich]

Hey there,

my question is:

Is Switches have MAC address?

thanks

[Martin L]

yes, there is 1 main mac that is sort of base id which other macs are base on. other macs are for each interfaces and internal processes/

see and search topics in https://learningnetwork.cisco.com/content?filterID=all~objecttype~objecttype%5Bthread%5D&itemView=detail

[Joseph W. Doherty]

Depends first whether the switch is manageable or not. If not, it would not. If yes, it would if configured to support some kind of on-net access to the switch itself. If manageable, but not configured to support any on-net access to the switch itself, it may or may not have a MAC, but even if it does, without having it configured for some kind of on-net access, it might not be possible to "see" the switch's MAC. (BTW, I'm presuming you're only asking about a L2 switch.)

[Giuseppe Larosa]

Hello Joseph,

I think the real discriminator here is the support of any form of STP protocol.

STP protocol requires each port to use its own MAC address as source MAC address of STP BPDUs sent out of the port.

In addition to MAC addresses used by ports and by port-channels there are MAC addresses used to build the STP Bridge ID.

In modern IOS switch a single MAC address is enough thanks to the use of extended system id as the STP two bytes priority is built as base priority + Vlan-id

And base priority must be a multiple of 4096 0, 4096, 8192 and so on.

Even an unmanaged switch running 802.1D classic STP needs to use MAC addresses as explained above.

The port specific MAC addresses are used in Cisco switches also for other L2 signaling protocols like CDP or LLDP and LLDP MED.

What a L2 switch cannot do is to change a user frame, because it needs to act as a transparent bridge.

Hope to help

Giuseppe

[Joseph W. Doherty]

Giuseppe, good point about STP! I would agree such a switch would/should have a MAC.

However, do you know of an actual L2 switch, that is (totally) unmanagable (i.e. cannot be configured in any manner) that runs STP? (BTW, I just Googled for one, didn't find one, but did find a previous article on these forums where you touched on this before. You've actually have encountered such a switch?)

Assuming though the L2 switch is completely dumb/transparent, you agree the switch would not have a MAC?

[Martin L]

every switch has MACs assigned to device.

[Joseph W. Doherty]

How would you verify that with a "dumb" (e.g. 4 or 8 port consumer grade L2 switch)? Switch cannot be pinged. Switch cannot be on-net (or console) managed or accessed. Switch likely doesn't support STP.

Could you please provide an example?

[balaji.bandi]

yes they do have unique MAC address each device.