Do Small Home Switch Port's have separate Mac Addresses?
-
Do small home switches like the Netgear ProSafe 5 Port Gigabit GS105 have Mac Addresses for Each physical port? If so how would you find out what they are?
What does the Managed switch see when there are several devices with NICs connected through a (dumb) switch such as these?
It was mentioned on an early CCENT episode or a Network Plus episode but I could not remember were it was. I think it was mentioned as a gotcha when doing a #show mac address-table
Feel free to point me to the episode that it was covered in. When tried to look it up online there was too many differing answers.
Thanks!
-
Do small home switches like the Netgear ProSafe 5 Port Gigabit GS105 have Mac Addresses for Each physical port? If so how would you find out what they are?
Not normally. Switches only have MAC addresses if they are managed switches, otherwise they are transparent to the network. If the switch is a normal layer 2 switch, it will usually just have one MAC address for the virtual management port. If the switch is a layer 3 switch (or layer 3 capable) then it will have a MAC address for each individual port as any one of them could be converted in to routed ports. The switches we use in the show are all layer 3 switches so they have MACs for every port.
What does the Managed switch see when there are several devices with NICs connected through a (dumb) switch such as these?
The dumb switch is basically invisible, so the managed switch would just see multiple MAC addresses on one port. Here's an example:
`Switch#show mac add Unicast Entries vlan mac address type protocols port -------+---------------+--------+---------------------+-------------------- 10 0004.f204.1a4e dynamic ip GigabitEthernet2/42 10 0004.f204.1a6e dynamic ip GigabitEthernet2/43 10 0015.179f.a4dc dynamic ip GigabitEthernet2/44 10 0015.179f.a4dc dynamic ip GigabitEthernet2/44 10 2286.87d1.1a0f dynamic ip,other GigabitEthernet2/44 10 2e54.5c3d.b361 dynamic ip,other GigabitEthernet2/44 10 6210.012b.2f61 dynamic ip,other GigabitEthernet2/44 10 b246.f107.1b9b dynamic ip,other GigabitEthernet2/44`
Hope that helps,
Don -
Don,
Thanks so much for the detailed explanation and the practical example. I'll be using it in the field. We discovered a wing of our building's ethernet drops had been mislabeled by a contractor after a renovation project. I actually think they made up the labels after they plugged everything straight it to switches without a punch down panel. Sloppy. This is really helpful for making it right!
Thanks,
Mike
