Host Mac address in multiple switches CAM table

Host Mac address in multiple switches CAM table

I would like to know if a MAC address of a computer or Router that is connected to Switch1 will be also found in CAM table of Switch2 , Switch3 ,etc... assuming all switches are connected to each other.

Thank you
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David Johnson, CDCommented:
Yes but only if there has been communication. It will not be the same on each switch

computer 1 | switch1-port 1 | switch 2-port20 | computer 2

switch 1 will have computer 1 and switch 2 mac address
switch 2 will have switch 1 and computer 2 mac address

switch 1 will not have computer 2 mac address it will use switch 2 mac adddress
Les MooreSr. Systems EngineerCommented:
Yes, the mac addresses are maintained throughout the  network all the way to the router that holds the arp cache.
nociSoftware EngineerCommented:


    switch 1 will have the computer2 macaddress  with reference/forwarding port = port48 (where it was seen from)
    switch 2 will have the computer2 macaddress with reference/forwarding port = port20

    switch 1 will see computer1 on port1 and
    switch 2 will see computer1 on port24.
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jskfanAuthor Commented:
Thank you Guys..

For the Mac Address of a host1 in  CAM table of SwitchA to exist  in CAM Table of SwitchN ,  does this happen automatically the first time Host1 is plugged to a port on SwitchA,  OR Host1 at somepoint needs to communicate with another Host on SwitchN  in order to have SwitchN register the Mac address of Host1
nociSoftware EngineerCommented:
A switch records the source MAC address  together with the interface (incl VLAN if applicable) when a packet is received.
So only when a host sends a packet. this is done.  And it expires (just forgets about it) the entry after some time (a minute or so).

When  a packet is to be sent to a host that is NOT in the CAM table then it will be broadcast to all interfaces.
(This is why Microsoft clusters can work as they do, the nodes never send packets with the actual source address of the cluster alias).
So the packets go everywhere the switch can send them. (within the (V)LAN.

There is no "registration procedure"  other than sending packets if you need to.

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jskfanAuthor Commented:
Thank you
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