Why in this diagram, the switch sees 5 devices instead of 4

[mohamadnaameh]

I try to make the example 5-8 in chapter 5 : Analyzing Ethernet LAN Switching but the (Why in this diagram the switch sees 5 devices instead of 4) any one can help in that

[ammahend]

one of the mac address is of switch 1 interface connecting to switch 0, do a show interface <interface-name> of switch 1 and compare the mac address with what you are seeing on switch 0

[mohamadnaameh]

this is the switch 1 interface

[ammahend]

share output for "show interface f0/4"

[mohamadnaameh]

output for "interface f0/4"

[ammahend]

so if you see the bia address on interface, thats what you are seeing on switch 0 mac table

[mohamadnaameh]

it's normal or I made a mistake ?

[ammahend · Accepted solution]

Its normal, you did not make a mistake.

[mohamadnaameh]

thanks for your support

[M02@rt37 · Accepted solution]

Hello @mohamadnaameh,

It is the Switch 1 interface MAC address. 

[Martin L]

I think the author of the book has simplified the output for the purpose of explanation/education.  It easier to show 4 PCs and their MACs in switch table rather then 4 of those  along with MACs of other switch.  The goal here -I think- is to learn how switch learns MACs and when it does;  Switches learn MACs when frames come thru and writes the Destination MAC of each frame with interface id and vlan id that such MAC came in. IF you see multiple MACs listed but they all have same interface x/y, such interfaces is a trunk interface. You can also use MAC address table on each switch to track MAC and end user device from source to destination.

What happens without any PCs connected or without any communication ?  does PT shows you 1 MAC per vlan 1?

Regards, ML
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[mohamadnaameh]

Thank you for this response. Yes one title appeared any PCs connected or without any communication