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the last digit of switch's base Ethernet MAC address changed in advertisements.

ssreejesh
Level 1
Level 1

Ive got a 3760 switch connecting via it's fa1/0/1 to a 3560 switch connecting on its fa 0/1.

the Base Ethernet MAC Address of my L3S1-3760 is    : 00:13:1A:E8:DC:00

and  Base Ethernet MAC Address of my L3S2-3650 is  : 00:1B:2B:E5:14:80

However in the mac tables the last digit of the neighboring switch's mac address is changed from a '0' to a '3'

 

L3S2-3560#sh dtp int fa 0/1 

DTP information for FastEthernet0/1: 

  TOS/TAS/TNS:                              TRUNK/AUTO/TRUNK 

  TOT/TAT/TNT:                              802.1Q/NEGOTIATE/802.1Q 

  Neighbor address 1:                       00131AE8DC03 
 

fyi: output trancated 

 

L3S1-3760#sh dtp int fa 1/0/1 

DTP information for FastEthernet1/0/1: 

  TOS/TAS/TNS:                              TRUNK/ON/TRUNK 

  TOT/TAT/TNT:                              802.1Q/802.1Q/802.1Q 

  Neighbor address 1:                       001B2BE51483 

 

fyi: output truncated 

  

L3S1-3760#sh mac- 

          Mac Address Table 

------------------------------------------- 

 
 

Vlan    Mac Address       Type        Ports 

----    -----------       --------    ----- 

    1    001b.2be5.1483    DYNAMIC     Fa1/0/1 

 

refer picture attached:

The Switch on the left, L3S1-3760 learns the MAC-address of the switch on the right as 001b.2be5.1483 

Via the interface fa 1/0/1 from incoming frames sent by the switch on the right L3S2.

the base Ethernet MAC address of L3S2 is  001b.2be5.1480. 

It however advertises its address as 001b.2be5.1483. The Last digit of the MAC address is changed from a

‘0’ to a ‘3’.

Both switches seem to have changed the last digit of their base mac address in their neighbor advertisements.

Why is that? Does DTP or some other protocol replace the last digit of the switch’s base MAC address with a code of some sort?

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