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cisco switch - switchport port-security maximum 2 - query

hi ive configured the following:

master dc/ad/dns/dhcp/gpmc (domain server):

int fa0/4
switchport mode access
switchport port-securty
switchport port-security maximum 2

if i do: sh port-security int fa0/4 - it shows me the mac address of the above server

host xp pc:

int fa0/8
switchport mode access
switchport port-security

if i do: sh port-security int fa0/6 - it shows me the mac address for host xp pc

qns1.  i thought as i have set on 'int fa0/4 with a dhcp server' ie the maximum 2 that this would detect the host xp pc, but it appears not so im wondering how this function works ?
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mikey250
Asked:
mikey250
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2 Solutions
 
Ernie BeekCommented:
when you set a maximum on a switchport it only allows that many mac addresses through it. And this is configured on a per port base.
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mikey250Author Commented:
hi yes i understand that part!! :)

qns1. so presumably only if a physical user unplugged the cable or some how took over that part would this 'command above' initialize ?

qns2.  i also assume that because int fa0/4 has a dhcp connected that it would stop more than 2 mac addresses although it appears not ?
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Ernie BeekCommented:
@qns1: If I understand correctly, not quite. In its most basic form, the Port Security feature remembers the Ethernet MAC address connected to the switch port and allows only that MAC address to communicate on that port. With switchport port-security maximum 2 it remembers (a maximum of) 2 MAC addresses.
Have a look at: http://www.techrepublic.com/article/lock-down-cisco-switch-port-security/6123047

@qns2: Also, not quite ;) If the DHCP server is the only machine connected to that port, there's only one MAC address on that port (because the DHCP clients are somewhere else) so nothing is blocked.
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mikey250Author Commented:
hi ernie,  thanks for that clarification!! :)
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mikey250Author Commented:
sound advice!!! appreciated.
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Ernie BeekCommented:
My pleasure :)
Thx 4 the points.
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