у меня чуть по другому
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monitor session 1 source vlan 956 rx
monitor session 1 destination interface Gi2/48
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interface GigabitEthernet2/48
description SPAN PORT
no ip address
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со switchport не работает
Cisco IOS Software, s72033_rp Software (s72033_rp-ADVENTERPRISEK9_WAN-M), Version 12.2(33)SXI6, RELEASE SOFTWARE (fc4)