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span port issue

here is the base info:

Session 1


Type : Local Session

Source VLANs :

Both : 2-3,104-107,110-111

Destination Ports : Gi1/0/5,Gi2/0/5,Gi2/0/15

Encapsulation : Native

Ingress : Disabled

Cisco IOS Software, C3750 Software (C3750-IPSERVICES-M), Version 12.2(25)SEB4, RELEASE SOFTWARE (fc1)

Copyright (c) 1986-2005 by Cisco Systems, Inc.

Compiled Tue 30-Aug-05 15:47 by yenanh

ROM: Bootstrap program is C3750 boot loader

BOOTLDR: C3750 Boot Loader (C3750-HBOOT-M) Version 12.2(25r)SEC, RELEASE SOFTWARE (fc4)

I added port g2/0/15 to the above session. port g1/0/5 stop working, no output data showed up under sho interf.

but g2/0/5 & 15 were working fine.

removed g1/0/5 and re-added it!

now data goes to it?

I deleted


Re: span port issue

I think the ability to see the 802.1Q-tagged frames is important only when the SPAN source port is a trunk port. With Cisco IOS Software Release 12.1(11)EA1 and later, you can enable and disable tagging of the packets at the SPAN destination port. Issue the monitor session session_number destination interface interface_id encapsulation dot1q command in order to enable encapsulation of the packets at the destination port. If you do not specify the encapsulation keyword, the packets are sent untagged, which is the default in Cisco IOS Software Release 12.1(11)EA1 and later.

The are guidelines for the configuration of the SPAN feature on the Catalyst 3750 Series Switches is provided in following URL please click it :

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