RE: SPAN Ingress

From: Huan Pham (Huan.Pham@peopletelecom.com.au)
Date: Tue Dec 16 2008 - 22:00:36 ARST


Hi Nick,

My understanding is that, when traffic already arrives on that port, it
is too late to tag it.

With your given command, the switch will treat any incoming UNTAGGED
packets as VLAN146 traffic. The IOS online help is quite clear on this:

Rack1SW1(config)#monitor session 1 destination interface fa0/24 ingress
?
  dot1q ingress forwarding using dot1q encapsulation
  isl ingress forwarding using isl encapsulation
  untagged ingress forwarding using untagged encapsulation
  vlan Set default VLAN for untagged ingress traffic

Rack1SW1(config)#$sion 1 destination interface fa0/24 ingress dot1q vlan
?
  <1-4094> Default VLAN for untagged ingress traffic

If you have another trunk to other switch, untagged traffic coming to
Fa0/24 when being forwarded to the other switch will have VLAN146 tag
(unless the trunk has Dot1Q encapsultion and native VLAN is 146).

On the other hand, if it is forwarded to another VLAN 146 access port,
there will be no tagging at all.

Regards,

Huan

 

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Nick
Sent: Wednesday, 17 December 2008 9:34 AM
To: Cisco certification
Subject: SPAN Ingress

Can anyone help me understand the following command:

monitor session 1 destination interface fa0/24 ingress vlan 146

Is this saying that as well as being the destination for SPAN session 1,
any packets coming into port f0/24 will be tagged with vlan 146?

Thanks

--
---

Nick

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