When configuring SPAN , if I understand it involves just one switch . Correct ?


 (config)#monitor session 1 source interface fa0/20
(config)#monitor session 1 destination interface fa0/25

** in case  fa0/20 and fa0/25 are in separate VLANs, would the packets capturing work?

** I also would like to know when configuring RSPAN  to capture traffic from  source port or source Vlan  on Switch1 and Destination port or Vlan  on Switch 25, when there is a chain of switches between Swith1 and Switch 25, do we need to configure RSPAN on all 25 switches ?
How can this be configured ?

Thank you
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(config)#monitor session 1 source interface fa0/20
(config)#monitor session 1 destination interface fa0/25

** in case  fa0/20 and fa0/25 are in separate VLANs, would the packets capturing work?
Ports don't have to be in the same VLAN, in fact you can send traffic from a few ports in a different VLANs to destination port. On some devices you also need to have one free port (besides source and destination port) so SPAN can use its ASIC for copying traffic.
Link for Catalyst 4500 series.
SPAN mirrors traffic from one or more source interfaces on any VLAN or from one or more VLANs to a destination interface for analysis. In Figure 59-1, all traffic on Ethernet interface 5 (the source interface) is mirrored to Ethernet interface 10. A network analyzer on Ethernet interface 10 receives all network traffic from Ethernet interface 5 without being physically attached to it. For SPAN configuration, the source interfaces and the destination interface must be on the same switch.
SPAN does not affect the switching of network traffic on source interfaces; copies of the packets received or transmitted by the source interfaces are sent to the destination interface.
RSPAN only need to be created on source, destination, and all switches in between.
So, if you want to have ability to do port mirroring from your chair, that would mean - it needs to be configured on all switches.
Quote from the same link.
RSPAN extends SPAN by enabling remote monitoring of multiple switches across your network. The
traffic for each RSPAN session is carried over a user-specified RSPAN VLAN that is dedicated for that RSPAN session in all participating switches. The SPAN traffic from the sources is copied onto the RSPAN VLAN and then forwarded over trunk ports that are carrying the RSPAN VLAN to any RSPAN destination sessions monitoring the RSPAN VLAN, as shown in Figure 59-2.
jskfanAuthor Commented:
When configuring RSPAN, do I need to propagate the RSPAN VLAN to all the downstream switches:

on Source Switch:
vlan 999
  monitor session 1 source interface FastEthernet 0/14
  monitor session 1 destination remote vlan 999

On Destination Switch
monitor session 1 source remote vlan 999
monitor session  1 destination interface FastEthernet0/30

Dow does Vlan 999 get propagated from Source to Destination switches as well as the downstream switches? do we need VTP in this case? and on each Trunk allow VLAN 999 (which I think by default all vlans are allowed)

It sounds like a project if you have not created RSPAN Vlan since the beginning of Network set up.
You can use VTP, or create VLAN manually. I never use VTP, so... I would SSH into every switch and paste already created part of config to each switch, check is VLAN 999 added to trunks and if needed I would add VLAN 999 to trunks. The worst part is documentation update.

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jskfanAuthor Commented:
Thank you
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