Multiple destination SPAN configuration

[Mike Bailey]

According to the following:

http://www.cisco.com/en/US/products/hw/switches/ps708/products_tech_note09186a008015c612.shtml#topic5

"Only one destination port is allowed per SPAN session"

however on both 2960 switch running 12.2 and 3560 switch running 15.0 I've managed to create a monitor session with two destination ports which appears to work:

2960-24-TT-L

3560-48PS

Is the documentation incorrect or is there something I should be careful of with the above configurations?

[John Blakley]

Mike,

I believe what they mean is that you can use multiple destinations for a single span session. As in your example above, you wouldn't be able to use port 21 for session 2. I can't see a problem with the configuration..

HTH,

John

[silverstr8p]

On my Cisco 4506 my source from multiple ports worked like:

#monitor session 1 source interface GigabitEthernet 2/2 - 8

but when I tried for multiple destinations it errored like:

#monitor session 1 destination interface GigabitEthernet 2/41 - 48

monitor session 1 destination interface GigabitEthernet 2/41 - 48
                                                                                                ^
% Invalid input detected at '^' marker.

I also tried

#monitor session 1 destination interface GigabitEthernet 2/41 ,  2/48

and it errored out as well. It worked when I did:

#monitor session 1 destination interface GigabitEthernet 2/48

And I can see packets on G2/48 like I should. I don't have any CAT6 cables plugged into G2/41-47, is that causing problems since some of the dest interfaces are down? What am I doing wrong?

[smehrnia]

Hi,

the Document is correct Mike, one destination PER SPAN, when you change the number after monitor session (1,2,3,4...) you change ur span session, and it could have a different set of port(s).

HTH,

plz Rate if it Helped,

Soroush.

[John Blakley · Accepted solution]

Soroush,

I don't believe the documentation is correct for this platform. I have a 3750 and I can submit a range of ports as well and they work fine. On older switches, the range wasn't an option and you could only specify 1 destination port. On my 3750 which is running 12.2, it does support a range which allows you to specify more than one port to use for a destination.

Here's documentation for the 2960 that also describes using the range in the destination:

http://www.cisco.com/en/US/customer/docs/switches/lan/catalyst2960/software/release/12.2_55_se/configuration/guide/swspan.html#wp1036829

Step 4

monitor session session_number destination {interface interface-id [, | -] [encapsulation {dot1q | replicate}]}

Specify the SPAN session and the destination port (monitoring port). For session_number, specify the session number entered in step 3. Note For local SPAN, you must use the same session number for the source and destination interfaces. For interface-id, specify the destination  port. The destination interface must be a physical port; it cannot be an  EtherChannel, and it cannot be a VLAN. (Optional) [, | -] Specify a series or range of interfaces. Enter a space before and after the comma; enter a space before and after the hyphen. (Optional) Enter encapsulation dot1q to specify that the destination interface uses the IEEE 802.1Q encapsulation method. (Optional) Enter encapsulation replicate to specify  that the destination interface replicates the source interface  encapsulation method. If not selected, the default is to send packets in  native form (untagged). Note You can use monitor session session_number destination command multiple times to configure multiple destination ports.

HTH,

John

[smehrnia]

John, reading form the document Mike posted, it says:

"Only one destination port is allowed per SPAN session, and the same port cannot be a destination port for multiple SPAN sessions. Therefore, you cannot have two SPAN sessions that use the same destination port."

i think, its more of writing issue, they wanted to point out that you can not use a same destination for two span session, not that you can only use ONE port at a same time.

or am i wrong?!  i just woke up neway lol

HTH,

Soroush.

[Mike Bailey]

Sorry for not replying sooner, tied up with various major projects.

Thanks all for the feedback, indeed I think the documentation is out of date, the configuration works perfectly for what I wanted to achieve (take the output from a bunch of port provided by supplier and present it to 3 different devices)

Thanks again

[ajit.shinde]

Hi Mike,

I configured SPAN ports today on one of our production switch (Cisco 2960) and was able to configure multiple destinations on it.

monitor session 1 source interface Gi0/4

monitor session 1 destination interface Gi0/10 , Gi0/22

and this worked perfectly fine.

Thanks

Ajit