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SPAN Questions

November 18th, 2019 Go to comments

Question 1

Explanation

We can add the “monitor session 1 filter vlan 10” command to limit monitored trafic from VLAN 10 only.

Question 2

Explanation

The network engineer is connecting to the Distribution switch but he wants to monitor an access switch -> remote SPAN must be used. An example of configuring remote SPAN which uses vlan 40 is shown below:

Access-Switch(config)# monitor session 1 source interface FastEthernet 0/1
Access-Switch(config)# monitor session 1 destination remote vlan 40
Distribution-Switch(config)#monitor session 2 source remote vlan 40
Distribution-Switch(config)# monitor session 2 destination interface FastEthernet 0/5

Question 3

Explanation

This command limits the monitored trafic on VLAN 1 to 8, 39, 52 only

Question 4

Explanation

From the output we see the status of gi0/12 is “monitoring”. It means this port is currently the destination of a SPAN session.

Question 5

Explanation

This is how to configure Remote SPAN (RSPAN) feature on two switches. Traffic on FastEthernet0/1 of Switch 1 will be sent to Fa0/10 of Switch2 via VLAN 40.

+ Configure on both switches
Switch1,2(config)#vlan 40
Switch1,2(config-vlan)#remote-span
+ Configure on Switch1
Switch1(config)# monitor session 1 source interface FastEthernet 0/1
Switch1(config)# monitor session 1 destination remote vlan 40
+ Configure on Switch2
Switch2(config)#monitor session 5 source remote vlan 40
Switch2(config)# monitor session 5 destination interface FastEthernet 0/10

So without the command “remote-span” on both switches, RSPAN cannot works properly.

Question 6

Explanation

The first command points out the source interface and the direction to be monitored, which is Gi0/4 and inbound traffic (rx) in this case. The second command tells our device to monitor only VLAN 3 running on Gi0/4 (notice that Gi0/4 is a trunk link). The last command requests monitored traffic to be sent to the destination port Gi0/5.

Question 7

Explanation

A source port can be monitored by some SPAN sessions but a destination port can be used for one session only. A destination port or a reflector port does not participate in STP while its SPAN session is active.

For more limitations of configuring SPAN please visit this link: http://www.cisco.com/c/en/us/td/docs/switches/datacenter/sw/5_x/nx-os/system_management/configuration/guide/sm_nx_os_cg/sm_14span.html#wp1239658

Question 8

Explanation

From the outputs we learn that the SPAN session 1 is incomplete because only source port is configured:

monitor session 1 source remote vlan 50

-> It needs to specify the destination port

while SPAN session 2 is configured correctly with source and destination ports:

monitor session 2 source interface fa0/14 (both)
monitor session 2 destination interface fa0/15

Question 9

Question 10

Question 11

Comments
  1. polarbear
    February 18th, 2020

    Q3
    We are filtering those VLANs aren’t we? Shoud it be NOT replicated?
    E. Traffic from VLANs 1 to 8, 39, and 52 is NOT replicated to the SPAN destination port?

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