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SPAN Questions

January 28th, 2021 Go to comments

Question 1

Explanation

SW1 has been configured with the following commands:

SW1(config)#monitor session 1 source remote vlan 50
SW1(config)#monitor session 2 source interface fa0/14
SW1(config)#monitor session 2 destination interface fa0/15

The session 1 on SW1 was configured for Remote SPAN (RSPAN) while session 2 was configured for local SPAN. For RSPAN we need to configure the destination port to complete the configuration.

Note: In fact we cannot create such a session like session 1 because if we only configure “Source RSPAN VLAN 50” (with the command “monitor session 1 source remote vlan 50”) then we will receive a “Type: Remote Source Session” (not “Remote Destination Session”).

Question 2

Explanation

RSPAN consists of at least one RSPAN source session, an RSPAN VLAN, and at least one RSPAN destination session. You separately configure RSPAN source sessions and RSPAN destination sessions on different network devices. To configure an RSPAN source session on a device, you associate a set of source ports or source VLANs with an RSPAN VLAN.

Traffic monitoring in a SPAN session has these restrictions:
+ Sources can be ports or VLANs, but you cannot mix source ports and source VLANs in the same session.

Reference: https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750x_3560x/software/release/12-2_55_se/configuration/guide/3750xscg/swspan.html

Therefore in this question, we cannot configure a source VLAN because we configured source ports for RSPAN session 1 already.

Question 3

Question 4

Question 5

Explanation

Encapsulated remote SPAN (ERSPAN): encapsulated Remote SPAN (ERSPAN), as the name says, brings generic routing encapsulation (GRE) for all captured traffic and allows it to be extended across Layer 3 domains.

Question 6

Explanation

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 -> This VLAN can be considered a special VLAN type -> Answer C is correct.

Reference: https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750x_3560x/software/release/12-2_55_se/configuration/guide/3750xscg/swspan.html

We can configure multiple RSPAN sessions on a switch at a time, then continue configuring multiple RSPAN sessions on the other switch without any problem -> Answer B is not correct.

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

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