What happens to a RSPAN packet sent to a switch without RSPAN config

[SondreSandberg]

What happens to a RSPAN packet sent to a switch without RSPAN configured, but has the VLAN?

RSPAN configured on switch1 with source vlan4, destination vlan5.
RSPAN not configured on switch2 or switch3.
VLAN 4 is a client VLAN and clients connected to sw1 is sending out arp's.

If I configure :
Switch1 with a trunk to Switch2, vlan 5 allowed, native vlan1 shut
Trunk from switch2 to Switch3 with only vlan 4 allowed, native vlan1 shut
Switch3 has vlan 4-5: vlan4 with a default route to the ISP. vlan5 has a route to a blackhole, native vlan1 shut

Question:
Will sw2 forward the packets to sw3, since it does not have SPAN configured and sees vlan4?

[Giuseppe Larosa]

Hello @SondreSandberg ,

I would suggest you to avoid to mix an OSI layer 2 concept like RSPAN VLAN and OSI layer 3 inter VLAN routing.

The RSPAN settings disable MAC address learning so likely on the switches with the destination VLAN 5 configured as a standard VLAN you can get warning logs about duplicated MAC addresses and so on, and what is more important your RSPAN traffic may not  reach the destination port on the last switch defeating the purpose of the RSPAN configuration.

Fix this  RSPAN scenario first. Then look at the routing issues if any

Hope to help

Giuseppe