Description

This article provides a method for configuring port-mirroring across multiple EX Switches (equivilent term - RSPAN - Remote Switched Port Analyzer)

Symptoms


Solution

Remote Analyzer works by configuring a Local Analyzer on each and every EX connected by  a trunk (cannot use access ports).

This test scenario describes how the traffic on ge-0/0/20 of EX1 is mirrored on ge-0/0/0 of EX3

PC-A (ge-0/0/20)----------------[EX1]------Trunk (VLAN444)-------[EX2]------Trunk (VLAN888)---------[EX3]------------ (ge-0/0/0)Analyzer


Configuration: 

==> Configure "Input Ingress & Egress interface ge-0/0/20" & "Output vlan 444" in EX1
#set ethernet-switching-options analyzer bal input ingress interface ge-0/0/20
#set ethernet-switching-options analyzer bal input egress interface ge-0/0/20
#set ethernet-switching-options analyzer bal output vlan 444
#set vlan v444 vlan-id 444
#set interface ge-0/0/10.0 family ethernet-switching port-mode trunk vlan members 444 
==> Configure "Input Ingress VLAN 444" & "Output VLAN 888" in EX2
#set ethernet-switching-options analyzer bal input ingress vlan 444
#set ethernet-switching-options analyzer bal output vlan 888
#set vlan v444 vlan-id 444
#set interface ge-0/0/10.0 family ethernet-switching port-mode trunk vlan members 444
#set vlan v888 vlan-id 888
#set interface ge-0/0/20.0 family ethernet-switching port-mode trunk vlan members 888 
==> Configure "Input Ingress VLAN 888" & "Output interface ge-0/0/0" in EX3
#set ethernet-switching-options analyzer bal input ingress vlan 888
#set ethernet-switching-options analyzer bal output interface ge-0/0/0
#set vlan v888 vlan-id 888
#set interface ge-0/0/20.0 family ethernet-switching port-mode trunk vlan members 888

Note: Analyzer VLAN(s) (VLAN444 and VLAN888) should not have more than one trunk interface being a member of it on each (respective) EX

Limitations of RSPAN:
==> Only one active Analyzer permissible per EX
==> Only one Trunk port permissible on any VLAN that is used in Analyzer
==> Mirrored packets exiting a tagged interface might contain incorrect VLAN ID
==> Tagged packets mirrored to an analyzer port might contain incorrect ether type
==> Packets with physical layer errors are filtered out and thus are not sent to the analyzer port or analyzer VLAN
==> Aggregated interfaces cannot be used either directly or using VLAN
==> Cannot mirror packets exiting or entering the following ports:

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