IOS XE 3.6.1S has just been released. Not many new features were introduced since 3.6.0S release but on useful is already deployed on this platform – Switch Port Analyzer (SPAN), sometimes called also as port mirroring. It’s useful if you want to capture traffic from particular interface and send it to other. It’s well known on other Cisco platforms
ASR903 supports SPAN only on physical ports. It’s not possible to apply session to EFP or VLAN. Up to 16 sessions are supported with one destination which is set as access port. By default it mirrors traffic sent in both ways. Traffic can only be mirrored locally – RSPAN is not supported.
configuration is simple and not differ from one know from other platforms
Router(config)# monitor session 2 source interface gigabitethernet 2/2 Router(config)# monitor session 2 destination interface gigabitethernet 2/1