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Level 10
Level 10


These are the limitations of Switched Port Analyzer (SPAN) and Remote SPAN (RSPAN) on the Cisco Catalyst 2950, 3550, 3560 and 3750 swtiches:

  • The Cisco Catalyst 2950 switches can only have one SPAN session active at a time. The Cisco Catalyst 2950 switches can monitor only source ports, not VLANs.
  • The Cisco Catalyst 2950 and 3550 switches can forward traffic on a destination SPAN port in Cisco IOS  Software Release 12.1(13)EA1 and later.
  • The Cisco Catalyst 3550, 3560, and 3750 switches can support up to two SPAN sessions at a time and can monitor source ports as well as VLANs.
  • The Cisco Catalyst 2970, 3560, and 3750 switches do not require configuration of a reflector port when a ReRSPAN session is configured.
  • The Cisco Catalyst 3750 switches support session configuration with source and destination ports that reside on any of the switch stack members.
  • Use a network analyzer in order to monitor interfaces.
  • You cannot mix source VLANs and filter VLANs within a SPAN session. You can have source VLANs or filter VLANs, but not both at the same time.
  • EtherChannel interfaces can be SPAN source interfaces; they cannot be SPAN destination interfaces.
  • When you specify source interfaces and do not specify a traffic type, for example, Tx, Rx, or both. "both" is used by default.
  • If you specify multiple SPAN source interfaces, the interfaces can belong to different VLANs.
  • You cannot have two SPAN sessions that use the same destination port. The destination port cannot be a source port; a source port cannot be a destination port.
  • You can configure a maximum of two source sessions and 64 RSPAN destination sessions on each switch stack. A source session is either a local SPAN session or an RSPAN source session.
  • If a 10-Gigabit Ethernet module port is configured as a SPAN or RSPAN destination port, its link rate decreases.
  • Enter the no monitor session number command with no other parameters in order to clear the SPAN session number.
  • The no monitor command clears all SPAN sessions.
  • You cannot configure a SPAN destination interface in order to receive ingress traffic.
  • SPAN destinations never participate in any spanning tree instance. SPAN includes BPDUs in the monitored traffic, so any bridge protocol data units (BPDUs) seen on the SPAN destination are from the SPAN source.

Note: Unlike the 2900XL and 3500XL Series switches, the Cisco Catalyst 2940, 2950, 2955, 2970, 3550, 3560 and 3750 Series switches support SPAN on source port traffic in the receive direction only (Rx SPAN or ingress SPAN), in the transmit direction only (Tx SPAN or egress SPAN), or both.

Refer to Configuring SPAN and RSPAN for more information.


What do you mean by ReRSPAN, please?

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