Cisco WS-C2980G-A Software Guide - Page 394
Trunk VLAN Filtering, SPAN Traffic, SPAN and RSPAN Session Limits, Configuring SPAN
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SPAN and RSPAN Session Limits Chapter 26 Configuring SPAN and RSPAN • Inactive VLANs are not allowed for VSPAN configuration. • A VSPAN session is made inactive if any of the source VLANs become RSPAN VLANs. Trunk VLAN Filtering In software release 6.3(1) and later releases, you can use the filter option to select a set of VLANs in a trunk that is used in a SPAN session. Trunk VLAN filtering is the analysis of network traffic on a selected set of VLANs on trunk source ports. If you specify a set of VLANs with the filter option, the traffic that is spanned by the session is limited to the VLANs that are specified. You can combine trunk VLAN filtering with other source ports that belong to any of the selected VLANs, and you can also use trunk VLAN filtering for RSPAN. Based on the traffic type (ingress, egress, or both), SPAN sends a copy of the network traffic in the selected VLANs to the destination port. Use trunk VLAN filtering only with trunk source ports. If you combine trunk VLAN filtering with other source ports that belong to VLANs that are not included in the selected list of filter VLANs, SPAN includes only the ports that belong to one or more of the selected VLANs in the operational sources. When a VLAN is cleared, it is removed from the VLAN filter list. A SPAN session is disabled if the VLAN filter list becomes empty. Trunk VLAN filtering is not applicable to VSPAN sessions. Trunk VLAN filtering is available for local SPAN sessions and RSPAN sessions. SPAN Traffic All network traffic, including multicast and bridge protocol data unit (BPDU) packets, can be monitored using SPAN (RSPAN does not support monitoring of BPDU packets). SPAN and RSPAN Session Limits You can configure (and store in NVRAM) up to five SPAN sessions in a Catalyst 4500 series switch. The five sessions can be split any way between SPAN, RSPAN source, and RSPAN destination sessions. Configuring SPAN The following sections describe how to configure SPAN. Understanding How SPAN Works SPAN selects network traffic for analysis by a SwitchProbe device or other RMON probe. SPAN mirrors traffic from one or more source ports (Ethernet, Fast Ethernet, or Gigabit Ethernet) on one or more VLANs to a destination port for analysis (see Figure 26-1). In Figure 26-1, all traffic on Ethernet port 5 (the source port) is mirrored to Ethernet port 10. A network analyzer on Ethernet port 10 receives all network traffic from Ethernet port 5 without being physically attached to it. 26-4 Catalyst 4500 Series, Catalyst 2948G, Catalyst 2980G Switches Software Configuration Guide-Release 8.1 78-15486-01