Cisco WS-C4003 Software Guide - Page 325
SPAN Configuration Guidelines
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Chapter 25 Configuring SPAN and RSPAN Figure 25-1 Example SPAN Configuration Port 5 traffic mirrored on Port 10 1 2 3 4 5 6 7 8 9 10 11 12 SPAN Configuration Guidelines E6 E7 E5 E8 E11 E4 E9 E12 E3 E10 E2 E1 44389 SwitchProbe For SPAN configuration, the source ports and the destination port must be on the same switch. SPAN does not affect the switching of network traffic on source ports; copies of the packets received or transmitted by the source ports are sent to the destination port. SPAN Configuration Guidelines Follow these guidelines when configuring SPAN: • Incoming traffic on the SPAN destination port is disabled by default. You can enable it using the inpkts enable keywords. However, while the port receives traffic for its assigned VLAN, it does not participate in spanning tree for that VLAN. To avoid creating spanning tree loops with incoming traffic enabled, assign the SPAN destination port to an unused VLAN. • In software release 5.2 and later, with the inpkts option enabled, you can prevent the switch from learning source MAC addresses from traffic received on the SPAN destination port using the learning disable keywords. If you want the switch to learn source MAC addresses from traffic received on the SPAN destination port, use the learning enable keywords. By default, the switch learns source MAC addresses from incoming traffic (learning enable) if the inpkts option is enabled. The source MAC address learning options only affect traffic received from a device attached to the SPAN destination port itself, not from traffic mirrored from the SPAN source. • When monitoring a VLAN on a switch, you must monitor both transmit and receive traffic (both). You cannot monitor only transmit (tx) or only receive (rx) traffic. • If you specify a set of VLANs with the filter option, the traffic spanned by the session is limited to the VLANs specified. • Any traffic between two network nodes on the same network segment attached to a switch port configured as a SPAN source port is not mirrored to the SPAN destination port. You can SPAN local traffic that passes through the switch. • You can have up to five SPAN sessions running at the same time with any combination of ingress and egress sessions. • You cannot configure SPAN on sc0. 78-12647-02 Software Configuration Guide-Catalyst 4000 Family, Catalyst 2948G, Catalyst 2980G, Releases 6.3 and 6.4 25-5