Installation guide

Release Notes for Catalyst5000 Family Software Release4.x

OL-2306-01

Usage Guidelines, Restrictions, and Troubleshooting

SPAN

This section contains usage guidelines, restrictions, and troubleshooting information that apply to the

Switch Port Analyzer (SPAN).

• If you configure a SPAN destination port with the inpkts disable option (the default), normal

incoming traffic on the port is not forwarded. However, if you reset the module on which the SPAN

destination port is configured, the port will forward normal incoming traffic after the module comes

online.

Workaround: Enter the set span inpkts disable command again after the module comes online.

(CSCdk61912)

• In software releases prior to 4.2, if the SPAN destination port is connected to another device, the

port always receives incoming packets for the VLAN it is assigned to but does not participate in the

spanning tree for that VLAN. To avoid creating spanning tree loops, assign the SPAN destination

port to an unused VLAN.

• In software release 4.2 and later, incoming traffic on the SPAN destination port is disabled by

default. You can enable it using the set span command with 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.

• A SPAN destination port receives flooded unicasts and broadcasts for the VLAN of the source

SPAN port.

• The RSM does not support SPAN.

Multicast

This section contains usage guidelines, restrictions, and troubleshooting information that apply to

multicast protocols and traffic on the switch.

• Due to a conflict with the Hot Standby Router Protocol (HSRP), Cisco Group Management Protocol

(CGMP) leave processing is disabled by default.

To enable CGMP leave processing, enter the set cgmp leave enable command.

Note If both HSRP and CGMP leave processing are enabled, you might experience some

unicast packet flooding.

• When CGMP leave processing is enabled, the Catalyst5000 family switch learns router ports

through PIM-v1, HSRP, and CGMP self-join messages. When CGMP leave processing is disabled,

the Catalyst5000 family switch learns router ports through CGMP self-join messages only.

• CGMP does not prune multicast traffic for any IP multicast address that maps into the Media Access

Control (MAC) address range of 01-00-5E-00-00-00 to 01-00-5E-00-00-FF. The reserved IP

multicast addresses, in the range 224.0.0.0 to 224.0.0.255, are used to forward local IP multicast

traffic in a single Layer3 hop.