Allied Telesis C613-02013-00 manual Interfaces to Layer 3 Protocols, IGMP Snooping

56		Rapier Switch User Guide
	Table 12: Parameters in the output of the SHOW STP COUNTER command
	Parameter	Meaning
	Port Disabled	The number of BPDUs discarded because the port that the
		BPDU was received on was disabled.
	Invalid Protocol	The number of STP packets that had an invalid Protocol
		Identifier field or invalid Protocol Version Identifier field.
	Invalid Type	The number of STP packets that had an invalid Type field.
	Invalid Message Age	The number of STP packets that had an invalid message
		age.
	Config BPDU length	The number of Configuration BPDUs that had an incorrect
		length.
	TCN BPDU length	The number of Topology Change Notification BPDUs that
		had an incorrect length.

If necessary, all the STP configuration that users have created on the switch can be removed, so that all STPs except the default STP are destroyed, and all other defaults are restored, using the command:

PURGE STP

The PURGE STP command should be used with caution, and generally only before major reconfiguration of the switch, as it removes all STP configuration entered on the switch.

Interfaces to Layer 3 Protocols

Interfaces can be configured to VLANs for IP, IPX and Appletalk routing protocols in the same way that other interfaces are created for other interface types. Concatenate VLAN with the VID of the VLAN giving VLANn, for instance:

INTERFACE=VLAN3

IGMP Snooping

IGMP (Internet Group Management Protocol) is used by IP hosts to report their multicast group memberships to routers and switches. IP hosts join a multicast group to receive broadcast messages directed to the multicast group address. IGMP is an IP-based protocol and uses IP addresses to identify both the multicast groups and the host members. For a VLAN-aware devices, this means multicast group membership is on a per-VLAN basis. If at least one port in the VLAN is a member of a multicast group, by default multicast packets will be flooded onto all ports in the VLAN.

IGMP snooping enables the switch to forward multicast traffic intelligently on the switch. The switch listens to IGMP membership reports, queries and leave messages to identify the switch ports that are members of multicast groups.

Multicast traffic will only be forwarded to ports identified as members of the specific multicast group.

Rapier Switch Software Release 2.2.1 C613-02013-00 Rev A