3Com 3500 manual Listed on the left, Routing interface index number. a T precedes a tunnel

ip multicast dvmrp cacheDisplay 519

Field	Description
inVif	Interface that receives incoming IP multicast traffic from
	the spanning tree for the source, subnetwork, and group
	listed on the left.
	The interface is presented as an index number and either
	an I or a T precedes the index number. An I precedes a
	routing interface index number. A T precedes a tunnel
	index number.
	A P after the index number indicates that a prune
	message has been sent to an upstream router.
	The entry <none> may appear if the system is not able to
	build the cache entry correctly. This temporary condition
	corrects itself quickly.
outVif	Interfaces to which traffic from the inVif is being
	forwarded.
	Each interface is presented as an index number and either
	an I or a T precedes each index number. An I precedes
	a routing interface index number. A T precedes a tunnel
	index number.
	A p after an index number indicates that the upstream
	router has pruned this branch of the delivery tree and no
	multicast packets are being forwarded through this local
	interface. Eventually this entry disappears from the cache
	display.
	Either no entry or <none> appears in this column if the
	system is not able to build the cache entry correctly. This
	temporary condition corrects itself quickly.
Ports	Physical ports that correspond to the interfaces that are
	listed in the outVifs field. The Ports field shows a dash (--)
	when there are no outgoing interfaces and when the
	outgoing interfaces are tunnels.