EXP Computer S200 manual Bridge Frame Handling

	Configuring the PathBuilder S200 Series Switch for Bridging Operation
Bridge Frame Handling
Introduction
	This section summarizes how PathBuilder S200 series switches handle frames
	during Source Route Bridge operation.
How Frame
	Once a PathBuilder S200 series switch station connected to a Token Ring and is
Handling Works	operating normally, non-MAC frames are copied from the ring as they pass through
	the bridge station only if they satisfy these requirements:
	• The Routing Information Present bit must be set in the source MAC Address
	of the frame.
	• If the frame is non-broadcast, the local ring number, bridge number, and
	remote ring number must match the bridge's stored values for these numbers,
	and the routing field must have less than 7 to 14 LAN/bridge couplets
	(depending on the configured maximum allowed).
	• If the frame is single route broadcast and forwarding of single route broadcast
	is enabled, then the Routing Information field must not contain the remote
	ring number since the frame has already been on the forward ring. If single
	route broadcast is disabled, the frame is not copied.
	• If the frame is All Route Broadcast, then the Routing Information field must
	not contain the remote ring number.
	These rules apply to frames with either locally or universally administered addresses
	and for frames with either individual or group addresses.
Broadcast Frame
	When the All Route Broadcast frame is received from the LAN and initiated by
Handling	another device on the LAN, it is sent to all remote bridges on all SVCs.
	The single route broadcast frame is sent only to the remote bridge that is part of the
	spanning tree. The specific route frame is sent to the remote bridge via the single
	SVC that connects the bridges.
	When received from the WAN, broadcast frames are sent to the Token Ring. They
	are sent to the other SVCs for general or spanning tree distribution, as appropriate,
	after the LAN port removes the frame from the local ring.
Routed Frame
	When a specifically routed frame is received from the WAN, it is sent to the Token
Handling	Ring if the next bridge listed in the Routing Information field does not correspond to
	a bridge formed by a local SVC. Otherwise, it is forwarded to the proper SVC for
	additional bridging without being sent to the LAN. This keeps transit traffic off rings
	where it can be avoided.

Bridging 39

T0008-16F Release 5.2M