Olicom 8605, 8600 manual Filtering, Srt/Srb

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Source-routed frames are switched across logical rings by Source-Route Bridging and within each logical ring by Source-Route Switching.

The Bridge Relay Function runs the IEEE 802.1D Spanning Tree Protocol. Duplicate MAC addresses are not allowed.

SRT/SRB

This is a special mode combining SRT and the SRB switching modes. Each Logical Ring will operate either in SRT mode or in SRB mode. Transparent bridging will only take place between logical rings in SRT mode. Source-route bridging will take place between all logical rings.

The purpose of the SRT/SRB mode is to allow duplicate MAC addresses to be used when in SRT mode. The ports on which the duplicate MAC addresses reside can be reached only by source routing.

The Bridge Relay Function runs the IBM Spanning Tree Protocol on the SRB logical rings to eliminate parallel paths with all source route bridges. It runs IEEE 802.1D Spanning Tree Protocol on the SRT logical rings to eliminate parallel paths with other SRT bridges. The two resulting spanning trees are joined together.

The IEEE 802.1D Spanning Tree Protocol is still used to eliminate parallel paths within each logical ring whether it is SRB or SRT.

The benefit of the SRT/SRB mode is that it allows part of the network to be run in SRT mode to accommodate applications that do not support source routing, while still supporting duplicate MAC addresses on a number of SRB ports (for example, for SNA gateway applications).

Filtering

Filtering is important for a LAN switch. Filters can be used to reduce broadcast traffic, block certain protocols and provide security functions.

The switch provides filters for:

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Destination or source MAC addresses

Destination service access point (DSAP)

Subnetwork Access Protocol (SNAP) type

Each protocol filter can be applied on a per-port basis for both input and output traffic. This feature allows certain protocols to be blocked from certain ports. For example, filters can be established to allow only Systems Network Architecture (SNA) traffic to flow to ports with SNA gateways.

Source and destination MAC address filtering can be applied to all incoming frames. The MAC address filters act in one of three ways:

CrossFire 8600/8605 Token-Ring Switches v. 1.2, P/N: 710001641 Switch Theory of Operation