Olicom 8600 Source Route Switching SRS, Source Route Bridging SRB, Source Route Transparent SRT

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There are two levels of relay functions supported by the switch. The first level is the TrCRF (Token Ring Concentrator Relay Function) to which the ports are assigned. The second level is the TrBRF (Token Ring Bridge Relay Function). This is the parent relay function to which TrCRFs are assigned. The switch maintains certain configuration information and management statistics on a per BRF/CRF basis. Therefore, when you access VLAN-specific switch configuration or management screens (such as the Current Spanning Tree Information screen), you will be prompted to specify the desired TrBRF for TrCRF.

Source Route Switching (SRS)

This mode is used between ports comprising a Logical Ring.

SRS switching combines the normal transparent bridge function with the ability to forward frames based on source route information to locally attached source-route bridges. The switch does not otherwise act as a source route bridge. For non source- routed packets, the switch decision is based upon destination MAC Addresses. For source-routed packets, it is based on the source-route information combined with the destination MAC address.

The switch learns MAC addresses and source-routing route descriptors of Source Route Bridges attached to local switch ports.

Parallel paths are eliminated via the IEEE 802.1D Spanning Tree Protocol.

Source Route Bridging (SRB)

The BRF acts as a multiport Source Route Bridge between CRFs with the following characteristics:

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Each Logical Ring has a different ring number

Source Route Frames are forwarded between the Logical Rings by the Bridge Relay Function based on the route information field

Non-source-route frames are not forwarded between logical rings

The Bridge Relay Function has a single bridge number and multiple ring numbers (one per Logical Ring)

SRS is used between the ports of each logical ring. The Bridge Relay Function runs the IBM Spanning Tree Protocol to eliminate parallel paths with other source-route bridges. The IEEE 802.1D Spanning Tree Protocol is still used with each logical ring. Duplicate MAC addresses are allowed only if they are on different Logical Rings.

Source Route Transparent (SRT)

The BRF can combine transparent switching with Source Route Bridging. Non source-routed packets are switched across logical rings by transparent bridging.

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