Cisco Systems EA6500 Manual De Usuario

For source routing, the Catalyst 6500 series switch appears as a single bridge between the logical rings. 
The TrBRF can function as a source-route bridge (SRB) or a source-route transparent (SRT) bridge 
running either the IBM or IEEE STP. If an SRB is used, you can define duplicate MAC addresses on 
different logical rings.

The Token Ring software runs an instance of STP for each TrBRF VLAN and each TrCRF VLAN. For 
TrCRF VLANs, STP removes loops in the logical ring. For TrBRF VLANs, STP interacts with external 
bridges to remove loops from the bridge topology, similar to STP operation on Ethernet VLANs.

Certain parent TrBRF STP and TrCRF bridge mode configurations can place the logical ports (the 
connection between the TrBRF and the TrCRF) of the TrBRF in a blocked state. For more information, 
see the 

To accommodate IBM System Network Architecture (SNA) traffic, you can use a combination of SRT 
and SRB modes. In a mixed mode, the TrBRF determines that some ports (logical ports connected to 
TrCRFs) operate in SRB mode while other ports operate in SRT mode

Token Ring Concentrator Relay Function (TrCRF) VLANs define port groups with the same logical ring 
number. You can configure two types of TrCRFs in your network: undistributed and backup.

TrCRFs typically are undistributed, which means each TrCRF is limited to the ports on a single network 
device. Multiple undistributed TrCRFs on the same or separate network devices can be associated with 
a single parent TrBRF (see 

). The parent TrBRF acts as a multiport bridge, forwarding traffic 

between the undistributed TrCRFs.

To pass data between rings located on separate network devices, you can associate the rings to the same 
TrBRF and configure the TrBRF for an SRB.

Token

Ring

001

Token

Ring

001

Token

Ring

002

Token

Ring

002

Token

Ring

011

Token

Ring

002

SRB  or SRT

BRF

CRF

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