IBM BC-203 Manuale Utente

All commands supported on the Cisco 7500 series routers are also supported on the 
Cisco 7000 series routers.

In contrast to Source-Route Bridging (SRB), which involves bridging between Token Ring media only, 
RSRB is Cisco’s first technique for connecting Token Ring networks over non-Token Ring network 
segments. (DLSw+ is Cisco’s strategic method for providing this function.)

Cisco’s RSRB software implementation includes the following features:

Provides for multiple routers separated by non-Token Ring segments. Three options are available:

Encapsulate the Token Ring traffic inside IP datagrams passed over a Transmission Control 
Protocol (TCP) connection between two routers.

Use Fast-Sequenced Transport (FST) to transport RSRB packets to their peers without TCP or 
User Datagram Protocol (UDP) header or processor overhead.

Use data link layer encapsulations over a single serial line, Ethernet, Token Ring, or Fiber 
Distributed Data Interface (FDDI) ring connected between two routers attached to Token Ring 
networks.

Provides for configurable limits to the size of the TCP backup queue.

Figure 85 shows an RSRB topology. The virtual ring can extend across any non-Token Ring media 
supported by RSRB, such as serial, Ethernet, FDDI, and WANs. The type of media you select determines 
the way you set up RSRB. 

If you bridge across Token Ring media, it is recommended that you do not use RSRB. Use 
SRB instead. Refer to the chapter “Configuring Source-Route Bridging.”

Token

Ring

Token

Ring

Token

Ring

Virtual ring

S2327

Token

Ring

Non-Token Ring

Media