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Table Of Contents
RFC 1483 for Token Ring Networks
Connecting Routers Back-to-Back
Single ATM PVC and Single Virtual Ring Per Router Example
Multiple ATM PVCs and Multiple Virtual Rings on One Router
Multiple ATM PVCs with a Single Virtual Ring on the Router
RFC 1483 for Token Ring Networks
Feature Summary
The Cisco IOS 12.0(3)T software supports RFC 1483 and enables the transfer of network interconnect traffic over ATM AAL5 layer, using LLC encapsulation. RFC 1483 defines an encapsulation type for transferring LAN data via ATM networks.
All LAN protocols that use the LLC format and run on Ethernet, Token Ring, or ATM networks are encapsulated in LLC data packets transported via ATM networks.
Support for RFC 1483 in the Cisco IOS 12.0(3)T software enables:
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Source-route bridging (SRB) between Token Ring LANs connected over and ATM network, using RFC 1483 bridged PDUs.
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SRB is accomplished by packet forwarding based on the next hop Route Descriptor.
Source Route/Translational Bridging (SR/TLB) can be configured to connect transparent bridging and SRB domains. Incoming transparent bridging packets are forwarded based on a destination MAC address that yields a RIF to be added to the packet. SRB packets are forwarded based on destination MAC address, which is listed in the transparent bridging table. Both SRB explorers and transparent bridging multicast packets are forwarded and extended.
Benefits
This section describes the benefits of the RFC 1483 features introduced in Cisco IOS Release 12.0(3)T:
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List of Terms
AAL5—ATM adaptation layer 5. One of the four AAL5 recommended by the ITU-T. AAL5 supports connection-oriented VBR services, and is used predominantly for the transfer of IP over ATM and LANE traffic.
ATM—Asynchronous Transfer Mode. International standard for cell relay in which multiple service types (such as voice, video, or data) are conveyed in fixed-length (53-byte) cells.
PDU—Protocol Data Unit. An OSI term for packet.
Supported Platforms
This feature is supported on the following platforms:
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Supported MIBs and RFCs
No MIBs are supported.
RFC 1483 is supported.
Configuration Tasks
This section describes the following configuration task for RFC 1483 support:
Configure SRB
Cisco IOS software offers the ability to encapsulate SRB traffic using RFC 1483 bridged LLC encapsulation. This provides SRB over ATM functionality that is interoperable with other vendors' implementations of SRB over ATM.
The following guidelines apply to RFC 1483 configuration:
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To configure SRB over ATM, use the following commands in interface configuration mode:
Configuration Examples
This section provides configuration examples for RFC 1483.
Connecting Routers Back-to-Back
shows a back-to-back scenario with two ATM adapters that are connected. There is no ATM switch in this example.
Figure 1
Connecting Routers Back-to-Back
Following are the configurations for routers A and B:
Router A
interface atm slot/port atm clockinterface atm slot/port.1 point-to-pointatm pvc 1 10 12 aal5snapsource-bridge 200 1 100 conserve-ringsource-bridge spanningRouter B
interface atm slot/port.1 point-to-pointatm pvc 2 10 12 aal5snapsource-bridge 100 1 200 conserve-ringsource-bridge spanningSingle ATM PVC and Single Virtual Ring Per Router Example
shows an example with frames from Token Ring 1 destined to Token Ring 2 and an ATM switch connecting the routers.
Figure 2
Single ATM PVC and Single Virtual Ring Per Router
Router A
interface atm slot/portinterface atm slot/port.1 point-to-pointatm pvc 1 10 12 aal5snapsource-bridge 200 1 100 conserve-ringsource-bridge spanningRouter B
interface atm slot/port.1 point-to-pointatm pvc 2 0 12 aal5snapsource-bridge 100 1 200 conserve-ringsource-bridge spanningThe following configuration does not use the conserve-ring argument in the configuration and the PVC is allocated its own virtual ring number.
Router A
interface atm slot/portinterface atm slot/port.1 point-to-pointatm pvc 1 0 12 aal5snapsource-bridge 5 1 100source-bridge spanningRouter B
interface atm slot/port.1 point-to-pointatm pvc 2 0 12 aal5snapsource-bridge 6 1 100source-bridge spanningMultiple ATM PVCs and Multiple Virtual Rings on One Router
shows multiple ATM PVCs and multiple virtual rings on a router.
Figure 3
Multiple ATM PVCs and Multiple Virtual Rings on a Router
Following are the configurations for routers A, B, and C.
Router A
interface atm slot/port.1 point-to-pointatm pvc 1 10 12 aal5snapsource-bridge 200 1 100 conserve-ringsource-bridge spanninginterface atm slot/port.2 point-to-pointatm 2 0 12 aal5snapsource-bridge 300 2 101 conserve-ringsource-bridge spanningRouter B
interface atm slot/port.1 point-to-pointatm pvc 3 0 12 aal5snapsource-bridge 100 1 200 conserve-ringsource-bridge spanningRouter C
interface atm slot/port.1 point-to-pointatm pvc 4 0 12 aal5snapsource-bridge 101 2 300 conserve-ringsource-bridge spanningMultiple ATM PVCs with a Single Virtual Ring on the Router
shows traffic going from Token Ring 1 to Token Ring 2 and Token Ring 3. Following are the configurations for routers A, B, and C.
Figure 4
Multiple ATM PVCs with a Single Virtual Ring on the Router
Router A
interface atm slot/port.1 point-to-pointatm pvc 1 0 12 aal5snapsource-bridge 200 1 100 conserve-ringsource-bridge spanninginterface atm slot/port.2 point-to-pointatm pvc 2 0 2 aal5snapsource-bridge 300 2 100 conserve-ringsource-bridge spanningRouter B
interface atm slot/port.1 point-to-pointatm pvc 3 0 2 aal5snapsource-bridge 100 1 200 conserve-ringsource-bridge spanningRouter C
interface atm slot/port.1 point-to-pointatm pvc 4 1 3 aal5snapsource-bridge 100 2 300 conserve-ringsource-bridge spanningCommand Reference
This section documents new or modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.0 command references.
source-bridge
Use the source-bridge interface configuration command to configure an interface for SRB. Use the no form of this command to disable SRB on an interface.
source-bridge source-ring-number bridge-number target-ring-number [conserve-ring]
no source-bridge source-ring-number bridge-number target-ring-number [conserve-ring]Syntax Description
Default
SRB is disabled.
Command Mode
Interface configuration
Usage Guidelines
The revised version of the source-bridge command to enable SRB over Frame Relay first appeared in Cisco IOS Release 11.2 F.
The source-bridge command was updated in Cisco IOS 12.0(3)T to provide support to ATM networks with the conserve-ring argument.
The parser automatically displays the word "active" in the source-bridge command in configurations that have SRB enabled. You do not need to enter the source-bridge command with the active keyword.
Examples
In the following example, Token Rings 129 and 130 are connected via a router:
interface tokenring 0source-bridge 129 1 130!interface tokenring 1source-bridge active 130 1 129In the following example, an FDDI ring on one router is connected to a Token Ring on a second router across a DLSw+ link:
dlsw local-peer peer-id 132.11.11.2dlsw remote-peer 0 tcp 132.11.11.3interface fddi 0no ip addressmultiring allsource-bridge active 26 1 10!dlsw local-peer peer-id 132.11.11.3dlsw remote-peer 0 tcp 132.11.11.2interface tokenring 0no ip addressmultiring allsource-bridge active 25 1 10In the following example, a router forwards frames from a locally attached Token Ring over the Frame Relay using SRB:
source-bridge ring-group 200!interface Serial0encapsulation frame-relay!interface Serial0.30 point-to-pointframe-relay interface-dlci 30 ietfsource-bridge 100 1 200 conserve-ringsource-bridge spanning!interface TokenRing0source-bridge 600 1 200Related Commands
debug frame-relay packet
debug source bridge
debug source error
debug source event
encapsulation frame-relay
frame-relay interface-dlci
source-bridge ring-group
source-bridge transparent
