Cisco Systems BC-109 Enable Token Ring LLC2-to-Ethernet Conversion, Enable 0x80d5 Processing

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Configure Translation between SRB and Transparent Bridging Environments

Enable Token Ring LLC2-to-Ethernet Conversion

The Cisco IOS software supports the following types of Token Ring-to-Ethernet frame conversions using Logical Link Control, type 2 (LLC2) Protocol:

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Token Ring LLC2 to Ethernet Type II (0x80d5 processing)

Token Ring LLC2 to Ethernet 802.3 LLC2 (standard)

For most non-IBM hosts, Token Ring LLC2 frames can be translated in a straightforward manner into Ethernet 802.3 LLC2 frames. This is the default conversion in the Cisco IOS software.

However, many Ethernet-attached IBM devices use nonstandard encapsulation of LLC2 on Ethernet. Such IBM devices, including PS/2s running OS/2 Extended Edition and RT-PCs, do not place their LLC2 data inside an 802.3 format frame, but rather place it into an Ethernet Type 2 frame whose type is specified as 0x80d5. This nonstandard format is called 0x80d5, named after the type of frame. This format is also sometimes called RT-PC Ethernet format because these frames were first widely seen on the RT-PC. Hosts using this nonstandard 0x80d5 format cannot read the standard Token Ring LLC2 to Ethernet 802.2 LLC frames.

To enable Token Ring LLC2 to Ethernet LLC2 conversion, you can perform one or both of the following tasks:

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Enable 0x80d5 Processing

Enable Standard Token Ring LLC2-to-Ethernet LLC2 Conversion

Enable 0x80d5 Processing

You can change the Cisco IOS software’s default translation behavior of translating Token Ring LLC to Ethernet 802.3 LLC to translate Token Ring LLC2 frames into Ethernet 0x80d5 format frames. To enable this nonstandard conversion, use the following command in global configuration mode:

Command

Purpose

source-bridge enable-80d5

Change the Ethernet/Token Ring translation behavior to translate Token

 

Ring LLC2 frames into Ethernet 0x80d5 format frames.

 

 

Enable Standard Token Ring LLC2-to-Ethernet LLC2 Conversion

After you change the translation behavior to perform Token Ring LLC2 frames into Ethernet 0x80d5 format frames, some of the non-IBM hosts in your network topology might use the standard Token Ring conversion of Token Ring LLC2 to 802.3 LLC2 frames. If this is the case, you can change the translation method of those hosts to use the standard translation method on a per-DSAP basis. The translation method for all the IBM hosts would still remain as Token Ring LLC2 to Ethernet 0x80d5 translation.

To define non-IBM hosts in your network topology to use the standard translation method while the IBM hosts use the nonstandard method, use the following command in global configuration mode:

Command

Purpose

source-bridge sap-80d5 dsap

Allow some other devices to use normal LLC2/IEEE 802.3 translation on

 

a per-DSAP basis.

 

 

BC-122Bridging and IBM Networking Configuration Guide

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Contents Configuring Source-Route Bridging SRB Configuration Task ListConfigure Source-Route Bridging Configure a Dual-Port BridgeConfigure a Multiport Bridge Using a Virtual Ring Multiple Dual-Port BridgesNo source-bridge ring-group ring-group Define a Ring Group in SRB ContextSource-bridge ring-group ring-group Interface fddi slot/port Configure SRB over FddiEnable SRB and Assign a Ring Group to an Interface Source-bridge route-cache cbusConfigure Fast-Switching SRB over Fddi Configure SRB over Frame RelayEnable the Automatic Spanning-Tree Function Limit the Maximum SRB Hops Configure Bridging of Routed Protocols Enable Use of the RIFConfigure a Static RIF Entry Configure the RIF Timeout IntervalOverview of SR/TLB Following notes and caveats apply to all uses of SR/TLB Enable Translation Compatibility with IBM 8209 Bridges Enable Bridging between Transparent Bridging and SRBDisable Fast-Switched SR/TLB No source-bridge transparent ring-group fastswitchEnable Standard Token Ring LLC2-to-Ethernet LLC2 Conversion Enable Token Ring LLC2-to-Ethernet ConversionEnable 0x80d5 Processing Source-bridge sap-80d5 dsapConfigure NetBIOS Support Specify Timeout and Enable NetBIOS Name Caching Source-bridge proxy-netbios-onlyCreate Static Entries in the NetBIOS Name Cache Configure the NetBIOS Cache Name LengthEnable NetBIOS Proxying Specify Dead-Time Intervals for NetBIOS PacketsNetbios name-cache recognized-timeout seconds Configure LNM SupportNetbios name-cache query-timeout seconds LNM Linking to a Source-Route Bridge on Each Local Ring How a Router Works with LNM LAN Network Manager Monitoring and TranslatingDisable LNM Functionality Disable Automatic Report Path Trace Function Enable Other LRMs to Change Router ParametersChange Reporting Thresholds Apply a Password to an LNM Reporting LinkEnable LNM Servers Lnm softerr milliseconds Change an LNM Reporting IntervalMonitor LNM Operation Secure the SRB Network Configure NetBIOS Access FiltersConfigure NetBIOS Access Filters Using Station Names Netbios access-list bytes name permit deny offset Configure NetBIOS Access Filters Using a Byte OffsetNetbios access-list host name permit deny pattern Netbios input-access-filter bytes nameFilter Frames by Protocol Type Configure Administrative Filters for Token Ring TrafficNetbios output-access-filter bytes name Filter Destination Addresses Filter Frames by Vendor CodeFilter Source Addresses Access Expression Example Configure Access Expressions Optimize Access ExpressionsAlter Access Lists Used in Access Expressions Tune the SRB NetworkEnable or Disable the Source-Route Fast-Switching Cache Optimize Explorer Processing Enable or Disable the SSEEstablish the Connection Timeout Interval Controlling Explorer Storms in Redundant Network Topologies Mac-address ieee-address Configure Proxy ExplorersEstablish SRB Interoperability with TI MAC Firmware Report Spurious Frame-Copied Errors Monitor and Maintain the SRB NetworkSRB Configuration Examples Source-bridge tcp-queue-max numberDual-Port Source-Route Bridge Configuration Basic SRB with Spanning-Tree Explorers ExampleOptimized Explorer Processing Configuration Example SRB-Only ExampleSRB and Routing Certain Protocols Example Multiport SRB ExampleConfiguration for Router a SRB with Multiple Virtual Ring Groups ExampleConfiguration for Router B SRB over Fddi Configuration ExamplesSRB over Fddi Fast-Switching Example Router aSRB over Frame Relay Configuration Example Frad Using SRB over Frame Relay to Connect to a Cisco RouterConfiguration on Router C Configuration of Router aConfiguration on Router B Adding a Static RIF Cache Entry ExampleAdding a Static RIF Cache Entry for a Two-Hop Path Example SR/TLB for a Simple Network ExampleBC-154Bridging and IBM Networking Configuration Guide SR/TLB with Access Filtering Example Example of a Bit-Swapped AddressNetBIOS Support with a Static NetBIOS Cache Entry Example Specifying a Static EntryWayfarer# show lnm config LNM for a Simple Network ExampleLNM for a More Complex Network Example NetBIOS Access Filters Example Filtering Bridged Token Ring Packets to IBM Machines Example Shows a router connecting four Token Rings Creating Access Filters Example Following access expression would resultAccess Filters Example Fast-Switching ExampleAutonomous Switching Example
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