Cisco Systems BC-109 manual Configure NetBIOS Support

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Configure NetBIOS Support

Configure NetBIOS Support

NetBIOS is a nonroutable protocol that was originally designed to transmit messages between stations, typically IBM PCs, on a Token Ring network. NetBIOS allows messages to be exchanged between the stations using a name rather than a station address. Each station knows its name and is responsible for knowing the names of other stations on the network.

Note In addition to this type of NetBIOS, which runs over LLC2, we have implemented another type of NetBIOS that runs over IPX. For information on the IPX type of NetBIOS, refer to the chapter “Configuring Novell IPX” in the Network Protocols Configuration Guide, Part 2.

NetBIOS name caching allows the Cisco IOS software to maintain a cache of NetBIOS names, which avoids the high overhead of transmitting many of the broadcasts used between client and server NetBIOS PCs (IBM PCs or PS/2s) in an SRB environment.

When NetBIOS name caching is enabled, the software performs the following actions:

•Notices when any hosts send a series of duplicated “query” frames and reduces them to one frame per period. The time period is configurable.

•Keeps a cache of mappings between NetBIOS server and client names and their MAC addresses. By watching NAME_QUERY and NAME_RECOGNIZED request and response traffic between clients and servers, the Cisco IOS software can forward broadcast requests sent by clients to find servers (and by servers in reply to their clients) directly to their needed destinations, rather than forwarding them for broadcast across the entire bridged network.

The software will time out the entries in the NetBIOS name cache after a specific interval of their initial storage. The timeout value is a user-configurable value. You can configure the timeout value for a particular Token Ring if the NetBIOS name cache is enabled on the interface connecting to that Token Ring. In addition, you can configure static name cache entries that never time out for frequently accessed servers whose locations or paths typically do not change. Static RIF entries are also specified for such hosts.

Generally, NetBIOS name caching is most useful when a large amount of NetBIOS broadcast traffic creates bottlenecks on WAN media connecting distant locations, and the WAN media is overwhelmed with this traffic. However, when two high-speed LAN segments are directly interconnected, the packet savings of NetBIOS name caching is probably not worth the processor overhead associated with it.

Note NetBIOS name caching is not recommended to be turned on in backbone routers, particularly if you have it enabled in all the routers connected to the backbone. NetBIOS caching should be distributed among multiple routers. NetBIOS name caching can be used only between Cisco routers that are running Software Release 9.1 or later.

To enable NetBIOS name caching, you must perform the tasks in the following sections:

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Enable the Proxy Explorers Feature on the Appropriate Interface

Specify Timeout and Enable NetBIOS Name Caching

In addition, you can configure NetBIOS name caching as described in the following sections:

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Configure the NetBIOS Cache Name Length

Enable NetBIOS Proxying

Configuring Source-Route Bridging BC-123

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Contents SRB Configuration Task List Configuring Source-Route BridgingConfigure a Dual-Port Bridge Configure Source-Route BridgingMultiple Dual-Port Bridges Configure a Multiport Bridge Using a Virtual RingDefine a Ring Group in SRB Context Source-bridge ring-group ring-groupNo source-bridge ring-group ring-group Source-bridge route-cache cbus Configure SRB over FddiEnable SRB and Assign a Ring Group to an Interface Interface fddi slot/portConfigure SRB over Frame Relay Configure Fast-Switching SRB over FddiEnable the Automatic Spanning-Tree Function Limit the Maximum SRB Hops Enable Use of the RIF Configure Bridging of Routed ProtocolsConfigure the RIF Timeout Interval Configure a Static RIF EntryOverview of SR/TLB Following notes and caveats apply to all uses of SR/TLB No source-bridge transparent ring-group fastswitch Enable Bridging between Transparent Bridging and SRBDisable Fast-Switched SR/TLB Enable Translation Compatibility with IBM 8209 BridgesSource-bridge sap-80d5 dsap Enable Token Ring LLC2-to-Ethernet ConversionEnable 0x80d5 Processing Enable Standard Token Ring LLC2-to-Ethernet LLC2 ConversionConfigure NetBIOS Support Source-bridge proxy-netbios-only Specify Timeout and Enable NetBIOS Name CachingSpecify Dead-Time Intervals for NetBIOS Packets Configure the NetBIOS Cache Name LengthEnable NetBIOS Proxying Create Static Entries in the NetBIOS Name CacheConfigure LNM Support Netbios name-cache query-timeout secondsNetbios name-cache recognized-timeout seconds LNM Linking to a Source-Route Bridge on Each Local Ring LAN Network Manager Monitoring and Translating How a Router Works with LNMDisable LNM Functionality Enable Other LRMs to Change Router Parameters Disable Automatic Report Path Trace FunctionApply a Password to an LNM Reporting Link Enable LNM ServersChange Reporting Thresholds Change an LNM Reporting Interval Monitor LNM OperationLnm softerr milliseconds Configure NetBIOS Access Filters Configure NetBIOS Access Filters Using Station NamesSecure the SRB Network Netbios input-access-filter bytes name Configure NetBIOS Access Filters Using a Byte OffsetNetbios access-list host name permit deny pattern Netbios access-list bytes name permit deny offsetConfigure Administrative Filters for Token Ring Traffic Netbios output-access-filter bytes nameFilter Frames by Protocol Type Filter Frames by Vendor Code Filter Source AddressesFilter Destination Addresses Access Expression Example Optimize Access Expressions Configure Access ExpressionsTune the SRB Network Alter Access Lists Used in Access ExpressionsEnable or Disable the Source-Route Fast-Switching Cache Enable or Disable the SSE Establish the Connection Timeout IntervalOptimize Explorer Processing Controlling Explorer Storms in Redundant Network Topologies Configure Proxy Explorers Establish SRB Interoperability with TI MAC FirmwareMac-address ieee-address Monitor and Maintain the SRB Network Report Spurious Frame-Copied ErrorsSource-bridge tcp-queue-max number SRB Configuration ExamplesBasic SRB with Spanning-Tree Explorers Example Dual-Port Source-Route Bridge ConfigurationSRB-Only Example Optimized Explorer Processing Configuration ExampleMultiport SRB Example SRB and Routing Certain Protocols ExampleSRB with Multiple Virtual Ring Groups Example Configuration for Router aRouter a SRB over Fddi Configuration ExamplesSRB over Fddi Fast-Switching Example Configuration for Router BFrad Using SRB over Frame Relay to Connect to a Cisco Router SRB over Frame Relay Configuration ExampleAdding a Static RIF Cache Entry Example Configuration of Router aConfiguration on Router B Configuration on Router CSR/TLB for a Simple Network Example Adding a Static RIF Cache Entry for a Two-Hop Path ExampleBC-154Bridging and IBM Networking Configuration Guide Example of a Bit-Swapped Address SR/TLB with Access Filtering ExampleSpecifying a Static Entry NetBIOS Support with a Static NetBIOS Cache Entry ExampleLNM for a Simple Network Example Wayfarer# show lnm configLNM 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 Following access expression would result Creating Access Filters ExampleFast-Switching Example Access Filters ExampleAutonomous Switching Example
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