3Com Corporation
 Restricted Rights Legend
Restricted Rights Notification for U.S. Government Users
 Proprietary Material
Page
 Overview
Solutions
Functionality
Multiple LANs
 Bridging
Translational
No Local Bridging
Transparent
 This Manual Topic
 This Notice Topic
 Switches
Bridging Features and Capabilities
Introduction
Bridging Primer
 Ethernet LAN
 Ethernet Bridge
Example
Operation
WAN application, but you can also bridge across an X.25 WAN
 Mixed LAN Bridging
 MAC Addressing
 LLC2 Local
LLC2 Local Termination
Termination
LT Example
 Autolearn for Local Termination
 Filtering
NetBIOS Name
Mac Address
Filtering
 Spanning Tree Protocol
What Is It? Automatic Manual Spanning Tree Support
 Dual Ethernet LANs
 Basic Remote Bridging Examples
Across a WAN
WAN or Permanent Virtual Circuit PVC for Frame Relay
 Example of Bridges in an SVC Arrangement
 Connections
Bridge
LAN Interface
Support
 Bridging
 Interface Connections Between WAN and LAN
Setting Up WAN Operation for Bridging
 Setting Up WAN Operation for Bridging
 Configure
 Parameters
Bridge Parameters
These parameters make up the Bridge Parameter Record
Maximum Number of Bridge Links
 Stpe Control
Bad Hello Timeout
AUTO, MAN
MAN
 Learn Only Period used for Ethernet only
Aging Period used for Ethernet only
Bridge WAN Data Priority used for Ethernet only
 Bridged Protocols
 Bridge Link Parameters
Parameters control the characteristics of this connection
Bridge links as links to the networks attached to it
Bridge Link
 Entry Number
These parameters make up the Bridge Link Record
BridgeType
SR, TB, Bothsrandtb
 Largest Frame Size
Hop Count Limit
MAC Address Filter Action
NONE, PASS, Block
 Netbios Name Filter Action
Protocol Filter Action
Stpe Link State
 NORMAL,RFC1294, Trans
Link Mode
Normal
Virtual Ring Number
 Over the WAN
LAN Connection Table
LAN Connection
Table Parameters
 ROUT, BRID, Brout
LAN Forwarder Type
Rout
LAN Connection Type
 Codex
Encapsulation Type
Autocall Mnemonic
Lcon Queue Limit
 OFF, on
Billing Records
OFF
Traffic Priority
 Limiting Bridge Frame Sizes
Where bridging is done remotely across a WAN
Overview
Transmission times for large frames become significant
 Sizes
Standard Frame
Maximum frame size
Max Frame Size Line Speed Range kbps
 Configuring Translational Bridging
 Translational Bridging Example
 Bridge Frame Handling
 Configuring
Configuring Source Route Bridging Operation
Node for SRB
Individual Bridge
 Bridging
 Procedure
Connecting a Station to a Server in Source Route Bridging
LAN for a Source Route Bridging operation
Located on remote LAN CCC Figure
 Server’s Destination MAC Address Not on LAN AAA
 LAN Bridge Link
 WAN Adapter Transmits Each are Frame Across the WAN
 Server Responds with Specifically Routed Test Frame
 Then
Step Action Result/Description
 Transparent Bridging for Ethernet LANs
Learning
Forwarder
 Forwarder Example
LAN link WAN link Link error
Statistics
Filtering
 Hardware
Accelerator LAN/WAN Handlers
Hardware Accelerator Functions
 Forwarder Functions Forwarder Initialization
 Aging
Learn Only Period
 Forwarder Database and Spanning Tree
 Using Filters
 Frame is dropped
Multicast Link
List, the frame is dropped
Control menu located in the Main menu
 TB Forwarding
Transparent Bridge Configuration Parameters
Local MAC Address
Bridge Link Number
 Bridge Filtering
What is It? How Filtering is Used
 Parameter Action
MAC Address Filtering
 Parameter Action Value
Parameter
 Process
MAC Filtering
 Example of a Frame Passing on a Bridge Link
Mac Filtering Process Incoming and Outgoing Frames
 Configuring the Bridge Link Record
How To Configure Example
MAC Address Filtering Examples
First Example
 Configuring the MAC Address Filter Table
 Why it is Important
Identifying Address Links for MAC Addressing
Address Links
 Series Switch Support
MAC Wildcard Filtering
Filtering works
 Configuring the MAC Address Filter Table
Broadcast frames in the LAN network
Categories
 Incoming Source Address Link Action
These parameters make up the MAC Address Filter Table
PASS, BLOCK, PASSLIST, Blocklist
Pass
 Incoming Destination Address Link Action
Outgoing Source Address Link Action
 List of Links
Outgoing Destination Address Link Action
 Protocol Filtering
 These parameters make up the Protocol Filter Table Record
Protocol Filter
 Protocol SAP hex value
Protocol Type
Protocol OUI/IP hex value
Protocol Value
 Outgoing Protocol Link Action
Incoming Protocol Link Action
 Dsap Values
 Parameter Actions
 NetBIOS Name Filtering
Broadcasts to and from the SVR* name pattern
Transparent Bridging
 Forcing a Local
Checking NetBIOS
Domain With
Filters
 How to Configure
Configuring NetBIOS Name Filtering
NetBIOS Name Filtering
Step Action
 Step Action Result
Select Configure Configure
Entry Number 1 appears
Bridge Bridge Link
 NetBIOS Name Filter Table
Configure NetBIOS
Bridge -NetBIOS Name Filter
Name Filter Table
 Typical Filtering
String Type
Ascii
 Incoming NetBIOS Name List of Links
Incoming NetBIOS Name Link Action
 Outgoing NetBIOS Name List of LInks
Outgoing NetBIOS Name Link Action
 NetBIOS broadcasts filtered on the link
NetBIOS Name Filtering Statistics
Each bridge link
Check Detailed
 IBM NetBIOS Formats When to Use NetBIOS Name Filtering
NetBIOS Packet Formats
All of the following are true
Either one of the following is true
 Spanning Tree Protocol Entity Stpe
Configuration Stpe Control= Auto Stpe Control = Manual Menu
Spanning Tree
Tree
 Bridge Links
 Spanning Tree Protocol Entity Stpe
 Stpe Parameter Setting Considerations
Example of a
Bridge Network
 Setting the Root Bridge Spanning Tree
Bridge ID equals Bridge Priority Value in hex + MAC Address
Determining Root Links Designated Links
 Type of Network Speed Stpe Path Cost
 Nature
Consider
Expected Number
SVCs
 Two Bridge Links Between B3 and B4
 Spanning Tree Protocol Entity Stpe
 Timer Parameters
Spanning Tree Timers
Hello Timer
Max Age
 Considerations
Other
 Message Events in Network
Bridge Forward Delay Timer
 Spanning Tree Protocol Entity Stpe
 Aging Timer
Bridges can adjust to the change
Location and forwards packets to it properly
 LLC2 Local Termination
Preventing session timeouts in a Bridging application
 Terminal session, causing
Well as network delays
Before Local
After Local
 Supported
Topologies
Improper LT
 Proper LT configuration
LLC Protocol LLC Frame Description LLC2 Frame Description
Type Name Description
 Local Termination does not spoof
Local Termination spoofs
 Bridging 105
 Local Termination
Configuring Local Termination
 Boot Type LLC LT Station
Step
Station Table Entry Number
 T2 Rx Ack Timer
WAN Parameters T1Reply Timer
Local SAP
LLC Profile Name
 Ti Inactivity Timer
Boot Type LLC LT WAN Parameters
N3 ACK Delay Count
N2 Retry Count
 Tx Window Size
Configuration Entry Number
LCC LT WAN Data Priority
HIGH, MEDIUM, LOW
 T1 Reply Timer
 112 Bridging
 Deleting LT Configuration Records
 27x switch, as shown in Figure
Mixed LAN Operation
Mixed LAN Environment Limitations
 Bridge Link Parameters menu
Select Configure Bridge
Bridge Link Parameters from
CTP Main menu, to activate Bridge link
 Bothsrandtb
 Dual LAN Ethernet
System powerup
 Supported
Routing
Dual Ethernet LAN
Cmem
 Parameters
For Details on
 LAN Server Subsystem
 Alarms
 Example of LCC
Configuring the LSS Record
Record
Virtual Port’s MAC Address
 Disable
ENABLE, Disable
Virtual Bridge ID
Path Trace Control
 Statistics Menu screen
Bridge Statistics
 Stpe Status
Spanning Tree Statistics
Status report
Term Description
 State
Disabled The Stpe is disabled. If Stpe Control
Are
Parameter is MAN
 Detailed Bridge Link Statistics First
Detailed Bridge Link Statistics
 Screen Terms
 RIF
 Link Filter
Bridge Link Filter Summary
Summary
Description
 Bridging 131
 Stats Example
Transparent Bridge Forwarding Table Statistics
Stats Descriptions
Shown in Figure
 Bridging 133
 Terms-Transparent Bridge Second
Transparent Bridge Detailed Bridge Link Statistics
 FF-FF-FF-FF-FF-FF
Frame Totals This is a count of the number of frames
Received/transmitted of all types on this link
 LAN Connection Statistics
Statistics Menu
Detailed LAN Connection Statistics
 Detailed LAN Connection Statistics Second
 Last clear diagnostic code This is the diagnostic code
Explains why the last call was cleared
Connection and explains why the call was cleared
SVCs. The possible states are Blank for PVCs blank
 Bridging 139
 Connection Summary Statistics
Example of LAN shows the LAN Connection Summary Statistics
 Heading Description
LLC2 LT Session Summary Statistics
SAP
Remote MAC Addr
 Heading
 Session Statistics
LLC2 LT Detailed Session Statistics
 Last Statistics Last time statistics were reset Reset
Routing information field used in all frames transmitted
Field, ring number, and bridge number information
 Heading Description Local Station Session Summary
 Heading Description Remote Spoofer Session Summary
 Reset Statistics
 148 Bridging
 Technical Support
 3ComFacts Automated Fax Service
Access by Analog Modem
Access by Digital Modem
Country Data Rate Telephone Number
 Support from
3Com
Country Telephone Number
 Country Telephone Number Fax Number
 Numerics
Index
 LAN
 OUI
 URL A-1
 Index-5