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bridge-group spanning-disabled
Bridging Commands
bridge acquire
To forward any frames for stations that the system has learned about dynamically, use the bridge acquire command in global configuration mode. To disable the behavior, use the no form of this command.
bridge bridge-group acquire
no bridge bridge-group acquire
Syntax Description
Defaults
Enabled
Command Modes
Global configuration
Command History
Usage Guidelines
When using the command default, the Cisco IOS software forwards any frames from stations that it has learned about dynamically. If you use the no form of this command, the bridge stops forwarding frames to stations it has dynamically learned about through the discovery process and limits frame forwarding to statically configured stations. That is, the bridge filters out all frames except those whose sourced-by or destined-to addresses have been statically configured into the forwarding cache. The no form of this command prevents the forwarding of a dynamically learned address.
Examples
The following example shows how to prevent the forwarding of dynamically determined source and destination addresses:
no bridge 1 acquireRelated Commands
bridge address
Filters frames with a particular MAC-layer station source or destination address.
bridge protocol
Defines the type of Spanning Tree Protocol.
bridge address
To filter frames with a particular MAC-layer station source or destination address, use the bridge address in global configuration mode. To disable the filtering of frames, use the no form of this command.
bridge bridge-group address mac-address {forward | discard} [interface]
no bridge bridge-group address mac-address
Syntax Description
Defaults
Disabled
Command Modes
Global configuration
Command History
Usage Guidelines
Any number of addresses can be configured into the system without a performance penalty.
Note
MAC addresses on Ethernet are "bit-swapped" when compared with MAC addresses on Token Ring and FDDI. For example, address 0110.2222.3333 on Ethernet is 8008.4444.CCCC on Token Ring and FDDI. Access lists always use the canonical Ethernet representation. When using different media and building access lists to filter on MAC addresses, remember this point. Note that when a bridged packet traverses a serial link, it has an Ethernet-style address.
Examples
The following example shows how to enable frame filtering with MAC address 0800.cb00.45e9. The frame is forwarded through Ethernet interface 1:
bridge 1 address 0800.cb00.45e9 forward ethernet 1The following example shows how to disable the ability to forward frames with MAC address 0800.cb00.45e9:
no bridge 1 address 0800.cb00.45e9Related Commands
bridge bridge
To enable the bridging of a specified protocol in a specified bridge group, use the bridge bridge command in global configuration mode. To disable the bridging of a specified protocol in a specified bridge group, use the no form of this command.
bridge bridge-group bridge protocol
no bridge bridge-group bridge protocol
Syntax Description
bridge-group
Bridge group number specified in the bridge protocol command.
protocol
Any of the supported routing protocols. The default is to bridge all of these protocols.
Defaults
Bridge every protocol.
Command Modes
Global configuration
Command History
Usage Guidelines
When integrated routing and bridging (IRB) is enabled, the default route/bridge behavior in a bridge group is to bridge all protocols. You need not use the bridge bridge command to enable bridging.
You can use the no bridge bridge command to disable bridging in a bridge group so that it does not bridge a particular protocol. When you disable bridging for a protocol in a bridge group, routable packets of this protocol are routed when the bridge is explicitly configured to route this protocol, and nonroutable packets are dropped because bridging is disabled for this protocol.
Note
Examples
The following example shows how to disable bridging of IP in bridge group 1:
no bridge 1 bridge ipRelated Commands
bridge forward-time
To specify the forward delay interval for the Cisco IOS software, use the bridge forward-time command in global configuration mode. To return to the default interval, use the no form of this command.
bridge bridge-group forward-time seconds
no bridge bridge-group forward-time seconds
Syntax Description
bridge-group
Bridge group number specified in the bridge protocol command.
seconds
Forward delay interval. It must be a value in the range from 10 to 200 seconds. The default is 30 seconds.
Defaults
30-second delay
Command Modes
Global configuration
Command History
Usage Guidelines
The forward delay interval is the amount of time the software spends listening for topology change information after an interface has been activated for bridging and before forwarding actually begins.
Each bridge in a spanning tree adopts the hello-time, forward-time, and max-age parameters of the root bridge, regardless of its individual configuration.
Examples
The following example shows how to set the forward delay interval to 60 seconds:
bridge 1 forward-time 60Related Commands
bridge hello-time
To specify the interval between hello bridge protocol data units (BPDUs), use the bridge hello-time command in global configuration mode. To return the default interval, use the no form of this command.
bridge bridge-group hello-time seconds
no bridge bridge-group hello-time
Syntax Description
bridge-group
Bridge group number specified in the bridge protocol command.
seconds
Interval from 1 to 10 seconds. The default is 1 second.
Defaults
1 second
Command Modes
Global configuration
Command History
Usage Guidelines
Each bridge in a spanning tree adopts the hello-time, forward-time, and max-age parameters of the root bridge, regardless of its individual configuration.
Examples
The following example shows how to set the interval to 5 seconds:
bridge 1 hello-time 5Related Commands
bridge irb
To enable the Cisco IOS software to route a given protocol between routed interfaces and bridge groups or to route a given protocol between bridge groups, use the bridge irb command in global configuration mode. To disable the feature, use the no form of this command.
bridge irb
no bridge irb
Syntax Description
This command has no arguments or keywords.
Defaults
Integrated routing and bridging (IRB) is disabled.
Command Modes
Global configuration
Command History
Usage Guidelines
IRB is supported for transparent bridging, but not for source-route bridging. IRB is supported on all interface media types except X.25 and ISDN bridged interfaces.
Examples
The following shows how to enable integrated routing and bridging:
bridge irbRelated Commands
bridge max-age
To change the interval the bridge will wait to hear Bridge Protocol Data Unit (BPDU) from the root bridge, use the bridge max-age command in global configuration mode. To return to the default interval, use the no form of this command.
bridge bridge-group max-age seconds
no bridge bridge-group max-age
Syntax Description
Defaults
15 seconds
Command Modes
Global configuration
Command History
Usage Guidelines
Each bridge in a spanning tree adopts the hello-time, forward-time, and max-age parameters of the root bridge, regardless of its individual configuration. If a bridge does not receive BPDUs from the root bridge within this specified interval, it considers the network to be changed and will recompute the spanning-tree topology.
Examples
The following example increases the maximum idle interval to 20 seconds:
bridge 1 max-age 20Related Commands
bridge protocol
To define the type of Spanning Tree Protocol, use the bridge protocol command in global configuration mode. To delete the bridge group, use the no form of this command with the appropriate keywords and arguments.
bridge bridge-group protocol {dec | ibm | ieee | vlan-bridge}
no bridge bridge-group protocol {dec | ibm | ieee | vlan-bridge}
Syntax Description
Defaults
No Spanning Tree Protocol is defined.
Command Modes
Global configuration
Command History
Usage Guidelines
The routers support two Spanning Tree Protocols: the IEEE 802.1 standard and the earlier Digital Spanning Tree Protocol upon which the IEEE standard is based. Multiple domains are supported for the IEEE 802.1 Spanning Tree Protocol.
Note
Examples
The following example shows bridge 1 as using the Digital Spanning Tree Protocol:
bridge 1 protocol decRelated Commands
bridge domain
Establishes a domain by assigning it a decimal value from 1 to 10.
bridge-group
Assigns each network interface to a bridge group.
bridge route
To enable the routing of a specified protocol in a specified bridge group, use the bridge route command in global configuration mode. To disable the routing of a specified protocol in a specified bridge group, use the no form of this command.
bridge bridge-group route protocol
no bridge bridge-group route protocol
Syntax Description
bridge-group
Bridge group number specified in the bridge protocol command.
protocol
One of the following protocols:
•
•
•
•
•
Defaults
No default bridge group or protocol is specified.
Command Modes
Global configuration
Command History
Examples
In the following example, AppleTalk and IP are routed on bridge group 1:
bridge crbbridge 1 protocol ieeebridge 1 route appletalkbridge 1 route ipRelated Commands
bridge-group aging-time
To set the length of time that a dynamic entry can remain in the bridge table from the time the entry was created or last updated, use the bridge-group aging-time command in global configuration mode. To return to the default aging-time interval, use the no form of this command.
bridge-group bridge-group aging-time seconds
no bridge-group bridge-group aging-time
Syntax Description
Defaults
300 seconds
Command Modes
Global configuration
Command History
Usage Guidelines
If hosts on a bridged network are likely to move, decrease the aging time to enable the bridge to adapt quickly to the change. If hosts do not send continuously, increase the aging time to record the dynamic entries for a longer time and thus reduce the possibility of flooding when the hosts send again.
Examples
The following example sets the aging time to 200 seconds:
bridge-group 1 aging-time 200Related Commands
bridge-group path-cost
To set a different path cost, use the bridge-group path-cost command in interface configuration mode. To choose the default path cost for the interface, use the no form of this command.
bridge-group bridge-group path-cost cost
no bridge-group bridge-group path-cost cost
Syntax Description
Defaults
The default path cost is computed from the interface's bandwidth setting. The following are IEEE default path cost values. The Digital path cost default values are different.
•
•
•
•
•
Command Modes
Interface configuration
Command History
Usage Guidelines
By convention, the path cost is 10000/data rate of the attached LAN (IEEE), or 100000/data rate of the attached LAN (Digital), in megabits per second.
Examples
The following example changes the default path cost for Ethernet interface 0:
interface ethernet 0bridge-group 1 path-cost 250Related Commands
bridge-group priority
To set an interface priority, use the bridge-group priority command in interface configuration mode. The interface priority is used to select the designated port for this bridge-group on the connected media. One designated port on each medium is needed to compute the spanning tree.
bridge-group bridge-group priority number
Syntax Description
Defaults
When the IEEE Spanning Tree Protocol is enabled on the router: 32768
When the Digital Spanning Tree Protocol is enabled on the router: 128Command Modes
Interface configuration
Command History
Usage Guidelines
The lower the number, the more likely it is that the bridge on the interface will be chosen as the root.
There is not a no form for this command.
Examples
The following example increases the likelihood that the root bridge will be the one on Ethernet interface 0 in bridge group 1:
interface ethernet 0bridge-group 1 priority 0The following example shows the bridge-group priority help information for 9-bit port number size:
Router(config-if)# bridge-group 1 priority ?<0-255> increments of 2 for IEEE or vlan-bridge, others 1The following example shows the bridge-group priority help information for 10-bit port number size:
Router(config-if)# bridge-group 1 priority ?<0-255> increments of 4 for IEEE or vlan-bridge, others 1Related Commands
bridge-group spanning-disabled
To disable the spanning tree on a given interface, use the bridge-group spanning-disabled command in interface configuration mode. To enable the spanning tree on a given interface, use the no form of this command.
bridge-group bridge-group spanning-disabled
no bridge-group bridge-group spanning-disabled
Syntax Description
bridge-group
Number of the bridge group to which the interface belongs. It must be a number in the range from of 1 to 255.
Defaults
Spanning tree is enabled.
Command Modes
Interface configuration
Command History
Usage Guidelines
To enable transparent bridging on an interface, use the bridge protocol command to specify the type of Spanning Tree Protocol to be used. The bridge-group spanning-disabled command can be used to disable that spanning tree on that interface.
When a loop-free path exists between any two bridged subnetworks, you can prevent Bridge Protocol Data Unit (BPDU)s generated in one transparent bridging subnetwork from impacting nodes in the other transparent bridging subnetwork, yet still permit bridging throughout the bridged network as a whole.
For example, when transparently bridged LAN subnetworks are separated by a WAN, you can use this command to prevent BPDUs from traveling across the WAN link. You would apply this command to the serial interfaces connecting to the WAN in order to prevent BPDUs generated in one domain from impacting nodes in the remote domain. Because these BPDUs are prevented from traveling across the WAN link, using this command also has the secondary advantage of reducing traffic across the WAN link.
Note
Examples
In the following example, the spanning tree for the serial interface 0 is disabled:
interface serial 0bridge-group 1 spanning-disabledRelated Commands
bridge-group
Assigns each network interface to a bridge group.
bridge protocol
Defines the type of Spanning Tree Protocol.
clear bridge
To remove any learned entries from the forwarding database and to clear the transmit and receive counts for any statically or system-configured entries, use the clear bridge command in privileged EXEC mode.
clear bridge bridge-group
Syntax Description
Defaults
No default behavior or values
Command Modes
Privileged EXEC
Command History
Examples
The following example shows the use of the clear bridge command:
Router# clear bridge 1Related Commands
bridge address
Filters frames with a particular MAC-layer station source or destination address.
bridge protocol
Defines the type of Spanning Tree Protocol.
interface bvi
To create the bridge-group virtual interface (BVI) that represents the specified bridge group to the routed world and links the corresponding bridge group to the other routed interfaces, use the interface bvi command in global configuration mode. To delete the BVI, use the no form of this command.
interface bvi bridge-group
no interface bvi bridge-group
Syntax Description
Defaults
No BVI is created.
Command Modes
Global configuration
Command History
Usage Guidelines
You must enable integrated routing and bridging (IRB) before attempting to create a BVI.
When you intend to bridge and route a given protocol in the same bridge group, you must configure the network-layer attributes of the protocol on the BVI. Do not configure protocol attributes on the bridged interfaces. No bridging attributes can be configured on the BVI.
Examples
The following example creates a bridge group virtual interface and associates it with bridge group 1:
interface bvi 1Related Commands
bridge irb
Enables the Cisco IOS software to route a given protocol between routed interfaces and bridge groups or to route a given protocol between bridge groups.
show bridge
To display classes of entries in the bridge forwarding database, use the show bridge command in privileged EXEC mode.
show bridge [bridge-group] [interface] [address [mask]] [verbose]
Syntax Description
Command Modes
Privileged EXEC
Command History
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0. The verbose keyword first appeared in
Cisco IOS Release 11.0.The following are possible variations of the show bridge command:
show bridge ethernet 0show bridge 0000.0c00.0000 0000.00FF.FFFFshow bridge 0000.0c00.0e1ashow bridgeshow bridge verboseIn the sample output, the first command would display all entries for hosts reachable via Ethernet interface 0, the second command would display all entries with the vendor code of 0000.0c00.0000, and the third command would display the entry for address 0000.0c00.0e1a. In the fourth command, all entries in the forwarding database would be displayed. The fifth command provides additional detail. In all five lines, the bridge group number has been omitted.
Examples
The following is sample output from the show bridge command. The second display is output from the
show bridge command with the verbose argument.Router# show bridgeTotal of 300 station blocks, 280 freeCodes: P - permanent, S - selfBridge Group 32:Bridge Group 32:Address Action Interface Age RX count TX count0180.c200.0000 receive - S 0 0ffff.ffff.ffff receive - S 0 00900.2b01.0001 receive - S 0 00300.0c00.0001 receive - S 0 00000.0c05.1000 forward Ethernet0/1 4 1 00000.0c04.4b5b receive - S 0 00000.0c04.4b5e receive - S 0 00000.0c04.4b5d receive - S 0 00000.0c04.4b5c receive - S 0 00000.0c05.4a62 forward Ethernet0/1 4 1 0aa00.0400.2108 forward Ethernet0/1 0 42 00000.0c12.b888 forward Ethernet0/2 4 1 00000.0c12.b886 forward Ethernet0/1 4 1 0aa00.0400.4d09 forward Ethernet0/1 4 1 00000.0c06.fb9a forward Ethernet0/1 4 1 00000.0c04.b039 forward Ethernet0/1 4 1 0Router# show bridge verboseTotal of 300 station blocks, 287 freeCodes: P - permanent, S - selfBG Hash Address Action Interface DLCI Age RX count TX count32 00/0 0180.c200.0000 receive - - S 0 032 00/1 ffff.ffff.ffff receive - - S 0 032 01/0 0900.2b01.0001 receive - - S 0 032 01/1 0300.0c00.0001 receive - - S 0 032 10/0 0000.0c04.4b5b receive - - S 0 032 15/0 0000.0c04.4b5e receive - - S 0 032 16/0 0000.0c04.4b5d receive - - S 0 032 17/0 0000.0c04.4b5c receive - - S 0 032 29/0 aa00.0400.2108 forward Ethernet0/1 - 0 48 032 30/0 0000.0c12.b888 forward Ethernet0/2 - 0 1 032 A4/0 0800.2002.ff5b forward Ethernet0/1 - 0 6 032 E2/0 aa00.0400.e90b forward Ethernet0/1 - 0 65 032 F2/0 0000.0c04.b042 forward Ethernet0/2 - 3 2 0Table 1 describes the significant fields shown in the display.
