Cisco IOS Software Releases 11.3

Table Of Contents

x Digital Subscriber Line
Bridge Support

Description

List of Terms

Platforms

Configuration Tasks

Configure a Subscriber Bridge Group

Monitor the Subscriber Bridge Group

Configuration Examples

Fast Ethernet Subscriber Port, Frame Relay Trunk Example

ATM Subscriber Ports, ATM Trunk Example

Command Reference

bridge subscriber-policy

bridge-group subscriber-trunk

show subscriber-policy

subscriber-policy

x Digital Subscriber Line
Bridge Support

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Description

The x digital subscriber line bridge support feature enables you to configure a router for intelligent bridge flooding for x digital subscriber line and other bridge applications.

List of Terms

Downstream—Indicates the traffic flow from the server to the client. In this document, downstream defines the traffic flow from the trunk port to the subscriber port.

Subscriber Bridge Group—Bridge group formed by the subscriber interfaces.

Subscriber Policy—Set of forwarding and filtering rules applied to the subscriber bridge group.

Trunk Port—Router interface connected to the backbone routers.

Upstream—Indicates the traffic flow from the client to the server. In this document, upstream defines the traffic flow from the subscriber to the trunk port.

xDSL—Digital subscriber line; x means different media.

Platforms

This feature is supported on all platforms.

Configuration Tasks

To configure the router for xDSL bridge support, perform the tasks in the following sections:

•Configure a Subscriber Bridge Group

•Monitor the Subscriber Bridge Group

Configure a Subscriber Bridge Group

To configure a subscriber bridge group, perform the following tasks, beginning in global configuration mode:

Task	Command
Define the bridge Spanning-Tree Protocol.	bridge bridge-group protocol {ieee | dec}
Define a subscriber bridge group and specify the subscriber policy for the group.	bridge bridge-group subscriber-policy policy
Define or modify the forward and filter decisions of the subscriber policy.	subscriber-policy policy [[no] [default] packet [permit] [deny]]
Configure a subinterface.	interface type number
Assign a subscriber bridge group and indicate whether the interface is upstream or downstream from the traffic flow.	bridge-group bridge-group [subscriber-trunk]

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Note   Standard access lists can coexist with the subscriber policy. However, subscriber policy will take precedence over the access list by being checked first. A packet permitted by the subscriber policy will be checked against the access list if it is specified. A packet denied by subscriber policy will be dropped with no further access list checking.

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Monitor the Subscriber Bridge Group

To monitor the subscriber bridge group, perform the following task in EXEC mode:

Task	Command
Display the details of the subscriber policy.	show subscriber-policy policy
Display details of the bridge group.	show bridge [bridge-group] [interface]

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Note   You can also use the EXEC commands show running-config and show startup-config. However, those two commands display only non-default values of the packets.

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Configuration Examples

This section provides the following subscriber bridge group configuration examples:

•Fast Ethernet Subscriber Port, Frame Relay Trunk Example

•ATM Subscriber Ports, ATM Trunk Example

Fast Ethernet Subscriber Port, Frame Relay Trunk Example

This example uses the Fast Ethernet subinterface as the subscriber port and Frame Relay as the trunk:

bridge 1 protocol ieee

# Form a subscriber bridge group using policy 1

#

bridge 1 subscriber-policy 1

bridge 1 protocol ieee

int fast0.1

encap isl 1

#

# Put fast0.1 into subscriber group 1

#

bridge-group 1

int fast0.2

encap isl 2

#

# put fast0.2 into subscriber group 1

#

bridge-group 1 

int serial0

encap frame-relay

int s0.1 point-to-point

#

# Use PVC 155 as the signal channel for setting up connections with the access-server

#

frame-relay interface-dlci 155 

#

# Set the trunk to go upstream

#

bridge-group 1 trunk

ATM Subscriber Ports, ATM Trunk Example

The following example uses ATM subinterfaces as the subscriber ports and the ATM as the trunk:

bridge 1 protocol ieee

#

# Use subscriber policy 3

#

bridge 1 subscriber-policy 3

#

# Change the ARP behavior from permit to deny

#

subscriber-policy 3 arp deny

#

# Change the multicast from permit to deny

#

subscriber-policy 3 multicast deny

int atm0

int atm0.1 point-to-point

#

# Use AAL5 SNAP encapsulation

#

atm pvc 1 0 101 aal5snap

bridge group 1

int atm0.2

#

# Use AAL5 SNAP encapsulation 

#

atm pvc 2 0 102 aal5snap

bridge-group 1

#

# Configure ATM trunk port 

#

int atm1.1

#

# Use AAL5 SNAP encapsulation

#

atm pvc 1 0 101 aal5snap

#

# Specify trunk

#

bridge-group 1 trunk

Command Reference

This section documents new or modified commands. All other commands used with this feature are documented in the Cisco IOS Release 11.3 command references.

•bridge subscriber-policy

•bridge-group subscriber-trunk

•show subscriber-policy

•subscriber-policy

bridge subscriber-policy

To bind a bridge group with a subscriber policy, use the bridge subscriber-policy global configuration command. Use the no form of this command to disable the subscriber bridge group feature.

bridge bridge-group subscriber-policy policy
no bridge bridge-group subscriber-policy policy

Syntax Description

bridge-group	Bridge group number, in the range of 1 to 256, specified in the bridge protocol command.
policy	Subscriber policy number in the range of 1 to 100.

Default

If no forward or filter decisions have been specified for the subscriber policy, the following defaults are applied:

Packet	Upstream
ARP	Permit
Broadcast	Deny
CDP	Deny/Disable
Multicast	Permit
STP	Deny/Disable
Unknown Unicast	Deny

Command Mode

Global configuration

Usage Guidelines

Standard access lists can coexist with the subscriber policy. However, subscriber policy will take precedence over the access list by being checked first. A packet permitted by the subscriber policy will be checked against the access list if it is specified. A packet denied by subscriber policy will be dropped with no further access list checking.

Example

The following example forms a subscriber bridge group using policy 1.

bridge 1 subscriber-policy 1

Related Commands

bridge protocol
show subscriber-policy
subscriber-policy

bridge-group subscriber-trunk

To specify that an interface is at the upstream point of traffic flow, use the bridge-group subscriber-trunk interface configuration command. Use the no form of this command to remove the specification and reset the interface to a non-trunking port.

bridge-group bridge-group subscriber-trunk
no bridge-group bridge-group subscriber-trunk

Syntax Description

bridge-group

Bridge group number, in the range from 1 to 256, specified in the bridge protocol command.

Default

The interface is set to a non-trunking port.

Command Mode

Interface Configuration

Example

The following example sets bridge-group 1 as the upstream point of traffic flow:

bridge-group 1 subscriber-trunk

Related Commands

bridge protocol
bridge subscriber-policy
show subscriber-policy
subscriber-policy

show subscriber-policy

To display the details of a subscriber policy, use the show subscriber-policy EXEC command.

show subscriber-policy range

Syntax Description

range

Range of subscriber policy numbers (range 1 to 100).

Default

If a range is not specified, the entire range (1 to 100) is displayed.

Command Mode

EXEC

Sample Display

The following is sample output from the show subscriber-policy command:

Router# show subscriber-policy 1

ARP: Permit 

Broadcast: Deny

Multicast: Permit

Unknown: Deny

STP: Disable

CDP: Disable

Related Commands

bridge protocol
bridge subscriber-policy
show bridge
subscriber-policy

subscriber-policy

To define or modify the forward and filter decisions of the subscriber policy, use the subscriber-policy global configuration command. Use the no or default form of this command to restore the default forward and filter values.

subscriber-policy policy [[no | default] packet [permit | deny]]

Command Syntax

policy	Subscriber policy number in the range 1 to 100.
no	Turn off the permit for the packet (this is an equivalent of the deny keyword).
default	Deny forwarding of the packet (this is an equivalent of the deny keyword).
packet	One of the following packets: •arp •broadcast •cdp •multicast •stp •unknown unicast
permit	Permit forwarding of the packet.
deny	Deny forwarding of the packet.

Default

If no forward or filter decisions have been specified for the subscriber policy, the following defaults are applied:

Packet	Upstream
ARP	Permit
Broadcast	Deny
CDP	Deny/Disable
Multicast	Permit
STP	Deny/Disable
Unknown Unicast	Deny

Command Mode

Global configuration

Usage Guidelines

As an alternative to the command syntax described above, you can enter subscriber-policy policy, followed by the specific forward or filter decisions for each packet.

Example

The following example changes the ARP behavior and the multicast behavior from permit to deny, using the command syntax shown in the Command Syntax section:

subscriber-policy 3 arp deny

subscriber-policy 3 multicast deny

The following example changes the ARP behavior and the multicast behavior from permit to deny, using the alternative syntax shown in the Usage Guidelines section:

subscriber-policy 3

arp deny

multicast deny

Related Commands

bridge protocol
bridge subscriber-policy
show subscriber-policy