To enable RFC 1483 ATM bridging or RFC 1490 Frame Relay bridging to map a bridged VLAN to an ATM permanent virtual circuit
(PVC) or Frame Relay data-link connection identifier (DLCI), use the
bridge-domain command in Frame Relay DLCI configuration, interface configuration, interface ATM VC configuration, or PVC range configuration
mode. To disable bridging, use the
no form of this command.
bridge-domain vlan-id [access | dot1q [tag] | dot1q-tunnel] [broadcast] [ignore-bpdu-pid] [pvst-tlv CE-vlan] [increment] [lan-fcs] [split-horizon]
no bridge-domain vlan-id
Syntax Description
vlan-id
|
The number of the VLAN to be used in this bridging configuration. The valid range is from 2 to 4094.
|
access
|
(Optional) Enables bridging access mode, in which the bridged connection does not transmit or act upon bridge protocol data
unit (BPDU) packets.
|
dot1q
|
(Optional) Enables Institute of Electrical and Electronic Engineers (IEEE) 802.1Q tagging to preserve the class of service
(CoS) information from the Ethernet frames across the ATM network. If this keyword is not specified, the ingress side assumes
a CoS value of 0 for quality of service (QoS) purposes.
|
tag
|
(Optional--ATM PVCs only) Specifies the 802.1Q value in the range 1 to 4095. You can specify up to 32
bridge-domain command entries using
dot1q tag for a single PVC. The highest tag value in a group of
bridge-domain commands must be greater than the first tag entered (but no more than 32 greater).
|
dot1q-tunnel
|
(Optional) Enables IEEE 802.1Q tunneling mode, so that service providers can use a single VLAN to support customers who have
multiple VLANs, while preserving customer VLAN IDs and segregating traffic in different customer VLANs.
|
broadcast
|
(Optional) Enables bridging broadcast mode on this PVC. This option is not supported for multipoint bridging. Support for
this option was removed in Cisco IOS Release 12.2(18)SXF2 and Cisco IOS Release 12.2(33)SRA.
|
ignore-bpdu-pid
|
(Optional for ATM interfaces only) Ignores BPDU protocol identifiers (PIDs) and treats all BPDU packets as data packets to
allow interoperation with ATM customer premises equipment (CPE) devices that do not distinguish BPDU packets from data packets.
|
pvst-tlv
|
(Optional) When the router or switch is transmitting, translates Per-VLAN Spanning Tree Plus (PVST+) BPDUs into IEEE BPDUs.
When the router or switch is receiving, translates IEEE BPDUs into PVST+ BPDUs.
|
CE-vlan
|
Customer-edge VLAN in the Shared Spanning Tree Protocol (SSTP) tag-length-value (TLV) to be inserted in an IEEE BPDU to a
PVST+ BPDU conversion.
|
increment
|
(PVC range configuration mode only) (Optional) Increments the bridge domain number for each PVC in the range.
|
lan-fcs
|
(Optional) Specifies that the VLAN bridging should preserve the Ethernet LAN frame checksum (FCS) of the Ethernet frames
across the ATM network.
Note
|
This option applies only to routers using a FlexWAN module. Support for this option was removed in Cisco IOS Release 12.2(18)SXF2
and Cisco IOS Release 12.2(33)SRA.
|
|
split-horizon
|
(Optional) Enables RFC 1483 split horizon mode to globally prevent bridging between PVCs in the same VLAN.
|
Command Default
Bridging is disabled.
Command Modes
Frame Relay DLCI configuration (config-fr-dlci) Interface configuration (config-if)--Only the
dot1q and
dot1q-tunnel keywords are supported in interface configuration mode. Interface ATM VC configuration (config-if-atm-vc) PVC range configuration
(config-if-atm-range)
Command History
Release
|
Modification
|
12.1(13)E
|
This command was introduced as the
bridge-vlan command for the 2-port OC-12 ATM WAN Optical Services Modules (OSMs) on Cisco 7600 series routers and Catalyst 6500 series
switches.
|
12.1(12c)E
|
This command was integrated into Cisco IOS Release 12.1(12c)E.
|
12.1(14)E1
|
This command was integrated into Cisco IOS Release 12.1(14)E1. The
dot1q-tunnel keyword was added.
|
12.2(14)SX
|
This command was integrated into Cisco IOS Release 12.2(14)SX. The
dot1q-tunnel keyword is not supported in this release.
|
12.1(19)E
|
The
split-horizon keyword was added.
|
12.2(18)S
|
This command was integrated into Cisco IOS Release 12.2(18)S. The
dot1q-tunnel and
split-horizon keywords are supported in this release.
|
12.2(17a)SX
|
Support was added for the
dot1q-tunnel keyword in Cisco IOS Release 12.2(17a)SX.
|
12.2(18)SXE
|
This command was renamed from
bridge-vlan to
bridge-domain . The
access ,
broadcast ,
ignore-bpdu-pid , and
increment keywords were added.
|
12.2(18)SXF2
|
Support for the
lan-fcs and
broadcast keywords was removed. The
ignore-bpdu-pid and
pvst-tlv keywords were added.
|
12.2(33)SRA
|
This command was integrated into Cisco IOS Release 12.2(33)SRA.
|
Usage Guidelines
RFC 1483 bridging on ATM interfaces supports the point-to-point bridging of Layer 2 packet data units (PDUs) over Ethernet
networks. RFC 1490 Frame Relay bridging on Packet over SONET (POS) or serial interfaces that are configured for Frame Relay
encapsulation provides bridging of Frame Relay packets over Ethernet networks.
The Cisco 7600 router can transmit BPDUs with a PID of either 0x00-0E or 0x00-07. When the router connects to a device that
is fully compliant with RFC 1483 Appendix B, in which the IEEE BPDUs are sent and received by the other device using a PID
of 0x00-0E, you must not use the
ignore-bpdu-pid keyword.
If you do not enter the
ignore-bpdu-pid keyword, the PVC between the devices operates in compliance with RFC 1483 Appendix B. This is referred to as
strict mode . Entering the
ignore-bpdu-pid keyword creates
loose mode . Both modes are described as follows:
-
Without the
ignore-bpdu-pid keyword, in strict mode, IEEE BPDUs are sent out using a PID of 0x00-0E, which complies with RFC 1483.
-
With the
ignore-bpdu-pid keyword, in loose mode, IEEE BPDUs are sent out using a PID of 0x00-07, which is normally reserved for RFC 1483 data.
Cisco-proprietary PVST+ BPDUs are always sent out on data frames using a PID of 0x00-07, regardless of whether you enter
the
ignore-bpdu-pid keyword.
Use the
ignore-bpdu-pid keyword when connecting to devices such as ATM digital subscriber line (DSL) modems that send PVST (or 802.1D) BPDUs with
a PID of 0x00-07.
The
pvst-tlv keyword enables BPDU translation when the router interoperates with devices that understand only PVST or IEEE Spanning Tree
Protocol. Because the Catalyst 6500 series switch ATM modules support PVST+ only, you must use the
pvst-tlv keyword when connecting to a Catalyst 5000 family switch that understands only PVST on its ATM modules, or when connecting
with other Cisco IOS routers that understand IEEE format only.
When the router or switch is transmitting, the
pvst-tlv keyword translates PVST+ BPDUs into IEEE BPDUs.
When the router or switch is receiving, the
pvst-tlv keyword translates IEEE BPDUs into PVST+ BPDUs.
Note
|
The
bridge-domain and
bre-connect commands are mutually exclusive. You cannot use both commands on the same PVC for concurrent RFC 1483 and BRE bridging.
|
To preserve class of service (CoS) information across the ATM network, use the
dot1q option. This configuration uses IEEE 802.1Q tagging to preserve the VLAN ID and packet headers as they are transported across
the ATM network.
To enable service providers to use a single VLAN to support customers that have multiple VLANs, while preserving customer
VLAN IDs and segregating traffic in different customer VLANs, use the
dot1q-tunnel option on the service provider router. Then use the
dot1q option on the customer routers.
Note
|
The
access ,
dot1q , and
dot1q-tunnel options are mutually exclusive. If you do not specify any of these options, the connection operates in “raw” bridging access
mode, which is similar to access, except that the connection does act on and transmit BPDU packets.
|
RFC 1483 bridging is supported on AAL5-MUX and AAL5-LLC Subnetwork Access Protocol (SNAP) encapsulated PVCs. RFC-1483 bridged
PVCs must terminate on the ATM interface, and the bridged traffic must be forwarded over an Ethernet interface, unless the
split-horizon option is used, which allows bridging of traffic across bridged PVCs.
Note
|
RFC 1483 bridging is not supported for switched virtual circuits (SVCs). It also cannot be configured for PVCs on the main
interface.
|
In interface configuration mode, only the
dot1q and
dot1q-tunnel keyword options are supported.
Examples
The following example shows a PVC being configured for IEEE 802.1Q VLAN bridging using a VLAN ID of 99:
Router# configure terminal
Router(config)# interface ATM6/2
Router(config-if)# pvc 2/101
Router(config-if-atm-vc)# bridge-domain 99 dot1q
Router(config-if-atm-vc)# end
The following example shows how to enable BPDU translation when a Catalyst 6500 series switch is connected to a device that
understands only IEEE BPDUs in an RFC 1483-compliant topology:
Router(config-if-atm-vc)# bridge-domain
100 pvst-tlv 150
The
ignore-bpdu-pid keyword is not used because the device operates in an RFC 1483-compliant topology for IEEE BPDUs.
The following example shows how to enable BPDU translation when a Catalyst 5500 ATM module is a device that understands only
PVST BPDUs in a non-RFC1483-compliant topology. When a Catalyst 6500 series switch is connected to a Catalyst 5500 ATM module,
you must enter both keywords.
Router(config-if-atm-vc)# bridge-domain
100 ignore-bpdu-pid pvst-tlv 150
To enable BPDU translation for the Layer 2 Protocol Tunneling ( L2PT) topologies, use the following command:
Router(config-if-atm-vc)# bridge-domain
100 dot1q-tunnel ignore-bpdu-pid pvst-tlv 150
The following example shows a range of PVCs being configured, with the bridge domain number being incremented for each PVC
in the range:
Router(config)# interface atm 8/0.100
Router(config-if)# range pvc 102/100 102/199
Router(config-if-atm-range)# bridge-domain 102 increment