N:1 PVC Mapping to PWE with Nonunique VPIs
The N:1 PVC Mapping to PseudoWire Emulation (PWE) with Nonunique virtual path identifiers (VPIs) feature maps one or more ATM permanent virtual circuits (PVCs) to a single pseudowire (PW). There are two modes of AAL0 encapsulation, N:1 and 1:1 mapping. In N:1 mapping, multiple unrelated virtual path identifier/virtual channel identifier (VPI/VCI) are carried over a single Multiprotocol Label Switching (MPLS) PW. This is an efficient mapping method because less resources are used from the MPLS network. In 1:1 mapping, a single VPI/VCI is carried over a single MPLS PW. Benefits of this feature include the following:
-
Aggregate quality of service (QoS) can be applied to related PVCs.
-
Bandwidth is conserved with the reduction in the number of pseudowires that are used.
 Note |
This is not applicable for Cisco ASR 900 RSP3 Module. |
Restrictions for N:1 PVC Mapping to PWE with Nonunique VPIs
-
N:1 permanent virtual circuits (PVC) mapping configuration is supported only on multipoint subinterfaces; it is not supported on main interfaces or point-to-point subinterfaces.
-
N:1 PVC mapping mode is not supported on Access Circuit Redundancy subinterfaces.
-
Preconfigured PVCs cannot exist on the multipoint subinterface on which you want to configure N:1 PVC mapping.
-
An attachment circuit that has been bound to a pseudowire cannot be removed unless all Layer 2 virtual circuits (VCs) have been removed.
-
Layer 3 PVCs cannot be configured on N:1 subinterfaces.
-
Cell packing values configured under a VC class attached to the PVC, main interface, or subinterface will not be inherited by N:1 PVCs.
-
Operation, Administration, and Maintenance (OAM) functionality is not supported on N:1 Layer 2 PVCs. OAM cells coming from the customer edge (CE) network will be treated as normal data traffic and will traverse through the pseudowire.
-
Only ATM adaptation layer type 0 (AAL0) encapsulation is supported for N:1 PVCs.
-
The service policy configuration can be configured only at the subinterface level for N:1 PVCs.
-
ATM N:1 and PVP modes cannot be configured on different subinterfaces that belong to a physical interface.
-
You cannot change the ATM interface mode from point-to-point to multipoint or from multipoint to point-to-point.
-
If you change a layer 2 ATM interface to a layer 3 ATM interface, traffic will not flow.
Information About N:1 PVC Mapping to PWE with Nonunique VPIs
N:1 PVC Mapping to PWE with Nonunique VPIs Feature Description
To transport ATM cells over Multiprotocol Label Switching (MPLS), a VC is established between the provider edge (PE) routers on both ends of the MPLS backbone. With the N:1 permanent virtual circuit (PVC) Mapping to PseudoWire Emulation (PWE) with Nonunique VPIs feature, multiple PVCs irrespective of their Virtual Path Identifiers (VPIs), are transported over a single pseudowire configured on a subinterface. (“N:1” refers to the number of PVCs transported over one pseudowire). ATM cells are packed together in a single frame and sent over the single pseudowire. The ATM cell header information is packed together with the cell payload on a per-cell basis in the packets so that packets received at the egress end are unpacked and the ATM cells are mapped to the respective PVCs.
In N:1 PVC mapping mode, the device can pack cells only from a single PVC in an MPLS packet to transmit over a pseudowire; cells from multiple PVCs cannot be packed in a single MPLS packet and mapped to a single pseudowire for transmission. However, if a device receives an MPLS packet that is packed with cells from multiple PVCs, then those cells will be unpacked and sent to the respective PVCs.
How to Configure N:1 PVC Mapping to PWE with Nonunique VPIs
Configuring N:1 PVC Mapping to PWE with Nonunique VPIs
Procedure
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
enable Example: |
Enables privileged EXEC mode.
|
| Step 2 |
configure terminal Example: |
Enters global configuration mode. |
| Step 3 |
interface atm slot/subslot/port Example: |
Enables the ATM interface and enters interface configuration mode. |
| Step 4 |
atm mcpt-timers timer1 timer2 timer3 Example: |
Sets the Maximum Cell Packing Timeout (MCPT) values in microseconds.
|
| Step 5 |
exit Example: |
Exits interface configuration mode. |
| Step 6 |
configure terminal Example: |
Enters global configuration mode. |
| Step 7 |
interface atm slot/subslot/port.subslot multipoint Example: |
Enters subinterface configuration mode and creates a multipoint subinterface on the given port on the specified ATM Shared Port Adapter (SPA). |
| Step 8 |
no ip address Example: |
Removes the interface IP address. |
| Step 9 |
atm enable-ilmi-trap Example: |
Generates an Integrated Local Management Interface (ILMI) atmfVccChange trap when an ATM interface or subinterface is enabled or shut down. |
| Step 10 |
cell-packing maxcells mcpt-timer timer-number Example: |
Enables ATM over MPLS to pack multiple ATM cells into each MPLS packet within the MCPT timing. |
| Step 11 |
xconnect peer-ipaddress vc-id encapsulation mpls Example: |
(Optional) Enables the attachment circuit and specifies the IP address of the peer, a VC ID, and the data encapsulation method. |
| Step 12 |
pvc vpi/vci l2transport Example: |
Assigns a VPI and virtual channel identifier (VCI). |
| Step 13 |
Repeat Step 12 for the number of PVCs that you want to configure. |
— |
| Step 14 |
end Example: |
Exits subinterface configuration mode and returns to privileged EXEC mode. |
Configuring N:1 PVC Mapping to PWE with Nonunique VPIs using the commands associated with the L2VPN Protocol-Based CLIs feature
Procedure
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
enable Example: |
Enables privileged EXEC mode.
|
| Step 2 |
configure terminal Example: |
Enters global configuration mode. |
| Step 3 |
interface atm slot/subslot/port Example: |
Enables the ATM interface and enters interface configuration mode. |
| Step 4 |
atm mcpt-timers timer1 timer2 timer3 Example: |
Sets the Maximum Cell Packing Timeout (MCPT) values in microseconds.
|
| Step 5 |
exit Example: |
Exits interface configuration mode. |
| Step 6 |
configure terminal Example: |
Enters global configuration mode. |
| Step 7 |
interface atm slot/subslot/portt.subslot multipoint Example: |
Enters subinterface configuration mode and creates a multipoint subinterface on the given port on the specified ATM Shared Port Adapter (SPA). |
| Step 8 |
no ip address Example: |
Removes the interface IP address. |
| Step 9 |
atm enable-ilmi-trap Example: |
Generates an Integrated Local Management Interface (ILMI) atmfVccChange trap when an ATM interface or subinterface is enabled or shut down. |
| Step 10 |
cell-packing maxcells mcpt-timer timer-number Example: |
Enables ATM over MPLS to pack multiple ATM cells into each MPLS packet within the MCPT timing. |
| Step 11 |
end Example: |
Exits to privileged EXEC mode. |
| Step 12 |
interface pseudowire number Example: |
Specifies the pseudowire interface and enters interface configuration mode. |
| Step 13 |
encapsulation mpls Example: |
Specifies that Multiprotocol Label Switching (MPLS) is used as the data encapsulation method. |
| Step 14 |
neighbor peer-address vcid-value Example: |
Specifies the peer IP address and virtual circuit (VC) ID value of the Layer 2 VPN (L2VPN) pseudowire. |
| Step 15 |
exit Example: |
Exits interface configuration mode. |
| Step 16 |
l2vpn xconnect context context-name Example: |
Creates a Layer 2 VPN (L2VPN) cross connect context and enters xconnect configuration mode. |
| Step 17 |
member pseudowire interface-number Example: |
Specifies a member pseudowire to form a Layer 2 VPN (L2VPN) cross connect. |
| Step 18 |
member gigabitethernet interface-number Example: |
Specifies the location of the Gigabit Ethernet member interface. |
| Step 19 |
end Example: |
Exits to privileged EXEC mode. |
| Step 20 |
pvc vpi/vci l2transport Example: |
Assigns a VPI and virtual channel identifier (VCI). |
| Step 21 |
Repeat Step 12 for the number of PVCs that you want to configure. |
— |
| Step 22 |
end Example: |
Exits subinterface configuration mode and returns to privileged EXEC mode. |
Configuration Examples for N:1 PVC Mapping to PWE with Nonunique VPIs
Example: Configuring N:1 PVC Mapping to PWE with Nonunique VPIs
The following example shows how to configure the N:1 ATM permanent virtual circuit (PVC) mapping to pseudowires with non unique virtual path identifiers ( VPIs):
Device> enable
Device# configure terminal
Device(config)# interface atm 0/1/0
Device(config-if)# atm mcpt-timers 500 5000 50000
Device(config-if)# exit
Device# configure terminal
Device(config)# interface atm 0/1/0.1 multipoint
Device(config-subif)# no ip address
Device(config-subif)# atm enable-ilmi-trap
Device(config-subif)# cell packing 20 mcpt-timer 2
Device(config-subif)# xconnect 10.1.1.1 100 encapsulation mpls
Device(config-subif)# pvc 10/100 l2transport
Device(config-subif)# pvc 11/122 l2transport
Device(config-subif)# pvc 19/231 l2transport
Device(config-subif)# end
Example: Configuring N:1 PVC Mapping to PWE with Nonunique VPIs using the commands associated with the L2VPN Protocol-Based CLIs feature
The following example shows how to configure the N:1 ATM permanent virtual circuit (PVC) mapping to pseudowires with non unique virtual path identifiers ( VPIs):
Router> enable
Router# configure terminal
Router(config)# interface atm 0/1/1
Router(config-if)# atm mcpt-timers 500 5000 50000
Router(config-if)# exit
Router(config)# configure terminal
Router(config)# interface atm 0/1/1.1 multipoint
Router(config-subif)# no ip address
Router(config-subif)# atm enable-ilmi-trap
Router(config-subif)# cell packing 20 mcpt-timer 2
Router(config-subif)# exit
Router(config)#interface pseudowire 100
Router(config-if)# encapsulation mpls
Router(config-if)# neighbor 10.1.1.1 100
Router(config-if)# pvc 10/100 l2transport
Router(config-if)# pvc 11/122 l2transport
Router(config-if)# pvc 19/231 l2transport
Router(config-if)# exit
Router(config)# l2vpn xconnect context A
Router(config-xconnect)# member pseudowire 100
Router(config-xconnect)# member atm 9/1/1
Router(config-xconnect)# endVerifying the N:1 PVC Mapping to PWE with Nonunique VPIs Configuration
To verify the N:1 PVC Mapping to PWE with Nonunique VPIs Configuration, use the show mpls l2transport vc command in user EXEC or privileged EXEC mode.
Router# show mpls l2transport vc
Local intf Local circuit Dest address VC ID Status
------------ ------------------------ -------------- ------- --------
AT0/1/1.1 ATM CELL ATM0/1/1.1 2.2.2.2 100 UP
interface ATM0/0/0.1/1/1/1
atm mcpt-timers 20 30 40
interface ATM0/0/0.1/1/1/1.1 multipoint
no ip address
no atm enable-ilmi-trap
cell-packing 2 mcpt-timer 1
xconnect 2.2.2.2 100 encapsulation mpls
pvc 10/100 l2transport
pvc 20/200 l2transport
pvc 30/300 l2transportAdditional References
Related Documents
|
Related Topic |
Document Title |
|---|---|
|
ATM commands |
Technical Assistance
|
Description |
Link |
|---|---|
|
The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password. |
Feedback