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Table Of Contents
Configure PPP over ATM with IETF-Compliant VC Multiplexed Encapsulation
Configure PPP over ATM with Frame Forwarding Encapsulation
PPP over ATM with Differing Encapsulation Types Example
Two Routers with Back-to-Back PVCs Example
Multiplexed Encapsulation Using VC Class Example
IETF-Compliant PPP over ATM
Feature Summary
Point-to-Point Protocol (PPP) over Asynchronous Transfer Mode (ATM) is now available on an ATM CES port adapter in a Cisco 7200-series router.
In previous releases of PPP over ATM, you configured permanent virtual circuits (PVCs) for PPP over ATM on point-to-point subinterfaces. In this release, each PPP over ATM connection no longer requires two interfaces, a virtual access interface and ATM subinterface. Instead, you can configure multiple PVCs for PPP over ATM on multipoint subinterfaces, thereby providing a significant increase in the number of PPP over ATM sessions per router.
Also in this release, PPP over ATM is enhanced to support virtual circuit (VC) multiplexed encapsulation and complies with the Internet Engineering Task Force (IETF) draft on multiplexed encapsulation titled PPP over AAL5. The previous version of PPP over ATM supported only the Frame Forwarding data encapsulation (aal5ciscoppp).
Note
The IETF PPP over ATM feature does not currently support LLC encapsulated PPP over ATM Adaptation Layer 5 (AAL5).
Benefits
This release of the PPP over ATM feature provides support for IETF-compliant PPP over ATM and significantly increases the maximum number of PPP over ATM sessions running on a router. The maximum number of PPP over ATM sessions supported on a platform depends on available system resources such as memory and CPU speed.
Restrictions
PPP over ATM is not supported on switched virtual circuits (SVCs) and can only be applied to PVCs. IETF-compliant PPP over ATM VC encapsulations can only be configured using the new ATM syntax. The Frame Forwarding PPP over ATM encapsulation can be configured using either the new command syntax or the old atm pvc command.
This release does not support NetFlow switching or optimum switching PPP over ATM traffic; however, PPP over ATM fastswitching will be supported.
Platforms
This feature is supported only on the Cisco 7200 series routers with ATM CES (and NPE-200 processor recommended) for the 11.3 AA release.
Prerequisites
The PPP over ATM feature supports both VC multiplexed and the Frame Forwarding data encapsulations. These configuration tasks are described in the following sections:
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Supported MIBs and RFCs
None
Configuration Tasks
Decide which encapsulation method you will use, VC multiplexed or Frame Forwarding data encapsulation, then perform one of the tasks in the following sections.
Configure PPP over ATM with IETF-Compliant VC Multiplexed Encapsulation
To configure PPP over ATM to support the VC multiplexed PPP payloads as specified by the PPP over AAL5 Internet Draft, perform the following tasks beginning in interface configuration mode:
Configure PPP over ATM with Frame Forwarding Encapsulation
To configure PPP over ATM to support the Frame Forwarding encapsulation type, perform the following tasks beginning in interface configuration mode:
Configuration Examples
This section provides the following examples of how to configure IETF PPP over ATM:
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PPP over ATM with Differing Encapsulation Types Example
Running PVCs with different PPP over ATM encapsulation types under the same subinterface is supported. In the following example, three PVCs are configured for PPP over ATM on subinterface ATM 2/0.1. PVC 0/60 is configured with VC multiplexed PPP payload encapsulation. Its traffic shaping parameter is an unspecified bit rate with peak cell rate at 500 kbps. PVC 0/70 is also configured with VC multiplexed PPP payload encapsulation, but its traffic shaping parameter is non-real-time variable bit rate, with peak cell rate at 1 Mbps, sustainable cell rate at 500 kbps, and burst cell size of 64 cells. PVC 0/80 is configured with the Frame Forwarding encapsulation. Its traffic shaping parameter is an unspecified bit rate with peak cell rate at 700 kbps.
int atm 2/0.1 multipointpvc 0/60encapsulation aal5mux ppp virtual-template 3ubr 500pvc 0/70encapsulation aal5mux ppp virtual-template 3vbr-nrt 1000 500 64pvc 0/80encapsulation aal5ciscoppp virtual-template 3ubr 700ADSL Termination Example
The IETF PPP over ATM feature was designed to support installations with Asymmetric Digital Subscriber Line (ADSL) circuits. illustrates a topology for ADSL termination. This topology allows you to establish a PPP connection to a Cisco 7200-series router.
The example also illustrates the use of PPP Tunneling using L2F to provide VPDN services, in this case for the domain cisco.com. Thus, a user who logs in as bob@cisco.com is automatically tunneled to IP address 10.1.2.3. (See the chapter Configuring Virtual Private Dialup Networks in the Cisco IOS release 11.3 Dial Solutions Configuration Guide for details about setting up VPDN services.)
The commands that you might enter to configure this topology are very similar to those in the previous example, and follow .
Figure 1 ADSL Termination
Sample Configuration Commands
int atm 4/0.1 multipointpvc 0/60encapsulation aal5mux ppp virtual-template 3ubr 500pvc 0/70encapsulation aal5mux ppp virtual-template 3vbr-nrt 1000 500 64pvc 0/80encapsulation aal5mux ppp virtual-template 3ubr 700Sample Tunnel Configuration
vpdn enablevpdn outgoing cisco.com dsl7200 ip 10.1.2.3username dsl7200 password password-1username cisco-gateway password password-2Two Routers with Back-to-Back PVCs Example
illustrates an ATM interface with two PVC session connections. (See the chapter Dial-In Terminal Service and Remote Node Configuration in the Cisco IOS release 11.3 Dial Solutions Configuration Guide for details on PPP configuration.) The sample commands following establish the back-to-back router configuration.
Figure 2 Two Routers with Back-to-Back PVCs
Router 1:
int atm 2/0atm clock internalpvc 0/60encapsulation aal5mux ppp virtual-template 1ubr 90!pvc 0/70encapsulation aal5mux ppp virtual-template 2vbr-nrt 90 50 1024!interface Virtual-Template1ip address 10.0.1.1 255.255.255.0!interface Virtual-Template2ip address 10.0.2.1 255.255.255.0!Router 2:
int atm 2/0.1 multipointpvc 0/60encapsulation aal5mux ppp virtual-template 1ubr 90!pvc 0/70encapsulation aal5mux ppp virtual-template 2vbr-nrt 90 50 1024!interface Virtual-Template1ip address 10.0.1.2 255.255.255.0!interface Virtual-Template2ip address 10.0.2.2 255.255.255.0!Multiplexed Encapsulation Using VC Class Example
In the following example, PVC 0/60 is configured on subinterface ATM 2/0.1 with a VC class attached to it. (See the chapter New VC Configuration in the Cisco IOS 11.3(2)T release Enhanced ATM VC Configuration and Management guide for details on assigning a VC class rather than an encapsulation method.) By rule of inheritance, PVC 0/60 runs with VC multiplexed PPP encapsulation using the configuration from interface virtual-template 1. Its parameter is an unspecified bit rate with peak cell at 90 kbps.
int atm 2/0.1pvc 0/60class pvc-pppvc-class atm pvc-pppencapsulation aal5mux ppp virtual-template 1ubr 90Command Reference
This section describes enhancements to the following commands:
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encapsulation
To configure the ATM adaptation layer (AAL) and encapsulation type for an ATM PVC, SVC, or VC class, use the encapsulation command in the appropriate command mode. Use the no form of this command to remove an encapsulation from a PVC, SVC, or VC class.
encapsulation aal-encap [virtual-template number]
no encapsulation aal-encap [virtual-template number]
Note
Syntax Description
Default
The global default encapsulation is aal5snap. See the "Usage Guidelines" section for other default characteristics.
Command Mode
Interface-ATM-VC configuration (for an ATM PVC or SVC)
VC-class configuration (for a VC class)
Usage Guidelines
This command first appeared in Cisco IOS Release 11.3 T.
Use of one of the aal5mux encapsulation options to dedicate the specified PVC to a single protocol; use the aal5snap encapsulation option to multiplex two or more protocols over the same PVC. Whether you select aal5mux or aal5snap encapsulation might depend on practical considerations, such as the type of network and the pricing offered by the network. If the network's pricing depends on the number of PVCs set up, aal5snap might be the appropriate choice. If pricing depends on the number of bytes transmitted, aal5mux might be the appropriate choice because it has slightly less overhead.
When configuring Cisco PPP over ATM, specify the aal5ciscoppp encapsulation for the aal-encap argument and specify the virtual template number.
It is possible to implicitly create a virtual template when configuring PPP over ATM. In other words, if the parameters of the virtual template are not explicitly defined before configuring the ATM PVC, the PPP interface will be brought up using default values from the virtual template identified. However, some parameters (such as an IP address) take effect only if they are specified before the PPP interface comes up. Therefore, we recommend that you explicitly create and configure the virtual template before configuring the ATM PVC to ensure such parameters take effect.
If you specify virtual template parameters after the ATM PVC is configured, you should issue a shutdown command followed by a no shutdown command on the ATM subinterface to restart the interface, causing the newly configured parameters (such as an IP address) to take effect.
If the encapsulation command is not explicitly configured on an ATM PVC or SVC, the VC inherits the following default configuration (listed in order of next highest precedence):
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Example
The following example configures an ATM PVC with VPI 0 and VCI 33 for a MUX-type encapsulation using IP:
pvc 0/33encapsulation aal5mux ipinterface atm
To configure an ATM interface type and enter interface configuration mode, use the interface atm global configuration command.
interface atm number (for the NPM on Cisco 4500 and 4700 routers)
interface atm slot/0 (for the AIP on Cisco 7500 series routers; for the ATM port adapter on
Cisco 7200 series routers)
interface atm slot/port-adapter/0 (for the ATM port adapter on Cisco 7500 series routers)To configure a subinterface, use the interface atm global configuration command.
interface atm number.subinterface-number {multipoint | point-to-point} (for the NPM on
Cisco 4500 and 4700 routers) interface atm slot/0.subinterface-number {multipoint | point-to-point} (for the AIP on
Cisco 7500 series routers; for the ATM port adapter on Cisco 7200 series routers)
interface atm slot/port-adapter/0.subinterface-number {multipoint | point-to-point} (for the
ATM port adapter on Cisco 7500 series routers)Syntax Description
Default
None
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.0 for the Cisco 7000 family routers.
This command first appeared in Cisco IOS Release 11.0 for the Cisco 4500 and 4700 routers.Example
The following example assigns an IP network address and network mask to the ATM interface in slot 1 on port 0 of a Cisco 7500 series router:
interface atm 1/0 ip address 1.1.1.1.255.255.255.0Related Commands
show interfaces atm
show atm pvc
To display all ATM PVCs and traffic information, use the show atm pvc privileged EXEC command.
show atm pvc [vpi/vci | name | interface atm interface_number | ppp]
Syntax Description
Command Mode
Privileged EXEC
Usage Guidelines
This command first appeared in Cisco IOS Release 11.3 T.
If the vpi/vci or name is not specified, the output of this command is the same as that of the show atm vc command but only the configured PVCs are displayed. See the first sample output below.
If the vpi/vci or name is specified, the output of this command is the same as the show atm vc vcd command, plus extra information related to PVC management including connection name, detailed states, and OAM counters. See the second sample output below.
If the interface atm interface-number option is included in the command, all PVCs under that interface or subinterface are displayed. See the third sample output below.
Sample Displays
The following is sample output from the show atm pvc command:
Router# show atm pvcVCD/ Peak Avg/Min BurstInterface Name VPI VCI Type Encaps Kbps Kbps Cells Sts2/0 1 0 5 PVC SAAL 155000 155000 UP2/0 2 0 16 PVC ILMI 155000 155000 UP2/0.2 101 0 50 PVC SNAP 155000 155000 UP2/0.2 102 0 60 PVC SNAP 155000 155000 DOWN2/0.2 104 0 80 PVC SNAP 155000 155000 UP2/0 hello 0 99 PVC SNAP 1000 UPThe following is sample output from the show atm pvc command with the vpi/vci specified:
Router# show atm pvc 0/99ATM 2/0.2: VCD 102, VPI: 0, VCI: 60UBR, PeakRate: 155000AAL5-LLC/SNAP, etype:0x0, Flags: 0xC20, VCmode: 0x1OAM frequency: 3 second(s), OAM retry frequency: 1 second(s)OAM up retry count: 3, OAM down retry count: 5OAM Loopback status: OAM SentOAM VC state: Not VerifiedILMI VC state: Not ManagedVC is managed by OAMInARP frequency: 15 minute(s)InPkts: 1, OutPkts: 1, InBytes: 32, OutBytes: 32InPRoc: 1, OutPRoc: 0, Broadcasts: 0InFast: 0, OutFast:0, InAS: 0, OutAS: 0OAM cells received: 14F5 InEndloop: 14, F5 InSegloop: 0, F5 InAIS: 0, F5 InRDI: 0F4 InEndloop: 0, F4 InSegloop: 0, F4 InAIS: 0, F4 InRDI: 0OAM cells sent: 25F5 OutEndloop: 25, F5 OutSegloop: 0, F5 OutRDI: 0OAM cell drops: 0PVC Discovery: NOT_VERIFIEDStatus: DOWN, State: NOT_VERIFIEDThe following is sample output from the show atm pvc command with the ATM subinterface specified:
Router# show atm pvc interface atm 2/0.2VCD/ Peak Avg/Min BurstInterface Name VPI VCI Type Encaps Kbps Kbps Cells Sts2/0.2 101 0 50 PVC SNAP 155000 155000 UP2/0.2 102 0 60 PVC SNAP 155000 155000 DOWN2/0.2 104 0 80 PVC SNAP 155000 155000 UPThe following is sample output from the show atm pvc command with PPP specified:
Router# show atm pvc pppVCD/ATM Int. Name VPI VCI Type VCSt VA VASt2/0.1 10 0 60 PVC UP 1 UPThe following is sample output from the show atm pvc command that shows the virtual access state:
stirling#sh atm pvc 0/100ATM2/0.100: VCD: 100, VPI: 0, VCI: 100PeakRate: 155000, Average Rate: 155000AAL5-CISCOPPP, etype:0x9, Flags: 0xC29, VCmode: 0xE000OAM frequency: 0 second(s), OAM retry frequency: 0 second(s)OAM up retry count: 0, OAM down retry count: 0OAM Loopback status: OAM DisabledOAM VC state: Not ManagedILMI VC state: Not ManagedInARP DISABLEDInPkts: 0, OutPkts: 22, InBytes: 0, OutBytes: 308InPRoc: 0, OutPRoc: 22, Broadcasts: 0InFast: 0, OutFast: 0, InAS: 0, OutAS: 0OAM cells received: 0F5 InEndloop: 0, F5 InSegloop: 0, F5 InAIS: 0, F5 InRDI: 0F4 InEndloop: 0, F4 InSegloop: 0, F4 InAIS: 0, F4 InRDI: 0OAM cells sent: 0F5 OutEndloop: 0, F5 OutSegloop: 0, F5 OutRDI: 0OAM cell drops: 0Status: UPvirtual-access: 1 virtual-access state: UPvirtual-template: 3describes significant fields shown in the displays.
