To configure the ATM adaptation layer (AAL) and encapsulation type for a virtual circuit
(VC) class, ATM permanent virtual circuit (PVC), or ATM permanent virtual path (PVP),
use the encapsulation command in the appropriate configuration
mode. To remove an encapsulation type, use the no form of this
command.
For point-to-point ATM PVCs and vc-classes:
encapsulation {aal5mux ipv4 | aal5nlpid | aal5snap}
no encapsulation {aal5mux ipv4 | aal5nlpid | aal5snap}
For ATM Layer 2 PVCs:
encapsulation {aal0 | aal5}
no encapsulation {aal0 | aal5}
Syntax Description
aal5mux ipv4
|
Specifies IPv4 encapsulation for multiplex (MUX)-type VCs.
Note
|
The aal5mux ipv4 keywords are available in ATM
PVC configuration and ATM VC-class configuration modes only.
|
|
aal5nlpid
|
Specifies the AAL and encapsulation type that allows ATM interfaces to
interoperate with High-Speed Serial Interfaces (HSSIs), which are using an
ATM data service unit (ADSU) and running ATM-Data Exchange Interface (DXI).
Supported on ATM PVCs only.
Note
|
The aal5nlpid keyword is available in ATM PVC
configuration and ATM VC-class configuration modes only.
|
|
aal5snap
|
Specifies the AAL encapsulation type that supports Inverse ARP. Logical Link
Control/Subnetwork Access Protocol (LLC/SNAP) precedes the protocol
datagram.
Note
|
The aal5snap keyword is available in ATM PVC
configuration and ATM VC-class configuration modes only.
|
|
aal0
|
Specifies the AAL encapsulation type that contains 48 bytes of data within
an ATM cell. AAL0 cells are also referred to as “raw cells.” The payload
consists of 48 bytes.
Note
|
The aal0 keyword is available in the ATM Layer
2 transport PVC configuration mode only.
|
|
aal5
|
Specifies the AAL encapsulation type that carries higher-layer datagrams
while enhancing the link layer with services available through ATM. AAL5 is
defined in the ITU standard I.363.5, and is typically used to carry IP
datagrams over ATM.
Note
|
The aal5 keyword is available in the ATM Layer
2 transport PVC configuration mode only.
|
|
Command Default
For point-to-point PVCs, the default encapsulation type is
aal5snap .
For Layer 2 PVCs, the default encapsulation type is aal5 .
Command Modes
ATM PVC configuration (config-atm-vc)
ATM VC-class configuration (config-vc-class-atm)
ATM layer 2 transport PVC configuration (config-atm-l2transport-pvc)
Command History
Release
|
Modification
|
Release 3.7.0
|
This command was introduced.
|
Usage Guidelines
To use this command, you must be in a user group associated with a task group that includes appropriate task IDs. If the user
group assignment is preventing you from using a command, contact your AAA administrator for assistance.
Use the aal5mux ipv4 encapsulation option 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 ipv4 or aal5snap
encapsulation depends on the type of network you are configuring, and the pricing
offered by that network. If the pricing of the network depends on the number of PVCs set
up, we recommend aal5snap encapsulation. If pricing depends on
the number of bytes transmitted, we recommend aal5mux ipv4
encapsulation because it has less overhead than aal5snap and
aal5mux
ipv4 encapsulation.
If you configure VC-class parameters for a PVC after that PVC is configured, you must
enter the shutdown command followed by the no
shutdown command on the ATM subinterface that hosts the PVC. This
action restarts the interface, causing the newly configured VC-class parameters to take
effect on that interface.
Unless specifically configured otherwise, a PVC automatically inherits the encapsulation
type of the VC-class that is assigned to the main interface or subinterface that hosts
the PVC. If no VC-class is assigned, then the PVC inherits the encapsulation type of the
main interface or subinterface that hosts the PVC. If no encapsulation is configured of
the main interface or subinterface, then the PVC inherits the default
aal5snap encapsulation.
Use the encapsulation command in ATM PVC configuration mode to
modify the inherited or default encapsulation assigned to a PVC. You can modify the
encapsulation for each individual PVC to be different from the encapsulation configured
for the VC-class that is assigned to the ATM main interface or subinterface that hosts
the PVC.
If you do not use the encapsulation command to configure the
encapsulation type for a new ATM PVC, then the PVC inherits the one of the following
default configurations (listed in order of precedence from lowest to highest):
- The encapsulation assigned to the VC-class that is assigned to the PVC itself.
- The encapsulation assigned to the VC-class that is assigned to the ATM subinterface
that hosts the PVC.
- The encapsulation assigned to the VC-class that is assigned to the ATM main
interface that hosts the PVC
- The default aal5snap encapsulation
When configuring a PVC range or an individual PVC within a PVC range, the following
encapsulation types are supported:
- encapsulation aal5mux
ipv4
- encapsulation aal5snap
Note |
For Layer 2 PVCs, the default encapsulation type is
aal5 , and the encapsulation type is not inherited
from the VC-class.
|
Task ID
Task ID
|
Operations
|
atm
|
read, write
|
Examples
The following example shows how to configure a VC-class with
aal5snap encapsulation:
RP/0/RP0/CPU0:router# configure
RP/0/RP0/CPU0:router(config)# vc atm classA
RP/0/RP0/CPU0:router(config-vc-class-atm)# encapsulation aal5snap
The following example shows how to configure an individual PVC with
aal5mux encapsulation:
RP/0/RP0/CPU0:router# configure
RP/0/RP0/CPU0:router(config)# interface atm 0/2/0/0.1 point-to-point
RP/0/RP0/CPU0:router(config-subif)# pvc 10/100
RP/0/RP0/CPU0:router(config-atm-vc)# encapsulation aal5mux
The following example shows how to remove aal5mux ipv4
encapsulation from a VC-class:
RP/0/RP0/CPU0:router# configure
RP/0/RP0/CPU0:router(config)# vc atm classA
RP/0/RP0/CPU0:router(config-vc-class-atm)# no encapsulation aal5mux ipv4
The following example shows how to configure an individual Layer 2 PVC with
aal0 encapsulation:
RP/0/RP0/CPU0:router# configure
RP/0/RP0/CPU0:router(config)# interface atm 0/6/0/1.10 l2transport
RP/0/RP0/CPU0:router(config-if)# pvc 30/300
RP/0/RP0/CPU0:router(config-atm-l2transport-pvc)# encapsulation aal0