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Configuring ATM Interface Encapsulation

To configure ATM encapsulation on a physical interface, include the encapsulation statement at the [edit interfaces interface-name] hierarchy level:



[edit interfaces interface-name] 

encapsulation (atm-ccc-cell-relay |
atm-pvc | ethernet-over-atm);

For ATM interfaces, the physical interface encapsulation can be one of the following:

ATM cell-relay—This encapsulation connects two remote virtual circuits or ATM physical interfaces with an LSP. Traffic on the circuit is ATM cells.
ATM PVC—ATM PVC encapsulation is defined in RFC 2684, Multiprotocol Encapsulation over ATM Adaptation Layer 5.
Ethernet over ATM—As defined in RFC 1483 (the previous version of RFC 2684), this encapsulation type allows ATM interfaces to connect to devices that support only bridged-mode protocol data units (BPDUs). The JUNOS software does not completely support bridging, but accepts BPDU packets as a default gateway. If you use the router as an edge device, then the router acts as a default gateway. It accepts Ethernet LLC/SNAP frames with IP or ARP in the payload, and drops the rest. For packets destined to the Ethernet LAN, a route lookup is done using the destination IP address. If the route lookup yields a full address match, the packet is encapsulated with an LLC/SNAP and media access control (MAC) header, and the packet is forwarded to the ATM interface.

Generally, you configure an interface’s encapsulation at the [edit interfaces interface-name] hierarchy level. However, for ATM encapsulations, you can also configure the encapsulation type that is used inside the ATM cell itself. To do this, include the encapsulation statement:




encapsulation (atm-ccc-cell-relay |
atm-ccc-vc-mux | atm-cisco-nlpid | atm-mlppp-llc |
atm-nlpid | atm-ppp-llc | atm-ppp-vc-mux | atm-snap |
atm-tcc-snap | atm-vc-mux | atm-tcc-vc-mux | ether-over-atm-llc |
ether-vpls-over-atm-llc);

You can include this statement at the following hierarchy levels:

[edit interfaces interface-name unit logical-unit-number]
[edit logical-systems logical-system-name interfaces interface-name unit logical-unit-number]

Table 32 shows the logical interface encapsulation types for ATM interfaces.

Table 32: ATM Logical Interface Encapsulation Types

Encapsulation Types	Comments
ATM CCC cell relay	This encapsulation type connects two remote virtual circuits or ATM physical interfaces with an LSP. This encapsulation type carries traffic in ATM cells. When you use this encapsulation type, you can configure the ccc family only.
ATM CCC VC multiplex	This encapsulation type is for CCC circuits. When you use this encapsulation type, you can configure the ccc family only.
ATM network layer protocol identifier (NLPID)	When you use this encapsulation type, you can configure the inet family only.
ATM SNAP
ATM SNAP encapsulation on translational cross-connect (TCC) circuits	When you use this encapsulation type, you can configure the tcc family only.
ATM VC multiplex	When you use this encapsulation type, you can configure the inet family only.
ATM VC multiplex on TCC circuits	When you use this encapsulation type, you can configure the tcc family only.
Cell-relay accumulation mode (CAM)	In this mode, the incoming 1 to 8 cells are packaged into a single packet and forwarded to the LSP. To configure CAM, include the atm-cell-relay-accumulation statement at the [edit chassis fpc slot-number pic pic-number] hierarchy level. This encapsulation type is for ATM1 interfaces only. For more information about CAM, see the JUNOS System Basics Configuration Guide.
Cisco ATM NLPID	When you use this encapsulation type, you can configure the inet family only.
Ethernet over ATM	This encapsulation type is for interfaces that carry IPv4 traffic. When you use this encapsulation type, you cannot configure point-to-multipoint interfaces.
Ethernet VPLS over ATM	This encapsulation type enables a VPLS instance to support bridging between Ethernet interfaces and ATM interfaces, as described in RFC 2684. Use this encapsulation type to support IEEE 802.1p classification binding on ATM VCs. This encapsulation type is for ATM2 IQ interfaces only. When you use this encapsulation type, you cannot configure point-to-multipoint interfaces.
Multilink PPP over AAL5 LLC	This encapsulation type is for ATM2 IQ interfaces only. When you use this encapsulation type, your routing platform must be equipped with a Link Services or Voice Services PIC.
PPP over AAL5 LLC	This encapsulation type is for ATM2 IQ interfaces only. When you use this encapsulation type, you cannot configure point-to-multipoint interfaces.
PPP over AAL5 multiplex	This encapsulation type is for ATM2 IQ interfaces only. When you use this encapsulation type, you cannot configure point-to-multipoint interfaces.

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