Configuring ATM2 IQ Interfaces for Layer 2 Circuits

You can configure Asynchronous Transfer Mode 2 (ATM2) intelligent queuing (IQ) interfaces for Layer 2 circuits by using Layer 2 circuit ATM Adaptation Layer 5 (AAL5) transport mode, Layer 2 circuit ATM cell relay mode, and the Layer 2 circuit ATM trunk mode.

The configuration statements are as follows:

• atm-l2circuit-mode aal5
• atm-l2circuit-mode cell
• atm-l2circuit-mode trunk

For more information on these statements, see the JUNOS System Basics Configuration Guide. For more information on how to configure ATM2 IQ interfaces, see the JUNOS Network Interfaces Configuration Guide.

The JUNOS software implementation of sequence number processing for Layer 2 circuit ATM cell relay mode and Layer 2 circuit AAL5 mode differs from that described in the Internet draft draft-martini-l2circuit-encap-mpls-version.txt, Frame Relay Encapsulation over Pseudo-Wires.

The JUNOS software implementation has the following differences:

1. A packet with a sequence number of 0 is treated as out of sequence.
2. A packet that does not have the next incremental sequence number is considered out of sequence.

When out-of-sequence packets arrive, the expected sequence number for the neighbor is set to the sequence number in the Layer 2 circuit control word.

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