Nortel Networks 8000 - Manual (Page 446)

Nortel Secure Router 8000 Series
Configuration -WAN Access 11 High-speed ATM configuration
• Plane Management is responsible for the system management and the communication
between different planes.
The relationships among layers and planes are shown in Figure 11-1.
Figure 11-1 ATM protocol model
The AAL is responsible for forwarding the information between the ATM Layer and the upper
layer protocols. The following are the four types of AAL :AAL1, AAL2, AAL3/4 and AAL5.
Each of these AALs supports certain special services. Most of the ATM equipments use AAL5
to support the data communication service.
The ATM also has the QoS mechanism. For details, refer to the Nortel Secure Router 8000
Series Configuration Guide - QoS.
11.1.2 ATM interface
The ATM physical layer is at the bottom of the ATM protocol reference model. It is not
dependent on transmission mechanism and transmission rate. The ATM physical layer
transmits valid cells and corresponding timing signals between the upper layers and the
transmission media.
The Secure Router 8012E provides various high-speed ATM interface cards, which are as
follows:
• 1-port ATM 155M optical interface module (RTP1A1CFF)
• 2-port ATM 155M optical interface module (P1A2CFF)
• 4-port ATM 155M optical interface module (RTP1A4CFF)
The Secure Router 8012E provides the high-speed ATM OC-3/STM-1 interface that carries
ATM service over SONET/SDH.
Issue 5.3 (30 March 2009) Nortel Networks Inc. 11-3