Nortel Networks 8000 - Manual (Page 391)

Nortel Secure Router 8000 Series
Configuration -WAN Access 10 Low-speed ATM configuration
The ATM OC-3/STM-1 interface that carries ATM service over SONET/SDH.
The single ATM E3 interface that carries ATM service over E3 line.
These ATM interfaces supported by the SR8000 have the following features:
Supports Permanent Virtual Circuit (PVC).
Supports tragic shaping based on VP/VC.
Supports User-to-Network Interface (UNI) signaling.
Supports RFC1483: Multiprotocol Encapsulation over ATM Adaptation Layer 5.
Supports RFC1577: Classical IP and ARP over ATM.
Supports F5 End to End Loopback OAM.
Supports AAL5 (ATM Adaptation Layer 5).
Supports non-real-time Variable Bit Rate (nrt_VBR).
Supports Unspecified Bit Rate (UBR).
Supports Real-time Variable Bit Rate (rt_VBR).
Supports Constant Bit Rate(CBR)
10.1.3 ATM OAM
Generally, OAM has two different definitions.
• OAM: Operation And Maintenance (ITU-T I.610 02/99)
• OAM: Operation Administration and Maintenance (LUCENT APC User Manual, 03/99)
OAM offers a mechanism of fault location, and performance detection. The mechanism is
realized through OAM cells inserted in user cell flow.
Broadband-Integrated Services Digital Network (ITU-T B-ISDN) I.610 defines the OAM
function on the ATM network and classifies the OAM function into the following five layers.
Table 10-1 Layer of the OAM functions
Layer Description
F1: Regenerator section layer Physical layer OAM: The OAM flow depends on the
concrete mechanism of the transmission system. The
ATM network includes the following three types of
transmission systems:
• Transmission system based on SDH (defined in
G.707 and G.783)
• Transmission system based on cell (defined in
I.432.1, I.432.2, and I.432.4)
• Transmission system based on PDH (defined in
G.702, G.804 and G.832)
F2: Digit section layer
F3: Transmission channel layer
F4: Virtual path layer ATM layer OAM: based on VP/VC and does not
depend on the transmission system.
F5: Virtual channel layer
The two types of operation flows are defined in the ATM layer: F4 flow and F5 flow.
Issue 5.3 (30 March 2009) Nortel Networks Inc. 10-5