Atm Applications; Atm Oam - HP MSR Router Series Wan Access Configuration Manual

ATM applications

An ATM interface can implement IPoA, IPoEoA, PPPoA, and PPPoEoA to carry data encapsulated in IP,
PPP, or Ethernet across an ATM network.
IPoA
IP over ATM (IPoA) enables ATM to carry IP packets. In an IPoA implementation, ATM acts as the data link
layer protocol for the IP hosts on the same network. To enable these hosts to communicate across an ATM
network, IP packets must be encapsulated in ATM cells.
By making full use of the advantages of ATM, IPoA delivers excellent network performance and mature
QoS assurance.
IPoEoA
IP over Ethernet over ATM (IPoEoA) uses a three-layer architecture, with IP encapsulation at the top layer,
IP over Ethernet (IPoE) in the middle, and IPoEoA at the bottom.
IPoEoA is suitable where Ethernet packets are to be forwarded through ATM interfaces. In IPoEoA
applications, you can associate multiple PVCs with one Layer 3 virtual Ethernet (VE) interface. PVCs
associated with the same VE interface are interconnected at Layer 2.
PPPoA
PPP over ATM (PPPoA) enables ATM to carry PPP protocol packets. With PPPoA, PPP packets, in which IP
packets or other protocols' packets are encapsulated, are encapsulated in ATM cells. In this
implementation, ATM is the carrier of PPP packets and the communication process of PPPoA is managed
by PPP, which allows for flexibility and rich applications. To transmit PPP packets across ATM, a
virtual-template (VT) interface is required.
PPPoEoA
PPPoE over ATM (PPPoEoA) enables ATM to carry PPPoE protocol packets. With PPPoEoA, Ethernet
packets are encapsulated in ATM cells, through which you can use a PVC to implement the functionality
of Ethernet. To carry Ethernet frames over ATM, the virtual Ethernet (VE) interface was introduced. The VE
interface has Ethernet characteristics and can be dynamically created. The following is the protocol stack
used by the VE interface:
• ATM PVC (the bottom layer).
Ethernet (the link layer).
•
Network layer and other upper layers (the same as those for common Ethernet interfaces).
•

ATM OAM

OAM has the following expansions:
Operation and Maintenance in the ITU-T I.610 recommendation (02/99).
•
• Operation Administration and Maintenance in LUCENT APC User Manual (03/99).
Whichever expansion is used, OAM provides a way of detecting faults, isolating faults, and monitoring
network performance without interrupting ongoing services. By inserting OAM cells, which are
constructed in the standard ATM cell format, in cell streams, you can obtain specific information about
the network.
ATM OAM provides the following functions:
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