Nokia T66280, M1122 user manual Point-to-Point Protocol over Ethernet PPPoE, Payload encapsulations

M1122 User Manual

4.8Point-to-Point Protocol over Ethernet (PPPoE)

Standard PPPoE mode is used when M1122 is operating as a bridge. PPPoE protocol defines how PPP sessions are mapped into Ethernet packets. When M1122 operates as a bridge, this protocol is transparent to M1122.

4.9Payload encapsulations

Both routed and bridged protocols are encapsulated in the ATM link by using either RFC 2684 LLC/SNAP encapsulation or VC multiplexing. M1122 also supports PPP over AAL5 encapsulation, in which routed protocols are first encapsulated in PPP (RFC 1661). PPP is then encapsulated in ATM according to the IETF PPP over AAL5 using RFC 2364 VC multiplexing or LLC/NLPID encapsulation.

4.10 Weighted Fair Queueing (Class of Service)

As a Class of Service (CoS) function, M1122 supports Weighted Fair Queueing (WFQ) for each ATM VCC. The CoS function ensures that different IP traffic flows are treated fairly in the upstream (towards the Internet) direction. This may be necessary, in some cases, because the upstream capacity of the ADSL line is somewhat limited compared to the Ethernet bandwidth on the office or home LAN. The WFQ CoS function classifies IP traffic flows based on IP address, protocol and port fields. It is capable of identifying the IP flow from all supported payload encapsulation formats. WFQ works properly only with IP-based protocols. If the flow is IP-based but is encrypted using IPSec or PPP encryption, then WFQ cannot identify the flows correctly. In this case, the default flow is used and the default flow is treated as a single flow.

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