Encapsulation And Mapping Protocol; Figure 4-14 Structure Of The Pause Frame - Huawei OptiX OSN 550 Configuration Manual

4 Configuring Ethernet Services
Realization Principle
The realization principle of the flow control function is described as follows:
1.
2.
3.
IEEE 802.3 defines the format of the PAUSE frame as follows:
l
l
l
l
l

Figure 4-14 Structure of the PAUSE frame

Destination address
Source address
Type/Length
MAC control opcode
MAC control parameter

4.2.5 Encapsulation and Mapping Protocol

To ensure that Ethernet frames can be transparently transmitted over the optical transmission
network, the Ethernet frames need to be encapsulated and mapped into VC containers at the
access point. The encapsulation and mapping protocols used by the Ethernet service board
include the high-level data link control (HDLC), link access procedure - SDH (LAPS), and
generic framing procedure (GFP).
4-14
When congestion occurs in the receive queue of an Ethernet port (the data in the receive
buffer exceeding a certain threshold) and the port is capable of sending PAUSE frames,
the port sends a PAUSE frame to the opposite end. pause-time value in the frame is N
(0<N≤65535).
If the Ethernet port at the opposite end is capable of processing PAUSE frames, this Ethernet
port stops sending data within a specified period of time N (the unit is the time needed for
sending 521 bits) after receiving the PAUSE frame.
If the congestion at the receive port is cleared (the data in the receive buffer is below a
certain threshold) but the pause-time does not end, the port sends a PAUSE frame whose
pause-time is 0 to notify the opposite end to send data.
Destination address: 01-80-C2-00-00-01 (multicast address)
Source address: MAC address of the source port
Type/Length: 88-08 (MAC control frame)
MAC control code: 00-01 (PAUSE frame)
MAC control parameter: pause-time (two bytes)
XX-XX-XX-XX-XX-XX
(pause-time)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
OptiX OSN 550 Multi-Service CPE Optical Transmission
01-80-C2-00-00-01 6 octets
6 octets
88-08 2 octets
00-01 2 octets
XX-XX 2 octets
Reserved
System
Configuration Guide
Issue 02 (2011-06-30)