Flow control method for synchronous digital system network transmission data business

Abstract

A flow control method relating to data information transmission used in transmitting data service of SDH network characterizing that, in the data transmission of SDH network, EOS equipment generates and packages LFP frames, images the E-E equipments transferred between destinated points in SDH net charge, the E-E equipment extracts LFP frames from SDH net charges and carries out the flow control information carried in LFP frame, which carrier can use PAUSE frame structure defined by standard 802.3x, the unpackage can be done applying a LFP transparent transmission way or regeneration way of LFP frame.

Description

technical field [0001] The invention relates to the transmission of digital information, in particular to a flow control method for transmitting data services through a synchronous digital system SDH network. Background technique [0002] With the rapid development of the Synchronous Digital Hierarchy (SDH) network, EoS (Ethernet over SDH / SONET: Transmission of Ethernet services through SDH / SONET network) technology has also been more widely adopted. How to efficiently implement data applications through the SDH network becomes even more important. Important, in the Ethernet transmission application of the metropolitan area network, because the distance between the sites can reach one to two hundred kilometers, and the mapping processing in the current EoS generally uses the virtual cascading working method, the delay between the two sites It may reach the level of several milliseconds or even tens of milliseconds, and considering the burst characteristics of Ethernet servic...

AI Technical Summary

Problems solved by technology

The disadvantage of this control mechanism is that it generally causes a large amount of packet loss. In a commonly used TCP / IP application, a large amount of packet loss will seriously degrade network performance, especially for the most widely used TCP / IP protocol, packet loss will The application performance is greatly reduced. For example, in a TCP application, if a 10M / b Ethernet device is used, if the value of the overtime retransmission timer AckTime is equal to 5 seconds, for a 1500Bytes long Ethernet frame, 1% of the frame is lost rate FLR will result in a 98% reduction in operational performance

[0006] Now assume that the bandwidth allocated by the SDH network is 1 VC3, that is, 45M. When the transmission rate of user data device A exceeds 1 VC3, in the existing processing technology, because the traffic of mapping part A is constant and is 1 VC3, Therefore, the extra Ethernet frames are accumulated in the encapsulation part A. When the cache of the encapsulation part A is exhausted, the MACA data cannot be sent to the encapsulation part A. Therefore, when PHY+MAC A is allowing Ethernet flow control , send a PAUSE frame (full-duplex) or back pressure (half-duplex) to the user equipment, namely figure 1 Dotted line 1 in (if Ethernet flow control is disabled, MACA discards excess Ethernet frames, please refer to IEEE 802.3x documents for Ethernet flow control), which will reduce the sending rate of device A to below 1 VC3 without packet loss, so as not to degrade network performance excessively

[0007] When the sending rate of device A is lower than 1 VC3, but the receiving rate of device B is lower than the sending rate of device A for some reason, for example, there are multiple 10M devices connected to device B, but only one is working, from device A to The sending end of EoS device B will not be blocked, but device B itself will be blocked. Therefore, according to the implementation of 802.3x, device B will send the flow control information defined by 802.3x to the port directly connected to it, that is figure 1 The dotted line 2 in , can be a PAUSE frame or a back pressure signal. According to the implementation of 802.3x, this flow control information will be terminated by MAC B. At the same time, MAC B will stop sending data to device B and will not be transmitted to device A. A continues to send data according to the original flow, so that the Ethernet frames from device A accumulate at decapsulation B or MAC B. When the buffers at these two places are exhausted, EoS#B must lose packets. Both device A and device B are devices that support 802.3x Ethernet flow control, but packet loss cannot be avoided after transmitting the device through EoS. Flow Control to Ethernet

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