SDH以太共享环在城域网的应用

随着因特网和数据业务的爆炸性增长，城域网的主要业务正在从话音向数据转移。然而过去的城域传送网是为话音业务设计的，所以采用的是TDMM网络(SDH、SONET)。本首先介绍了基于SDH网络传送数据业务的几种新技术，如：POS、GFP、LCAS、RPR、共享以太环等，以及可以实现业务隔离、保证安全的VLAN、VLAN嵌套技术，然后对各种城域网数据传输技术进行了比较，最后分新了薪一代的MSTP设各府该具有的几个特点。

Application of the Ethernet-Shared-Ring over SDH

This article discussed the metro area network data service and transport requirements.With the explosive Internet and data traffic growth,the major traffic in the metro area networks are gradually shifting from voice to data.However,the metro transport was built over time by using TDM network(SDH/SONET),which is designed for voice traffic.This article has discussed the data network evolution and its corresponding transport network changes.There are several technologies have been used to adapt the data traffic for SDH transport:including packet over SDH(PoS)using PPP/ML-PPP mapping techniques and transparent transport,GFP mapping using virtual concatenation VC-X- Xv,X can be4,3,12with link capacity adjustment scheme(LCAS),layer2switching for data aggregation for shared ethernet ring over the SDH,using VLAN and double VLAN tag techniques to do the rate limiting,traffic segregation and security isolation,and resilient packet ring(RPR).Those technologies and network topologies have been discussed and compared to understand the price/performance relations for the data transport.