The Use of EoPoS
As stated in the General Description, by first mapping into one or more PDH tributaries such as T1, E1, or DS3, the component Ethernet contained in separate PDH signals from a central location can be fanned out to multiple locations. EoPoS allows transport of native Ethernet frames over a SONET/SDH network. Then the component PDH can then be separately dropped using a legacy ADM. Finally, the PDH links are resolved back to Ethernet connections by equipment supporting EoPDH. For proper operation each of the VLAN must be individually tagged.
Read more about this topic: Ethernet Over PDH Over SONET/SDH