Deploying a Full-Mesh IPRAN Network over DWDM Backbone

Felipe Sevillano, Transport & Data Planning Department, TELECOM PERSONAL PARAGUAY

In my company we decide to implement an IPRAN Network over our national DWDM Backbone (OSN8800-T16). The first issue we had was deciding if the service protection would be done by the DWDM device or by the ATNs.

The DWDM device is equipped with an LEM24 muxponder to give access to the routers to the backbone. So we analyze which protocols can be deployed with the LEM24 to give service protection and the possibilities were to deploy Rapid Spanning Tree, Multi-Spanning Tree (MSPT) and Ethernet Ring Protection (ERP). Because the services to be carried by the ATNs are mobile services, the convergence time of the protocol is essential. On the one hand, the ERP had good convergence time but only works with single rings and because our DWDM backbone is not a single ring we discard this option. Also MSPT can work with multiple rings but convergence time is not as good as we need. So finally we decide to leave the DWDM only for transport services and the protection to the ATNs using MPLS-TE tunnels which can assure a 50ms convergence time.

The second issue to be solved was deploying full protection for the services, which means that if an ATN can send services over three or more paths, these paths must be available for the services. To solve this, we made a mesh with logical links between aggregation routers as you can see below:

Each link means a VLAN configured in the LEM24 following one path over the transport backbone. Using this mesh, each ATN can send services to two aggregation routers that belong to his area (the network is divided in three different areas) as you can see below:

Each link means a VLAN configured in the LEM24 following one path over the transport backbone. Using this mesh, each ATN can send services to two aggregation routers that belong to his area (the network is divided in three different areas) as you can see below: