Mobile local network PTN networking plan and strategy

The rapid development of 3G networks has stimulated the demand for large-scale services such as various groups, WLAN (wireless local area network), and community data services, and has put forward higher requirements for the new generation of metropolitan area transmission networks. In order to improve the IP and packet capabilities of the transmission network, mobile local networks in various places have increased their efforts in PTN construction.

Networking principles and strategies

The overall construction principle of the mobile local network PTN is: the mobile local network adopts PTN technology in principle, is planned as a whole according to the principle of full-process and full-network, and is implemented in a distributed manner, taking into account the full-service access needs of GSM base stations and important group customers, and coexists with the existing MSTP network and is constructed in a coordinated manner.

The network planning principle is: adopt a flat networking structure and coordinate the planning of the core layer, aggregation layer, and access layer.

1. Core layer PTN networking principles

The core layer should use large-capacity or medium-capacity equipment, with an NNI (network interface) rate of no less than 10G, a ring structure or mesh structure, and connect to the core network with a GE optical interface, responsible for the scheduling of various business IP circuits.

2. Convergence layer PTN networking principles

The aggregation layer PTN network should adopt a ring structure, and the number of ring nodes should be 3 to 6.

The TDM (time division multiplexing) circuits converged by the PTN network should be connected to the SDH convergence layer network in STM-1 mode at the convergence layer.

3. Access layer PTN networking principles

The PTN network access layer is mainly a ring structure, and the terminal access can adopt a chain or star structure.

The access layer generally forms a GE loop, and the number of loop nodes is generally 4 to 6 nodes; in densely populated urban areas with large business volumes, a 10GE loop can be formed, and the number of loop nodes is generally 6 to 8 nodes.

The original TD base stations that used MSTP access in the early days can be gradually replaced with PTN equipment based on the overall PTN planning.

4.MSTN and PTN hybrid networking ideas

In principle, hybrid networking is mainly based on the access layer. Method 1: build a new PTN access ring network and hang it under the traditional MSTP aggregation node; Method 2: build a new MSTP ring network and hang it under the PTN aggregation node; Method 3: access layer MSTP and PTN equipment are directly networked; Method 4: the traditional MSTP ring network and the newly built PTN ring network are interconnected at the aggregation layer to achieve the interconnection between the traditional MSTP network and the newly built PTN network.

PTN equipment port and service configuration requirements

TD base station access points (including macro base stations and indoor distribution systems) are mainly divided into the following two categories: pure TD base stations and 2G/3G co-location stations. For pure TD base stations, if there is no group customer access demand in the near future, PTN equipment with lower switching capacity can be configured, and only IP interfaces can be configured; for existing GSM base stations in 2G/3G co-location stations that have been carried by MSTP equipment, PTN only configures IP interfaces; for newly built 2G/3G base stations, PTN equipment is configured with both IP interfaces and TDM interfaces.

The PTN service configuration for TD network mainly adopts Ethernet virtual dedicated line access, and its service protection mode mainly adopts 1:1 protection of end-to-end label switching path (taking into account the dual-homing protection capability of services and equipment in RNC POOL and LTE stages, and OTN network protection).

Local Network PTN Construction Plan

1. Local network PTN network architecture

The mobile local network PTN is mainly divided into the aggregation layer and the access layer. The aggregation layer uses 10GE rate equipment for networking. The access layer uses 10GE/GE equipment for dual-node uplink access according to the service aggregation situation to achieve access to base stations, indoor distribution, and key customer services. The core business room uses large cross-capacity 10GE equipment as TM terminal equipment to achieve connection with the RNC.

The PTN network's aggregation ring and core node use OTN's connection mode: GE link, that is, each aggregation ring uses OTN to achieve different GE link connections to the core RNC room. On the same aggregation ring, using PTN and OTN connections can not only perform NodeB service diversion (different NodeB services to the same RNC are reasonably shared on the PTN node), but also protect PTN node services.

In this networking mode, 2G services continue to use the original MSTP plane, and the newly added TD services are opened in PTN. The PTN network structure is similar to 2G MSTP, with GE rate rings at the access layer and 10GE rate rings above the aggregation layer. Each network plane is networked with intersecting rings. At the same time, the TDM circuits converged by the PTN network should be connected to the traditional MSTP aggregation layer network in the aggregation layer with 155M optical ports to make full use of the original TDM circuit resources.

2. Implementation and effect of the plan

At present, the construction of mobile local PTN networks has gradually matured and has begun to be applied to various multi-service bearing scenarios, such as 3G network access, CMNET metropolitan area network expansion, and township OLT data network construction.

(1) TD Phase III network access

TD network is a multi-service network, and different services have different requirements and characteristics. Through the establishment of PTN local network, Jiangsu Mobile successfully completed the bearing of TD Phase III project base station services, ensuring the official commercial use of TD-SCDMA network.

(2) Data metropolitan area network expansion

The backbone layer of the metropolitan area network is generally carried by the DWDM/OTN system to protect the transmission links between nodes. The traditional MSTP aggregation layer network is no longer suitable for the development needs of large-granularity services. The PTN network can well solve the problems existing in the metropolitan area aggregation layer, mainly expanding the link bandwidth between the aggregation layer BRAS/SR/OLT network, improving equipment performance and capacity. The PTN network can also protect the transmission links between access points, optimize the network structure and realize multi-service bearing of the metropolitan area network.

(3) Access to ports and industrial parks

To meet the strategic needs of the country's coastal development and the business development needs of coastal ports and industrial parks, Jiangsu Mobile has extended the coverage of the PTN+OLT local network. Currently, a new PTN+OLT local network covering key coastal towns and ports has been built to meet the business development needs in the current and future period.

The networking is mainly based on the establishment of a dual-node PTN ring to improve network security; in important integrated service access scenarios such as various ports, township parks, etc., it is ensured that OLT achieves dual uplinks, and the uplinks are to different integrated service convergence points to achieve dual protection of services. By setting up aggregation switches at core/aggregation nodes, various types of services such as internal dedicated lines of the group, Internet dedicated lines, DCN, IPTV, etc. are diverted.

The construction of metropolitan PTN networks also poses certain challenges to network operation and maintenance, mainly in terms of high maintenance skill requirements, high difficulty in service maintenance, and complex resource management. Jiangsu Mobile will refer to the relevant mature maintenance model of SDH networks and gradually build the PTN local network into a high-quality network.