Intelligent, Converged Bearer Networks

Converged Bearer Networks to Meet Diverse Demands

The service structure of telecommunications networks is undergoing big changes, and data is gradually becoming the dominant business. Emerging industries such as smart city, smart grid, M2M, and tri-network convergence are constantly improving, and new applications and services have appeared.

Large-granule services such as TV shopping, HD TV, online video, and high-speed internet are mushrooming, as are enterprise IP services such as IP SAN, multimedia conferencing, and broadband VPN. To develop new services, many countries have begun constructing national broadband networks with 100 Mbps as the starting speed. In many cases, this will gradually be increased to 1000 Mbps. With the rapid deployment of 3G, LTE, and mobile internet, legacy TDM (E1/STM-1) services in backhaul networks have been replaced by IP over FE/GE, and E1/STM-1 has been forced to coexist with FE/GE. The centralized deployment of wireless BBUs has also meant that a vast number of large-granule CPRI signals are being transported between BBUs and RRUs. Co-existence of services and high access bandwidth have become development trends in both fixed and mobile networks.

Emerging services such as financial disaster recovery, IP SAN, bandwidth leasing, and government and enterprise networking have new features and applications. A bearer network has to provide functions ranging from transparency to intelligence, and it needs to support services ranging from regular Ethernet and GDPS to specific-rate videos and bear-all services.

OTN Solution for Different Scenarios

Full-Service Bearer Network for Operators

More and more operators are turning to full-service networks, so their bearer networks have to follow this trend.  Full-service bearing greatly changes the bearer networks in fixed and mobile networks. Therefore, ZTE has launched a compact iOTN product called ZXMP M721 that meets the full-service-bearing needs of operators (Fig. 1).

Full-service bearing involves:

●    xPON OLT/MSAG/MSAN uplink service bearing. xPON OLT can be connected to BRAS/SR on the uplink through a single-node or dual-node networking. Typical uplink service ports support 4GE to 8GE, and future uplink ports will support 10GE. New DSLAM is generally IP-DSLAM, and its typical uplink service is GE. Conventional ATM-DSLAM has an STM-1/STM4 interface. The typical uplink service of the MSAN equipment is GE/FE. ZXMP M721 provides high capacity and large bandwidth to reach the requirements of fixed networks for massive bandwidth.

●    SDH network transformation. There are a large number of STM-1/4/16 SDH networks at the access layer. The growing bandwidth demand and accelerated IP-centered network construction is putting a strain on optical fiber resources so that existing SDH networks desperately need to be transformed. An OTN based on ZXMP M721 can bear the existing SDH networks. SDH occupies some wavelength of the OTN while releasing occupied optical fiber resources.

●    PTN/IP RAN bearing. Similar to SDH networks, PTN/IP RANs occupy many fiber resources when they bear wireless backhaul network services. In a large-scale LTE deployment, fiber resources are strained. An OTN based on ZXMP M721 has sufficient wavelength to bear PTN/IP RAN services. In addition, the OTN based on ZXMP M721 supports 1588V2 and Sync E to meet the clock synchronization requirements of wireless bearing.

●    wireless backhaul network bearing. The high-bandwidth backhaul and flat network structure are reasons that the OTN is used to bear backhaul traffic. OTN equipment is deployed at the base station side or at aggregated microwave sites. ZXMP M721 supports L2 functions, E1/T1, STM-1/4/16, FE and GE access, and 1588V2 and Sync E clock synchronization. This meets the bearing demands of backhaul.

●    wireless fronthaul network bearing. 3G, LTE and BBU centralized deployment has become more mainstream. The high-speed CPRI signal between the BBU and RRU needs to be transmitted effectively. ZXMP M721 supports the mainstream applied CPRI option 2, 3, 6 and 7 to satisfy the stringent requirements of frequency accuracy and delay jitter. In addition, it can build a star network and ring networks according to network deployment needs.

●    broadcast. Broadcast services generally use L2 technology. However, with the demand for high-bandwidth and large-granule services, the use of OTN rigid bandwidth has been proposed. ZXMP M721 supports DSS distributed electrical cross-connection as well as ODUk granule-based broadcast.

Government and Enterprise Network Scenarios

 Each government or enterprise network scenario has its own unique networking mode for specific needs. These needs include:

●    disaster recovery. Finance, taxation, social security center and other institutions require very high data security. They generally transmit services via dedicated fiber channel switches. Remote disaster recovery is the mainstream security requirement. ZXMP M721 supports 1G/2G/4G/8G/10G FC, FICON and Infiniband services. A single-fiber bidirectional mode is usually used for networking, and the two systems operate in 1+1 backup mode.

●    data center interconnection. Large internet companies and bandwidth leasing companies need large-granule data interactive transmission and disaster recovery between data centers. 10GE dominates their services. ZXMP M721 supports 40×10G DWDM application to transmit large-capacity data. Moreover, it supports AC and HVDC to make full use of the limited power supply in equipment rooms.

Industry-Leading Performance Indexes

ZXMP M721 has industry-leading performance indicators and has the following features:

●    high integration. The subrack height is only 1U, 2U or 3U. It supports the industry’s most effective service slots compared to the equal volume of similar devices.

●    powerful transmission. It supports the 40×10G DWDM application or 18×2.5G/10×2.5G+8×10G CWDM application. DWDM supports multi-span radio relay (18×22 dB, 7×30 dB, 1×45 dB, etc.). CWDM 2.5G supports up to 28 dB transmission. The target transmission distance of CWDM 10G is 70 km.

●    rich service access. It can access any-rate-service (100 Mbps~7.5 Gbps) signals in multiple formats and a variety of 10G services.

●    flexible service grooming. It supports the ODU0/1/flex granule-based distributed electrical cross platform. It also supports L2 switching aggregation from 8×GE+2×10GE to 10GE.

●    clock synchronization. It supports 1588V2 inband/outband transmission as well as Sync E.

●    perfect protection. It supports 1+1 protection for the main control board and power board. In addition, it supports OCh 1+1, OMS1+1, ODUk 1+1, ESR and ERPS protection.

●    excellent monitoring information transmission. It supports inband/outband monitoring as well as OSC and ESC.

As new services and applications emerge, service networks trends will change. The OTN bearer network plays an increasingly important role in converging all services, and all the more so for the OTN network closest to the client side.