DCN Middle&Small Operator Solution

With rapid growing of Internet businesses, types of services carried on operator networks have been evolving substantially and integrated information services have become basic needs. Large bandwidth, strong reliability, variety of businesses, flexible scalability and low IT costs have been top priorities in operator network construction. An operator network must provide a large variety of applications including sound, video and data services, which have strict requirements on network safety, reliability, QoS and synchronism.
DCN provides a series of multi-service network solutions to meet operator network requirements and sharpen Internet service providers’ competitive edges. 10GB Ethernet switches are adopted to build networks whose bandwidth is 10 times as large as tradition structures, thus speeding up various applications. In addition, many new functions and characteristics are incorporated into networks to provide high-return services for scattered users in the local network while ensuring high network reliability and safety.
General Topology
Mid-sized operator solution topology:
The solution is provided for mid-sized operators with large customer bases and coverage. Given mass data services carried by such networks, the solution topology is a 40G backbone ring network built by several CS6500s. The 40G backbone ring network comprises multiple 10G branch ring networks composed of multiple S5750E. The solution is featured by high efficiency and low costs.
Mid-sized operator solution topology

Small-sized operator solution topology:
The solution is designed for small-sized operators with small and concentrated customer bases. The solution adopts a 10G backbone ring network built with multiple CS6200s, and S3900E serve as access switches. The solution is featured by high cost-performance, a simple structure and high efficiency.

Small-sized operator solution topology


High reliabilityThe reliability of an operator’s network depends on reliability of devices and links. To ensure reliable operation of devices and prevent networks from being paralyzed due to accidents, DCN provides professional devices designed for network operators and offers redundancy measures for key parts including power supplies and fans.
In Metropolitan Area Network (MAN), the maintenance of one redundancy line for each access switch will cost a large waste of money and time, not to mention maintenance of two redundancy lines. Ring networks are widely adopted by network operators to prevent a single point of failure. Spanning Tree Protocol (STP, RSTP and MSTP), which is widely applied in traditional Ethernet, is not fully compatible with the topology. Therefore, Ethernet Automatic Protection Switching (EAPS) has been widely adopted by operator as the optimal substitute of STP in ring networks. Unlike STP, EAPS can immediately open the slave port of the master node within 200 ms when the network is broken to ensure that data flows can be forwarded immediately, thus facilitating instant network services including IPTV and VOIP.
High safetyWhen authorization and fee charging mechanism are enabled under the IPoE environment, the first problem facing users is binding and monitoring each user on the port. This problem can be well solved via DHCP relay, DHCP information option 82, DHCP snooping and IP source guard.
As an enhancement option of DCHP, DHCP information option 82 can add information including the switch interface to which users are connected into DHCP request packets, so that the DHCP server can choose different IP address strategies for varied users, thus realizing services including user flow counting and rate limiting. DHCP snooping can collect DCHP response packets sent from the DHCP server to users and store IP information of reach user, through which IP source guard can realize special flow control measures. For example, when a hacker invades a network by revising the IP address, the switch can check whether the IP address is authenticated by the DHCP server. If not, flows will be discarded.
DAI can safely prevent ARP spoofing, which is an address spoofing attack on users in the network by hackers carrying ARP packets with wrong MAC and IP addresses. DAI can filter spoofing packets by checking ARP packets’ information and comparing it with static ARP table entries of the switch.
Super VLAN enables multiple VLANs to use one layer-3 interface so that multiple users can use addresses within the same network segment. Despite one address is used as the gateway when data is sent, users are separated and cannot communicate with each other.
ARP Proxy allows users to communicate with each other while using Super VLAN. What’s more, the data is processed through the switch rather than forwarded directly through hardware. By doing this, users can choose various strategies according to flows, which means user communication can be controlled.
Multi-Service SupportReal-time video services (such as live, VOD, carousel, etc.), network latency, packet loss is very sensitive. DCN provides perfect QoS function on network switches to guarantee real-time video services for operator. It include that corresponding tags are marked flexibly on flows sent from the user end and external networks according to various categories.  DCN switches  support at least four priority queues. So operators can configure different flow strategies for the queues to rank most flows in priority.
To provide the IPTV service, various multicast protocols and multicast flow strategies need be supported by network devices. DCN switch support abundant multicast protocols and standard to guarantee IPTV service can be working smoothly. The protocols include IGMP, IGMP snooping and dynamic multicast routing protocols such as PIM-DM, PIM-SM and. In addition, as a key for realizing multicast duplication between VLANs, MVR can effective save network bandwidth and ensuring quality of the IPTV service.
QinQ technology can solve the VLAN ID of increasingly scarce resources for small MANs and provide a relatively simple Layer 2 VPN solution. It has been widely deployed on operator network. DCN switches support Port-based QinQ, Selective QinQ and Flexible QinQ to meet individual needs of different operators. QinQ was developed to reserve VLAN information between two branches of a company through the operator’s network. After the operator’s switch receives flows from one branch through one port, it will add an 802.1Q tag in addition to the 802.1Q tag. This is also known as Port-based QinQ. Selective QinQ is a more complex technology, which can add external tags based on internal tags of users. Flexible QinQ can add external VLAN tags based on various properties of flows such as MAC address and protocol port number. It applies to some special applications. For example, it can add a separate VLAN tag to all voice flows received from the user end and give them a highest priority in the network to ensure that the voice communication is smooth.
VPLS (VirtualPrivateLanService) is the multi-point interactive layer-2 VPN technology developed based on the point-to-point MPLS. It can simplify operators’ requirements on devices on the CE end. Based on MPLS, VPLS is independent from specific physical topology and can optimize resource allocation using MPLS flow engineering. VPLS also supports ACL scalable on layer 2, 3 and 4 and ACL control on each user. It provides safer control and policies with a solid layer-2 aggregation capability. Moreover, it breaks the limit on the number of VLANIDs of a traditional Ethernet network, which only support 4,096 VLANIDs at most. VPLS can trim off maintenance costs for operators, simplify routing configuration, save routing resources and facilitate business operation, thus helping operators build simple networks that can generate remarkable profits and added value.
As the next-generation Internet protocol, IPv6 is the best substitute for the dying IPv4 to provide adequate addresses. All the existing network protocols need to be upgraded to support IPv6. However, long-term coexistence of IPv4 and IPv6 users in networks of operators seems to be inevitable. Therefore, all network devices must support two protocol stacks concurrently so that users can shift from IPv4 to IPv6.


CS6500-48S4Q-SI40G Ethernet Optical Routing Switch, 48 * 10G SFP+ and 4 * 40G QSFP+ ports (2 power modules at most, 1+1 redundancy. 5 fan modules at most, 4+1 redundancy)
CS6200-28X-HI-24F10G Ethernet Routing Switch, 16 x GE Combo(GT/SFP) + 8 x GE(SFP) + 4 x 10GE(SFP+) + 2 stacking port, modular power (2 power modules at most, 1+1 redundancy. Standard with no power module)
S5750E-28X-SI-24F-DL3 Gigabit Intelligent Ethernet Switch with 20 100/1000Base-X, 4 GbE Combo(SFP/RJ45) and 4 10GbE (SFP+) ports, 100-240VAC + 48VDC Power Input
S5750E-28P-SIL3 Gigabit Intelligent Ethernet Switch with 24 10/100/1000Base-T and 4 1000Base-X(SFP) ports, 100-240VAC Power Input
S5750E-52P-SIL3 Gigabit Intelligent Ethernet Switch with 48 10/100/1000Base-T and 4 1000Base-X(SFP) ports, 100-240VAC Power Input
S5750E-28X-SIL3 Gigabit Intelligent Ethernet Switch with 24 10/100/1000Base-T and 4 10GbE (SFP+) ports, 100-240VAC Power Input
S5750E-52X-SIL3 Gigabit Intelligent Ethernet Switch with 48 10/100/1000Base-T and 4 10GbE (SFP+) ports, 100-240VAC Power Input
S3900E-10P-SIL2 Fast Ethernet Intelligent Ethernet Switch with 6 10/100Base-T, 2 10/100/1000Base-T and 2 100/1000Base-SFP ports, 100-240VAC Power Input
S3900E-28P-SIL2 Fast Ethernet Intelligent Ethernet Switch with 20 10/100Base-T, 4 10/100/1000Base-T and 4 100/1000Base-SFP ports, 100-240VAC Power Input