What is BNG?
BNG (Broadband Network Gateway) is a device that plays a critical role in a service provider’s network, sitting at the server layer and performing several key boundary functions.
The main responsibilities of BNG include:
- Aggregation of client connections from DSLAM devices when using xDSL technology.
- Support for user sessions performed over PPP or ATM protocols.
- Implementation of Quality of Service (QoS) policies.
- Configuration of user tunnel parameters, including IP addresses, when the device acts as a terminator.
- Routing traffic to the provider’s backbone network.
A typical interaction method of a Broadband Access Router (BNG) with other network nodes is the termination of point-to-point tunnels, including encapsulated PPPoE tunnels. In this context, DSLAM aggregates data from multiple users and sends it to the BNG. Authentication, authorization, and accounting for client access to the network are carried out using the AAA protocol.
Cisco has implemented advanced aggregation technologies based on a distributed architecture and integrated services implemented on the Cisco ASR 1000 platform. According to the manufacturer, the new generation of network architecture, created using this equipment, effectively addresses tasks related to complex hierarchical QoS schemes, as well as video stream processing in IPv4 or IPv6 Multicast formats. Moreover, this architecture integrates these solutions with MPLS PE (MPLS Provider Edge), supporting a variety of traffic tunneling modes. Thus, the new architecture minimizes packet loss risk for priority applications even in network failures, ensuring efficient bandwidth planning without compromising performance.
Current Market Offerings and Their Costs
The current market offers several BNG solutions from various manufacturers:
- Ericsson presents the Smart Edge series, including models SE100, SE400, and SE600. The price range for these products is from $6,667 to $60,000.
- Cisco stands out with router lines such as 7200, 7500, 7600, ASR, and ISR. For example, the base model Cisco ASR1002 costs $17,333.
- Juniper offers routers from the MX and ACX series. The Juniper MX960 on the secondary market is priced around $73,333.
- Stingray Service Gateway is available starting at $3,200, depending on the selected license.
Additionally, there are several open-source projects based on UNIX-like systems. In some cases, the operating system can be optimized to function as a BNG. These systems include FreeBSD, NetBSD, and CentOS.
Advantages and Disadvantages of Hardware Systems
Each manufacturer and their BNG solution has specific advantages and disadvantages. Some notable advantages include:
- Compactness: Devices easily fit into standard 19-inch racks. However, it should be noted that some models take up not 1-2U (the standard height in units is 44.45 mm or 1.75 inches), but a full 4U, which can be considered a drawback.
- Specialization: The proposed solutions are perfect for solving specific, well-defined tasks due to their narrow specialization and optimization.
- Compatibility: Full compatibility with other products from the same manufacturer.
However, despite these advantages, there are certain disadvantages and specific features of these solutions that need to be taken into account.
For example, in the configuration ASR1002 + Radius + PPPoE/L2TP, errors may arise such as: “Session creation failed due to Full Virtual-Access Interfaces not being supported. Check that all applied Virtual-Template and RADIUS features support Virtual-Access sub-interfaces.” The issue lies in the fact that the ASR device cannot effectively manage traffic in both directions (incoming and outgoing). The reason is that the ASR1002 does not support radius parameters: Framed-Compression = Van-Jacobson-TCP-IP and does not recognize the rate-limit command on interfaces of any type. This specificity arises when using Layer 2 access protocols such as PPPoE and L2TP. However, if we talk about PPTP, a Layer 3 protocol, the ASR accepts the connection but does not send the required data back to the client, causing the connection to be terminated by the client-side timeout.
Another issue is that Cisco’s equipment performance is not always clearly and accurately described. The problem is that when choosing equipment, attention often focuses solely on interface speed, switching matrix speed, or internal bus speed, as well as the maximum number of sessions. However, little attention is given to maximum performance in packets, which is especially important during peak traffic hours.
For example, when using Cisco 7201 as a BNG, the load can reach 95% with an uplink load of 570 Mbps, while the number of packets per second is only 10,800. Calculations show that the packet size in this case will be 615 bytes, even though the routing performance specification indicates a maximum of 2 million packets at a bandwidth load of 1 Gbps.
Interestingly, the performance of the ISR 3845 according to routing performance looks as follows: 500 kpps at a load of 256 Mbps. Practical testing revealed that the 7200-NPE-G2 does not even reach half of the stated performance, while the ISR 3845 exceeds expectations. Of course, it is difficult to predict the actual traffic processing capacity during peak hours based solely on the official documentation.
A similar situation is observed with ASR 1002 ESP5 and ESP10. Additionally, there is a risk of reaching the maximum number of created sessions, which is a critical point for providers.
Among the various manufacturers on the market, Ericsson’s products stand out. The SmartEdge models, specifically the SE100 and SE600, are widely used across different industries. The SE100 is marketed as an access server, while the SE600 is a router. The SE100 supports up to 12 Gbps with a performance of 8 Mpps. It comes with two combo ports (1000BaseT/SFP), two dual-port 1000Base-X (SFP) modules, and a license for IPv6 support. The maximum number of subscriber sessions for this model is 8,000. Options like CG-NAT and IPv6 are available as licensed features, which means additional costs apply if they are used.
The SE600 router can support up to 16,000 active subscriber sessions (PPPoE, IPoE, VLAN, DHCP) with a throughput of up to 20 Gbps in full-duplex mode per port. Licensing is related to the number of connections, CG-NAT, IPv6, and session reservation via the management module. It is important to note that both models are considered outdated: the SE100 was released in 2006 and the SE600 in 2009, and key components such as power supplies and fans are no longer manufactured. Despite their age, the modules’ prices remain high. For example, a 10GE (XFP) port slot for the SE600 costs 3.5 million rubles, while a DPI module costs 700,000 rubles, excluding the chassis and licenses. The SE100 costs approximately 450,000 rubles for supporting 24,000 active clients. The question arises: if used equipment is priced so high, how much will new equipment cost?
Also, take into account additional costs related to traffic shaping computations.
General Disadvantages of Hardware Systems
Based on years of experience with the described devices, several significant drawbacks of hardware BNG systems can be highlighted:
- Fast obsolescence. Technologies evolve rapidly, and equipment becomes outdated in a short period.
- High cost of components and spare parts. The prices for parts required to expand functionality or replace broken components are excessively high. Additionally, some components are difficult to find, leading to downtime (business interruptions).
- Narrow specialization. Some systems offer limited functionality, and expanding it requires additional financial investments, such as acquiring licenses to support more clients.
- CPU load. Additional system features may place a significant load on the CPU, especially when using NAT, traffic shaping, and traffic filtering together.
- Incompatibility with other manufacturers’ products. This applies both to interface aggregation and standard protocol incompatibilities.
- Large device size. While 1-2U height is an advantage, larger sizes can cause installation issues. Devices weighing over 30 kg are too bulky to be installed on the top racks of a server.
- Increased power consumption.
- Problems during acceptance by regulatory authorities. Some types of equipment only have an RCT certificate. While the CCC certificate or declaration may be missing or expired, if the equipment was purchased during the validity of the CCC certificate, it can still be used.
Advantages and Disadvantages of Open-Source Products
Open-source products deserve special attention. In practice, providers approve and actively use only two combinations of software products: FreeBSD + mpd5 and Ubuntu (Debian) or CentOS + Accell. Here are several significant advantages of these solutions:
- Computational capabilities of the hardware. They are limited only by the processor’s characteristics and the available RAM, not “compressed” or “trimmed” by the manufacturer at the factory.
- Affordable hardware cost. The price of physical components is significantly lower compared to analogs.
- Flexible configuration. Open-source software allows flexible system customization to meet specific needs and requirements.
- Availability of spare parts. Spare components are always available for purchase, and system upgrades are straightforward.
- Free software. Open-source software is distributed for free, significantly reducing the total cost of ownership and operation.
Despite the many advantages, open-source products also have certain drawbacks:
- Low reliability. This is due to the non-commercial nature of the development. Both system and software failures are possible.
- Need for qualified personnel. To ensure stable server operation and recovery in case of failures, personnel with specific skills and knowledge are required.
- Dependency on hardware. The specifics of operating systems can lead to situations where, for example, increased load on the hard drive paralyzes the entire system’s operation.
- Absence of some network protocols and features. This can apply to both individual applications and the operating system kernel.
There are also alternative solutions, such as Stingray Service Gateway from VAS Experts. Stingray Service Gateway is a software platform for deep traffic analysis and filtering, effectively implementing BNG functions with several key advantages:
- Flexible configuration.
- Independence from specific server hardware manufacturers.
- Dynamic product development. Optimization of individual system components is ongoing, with new parameters added for more flexible configuration.
- Technical support 24/7.
Conclusion
Hardware BNG platforms represent an optimal choice for medium and large providers whose regulations require the use of specific brand equipment. For many small B2C telecom operators, open-source solutions can be a perfectly acceptable option. However, due to their drawbacks, such as the need for qualified personnel and long implementation times, their use may be complex. In this context, applying the Stingray Service Gateway system becomes a reasonable solution.
For more detailed information about the advantages of the Stingray Service Gateway traffic analysis system, its effective use in telecom networks, and the migration process from other platforms, contact VAS Experts specialists.