Stream-based applications

Packet processing in the domain of (Inter)networking is a demanding task. The requirements on performance and flexibility of packet processing equipment as well as on security and availability rise permanently. Currently, important driving forces in the Internet are new technologies, the growing number of Internet users and oversubscription of transmission lines. Hence, only hardware solutions provide sufficient performance for packet classification, manipulation and forwarding. Due to their flexibility, we use FPGAs as target platform.

MATMUNI is such a packet processing solution. It is currently designed for a Xilinx Virtex-4 FX20 platform FPGA. MATMUNI?s functional submodules offer mechanisms for medium access controller address translation (MAT), traffic management (TM) and a multi protocol label switching user-to-network interface (MPLS-UNI). The following section briefly describes the functionality and architecture of MATMUNI?s current architecture.

Application scenario

Figure 4: Typical structure of an access network and location of MATMUNI

As sketched in Figure 1, MATMUNI is located in the access network behind the line cards (LC) and the central switching unit (CXU). The CXU aggregates several thousand digital subscriber lines (DSLs). On independent channels, traffic of multiple Gbit/s must be handled concurrently. MATMUNI covers packet processing tasks that prepare and format traffic for the core area.

  • MAT targets scalability and security issues by flexible n:1 translation of data link layer addresses - Ethernet addresses of the medium access controller (MAC) in our scenario. Untrustworthy customer MAC addresses are translated into distinct, trustworthy MAC addresses of the Provider.
  • TM functionality is to meter traffic on a per customer basis. Each frame is color-marked either green, yellow, or red according to the customers current bandwidth utilization. With policing mechanisms, the subscribed bandwidth is ensured as long as possible for each customer.
  • MPLS-UNI encapsulates complete frames and marks them with MPLS labels. Forwarding decisions of core routers solely depend on these labels? information. Usually, a full-blown label edge router (LER) is required. But in the case of MATMUNI, only a subset of an LER?s functionality is necessary. Therefore, an adapted, compact MPLS module was realized in hardware.