A Practical Range Encoding Scheme for TCAMs

International Journal of Electrical and Computer Engineering (IJECE), 2022

Multi-filed packet classification is a powerful classification engine that classifies input packets into different fields based on predefined rules. As the demand for the internet increases, efficient network routers can support many network features like quality of services (QoS), firewalls, security, multimedia communications, and virtual private networks. However, the traditional packet classification methods do not fulfill today's network functionality and requirements efficiently. In this article, an efficient range enhanced packet classification (REPC) module is designed using a range bit-vector encoding method, which provides a unique design to store the precomputed values in memory. In addition, the REPC supports range to prefix features to match the packets to the corresponding header fields. The synthesis and implementation results of REPC are analyzed and tabulated in detail. The REPC module utilizes 3% slices on Artix-7 field programmable gate array (FPGA), works at 99.87 Gbps throughput with a latency of 3 clock cycles. The proposed REPC is compared with existing packet classification approaches with better hardware constraints improvements.

IEEE Micro, 2004

IEEE GLOBECOM 2007-2007 IEEE Global Telecommunications Conference, 2007

Packet classification is an enabling function in Internet routers for a variety of Internet applications. In order to classify Internet packets into flows, Internet routers must perform searches over a set of filters using multiple fields of the packet as the search key. Because of its speed and simple filter management the Ternary Content Addressable Memory (TCAM) is currently the dominant hardware solution for IP lookups, i.e., a one-dimensional packet classification. To make TCAM the solution for the multi-dimensional packet classification, efficient methods that store the range fields of the classification tables in TCAM are needed. In this paper, we propose a set of novel range encoding schemes based on Gray code. Many range-encoding techniques are used to improve the existing elementary intervalbased range encoding schemes. The present experiment's results show that the proposed Gray code-based schemes consume less TCAM storage space than the existing schemes.

IEEE/ACM Transactions on Networking, 2010

Ternary content-addressable memories (TCAMs) may be used to obtain a simple and very fast implementation of a router's forwarding engine. The applicability of TCAMs is, however, limited by their size and high power requirement. Zane et al. [1] proposed a method and associated algorithms to reduce the power needed to search a forwarding table using a TCAM. We improve on both the algorithms proposed by them. Additionally, we show how to couple TCAMs and high bandwidth SRAMs so as to overcome both the power and size limitations of a pure TCAM forwarding engine.

2008

Ternary Content Addressable Memory (TCAM) is a special type of memory used in routers in order to achieve high speed packet classification. The classification is performed using the five fields in an Access Control List (ACL), port numbers being one of them. Since port numbers that are expressed in ranges require multiple entries in storage, this results in an increased cost of hardware. In this paper we propose a method to reduce the number of entries when expressing ranges in TCAM. We use Range Matching Devices integrated within the TCAM's control logic and optimized prefix expansion that utilizes logical AND and NOT gates in the TCAM array itself. In addition, we use real data of an existing network to show that the proposed architecture can store the ACL in an efficient way.

2003

CAMs are the most popular practical method for implementing packet classification in high performance routers. Their principal drawbacks are high power consumption and inefficient representation of filters with port ranges. A recent paper showed how partitioned TCAMs can be used to implement IP route lookup with dramatically lower power consumption. We extend the ideas in to address the more challenging problem of general packet classification. We describe two extensions to the standard TCAM architecture. The first organizes the TCAM as a two level hierarchy in which an index block is used to enable/disable the querying of the main storage blocks. The second incorporates circuits for range comparisons directly within the TCAM memory array. Extended TCAMs can deliver high performance (100 million lookups per second) for large filter sets (100,000 filters), while reducing power consumption by a factor of ten and improving space efficiency by a factor of three.

2015 IEEE Global Communications Conference (GLOBECOM), 2014

Software Defined Networking (SDN) is gaining momentum with the support of major manufacturers. While it brings flexibility in the management of flows within the data center fabric, this flexibility comes at the cost of smaller routing table capacities. In this paper, we investigate compression techniques to reduce the forwarding information base (FIB) of SDN switches. We validate our algorithm, called MINNIE, on a real testbed able to emulate a 20 switches fat tree architecture. We demonstrate that even with a small number of clients, the limit in terms of number of rules is reached if no compression is performed, increasing the delay of all new incoming flows. MINNIE, on the other hand, reduces drastically the number of rules that need to be stored with a limited impact on the packet loss rate. We also evaluate the actual switching and reconfiguration times and the delay introduced by the communications with the controller.

2009 IEEE Symposium on Computers and Communications, 2009

We investigate various TCAM architectures recently proposed for TCAM power and memory reduction and show that far better power and memory performance is possible when we use an optimal prefix set for the given router table than when the original prefix set or the reduced prefix set as proposed in other work is used. For EaseCam [8, 9], our experiments show a power and TCAM memory reduction of 96% to 98% and 62% to 69% respectively. For the suffix node architecture of [3], we get a power and TCAM memory reduction of 16% to 25% and 45% to 78% respectively.

2013 IEEE 31st International Conference on Computer Design (ICCD), 2013

In the internet, packets are classified by source and destination addresses and ports, as well as protocol type. Ternary content addressable memories (TCAMs) are often used to perform this operation. This paper shows a method to reduce the number of words in TCAM for multi-field classification functions. We use head-tail expressions to represent a multi-field classification rule. Furthermore, we present an O(r 2)-algorithm, called MFHT, to generate simplified TCAMs for two-field classification functions, where r is the number of rules. Experimental results show that MFHT achieves a 58% reduction of words for random rules and a 52% reduction of words for ACL and FW rules. Moreover, MFHT is fast and useful for simplifying TCAM for packet classification.

Proceedings IEEE 24th Annual Joint Conference of the IEEE Computer and Communications Societies.

Packet Classification (PC) has been a critical data path function for many emerging networking applications. An interesting approach is the use of TCAM to achieve deterministic, high speed PC. However, apart from high cost and power consumption, due to slow growing clock rate for memory technology in general, PC based on the traditional single TCAM solution has difficulty to keep up with fast growing line rates. Moreover, the TCAM storage efficiency is largely affected by the need to support rules with ranges, or range matching. In this paper, a distributed TCAM scheme that exploits chip-level-parallelism is proposed to greatly improve the PC throughput. This scheme seamlessly integrates with a range encoding scheme, which not only solves the range matching problem but also ensures a balanced high throughput performance. Using commercially available TCAM chips, the proposed scheme achieves PC performance of more than 100 million packets per second (Mpps) , matching OC768 (40 Gbps) line rate.