Kimberly K. Hiller, Gerald Arcuri Technology Overview 27 August 2003 Routers: Overview Summary Routers continue to evolve with better performance and a larger variety of WAN and LAN options, and security. Routers remain essential networking devices for small to large enterprise networks. Table of Contents Technology Basics Security Management Technology Analysis Business Use Standards Selection Guidelines Technology Leaders Insight List Of Tables Table 1: Common Routing Protocols Gartner Reproduction of this publication in any form without prior written permission is forbidden. The information contained herein has been obtained from sources believed to be reliable. Gartner disclaims all warranties as to the accuracy, completeness or adequacy of such information. Gartner shall have no liability for errors, omissions or inadequacies in the information contained herein or for interpretations thereof. The reader assumes sole responsibility for the selection of these materials to achieve its intended results. The opinions expressed herein are subject to change without notice.
Technology Basics Routing is the function of transferring packets across a network from a source to a destination. The router is connected to at least two networks and determines the next point on the network to which a packet must progress to reach its ultimate destination. Typically a packet travels through a number of network points via routers before arriving at its destination. Routing Functions Routing performs primarily two basic activities: 1. Calculating the optimal paths through the network (path determination) and 2. Transporting the payload or packets along the route (packet switching). In order to accomplish these activities, the router creates and maintains a table of the available routes and their conditions, and uses this information in conjunction with other parameters (such as, distance, cost, latency and others) as part of a routing algorithm to determine the optimal path for a packet. Routing protocols (see the Common Routing Protocols table) are different than routed protocols. Routed protocols are routed over an internetwork and can include Internet Protocol (IP), DECnet, AppleTalk, Novell NetWare, Banyan Vines and Xerox Network System. Routing protocols implement the routing algorithms and are used by intermediate systems to create the routing tables to determine the path. Table 1: Common Routing Protocols Routing Protocols Interior Gateway Routing Protocol (IGRP) Enhanced Interior Gateway Routing Protocol (Enhanced IGRP) Routing Information Protocol (RIP) Open Shortest Path First (OSPF) Exterior Gateway Protocol (EGP) Border Gateway Protocol (BGP) Intermediate System-to- Intermediate System (IS-IS) Description Cisco Systems proprietary routing algorithm. An Interior Gateway Protocol (IGP) that transfers packets from one network to another adjacent one. An internal router protocol used for informing network computers of changes in configuration. An IGP that transfers packets from one network to an adjacent one. The Transmission Control Protocol/Internet Protocol (TCP/IP) used by exterior routers to move data from one autonomous system to another. The interdomain routing protocol implemented in TCP/IP networks. A routing method among intermediate systems that requires the end systems, rather than the intermediate systems, to be responsible for providing error correction. It reduces complexity and overhead of routing protocols. 27 August 2003 2
Table 1: Common Routing Protocols Routing Protocols Description Link State Protocol Any routing protocol derived from the Dijkstra algorithm, such as Shortest Path First (SPF), OSPF and IS-IS. Routers that use link state protocols update each other and learn network topology by periodically broadcasting link state data across the network. The data from each router includes only the cost and identification of those networks directly connected to that router. All routers on a network compile tables of routers and connections and can then calculate optimal paths from themselves to each link. Distance Vector Any routing protocol derived from the Bellman-Ford algorithm, such as DECnet or Protocol Routing Information Protocol (RIP). The routers using such protocols create a network map by communicating in a periodic and progressive sequence. Source: Gartner Glossary. Many routers offer application-based quality of service (QOS) and traffic-shaping controls without reducing performance, thus facilitating the evolution toward higher-bandwidth application demand. QOS technologies handle the timely delivery of specific applications data or resources to a particular destination. QOS guarantees bandwidth for key applications and users, and sometimes can have an added business benefit of putting off the need for faster network infrastructure. QOS polices can be broad enough to encompass all the applications in the network, or relate specifically to a single host-to-host application flow. Traffic shaping is a form of bandwidth management that incorporates QOS capabilities, such as buffering, congestion detection and avoidance, and rate limiting. Traffic shaping capabilities configured in a WAN edge enable enterprises to define a subset of the capacity of a network link or a private virtual circuit (PVC). This subset is the maximum amount of bandwidth that can be consumed by traffic of a certain type. Then, depending on the type of shaping being used, the enterprise network device either buffers or discards traffic that is exceeds the maximum allotted bandwidth. Security The explosion of the Internet and the dramatic growth in collaborative applications and e-based activities has forced enterprises to give security measures very serious attention. As a result, router vendors have responded and have incorporated a wide range of security functions into their routers, from small office/home office (SOHO) through high-end backbone routers. The integration of security measures is standard in nearly all router offerings today. In addition to the routing functions, the products can include integrated firewall, virtual private network (VPN) creation with encryption and even intrusion detection. All of this is offered in a centralized management environment. Many router-based firewalls are policy-managed and even include stateful inspection which provides one of the highest levels of security. Stateful inspection not only filters packets according to the data in the packet header, but also assesses the packet s payload and looks at the application protocol. After this evaluation it gives access decisions based on the source, destination and services requested by the packet. The term stateful inspection refers to the firewall s capability to remember the status of a connection and build a context for each data stream in its memory. Stateful inspection can detect more sophisticated hacker attacks, such as IP spoofing, in which the hacker attempts to send malicious packets through the router by making them appear to originate from within the local network. VPN capabilities include site-to-site and remote access VPNs, with the incorporation of tunneling protocols. Newer routers are capable of up to 5,000 and 10,000 VPN tunnels and high-speed throughput. 27 August 2003 3
Some vendors have also introduced cards that accelerate VPN encryption for both Triple Data Encryption Standard (3DES) and advanced encryption standard (AES). Management As the number of networking devices and the variety of networking options continue to increase in the enterprise, network management becomes a more difficult and more critical component for network administrators. Some software vendors deliver an enterprise network management system that offers fault, configuration, accounting, security and performance management, while other vendors offer routerspecific management capabilities to improve the productivity and performance of network operations. Some router vendors have incorporated powerful management and configuration support tools in their products to ease the burden of providing secure, policy-managed solutions for the enterprise. Some fuller-featured network management tools can prioritize network traffic, optimize routing, and support voice and video application, among other functions. Some of these can support a variety of routed protocols, such as IP, Internetwork Packet Exchange (IPX), AppleTalk, DECnet, Systems Network Architecture (SNA) and other protocols, and can accommodate nearly any host or operating system environment. Technology Analysis Business Use Most of the business uses for routers evolve from technology enhancements, which ultimately result in increased benefits, cost reductions and efficiencies that derive from those enhancements. For example, router vendors are continually increasing performance, adding additional WAN and LAN options, and integrating security features. The purpose of these enhancements is to meet increasing business requirements, such as the evolution toward collaborative-based business processes and the use of applications requiring more bandwidth, such as video and voice traffic. Standards IPv6 Internet Protocol version 6 (IPv6) is the Internet Engineering Task Force s (IETF) next-generation Internet communications protocol, replacing IPv4. The IPv6 protocol fixes many IPv4-related problems, most notably the limited number of available IPv4 addresses. IPv6 will gradually replace IPv4, although the two will co-exist for several years during the transition. IPv6 has a 128-bit address space compared to IPv4 s 32-bit space, which will allow for a geometric increase in the number of possible addresses. This means a much higher number of users will be able to connect directly to the Internet and also that IP-based enterprise networks should scale more effectively. In addition to the dramatic increase in network addresses, IPv6 also adds enhancements in the areas of routing and network auto-configuration. IPv6 will enable host machines to automatically discover the information, such as the address of a local router, needed to connect to the Internet or a corporate IP backbone; this feature will reduce much of the manual configuration operations required for network administrators. Selection Guidelines Router Classification 27 August 2003 4
Gartner classifies routers based on the size of the environment in which they operate SOHO, branch offices, midrange backbone routers and high-end enterprise backbone routers. Service provider routers are usually the largest routers, with high-capacity switching fabrics, a Network Equipment Building System (NEBS)-compliant chassis, granular QOS features, and multiservice options to support the largest number of customers, giving service providers greater revenue-generating capability. This report focuses exclusively on enterprise routers. SOHO SOHO routers provide small office environments or teleworkers with business class features for a variety of access solutions, WAN technologies, security and even management. SOHO routers support one of several access technologies, including ISDN (Integrated Services Digital Network), DSL (Digital Subscriber Loop) and Ethernet or Token Ring; some also accommodate xdsl over ISDN or over plain old telephone service (POTS). Higher-end SOHO routers can provide QOS features for data, voice and video applications. In addition, SOHO routers can also accommodate integrated analog phone ports, or serial ports for fractional T1 or frame relay connections. Today, more and more routers (even the smallest SOHO routers) offer security features with support for a stateful inspection firewall and IP Security (IPsec) and 3DES encryption for VPN applications. Branch Office Routers Branch office routers link remote LANs to corporate networks. They typically offer two or more WAN ports to support resilience, and provide WAN speeds over 1 Mbps. Although primarily fixed-function, they can have slots for WAN options. These WAN options can hold cards for 56 Kbps, T1 or xdsl; many also have 10/100-Mbps Ethernet ports with support for dial backup. Branch office routers also accommodate asynchronous transfer mode (ATM) protocols and functions for ATM service, multiple virtual channel connections and virtual channel multiplexing. Other branch routers incorporate a 10/100-Mbps switch to provide each connection with dedicated 10/100-Mbps bandwidth in order to increase throughput for bandwidth-sensitive applications; this contrasts with the incorporation of a hub where the bandwidth is shared by all stations. Branch office routers can also deliver a built-in PPP over Ethernet (PPPoE) feature, which reduces the support costs of installing PPPoE software to different computer platforms and enables the product to become plug-andplay. Midrange Backbone Routers Midrange Backbone Routers are modular routers that support flexible WAN combinations. Typically, midrange backbone routers offer a minimum of four WAN ports supporting speeds of 1 Mbps or greater, and at least one high-speed serial interface (HSSI) or OC-3/STM1 port. These devices also must provide at least one 100-Mbps or faster LAN port. However, many deliver more than this minimum with multiport 10/100 Ethernet network modules; LAN networking modules with support for Ethernet, Fast Ethernet or Gigabit Ethernet; serial connectivity, including support for HSSI, T1 and ISDN modules, or ATM network modules with speeds up to OC-3. Many midrange routers deliver high-performance processors to support performance and features that address the WAN, firewall and VPN needs of enterprise organizations, with capabilities to accommodate VPN connections to thousands of users; some also have an option for redundant power, giving them the capability to accommodate mission-critical applications. Routers with multiple network interface modules target regional offices having WAN aggregation requirements, with the capability of terminating multiple T3 or T1 connections. 27 August 2003 5
High-End Routers Many high-end and midrange backbone routers integrate routing, VPN capabilities, firewalls and WAN ports in a single device. The high-end backbone routers are module and support a combination of flexible WAN ports; they typically offer a minimum of 32 ports with WAN speeds of 1 Mbps or greater and four or more OC-3/STM1 ports. Like the midrange backbone routers, these high-end routers must also offer multiple 100-Mbps or single/multiple 1000-Mbps LAN ports, plus fault-tolerant features, such as dual power supplies. Larger, high-end backbone routers support 10-Gigabit Ethernet and maintain wire-speed performance even with all services enabled. High-end routers target central-site VPN and WAN link aggregation, and support for QOS enables voice over IP (VoIP) and other priority-sensitive applications, such as video. Many of these routers use layer 2, 3 and 4 data to deliver application-based QOS functions and traffic-shaping controls, without loss of performance, because in most of these routers, application awareness is an inherent feature, as opposed to a software add-on. These routers can guarantee bandwidth on an application-by-application basis, and in order to support high-priority traffic, the QOS policies can be broad enough to encompass all the applications in the network, or relate specifically to a single host-to-host application flow. Technology Leaders Gartner Dataquest research shows the following companies as leaders in the enterprise router market: SOHO Routers: Cisco, D-Link, BinTec (Europe), ZyXEL, Yamaha. Vendors to watch in this space: Netgear. Branch Office Routers: Cisco, Fujitsu, Nortel, BinTec (Europe), Netopia. Vendors to watch in this space: Adtran, Allied, Enterasys, Huawei, NTT (Japan), Tasman. Midrange Routers: Cisco, Fujitsu, Nortel Networks, NEC, BinTec (Europe). Vendors to watch in this space: Enterasys. High-End Routers: Cisco, NEC, Nortel. Vendors to watch in this space: Enterasys. Insight Routers continue to evolve to keep pace with the increased business demand. The explosive growth of the Internet, the trend toward teleworking, the greater reliance on real-time collaborative applications, the increased use of voice/video over the Internet, and a growing mobile workforce have contributed to network congestion and a greater demand on routers to ease that congestion. As a result, router vendors have integrated a wealth of features to overcome the networking challenges and to improve performance. Enterprises should carefully evaluate their current and planned application requirements, and ensure that the chosen router product line can accommodate the potential increased demand that those applications will place on the network. 27 August 2003 6