Packet™ Magazine Archives, Fourth Quarter 1998 IP Advances in Cisco IOS Software By Martin McNealis, IP Product Line Manager, Cisco Systems, Inc. It's a good thing that one of IP's major architectural strengths is its flexibility. As the IP-based Internet and intranets continue to expand and evolve, Cisco Systems has been able to enhance its own Cisco IOS® products to stay ahead of the IP curve. The Internet is expanding rapidly, both in terms of the raw numbers of packet flows and the growing number of enterprise networks connecting to it. Corporate users are now running business-critical intranet applications across the global Internet. IP-based personal digital assistants (PDAs) and Internet telephony are expected to take off, adding their own unique needs to the mix. The result: switches and routers are coping with an unprecedented volume, diversity, and complexity of traffic patterns. As the leading provider of networking equipment for both Internet service providers (ISPs) and enterprises, Cisco is uniquely placed to anticipate these developments and respond to them with timely, effective solutions. Ongoing software development at Cisco has produced a bevy of new enhancements and features that enable Cisco IOS-based products to handle IP traffic faster, more flexibly, and more intelligently. What follows is an overview of these technologies.

New Cisco IOS Functionality A number of key new services are now available as part of Cisco IOS Software Releases 12.0 and 12.0(T). Cisco Express Forwarding The pervasiveness of the Web and the popularity of Web surfing have significantly changed Internet traffic patterns. Instead of logging onto an application server for a long session, today users hop from site to site and from server to server, a pattern that translates into increased numbers of shorter-duration IP flows, all destined for topologically diverse locations. Cisco Express Forwarding (CEF) evolved as an optimal way to accommodate these changing network dynamics and traffic characteristics. CEF is what's termed a full topology-driven architecture. Unlike previous switching architectures that used the first packet in a flow to build an IP destination cache for use by subsequent packets to the same network destination (a technique known as "demand-caching"), CEF uses all available routing information to build an IP Forwarding Information Base (FIB). The FIB then enables the router or switch to make an expedited switching decision, even for the first packet to a new destination. This switching architecture is becoming increasingly beneficial in light of changing traffic profiles and network topologies. CEF lends itself to the distributed architecture of Cisco's high-end products in that Distributed CEF (dCEF) enables each intelligent switching line card in Cisco IOS platforms -- such as the Cisco 7500, Catalyst® 8500, and Cisco 12000 GSR -- to forward IP traffic independently. This ability maximizes the switching capacity and IP services delivery of the router or switch. NetFlow Services Cisco IOS-based NetFlow services encompass a comprehensive suite of products and technologies that enable users to implement capabilities such as network accounting, capacity planning, quality-of-service (QoS) bandwidth management, and security policies. NetFlow Switching provides real-time visibility of application-layer information such as who is sending, who is receiving, what application is involved, and the duration of the communication. Cisco IOS platforms can then apply that information to implementing appropriate policies for traffic engineering and prioritization for QoS delivery. Through the NetFlow Data Export feature, traffic information can be passed to an external application: accounting or network performance analysis software, for example. Tag Switching Cisco's Tag Switching technology represents the next-generation architecture for the Internet backbone and large intranets. Tags placed on the fronts of packets contain forwarding information used for making switching decisions and applying network services. Originally conceived by Cisco Fellow Dr. Yakov Rekhter, Tag Switching has become the foundation for flexible Layer 3 virtual private networks (VPNs), QoS, and traffic engineering. It also now forms the basis for the emerging IETF standard Multiprotocol Label Switching (MPLS). A Tag Switching infrastructure combines with advanced routing protocol capabilities to define IP VPNs by selectively advertising IP reachability information to just those subscribers within the same VPN or extranet, thus keeping different VPN traffic logically separate. The subscribers are then all connected via Tag switch paths (TSPs). Forwarding is based entirely upon the assigned Tag values (rather than IP destination prefixes), so there is no requirement for uniqueness in the IP addresses used. This feature saves subscribers to different VPNs from having to concern themselves with IP addressing issues or ambiguities. Supporting the Mobile User As enterprises embrace the business flexibility offered by the "virtual office" and "road-warrior" work styles, new intranet and Internet mobility services are emerging. Local-Area Mobility within the Enterprise Local-area mobility (LAM), an innovation unique to Cisco IOS software, enables intranet users to move freely among locations and access the enterprise network at any available point of attachment without having to reconfigure or renegotiate their IP addresses. LAM's support of host routing gives users transparent connectivity to their network resources when they move and reconnect. Unlike Dynamic Host Configuration Protocol (DHCP), which requires client support on each PC or device in order to request an address, LAM enables the use of a constant IP address from anywhere within the enterprise intranet. Mobility across the Internet In order to support mobile data access that can span the Internet, Cisco IOS software now incorporates support for the IETF Mobile IP standard. This standard leverages tunneling technology to provide remote users with seamless, secure access to their enterprise networks across IP backbones. Typically, Mobile IP is deployed over a wireless infrastructure to support continuous data services, even if subscribers roam between regions. This infrastructure gives users, unencumbered by the need for physical attachment to a terrestrial link, the freedom to connect to their enterprise networks or the Internet from anywhere. Such liberation is becoming crucial for many types of road warriors, including salespeople, job-dispatch workers, or executives toting Internet-enabled telephones and PDAs. By supporting Mobile IP on Cisco IOS software now, Cisco has ensured that customers will be able to take advantage of mobile data access across the Internet as carriers such as cellular providers roll out new services. Keeping Up with Standards Incorporating new industry standards as well as the latest versions of existing ones has always been a key element of Cisco's IOS product development strategy. Some examples include the following. IPv6 Cisco is in the process of implementing full IPv6 support. The key IPv6 advance is the expansion of the 32-bit IPv4 address space to 128 bits, ensuring enough addresses for everybody into the foreseeable future. It should be noted, however, that IPv6 is still a work in progress. The Cisco IOS IPv6 implementation will support translation between IPv6 and IPv4 domains, allowing customers to migrate to the new standard gradually while maintaining communication among all nodes. Inter- and Intradomain Routing Protocols Cisco is fully committed to helping define and implement the latest industry standards and to continuously offering routing protocol enhancements based on the company's extensive deployment experience. This commitment is reflected in the Cisco IOS 12.0 introduction of triggered RIP extensions (RFC 2091) and OSPFv2 (RFC 2328), as well as adding scalability work such as packet pacing (which first appeared in the Enhanced Interior Gateway Routing Protocol, or Enhanced IGRP) to OSPF. On the interdomain routing front, Cisco continues to enhance its BGP4 support in Cisco IOS software for key areas such as multihoming, where an enterprise will connect to multiple ISPs from the same site to attain better redundancy, optimized routing, and load-sharing. Additionally, Cisco is enhancing its implementation of BGP4 to extend support to other protocols, including IP Multicast and IPv6, in accordance with the IETF draft Multiprotocol Extensions for BGP4. While sophisticated BGP interdomain routing has been the province of ISPs that route traffic between customers' networks across the Internet, enterprise users are now increasingly deploying BGP for provider selection and traffic engineering. (For more information on BGP, see story "Border Patrol.") Evolving Solutions for an Evolving World Cisco understands the need for continuous improvements in IP technologies and services to meet the needs of a constantly changing internetworking environment. The technologies described herein are by no means its final answer to the world's routing and switching needs. Rather, they are just the latest in a continuing stream of technologies and enhancements that Cisco is developing to provide customers with scalable, flexible, integrated solutions to meet their present and future networking needs.

Cisco's NetFlow FlowCollector, FlowAnalyzer, and Flow Server Cisco's NetFlow FlowCollector provides fast, scalable, and economical data collection from multiple NetFlow Export-enabled devices. A UNIX application supported on Solaris and HP-UX platforms, the FlowCollector performs these tasks: Consumes flow datagrams from multiple NetFlow Export-enabled devices Performs data volume reduction through selective filtering and aggregation Stores flow information in flat files on disk for post-processing by NetFlow data consumers, including third-party billing applications, traffic analysis tools, and so on The FlowAnalyzer application is a network traffic analysis tool that combines a graphical user interface with other companion modules. Together, these modules enable a user to retrieve, display, and analyze NetFlow data collected from NetFlow FlowCollector flat files. The FlowAnalyzer provides several major categories of functionality, including: NetFlow export data visualization policies (what to visualize and how to visualize it) Graphical data display based on the specified visualization policies Data export to external applications (for example, Excel spreadsheets) for reporting purposes The NetFlow Flow Server consolidates statistics from multiple distributed FlowCollectors and supports the following capabilities: Provides a single repository of network-wide statistics Further summarizes NetFlow statistics by enabling bidirectional consolidation, as well as creating daily, monthly, quarterly, and yearly summaries Stores NetFlow statistics in a common commercially accepted relational database management system (RDBMS) to leverage SQL and other database tools for complex queries and reporting, as well as to give end-user applications easy access to NetFlow data Encrypts and compresses NetFlow statistics for transmission over WAN links The NetFlow Flow Server collects user-specified data files from one or more NetFlow FlowCollectors in the network, optionally stores them in the database, and optionally performs time-based consolidation of the data. The NetFlow Server makes the data available in a central database, thereby providing a single point of application and end-user access to NetFlow statistics.

Martin McNealis created the Networkers session, "Advanced IP Routing and Switching," which drew huge attendance at both US events this year. McNealis is IP Product Line Manager in the Cisco IOS Product Marketing organization, where he leads a team with overall responsibility for the IP, routing, and switching functionality within Cisco IOS software. To contact him, e-mail mmcnealis@cisco.com.

Top of Page Table of Contents Posted: Thu Feb 4 17:12:22 PST 1999 Copyright © 1998 Cisco Systems, Inc.