Showing papers on "Virtual routing and forwarding published in 1997"

Small forwarding tables for fast routing lookups

Abstract: For some time, the networking community has assumed that it is impossible to do IP routing lookups in software fast enough to support gigabit speeds. IP routing lookups must find the routing entry with the longest matching prefix, a task that has been thought to require hardware support at lookup frequencies of millions per second.We present a forwarding table data structure designed for quick routing lookups. Forwarding tables are small enough to fit in the cache of a conventional general purpose processor. With the table in cache, a 200 MHz Pentium Pro or a 333 MHz Alpha 21164 can perform a few million lookups per second. This means that it is feasible to do a full routing lookup for each IP packet at gigabit speeds without special hardware.The forwarding tables are very small, a large routing table with 40,000 routing entries can be compacted to a forwarding table of 150-160 Kbytes. A lookup typically requires less than 100 instructions on an Alpha, using eight memory references accessing a total of 14 bytes.

IP switching and gigabit routers

Abstract: To cope with the growth in the Internet and corporate IP networks, we require IP routers capable of much higher performance than is possible with existing architectures. This article examines two approaches to the design of a high-performance router, the gigabit router and the IP switch, and then provides some detail on the implementation of an IP switch and the protocols associated with IP switching.

Cisco Systems' Tag Switching Architecture Overview

Abstract: This document provides an overview of a novel approach to network layer packet forwarding, called tag switching. The two main components of the tag switching architecture - forwarding and control - are described. Forwarding is accomplished using simple label-swapping techniques, while the existing network layer routing protocols plus mechanisms for binding and distributing tags are used for control. Tag switching can retain the scaling properties of IP, and can help improve the scalability of IP networks. While tag switching does not rely on ATM, it can straightforwardly be applied to ATM switches. A range of tag switching applications and deployment scenarios are described.

Mapping of routing traffic to switching networks

Abstract: IP based networks use a number of different IP routing protocols to determine how packets ought to be routed. However, due to the rapid growth of the Internet, there is a great need for higher packet forwarding performance. This invention describes a way to map IP routing information onto a technology that uses label switching and swapping, such as ATM, without the need to change the network paradigm. This allows a network to continue to function and appear as a standard IP network, but with much higher performance. In this invention, an Integrated Switch Router (ISR), is a switch that has been augmented with standard IP routing support. The ISR at an entry point to the switching environment performs standard IP forwarding of datagrams, but the "next hop" of the IP forwarding table has been extended to include a reference to a switched path (for example, the VCC in ATM technology). Each switched path may have an endpoint at a neighboring router (comparable to existing IP next hops on conventional routers), or may traverse a series of ISRs along the best IP forwarding path, to an ISR endpoint. This allows datagrams to be switched at hardware speeds through an entire ISR network.

Method and apparatus for assignment of ip addresses

Abstract: A preferred embodiment of the present invention includes a method and apparatus for allocating and using IP addresses in a network of client systems. More specifically, the present invention includes a router which monitors the assignments of IP adresses by a DHCP server. As each IP address is assigned, the router associates the assigned IP address with a trusted identifier which identifies the client system. Subsequently, if the router receives a packet directed at the assigned IP address, the router forwards the packet to the client system having a trusted identifier associated with the destination address of the IP packet. Additionally, if the router receives a packet from a client system, it uses the trusted identifier of the client system to find IP addresses associated with the client system. If the source address of the IP packet is not included in the IP addresses associated with the client system, the packet is discarded.

Technique for handling forwarding transients with link state routing protocol

Abstract: A detection technique detects inconsistencies in forwarding databases of a router and its neighbor, i.e., a next-hop router, during routing transients in a computer network. The technique enables the router to detect when its view of a computed path to a destination station is inconsistent with the view of its neighbor along that path. Upon detecting such an inconsistent state, the router invokes one of a plurality of forwarding mechanisms with respect to a packet intended for the destination station in an attempt to suppress forwarding loops that may arise during the transients.

Tag switching architecture overview

Abstract: Tag switching is a way to combine the label-swapping forwarding paradigm with network-layer routing with particular application to the Internet. This has several advantages. Tags can have a wide spectrum of forwarding granularities, so at one end of the spectrum a tag could be associated with a group of destinations, while at the other end, a tag could be associated with a single application flow. At the same time, forwarding based on tag switching, due to its simplicity, is well suited to high-performance forwarding. These factors facilitate the development of a routing system that is both functionally rich and scalable. Last, tag switching simplifies the integration of routers and asynchronous transfer mode switches by employing common addressing, routing, and management procedures.

Enhanced internet packet routing lookup

Abstract: The invention provides a method and system for routing information lookup for packets using routing protocols such as IP or IP multicast (IGMP), or MPLS (multiprotocol label switching, also known as tag switching or label switching) or MPLS multicast, in which both the destination address and the length of that destination address are matched using a lookup table having separate entries for selected addresses and their lengths, which can be accessed in parallel for multiple representations of destination addresses, and in which the input interface associated with the packet is included in the information used for matching.

Development of router clusters to provide fast failover in IP networks

Abstract: Vol. 9 No. 3 1997 A DIGITAL router engineering team has refined and extended routing protocols to guarantee a five-second maximum loss-of-service time during a single failure in an Internet Protocol (IP) network. We use the term router cluster to describe our improved implementation. A router cluster is defined as a group of routers on the same local area network (LAN), providing mutual backup. Router clusters have been in service since mid-1995.

QoS path management with RSVP

Abstract: This paper addresses the issue of QoS path management in IP networks. We describe a proposal aimed at allowing management through the RSVP (Braden et al. 1966) protocol of oaths selected by a QoS routing algorithm such as those of Guerin et al. (1997) and Zhang et al. (1996). The goals of the proposal are to allow efficient management of such QoS paths with a minimal impact to the RSVP protocol and the existing routing infrastructure. Basic features of the approach include leveraging of RSVP soft state mechanisms, and simple extensions to enable soft pinning (sticking) of paths selected by the QoS routing algorithm. In addition, the proposal addresses the issue of preventing the formation of data path loops, and of avoiding potential race conditions.

IP switching over fast ATM cell transport (IPSOFACTO): switching multicast flows

Abstract: This paper describes a method for mapping IP flows to ATM switches. No signaling is necessary to setup a path through ATM switches. Switch controllers run a IP routing protocol and execute IP forwarding. The IPSOFACTO component is responsible for mapping a IP flow to a switched path. The focus of this paper is primarily on switching IP multicast flows.

Virtual computer system of multi-processor constitution

Abstract: A virtual computer system of a multi-processor arrangement reduces the overhead of XPTLB processing. The processing of a PTLB (translation look-aside buffer processing) is controlled using IP dispatch information about virtual computers that is stored a hardware share area (HSA). A control unit (CU) has a group of bit-map BIM (broadcast IP mask) latches which correspond to the configured IP's and in which the IP dispatch information is set upon purging of a translation look-aside buffer. Through AND gate logic provided in the CU, whether or not an IP is to receive a PTLB request is determined on the basis of the information set in the BIM masks. Specifically, the AND gates compute the logical AND of each of the BIM masks with the control line of a XPTLB REQ from an IP being dispatched by a particular virtual computer. The AND gates provide an XPTLB REQ output designating PTLB processing to the other IP's if the associated BIM mask is set in accordance with IP dispatch information indicating that an IP has been dispatched by that particular virtual computer in the past.

Preventing misuse of call forwarding service

Abstract: A method and an arrangement for detecting the misuse of the call forwarding service in a mobile communication system. In the invention, call forwarding is activated for routing a call addressed to a mobile subscriber to a forwarding number supplied by the mobile subscriber; the forwarding number is modified by registering call forwarding to another number; the number of call forwarding registrations is counted subscriber-specifically; and an alarm is generated when the number of call forwarding registrations exceeds a predetermined maximum value during a predetermined period of time.

Efficient routing table lookup for IPv6

Abstract: High performance internetworking units, such as routers and bridges are key building blocks of current and emerging high performance networks. The aggregate data rate flowing through a router can be in the range of gigabits per second. In order to keep up with very high data rates, processing within the internetworking unit needs to be optimized. This paper concentrates on routing table look up. It presents a design for a routing table look up for gigabit routers running the new version of IP, EPv6. The proposed approach, HeaRT, is viewed as the core engine of an IM router.

Framework for IP switching over fast ATM cell transport (IPSOFACTO)

Abstract: This paper describes a method for mapping IP flows to ATM switches. No signaling is necessary to setup a paththrough ATM switches. Switch controllers run a IP routing protocol and execute IP forwarding. The IPSOFACTOcomponent is responsible for mapping a IP flow to a switched path. Mechanisms for switching both multicastand unicast flows are described. Keywords : IP Switching, ATM, Multicast, Switching 1 Introduction IPSOFACTO is a methodology for executing the IP protocol stack directly on ATM switches. The ATM signalingstack is not used. This paper describes how IP multicast and unicast may be mapped directly to ATM switches.The target scenario consists of (a) a cloud of ATM switches running the IP protocol stack and optionally, (b) hosts that are directly connected to this cloud. Each switch in this cloud runs the IP protocol stack along with an Ipsofacto component for mapping IP flows to switched paths. The description in this paper assumesconfiguration (a). 2 Switch Configuration

Tag switching architecture overview : Global information infrastructure

Abstract: Tag switching is a way to combine the label-swapping forwarding paradigm with network-layer routing. This has several advantages. Tags can have a wide spectrum of forwarding granularities, so at one end of the spectrum a tag could be associated with a group of destinations, while at the other end, a tag could be associated with a single application flow. At the same time, forwarding based on tag switching, due to its simplicity, is well suited to high-performance forwarding. These factors facilitate the development of a routing system that is both functionally rich and scalable. Last, tag switching simplifies the integration of routers and asynchronous transfer mode switches by employing common addressing, routing, and management procedures.

Cisco TCP/IP routing professional reference

Abstract: The basic of TCP?IP TCP/IP communications overview routing protocols used in TCP/IP networks the basic of Cisco Routers - product overview Routers Basics configuring Cisco Routers getting started with a network - when things go wrong Troubleshooting Router hardware Troubleshooting TCP/IP connectivity Troubleshooting LAN, WAN, and serial line problems Troubleshooting performance problems network security.

An overview of IP switching and Tag switching

Abstract: Both IP switching and Tag switching were recently proposed to improve the performance of IP routers. They are all based on a multi-layer label-swapping mechanism, but their implementations are quite different. In this paper, we present an overview of both switching mechanisms, compare their key features, identify their constraints, and analyze the effect of these constraints on performance. Our study shows that both IP switching and Tag switching are better than the conventional IP routing, but neither of them is universally superior to the other.

A comparison of pre-planned routing techniques for virtual path restoration

Abstract: Network restoration techniques will be vital to ensure B-ISDN service survivability in the event of high capacity link and node failures. Reliable ATM crossconnect networks can be implemented by the strategic pre-assignment of protection Virtual Path (VP) routes to permit recovery from a realistic subset of all possible failures, eg single span failures. The method of protection route assignment influences the quantity of redundant resources like spare capacity and Virtual Path Identifiers (VPIs), whilst nodal hardware costs are incurred due to the requirement of pre-stored alternate routing information. In addition to implementation costs, the impact that the choice of rerouting scheme has on other factors must be considered. For example, the degree of path elongation following restoration may adversely affect the delay performance of certain connections. Also, the amount of computation required to design the protection routes, and the effort needed to activate such routes have to be taken into account. This paper formulates metrics to facilitate a comparative evaluation of four distinct routing strategies for VP restoration, and in conjunction with a discussion of qualitative properties of each scheme, it concludes that failure independent rerouting is the preferred approach.

A Comprehensive Comparison of IP Switching and Tag Switching

Abstract: Both IP switching and Tag switching were recently proposed to improve the performance of IP routers. They are all based on a multi-layer label- swapping mechanism, but their implementations are quite different. In this paper, we present an overview of both switching mechanisms, compare their key features, identify their constraints, and analyze the effect of these constraints on performance. Our study shows that both IP switching and Tag switching are better than the conventional IP routing, but neither of them is universally superior to the other.

Future mobile requirements for IP routing and ATM switching

Abstract: Today's telecommunication networks are at an important cross-roads in trying to determine the future switching and routing technology to use. Currently the predominant technology used is N*64 kbit/s switching and transmission. Already we have started to see the embryonic introduction of ATM and even more so of Internet (IP). In the middle of this debate then comes UMTS (Universal Mobile Telecommunications System), targeted to be delivered round the year 2002/2005, which will be reliant on one or more of these transport technologies. Additionally, of course, UMTS with its inherent mobility needs, will introduce new requirements across the whole system level, including transport. Currently neither ATM nor IP fully support the identified transport criteria for UMTS. The paper explains these requirements and discusses the weaknesses and strengths of both IP and ATM in view of fully supporting UMTS.

To cope with the growth in the Internet and corporate IP networks we require IP routers capable of much higher performance than is possible with existing architectures. This paper examines two approaches to the design o f a h igh-performance router, the gigabit router and the IP switch, and then p rovides s ome detail on the implementation of an IP switch and the protocols associated with IP switching.

Abstract: ‡ The Internet is growing rapidly. The number of hosts on the Internet has doubled approximately every 56 weeks since 1989 (14) and the number of web servers has doubled at least every 23 weeks for the last three years (15). As such growth persists, and as common access line speeds increase, we require IP routing capacity of many gigabits/s (Gbps) of aggregate traffic. Existing bus and central processor based architectures can handle a maximum load in the region of 1 Gbps and a few hundred thousand packets per second (kpps) but to get much beyond this requires alternative architectures. This paper examines two such approaches, the gigabit router and the IP switch, and then provides some detail on the implementation of an IP switch and the protocols associated with IP switching.