Showing papers on "Virtual routing and forwarding published in 1999"

BGP/MPLS VPNs

Abstract: This document describes a method by which a Service Provider with an IP backbone may provide VPNs (Virtual Private Networks) for its customers. MPLS (Multiprotocol Label Switching) is used for forwarding packets over the backbone, and BGP (Border Gateway Protocol) is used for distributing routes over the backbone. The primary goal of this method is to support the outsourcing of IP backbone services for enterprise networks. It does so in a manner which is simple for the enterprise, while still scalable and flexible for the Service Provider, and while allowing the Service Provider to add value. These techniques can also be used to provide a VPN which itself provides IP service to customers.

MCEDAR: multicast core-extraction distributed ad hoc routing

Abstract: In this paper, we present the MCEDAR (multicast core extraction distributed ad hoc routing) multicast routing algorithm for ad hoc networks. MCEDAR is an extension to the CEDAR architecture and provides the robustness of mesh based routing protocols and the approximates the efficiency of tree based forwarding protocols. It decouples the control infrastructure from the actual data forwarding infrastructure. The decoupling allows for a very minimalistic and low overhead control infrastructure while still enabling very efficient data forwarding.

Photonic IP routing

Abstract: A photonic Internet protocol (IP) routing is proposed in which the IP address, mapped onto optical code, is recognized by performing optical correlation in the time domain in a parallel manner. Preliminary experiment shows that it can process 6.5/spl times/10/sup 9/ packets per second. It will help overcome the bottleneck in current electrical IP routers; i.e., the time it takes to look up addresses in the routing table.

IP services over Bluetooth: leading the way to a new mobility

Abstract: We present protocol concepts for an extension of IP for mobility issues in Bluetooth networks. The protocol is called BLUEPAC IP, where BLUEPAC stands for "BLUEtooth Public ACcess". "Public access" means access to various kinds of information in public areas, e.g. airplane, train, hotel room, department store, museum. Bluetooth will reside in low-cost chips that provide wireless communication up to OSI Layer 2. By the end of this year many mobile devices, e.g. notebooks, PDAs, cell phones, will contain Bluetooth chips as a cable replacement. But Bluetooth is move powerful: with a suitable network protocol that inherits all aspects of IP, it will be possible to provide IP services over Bluetooth. BLUEPAC IP takes IP as a basis and additionally includes functionalities of mobile IP and cellular IP for local IP address assignment, routing issues and handoff support.

High-performance IP routing table lookup using CPU caching

Abstract: Wire-speed IP (Internet Protocol) routers require very fast routing table lookup for incoming IP packets. The routing table lookup operation is time consuming because the part of an IP address used in the lookup, i.e., the network address portion, is variable in length. This paper describes the routing table lookup algorithm used in a cluster-based parallel IP router project called Suez. The innovative aspect of this algorithm is its ability to use CPU caching hardware to perform routing table caching and lookup directly by carefully mapping IP addresses to virtual addresses. By running a detailed simulation model that incorporates the performance effects of the CPU memory hierarchy against a packet trace collected from a major network router, we show that the overall performance of the proposed algorithm can reach 87.87 million lookups per second for a 500-MHz Alpha processor with a 16-KByte L1 cache and a 1-MByte L2 cache. This result is one to two orders of magnitude faster than previously reported results on software-based routing table lookup implementations. This paper also reports the performance impacts of various architectural parameters in the proposed scheme and its storage costs, together with the measurements of an implementation of the proposed scheme on a Pentium-II machine running Linux.

MPLS advantages for traffic engineering

Abstract: This article discusses the architectural aspects of MPLS which enable it to address IP traffic management. Specific MPLS architectural features discussed are separation of control and forwarding, the label stack, multiple control planes, and integrated IP and constraint-based routing. The article then discusses how these features address network scalability, simplify network service integration, offer integrated recovery, and simplify network management. Scalability is addressed through integrated routing enabling a natural assignment of traffic to the appropriate traffic engineering tunnels without requiring special mechanisms for loop prevention. Change is greatly reduced. The label stack enables an effective means for local tunnel repair providing fast restoration. Feedback through the routing system permits fast and intelligent reaction to topology changes. Service integration is simplified through a unified QoS paradigm which makes it simple for services to request QoS and have it mapped through to traffic engineering.

A novel IP-routing lookup scheme and hardware architecture for multigigabit switching routers

Abstract: One of the pertinent design issues for new generation IP routers is the route-lookup mechanism. For each incoming IP packet, the IP routing is required to perform a longest-prefix matching on the route lookup in order to determine the packet's next hop. This study presents a fast unicast route-lookup mechanism that only needs tiny SRAM and can be implemented using a hardware pipeline. The forwarding table, based on the proposed scheme, is small enough to fit into a faster SRAM with low cost. For example, a large routing table with 40000 routing entries can be compacted into a forwarding table of 450-470 kbytes costing less than US$30. Most route lookups need only one memory access; no lookup needs more than three memory accesses. When implemented using a hardware pipeline, the proposed mechanism can achieve one routing lookup every memory access. With current 10-ns SRAMs, this mechanism furnishes approximately 100/spl times/10/sup 6/ routing lookups/s, which is much faster than any current commercially available routing-lookup scheme.

System, device, and method for reducing multicast forwarding states in a multicast communication system

Abstract: A system, device, and method for reducing multicast forwarding states in a multicast communication system maintains forwarding states in such a way that the non-default forwarding states have non-overlapping source address ranges. Each forwarding state is associated with a source address range encompassing one or more source addresses. When a non-default forwarding state is installed, the source address range for the forwarding state is selected so that the source address range does not overlap with the source address ranges of any other non-default forwarding states. The source address range for a particular forwarding state may be adjusted as new routes are learned or existing routes are changed or aged.

Method and apparatus for updating and synchronizing forwarding tables in a distributed network switch

Abstract: A mechanism and technique updates and synchronizes forwarding tables contained on line cards that are interconnected by a switch fabric of a distributed network switch. The network switch is preferably a L3 or L4 switch comprising a plurality of forwarding engines distributed among the line cards. Each forwarding engine has an associated forwarding table, which preferably includes a L2 portion and L3/L4 portions. The L2 portion of the table is used to execute forwarding decision operations for frames forwarded among ports of the line cards, whereas the L3/L4 portions of the table are used to execute shortcut and forwarding operations for frames routed among the ports. The mechanism comprises a media access control (MAC) notification (MN) frame for updating and synchronizing the location of a destination port stored in the L2 portions of the forwarding tables.

Reliable services in MPLS

Abstract: MPLS (multiprotocol label switching) is a convergence of various implementations of IP switching using ATM-like "label swapping" to speed up packet forwarding without changes to existing IP routing protocols. An important practical issue is the capability to recover quickly from faults. We examine distributed methods for fast fault recovery using modified label distribution protocol messages. To maintain and verify service continuity, methods are proposed for traffic and performance monitoring.

A fast IP routing lookup scheme for gigabit switching routers

Abstract: One of the key design issues for the new generation IP routers is the route lookup mechanism. For each incoming IP packet, the IP routing requires to perform a longest prefix matching on the address lookup in order to determine the packet's next hop. This paper presents a fast route lookup mechanism that only needs tiny SRAM and can be implemented in a pipelined skill in hardware. Based on the proposed scheme, the forwarding table is tiny enough to fit in SRAM with very low cost. For example, a large routing table with 40,000 routing entries can be compacted to a forwarding table of 450-470 Kbytes. In the worst case, the number of memory accesses for a lookup is three. When implemented in a pipeline skill in hardware, the proposed mechanism can achieve one routing lookup every memory access. With current 10 ns SRAM, this mechanism furnishes approximately 100 million routing lookups per second. This is much faster than any current commercially available routing lookup schemes.

Method and apparatus for multiprotocol switching and routing

Abstract: A packet forwarding method and apparatus performs multiprotocol routing (for IP and IPX protocols) and switching. Incoming data packets are examined and the flow (i.e., source and destination addresses and source and destination socket numbers) with which they are associated is determined. A flow table contains forwarding information that can be applied to the flow. If an entry is not present in the table for the particular flow, the packet is forwarded to the CPU to be processed. The CPU can then update the table with new forwarding information to be applied to all future packets belonging to the same flow. When the forwarding information is already present in the table, packets can thus be forwarded at wire speed. A dedicated ASIC is preferably employed to contain the table, as well as the engine for examining the packets and forwarding them according to the stored information. Decision-making tasks are thus more efficiently partitioned between the switch and the CPU so as to minimize processing overhead.

Circulating parallel-search engine with random inputs for network routing table stored in a wide embedded DRAM

Abstract: A search engine for a network switch reads a routing table for an entry with a matching MAC or IP address. The routing table is contained in an embedded DRAM. The search engine and the embedded-DRAM routing table are integrated together on the same integrated circuit chip, allowing a very wide data path between the search engine and the routing table. A free-running sequencer outputs addresses to the routing table so that each entry is read in a continuous-loop sequence. The same entry is sent to comparators for all active searches. Destination addresses for different input ports are compared to the entry read from the table. A match ends the search for a port while searches for other ports continue. Since ports can begin and end searches at any point in the continuous-loop sequence, a same low latency is provided for all input ports, even when other searches are in progress. The wide data path from the embedded-DRAM allows several entries to be read and compared for each cycle and for each port. Thus multiple entries are compared in parallel for each port, and ports are searched in parallel.

Method and apparatus for allowing proprietary forwarding elements to interoperate with standard control elements in an open architecture for network devices

Abstract: A computer system for allowing proprietary forwarding elements to interoperate with standard control elements in an open network architecture. The computer system comprises a forwarding element that is adapted to perform data forwarding functions in a computer network. A control element is adapted to perform network signaling and control functions in the computer network. The control element is adapted to generate a standardized data set for configuring the forwarding element. An interconnecting element operatively connects the forwarding element to the control element. A forwarding element plugin is integrated with the control element for receiving the standardized data set from the control element, translating the standardized data set into a specialized data set, and transmitting the specialized data set to the forwarding element to configure the forwarding element. The forwarding element utilizes the specialized data set to configure the forwarding element for performing data forwarding in the computer network.

MPLS and the evolving Internet architecture

Abstract: The Internet architecture has evolved over time, adapting to the needs of its users and incorporating new technology as it has been developed. The introduction of multiprotocol label switching (MPLS) as a part of the Internet forwarding architecture has immediate applications in traffic engineering and virtual private networks. In the longer term, MPLS may affect how traffic transits the Internet and the services that the Internet delivers.

Method of managing and using multiple virtual private networks in a router with a single routing table

Abstract: A method of maintaining multiple routing tables within a global table of a network router including the steps of providing the router with a route table generator to maintain the global table, and a forwarding engine to perform table lookups, the performing of table lookups in one of the multiple routing tables of the global table using a key, the key representing an index into the one of said multiple routing tables within said global table, the key created by combining a virtual private network identification (VPN ID) and an address prefix, and maintaining a plurality of table entries in the global table by using the key as a pointer to one of said table entries.

IP caching for terabit speed routers

Abstract: As network speeds continue to grow, current methods of translating destination IP addresses to output port numbers during routing become inadequately slow. Even though this lookup is often performed in hardware, it may still be limited by DRAM access latencies. We present a method of speeding up access to DRAM based lookup mechanisms by more than a factor of 10 using CPU style memory caches. Real IP router traces taken from several sites are used to validate the caching scheme over a variety of parameters as well as used to study IP address properties that may affect caching performance.

Voice-and-fax-over-IP dialing plan

Abstract: A method for a user of telecommunication services to dynamically interchange routing paths between a carrier network circuit and the Internet for connecting to a destination. A user code is allocated which marks a connection request as requesting switching/routing via an IP network. When the code is detected by a carrier switch, the call connections are routed through the IP network. The user is provided with the option of terminating the IP network connection and selecting carrier network connection without call interruption.

Method and apparatus for providing distributed communication routing

Abstract: A method and apparatus that includes processing for providing distributed communication routing that begins by obtaining registration information from a plurality of forwarding engines. The processing continues by identifying the plurality of forwarding engines based on the registration information. Having done this, the process proceeds to generate at least one specific forwarding table for at least one corresponding forwarding engine of the plurality of forwarding engines. The processing then continues by forwarding the specific forwarding table to the corresponding forwarding engine. In an alternate embodiment, the processing determines internal routing connections and external routing connections for the plurality of forwarding engines after identifying the forwarding engines. The alternate processing continues by generating at least one external forwarding table, which provides forwarding information to routers external to a distributed router, for at least some of the plurality of forwarding engines. The processing then continues by generating at least one specific internal forwarding table, which provides information to a specific forwarding engine to route data within the distributed routing to other forwarding engines, for a corresponding forwarding engine. Having generated the internal and external forwarding tables, the tables are forwarded to the corresponding forwarding engine or engines.

Efficient internet service implementation for mesh satellite networks using centralized router server for distribution of destination tables

Abstract: A centralized route-server architecture permits Internet Protocol (IP) services to be offered over satellite mesh networks. Individual satellite terminals perform forwarding of IP traffic to destination terminals based on routing information provided by the route-server. External routers connecting to terminals exchange OSPF and BGP routing protocol packets only with the central route-server.

Integrating service managers into a routing infrastructure using forwarding agents

Abstract: A method of providing a network service is disclosed. The method includes implementing a forwarding agent on a router. The forwarding agent is operative to receive instructions from a service manager. Packets are forwarded from the forwarding agent to the service manager, and the forwarding agent receives instructions from the service manager detailing how to handle the forwarded packets.

System, device, and method for reducing forwarding states in a communication system

Abstract: A system, device, and method for reducing forwarding states in a network domain designates a forwarding device to forward multicast packets for the (source, group) pair. A number of (source, group) pairs may be aggregated to form an aggregated (source, group) pair that is rooted at the forwarding device. For each multicast packet forwarded by the forwarding device, the forwarding device inserts an option field identifying the forwarding device. Interior devices in the network domain forward multicast packets based upon at least the forwarding device identified in the option field of the multicast packet, particularly by maintaining a list of forwarding devices in the network domain and electing a designated forwarding device from which to receive multicast packets. The interior devices forward multicast packets received from the designated forwarding device, and drop multicast packets received from other forwarding devices.

Routing with a clue

Abstract: We suggest a new simple forwarding technique to speed-up IP destination address lookup. The technique is a natural extension of IP, requires 5 bits in the IP header (IPv4, 7 in IPv6) and performs IP lookup nearly as fast as IP/Tag-switching but with a smaller memory requirement and a much simpler protocol. The basic idea is that each router adds a "clue" to each packet, telling its downstream router where it ended the IP lookup. Since the forwarding tables of neighboring routers are similar, the clue either directly determines the best prefix match for the downstream router, or provides the downstream router with a good point to start its IP lookup. The new scheme thus prevents repeated computations and distributes the lookup process across the routers along the packet path. Each router starts the lookup computation at the point its up-stream neighbor has finished. Furthermore, the new scheme is easily assimilated into heterogeneous IP networks, does not require routers coordination, and requires no setup time. Even a flow of one packet enjoys the benefits of the scheme without any additional overhead. The speedup we achieve is about 10 times faster than current standard techniques. In a sense this paper shows that the current routers employed in the Internet are clue-less; Namely, it is possible to speedup the IP-lookup by an order of magnitude without any major changes to the existing protocols.

A fast and compact longest match prefix look-up method using pointer cache for very long network address

Abstract: We propose a fast and compact longest match table look-up method for very long network addresses like IP version 6. This method uses two ideas for a routing-table arranged in a tree-structure. The first idea is to make table look-up fast by caching pointers to intermediate nodes in the tree, reducing the number of node traversals. The second idea is to reduce the memory size required for each node in the tree by one-third by eliminating common parts of addresses of adjacent nodes. Evaluating the performance of this method by using actual routing table data of an IP backbone network, we found it was five to ten times faster than a conventional method.

Method and system for managing forwarding tables

Abstract: A system and a method for managing forwarding table lookups and updates involve maintaining a first forwarding table in a first memory and a second forwarding table in a second memory, and then utilizing the first forwarding table to forward packets while the second forwarding table is updated with current route entries. The second forwarding table is updated in the background and therefore conventional CPU speeds do not cause performance problems. Once the second forwarding table is completely updated, a forwarding table pointer is switched and the second forwarding table is utilized to forward packets while the first forwarding table is updated. Because the second forwarding table has been completely updated in the background, switching the forwarding table pointer causes newly arriving packets to be forwarded according to a forwarding table that is free of inconsistencies.

IP Routing Fundamentals

Abstract: From the Publisher: A comprehensive ntroduction to routing concepts and protocols in IP networks. Comprehensive review of the operational mechanics of today's leading routing protocols, including IGRP, EIGRP, OSPF, RIP, and RIP-2Detailed explanation of IP addressing, including classful and classless addresses, subnetting, supernetting, Classless Interdomain Routing (CIDR), and Variable Length Subnet Masks (VLSM)Side-by-side comparisons of various LAN segmentation technologies, including bridges, switches, and routersExploration of how routers are used to build wide area networksExamination of the future of routing, including IPv6, next generation routing protocols, host-based routing, and IP Switching IP Routing Fundamentals is the definitive introduction to routing in IP networks. This comprehensive guide explores the mechanics of routers, routing protocols, network interfaces, and operating systems. This reference provides essential background information for network professionals who are deploying and maintaining LANs and WANs, as well as IT managers who are seeking information on how evolving internetworking technology will affect future networks. Part I discusses the many roles routers play in networks, Part II talks about the inner working of routers, Part III works with the operational issues of routing protocols, and Part IV addresses implementation issues that provide practical insight, in addition to a discussion of the future of routing.

The cost of QoS support in edge devices an experimental study

Abstract: This paper investigates the problem of making QoS guarantees available in access devices such as edge routers, that are commonly deployed in today's IP networks. We propose a specific design which we evaluate by carrying out a complete implementation, whose performance we then measure in the context of an experimental testbed. The results indicate that a reasonable level of service differentiation, i.e., rate and delay guarantees, can be provided with a minimal impact on the raw packet forwarding performance of edge devices.

A fast and scalable IP lookup scheme for high-speed networks

Abstract: One of the key design issues for the next-generation IP routers is the IP lookup mechanism. For each incoming IP packet, the IP routing needs to perform a longest prefix matching on the address lookup in order to determine the packet's next hop. Currently, the process is done in software and has become a major bottleneck of the router performance. In this paper, we propose a high-speed IP lookup scheme for the best matching prefix (BMP) by using forwarding tables consisting of prefix information tables (PIT) and lookup tables (LT) that provide guidelines for efficient search. The scheme scales very well as the sizes of the address and the routing table increase. For IP lookup in IPv4, the scheme needs 1 memory access in the best case, and 2 memory accesses plus one hash in the worst case to locate the BMP, if one exists. It requires only 560 KBytes to 670 KBytes of memory space when about 45000 routing tables entries in the backbone are logged for simulation. When 50 ns DRAM is used for the forwarding tables, the scheme offers lookup speed of 10 millions packets per second. The lookup speed can be improved linearly with the speedup of the type of memory used.

Integrated Routing and Bridging in EVPN

Abstract: Ethernet VPN (EVPN) provides an extensible and flexible multi-homing VPN solution over an MPLS/IP network for intra-subnet connectivity among Tenant Systems and End Devices that can be physical or virtual. However, there are scenarios for which there is a need for a dynamic and efficient inter-subnet connectivity among these Tenant Systems and End Devices while maintaining the multi-homing capabilities of EVPN. This document describes an Integrated Routing and Bridging (IRB) solution based on EVPN to address such requirements.

Fast IP lookups using a two-trie data structure

Abstract: IP routing table lookup has been considered as a major bottleneck for high performance routers. We propose a new way to do IP route lookups based on a so-called two trie structure. The two-trie structure shares the nodes representing the front and the rear parts of the prefixes. This results in reducing the number of nodes in the structure. Our results indicate that the memory can be saved around 27% over the standard trie while it still provides the fast lookup (around 1.6 memory accesses in the average case and 8 memory accesses in the worst case). Also, the structure is not based on any assumptions about the distribution of prefix lengths in routing tables. Thus, it can be applied to the larger addresses of IPv6 without affecting the main structure.