David Lloyd

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David Lloyd is a postgraduate research student with the Networks and Telecommunications Research Group(NTRG) in the Department of Computer Science in Trinity College Dublin.

Research Area

IP on Asychronous Transfer Mode (ATM) Hardware, or as it is most often referred to, IP Switching. In my M.Sc. Thesis, I propose a new scheme called Smart IP Switching.

The concept of IP on ATM Hardware is based on retaining IP (Internet Protocol) as the internetworking protocol, however, instead of implementing IP on traditional routers, implementing it directly on ATM switches. The intention is to combine the advantages of IP, a protocol that has proved itself in terms of intelligence, robustness and scalability, while harnessing the high speed switching capability of ATM hardware. IP on ATM hardware differs from "IP over ATM" approaches, which emulate an IP network on top of an underlying ATM network.

These traditional "IP over ATM approaches" are described in specifications such as:

IETFs' Classical IP over ATM as defined in RFC-1577.
IETF's Next Hop Routing Protocol
The ATM Forums' LAN Emulation (LANE).(Spec. available here in various formats).
MultiProtocol Over ATM (MPOA) specified by the ATM Forum is available here in various formats.

Although "IP over ATM" approaches do offer a solution, their implementation is somewhat complex since the overhead of both IP routing and ATM signalling protocols are involved.

IP on ATM Hardware Schemes

In the past year or so, a number of schemes for implementing IP on ATM hardware have been proposed. In March 1996 Ipsilon Networks, Inc Palo Alto, CA, announced the industries first IP Switch. Following Ipsilons' announcement a number of similar proposals have emerged. The following is a list of the main proposals:

Ipsilon Networks IP Switching.
Cisco Systems Tag Switching.
Toshibas' Cell Switch Router, CSR.
IBM Aggregrate Route-Based IP Switching, ARIS.
Telecom Finlands'Switching IP Through ATM, SITA.
Switch-Borne Router proposal by Fahad Hoymany and Daniel Mossé, University of Pittsburg

All these approaches have in common a mechanism to allow packets from IP flows to be switched at layer 2, rather than being forwarded at layer 3, thereby, vastly reducing the overhead involved in layer 3 processing. Some approaches make a distinction between short-lived flows and long-lived flows and set up paths only for the long-lived flows, on the basis that the extra effort involved in setting up the switched path is only worth while for the longer lived flows. Other schemes setup switched paths across the network automatically, prior to the arrival of IP packets. These schemes then switch all IP packets at layer 2.

Each approach incorporates specialised protocols to setup switched paths and in general passing control messages between cooperation nodes.

The following section lists some of the applicable specifications and associated documentation of each approach.

Specifications and Related Documentation

Ipsilons' IP Switching

For an overview of IP Switching see "Flow labelled IP: A connectionless Approach to ATM"(Postscript) by Peter Newman et al., IEEE Infocom, March 1996, or, for further links see IP Switch Technology document list.

Cisco Systems' Tag Switching

Further links and information are available from Tag Switching Architecture

Toshibas' Cell Switch Router (CSR)

For an overview of the Cell Switch Router see this white_paper, (Postscript) from Toshiba.

Further information and links are available from CSR Index

IBM's Aggregate Route-Based IP Switching (ARIS)

Further links to ARIS documentation are available here

Telecom Finlands' Switching IP Through ATM (SITA)

SITA is a proposal by Juha Heinanen, of Telecom Finland. The proposal and related discussion are available on mailing list archive available here

Related Links

Smart IP Switching

The subject matter of my work is not be based on whether IP on ATM hardware is a good idea, instead, the focus is on determining the most effective way to implement it. The research has showed that the different schemes for implementing IP on ATM hardware may be classified by the approach they employ for setting up switched paths. The two principal approaches are traffic-driven and control-driven (sometimes called topology-driven). In my thesis entitled "Efficient Transport of IP using Smart IP Switching", a new scheme called Smart IP Switching is proposed.

Smart IP Switching is a traffic-driven scheme that exhibits advantages of both the traffic-driven and control-driven approaches. A paper entitled "Smart IP Switching: A Hybrid System for Fast IP-based Network Backbones", based on the work done for the thesis has been presented at the 1st IEEE International Conference on ATM (ICATM'98) held in Colmar, France in June 1998. Here is a copy of the slides in Power Point 97 format.

I have used the Vendor Independent Network Control Entity (VINCE) environment for my development and experimentation. VINCE is a software package developed by the Naval Research Laboratory (NRL). The VINCE API manual and latest version of VINCE are available here.

Further VINCE links ...

In the meantime, why not visit ND Systems, a subsidary of Telenor where I have worked as a Network Engineer on Bay Networks , and Cascade Communications equipment.

Currently I and a systems developer with Telenor Research and Development Ireland (RDI), based in Dublin.

Contact Details

Email :djlloyd@iol.ie

Phone: 353-1-8037300

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Last Updated : 26th June 1998