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The Hill Associates ATM Switch Page

Walter J. Goralski

Last Update: 6 February 1998
Copyright Hill Associates, Inc. All Rights
Reserved.

This page has links to information on 27 ATM switches in two formats: an Excel spreadsheet (.xls) and an Acrobat PDF file (.pdf). Either one can be downloaded, viewed, or printed. There are two tables. The first is a listing of major ATM features, and the second is a listing of miscellaneous features for reliability and network management.

The list is meant to be representative and not exhaustive. Only one switch per vendor has been profiled. In cases where a vendor makes more than one ATM switch, the most powerful package has been profiled. This list is meant to be as accurate as possible, but reflects the state of the products as of the beginning of 1998.

A few words about each category are in order.

  • List price: gives the price range for the product from minimal to maximum configuration.
  • Backplane: gives the total aggregate bit rate of the switching fabric. Does not specify the exact structure of the fabric, however.
  • Expansion slots: gives the total number of slots in the switch.
  • Media slots: some slots might be reserved for the fabric itself and so on. This gives the total number of slots available for supporting input and output ports.
  • Media support: gives the type of fiber and/or UTP media that the ports can support.
  • OC-3c: total number of 155 Mbps ports that the switch can have.
  • OC-12s: total number of 622 Mbps ports that the switch can have.
  • OC-3s: total number of 155 Mbps ports on UTP that the switch can have.
  • Features: these miscellaneous and network management features are listed on the second sheet.
  • LAN servers: types of LAN-specific ATM server functions the switch can support. Three are considered: Classical IP over ATM (RFC 1577), LAN emulation configuration server (LECS), which includes support), LAN emulation servers (LES) and the broadcast unknown server (BUS), and the multiprotocol over ATM (MPOA) server.
  • LAN clients: types of LAN-specific ATM client functions the switch can support. The IP, LAN emulation client (LEC), and MPOA client functions are considered.
  • Redundant LES/BUS: whether the switch supports more than one LES/BUS in the ATM network.
  • Redundant LECS: whether the switch supports more than one LECS in the ATM network.
  • Interoperation: whether the switch can interoperate in standard fashion with different vendor's devices.
  • COS support: gives what ATM Forum classes of services (COS) the switch supports.
  • ABR flow control: if the switch supports the ABR COS, lists which of the three forms of ABR flow control (explicit forward congestion indicator (EFCI), explicit rate, or relative rate) that the switch supports.
  • PNNI support: gives whether the switch support PNNI Phase I or "Phase II." PNNI Phase II is not complete, but support is listed for vendors who have implemented some form of this already.
  • Mirroring: whether VCC configurations are duplicated for reliability purposes.
  • Packet discard: ways in which the switch can discard cells that are defective, which includes early, partial, and selective.
  • Number of VCCs: maximum number of VCCs that can be configured. Good measure of switch "size."
  • Cell buffers: maximum number of cell buffers that can be configured. Another good indicator of switch "size."
  • Buffer location: some switches have only central buffers. Others buffer on the line cards themselves, or in both places.
  • Priority queues: somewhat confusing. Some vendors list priorities more or less by COS (2, 3, 4, etc.). Others list the total number of priority queues, no matter the category, giving much higher numbers.
  • Queuing mechanism: gives the ways that the priority queues are enforced. There are three listed: by priority (previous item), by port (i.e. a port can have a priority), or per VC (i.e. each VCC can be assigned a priority).

The second table lists 8 miscellaneous or network management features. There are:

  • Redundant power? Does the switch have a second, backup power supply?
  • Redundant switching? Does the switch have a second, backup fabric that can take over if the first fails?
  • Hot-swap switch? Can the idle switch fabric itself be changed without shutting the switch down?
  • Hot-swap line cards? Can the input and output cards be changed without shutting the switch down?
  • Serial console? Is there a serial port for connecting a terminal for management and configuration?
  • Ethernet console? Is there an "Ethernet" port for connecting the switch to a LAN for management and configuration?
  • SLIP/modem port? Is there a port that can be attached to a modem and running the serial line interface protocol (SLIP) from the Internet protocol suite (TCP/IP) for management and configuration?
  • Telnet? Can telnet be used to access the switch for management and configuration?

Questions, comments, and updates can be sent to Walter at w.goralski@hill.com.
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