IGT (Integrated Telecom Technology ) : WAC-487-A

ATM Quad Routing Table

The QRT is an advanced communications device supporting large, high performance ATM systems. Its support of per-Virtual Channel (VC) receive queues and 16 traffic classes allows systems built with the QRT to support sophisticated network service offerings.The QRT supports architectures from 800 Mbps to 320 Gbps, including a stand-alone 800 Mbps switch mode. Per-VC receive queues and two forms of switch fabric Negative Acknowledgment congestion indication (NACK) prevent head-of-line blocking. The QRT supports a multi-service class extension of the Explicit Rate Indication for Congestion Avoidance (ERICA+) algorithm for superior Available Bit Rate (ABR) support. It also provides five separate congestion thresholds, each with hysteresis, that selectively control AAL5 early packet discard and/or Cell Loss Priority (CLP)-based cell dropping for Unspecified Bit Rate (UBR) support. The QRT provides a connection between a UTOPIA Level 2 interface and a switch fabric composed of IgT WAC-188 ATM Switch Elements and/or IgT WAC-488 ATM Quad Switch Elements (QSEs). Features are

• Provides for weighted, bandwidth controlled service of 16 service classes.
• Provides per-VC, per-service class, per-same service class, per-virtual output, and per-device congested queue depth limits.
• Provides per-VC, per-service class, per-same service class, per-virtual output, and per-device maximum queue depth limits.
• Maintains 16 service classes.
• Provides round robin servicing of queues within each priority with support for two forms of switch fabric NACK.
  • Provides 31 virtual outputs.
  • Maintains 16 service classes with per-VC accounting for each virtual output.
  • Executes a multi-service class extension of the ERICA+ algorithm developed at Ohio State University for ABR traffic.
  • Supports early packet discard for UBR traffic and as a backup for ABR traffic.
  • Supports CLP-based cell discard.
  • Supports all 12 Virtual Path (VP) and 16 VC bits through the use of a double indirect lookup table.
  • Performs header translation at both the input and the output directions. The input header translation is used to pass the output queue channel number through the switch.
  • Supports multi cast with a superior queue-clearing multi cast algorithm for both the receive and transmit directions.
  • Checks the parity of the header.
  • Counts tagged cells.
  • Checks for liveness of signal lines.
  • Generates and traps cells.
  • Counts cells transmitted.
  • Counts cells dropped.
  • Supports the external collection of enhanced statistics through a synchronous statistics interface.
  • Provides four switch element interfaces with phase aligner. The phase aligner allow for external serialization of the data stream and allow for systems to be built with shelves up to 10 meters apart.

  Technology:	unknown
  Package:	unknown 0 Pin

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