t priority, weighted fair queuing (WFQ), and weighted round robin (WRR). AMCC also refers to a feature called virtual SAR. This means that expensive external segmenta- tion and reassembly (SAR) devices are not required when the nPX5700 is used. Instead, the SARing function is inherent in the chipset and is a natural result of the way in which the nPX5700 accom- plishes per-flow queuing and scheduling. This explains the term virtual SAR. Another interesting feature is its ability to support point-to-point multicast connections. This indi- cates that traffic that is received on one input flow can be sent to one or more output flows, either on separate output ports (physical multicast) or on the same output port (logical multicast). Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. AMCC nPTM FAMILY OF NETWORK PROCESSORS 98 NETWORK PROCESSORS The nPX5700 can also operate in snooping mode. This means that it can send a duplicate flow originally meant for another port to an output. This is useful if someone tracks items with an attached network protocol analyzer, eliminating the need to move the analyzer from one switch port to another. One of the useful capabilities of the 5700 chipset is that it enables packets entering on separate ports to be merged to exit from a single port, as is required in Multiprotocol Label Switching (MPLS). In addition to standard OC-3/OC-12 Asynchronous Transfer Mode (ATM) and 10/100 Ethernet ports, the nPX5700 can handle multiple slower speed pipes, such as T1, fractional T1, and DS-0, aggregated into a single physical port. Conversely, multiple ports can be aggregated into a single high- speed pipe. For example, up to 16 OC-3 ATM ports can be combined into a single OC-48 ATM port. In very high-speed applications, two separate traffic managers will be needed: one on the ingress path of the switch/router and one on the e