8 subports. This means that one C192 Queue Manager chip can handle up to eight Q64G chips arranged in each one of two different banks per OC-192 port. This configuration example, as shown in Figure 14.13, can be multiplied up to 32 times depending on how many OC-192 links must be sup- ported. One of these Q64G banks is usually the primary fabric, whereas the other one is used as redun- dancy support for protection in case of failure or field service. The CSIX-L1 interface at the other side of the C192 ensures an adaptable link operating with a clock of 125 MHz or 250 MHz and a 32-, 64-, or 128-bit-wide interface (breakable in up to 4 sub- ports). Communication with a network processor on top of the regular inbound flow-control modes IBM PowerPRSTM redundant fabric Q-64G for protection primary active switch fabric IBM PowerPRSTM Q-64G 8 times 64 Gbps CSIX or OC-192 or 8 times 64 Gbps 4 X OC-48 IBM queue manager FIGURE 14.13 Two redundant IBM PowerPRS Q64G switch fabric banks (with eight fab- ric chips each) are used with one C192 Queue Manager per OC-192 port. (Source: IBM) 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. SWITCH FABRICS SWITCH FABRICS 295 defined by the CSIX-L1 specifications can also be handled via an Xon/Xoff out-of-band protocol and support of CSIX CFrames. IBM therefore supports natively both of these techniques. More informa- tion about CSIX is provided in the Appendix III. The 64G fabric interfaces directly with the NP4GS3 network processor as we saw via the Data Aligned Synchronous Links (DASLs). Other line cards that have been implemented around different NPUs or protocol processors can be interfaced with the switch fabric through two options: Take the approach of the standard UTOPIA-3 interface and link through an IBM PRS UTOPIA-to-DASL Serial Interface Converter chip into the switch fabric's DASL ports, or use the C1