Summary

This chapter provided architecture descriptions of the various VSI master and slave implementations running in Cisco Systems, Inc.'s BPX, IGX, and MGX product lines. The MPLS LSC can exist in a standalone platform that is physically linked to a BPX or IGX. Otherwise, an RPM or URM service module resides in an MGX or IGX, respectively, and contains the LSC implementation. Similar to MPLS, PNNI controllers either are implemented in external platforms such as the SES, which directs PNNI operation in the BPX, or reside in an MGX switch's PXM control card.

After discussing protocol controller and VSI master implementations, we focused on VSI slaves. VSI slaves are categorized into hybrid models, such as the MGX, or distributed models, found in the BPX and IGX. Remember that hybrid or distributed classification depends on the location of the VSI slaves.

Additional topics in this chapter included a description of the legacy AutoRoute and Portable AutoRoute connection routing algorithms, as well as a detailed explanation of and reason for LINs.

The next chapters delve more deeply into MPLS and PNNI multiservice switching networks.