Cisco Systems Network Router manual 4 shows an example topology of a PNNI MPG WAN

Chapter 3 Address and Closed User Group Planning

Planning Address Configuration Settings

Figure 3-3 PNNI Network Physical Topology

PNNI network

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The topology shown in Figure 3-3becomes a Single Peer Group (SPG) PNNI WAN if no hierarchy is applied. In an SPG WAN, every node stores information about every other node and the CPE that connect to it. To distribute information about all the nodes in the WAN, the PNNI switches send PNNI Topology State Element (PTSE) messages to each other on a regular basis. In a small WAN, an SPG application is appropriate. When the WAN grows beyond 100 nodes, PTSE distribution and the size of the node PNNI databases begins to affect network performance. At this point, you might want to consider creating a Multiple Peer Group (MPG) WAN.

Figure 3-4shows an example topology of a PNNI MPG WAN.

Figure 3-4 MPG WAN Topology

Level 40

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Level	Level
56	56

Level

56

Level 56

Level

56

	Cisco PNNI Network Planning Guide for MGX and SES Products, Release 5
Part Number OL-3847-01 Rev. D0, April, 2004		3-7