Cisco Systems Network Router manual Single Peer Group Topology

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Chapter 1 Introduction to PNNI

The Single Peer Group Topology

Tip A node is a network device that communicates with other network devices. Cisco PNNI-compatible devices serve as nodes in a PNNI network. In this document, the terms node and switch are often used interchangeably. However, in most cases, the PNNI node is a component of a Cisco PNNI-compatible device. For example, some Cisco MGX switches, Release 2.0 and later, can operate as both a PNNI node and as an MPLS device.

The PNNI protocol communicates the state of a PNNI network in PNNI Topology State Elements (PTSEs). PTSEs are discrete messages that contain information about one of the following types of network components:

•PNNI nodes

•Reachable addresses

•PNNI links between nodes

To enable communications with other nodes, each switch needs to have all the PTSE information for each switch in the network. Each node is responsible for flooding out its own PTSE information to all the other switches in the network.

Since up-to-date PTSE information is required for optimal routing decisions to be made, there are several different mechanisms in place to help ensure that all nodes have reasonably accurate PTSE information. The five common reasons for updating PTSEs are as follows:

•Resources administratively added, removed or altered on a node.

•Resource failure such as an Loss of Signal (LOS) on a link.

•A significant change in link resources due to virtual circuits (VCs) routing or derouting.

•Periodic updates defined by the PTSE refresh and PTSE lifetime interval timers.

•A processor switch module (PXM) switchover.

PTSE information is passed between nodes using PNNI Topology State Packets (PTSPs). These packets utilize the Routing Control Channel (RCC; VPI = 0 and VCI = 18) between adjacent nodes. The RCC is also used for Hello packets and other PNNI messages. If the switch is unable to establish the RCC with the adjacent node, then PTSE information is not exchanged. Once a node receives PTSE information, the node stores the contents, or element information, in the database. This information is used to generate precomputed routing tables that identify routes to other network devices. The PNNI database is also used to perform on-demand routing when the appropriate routing table does not contain a viable path.

The Single Peer Group Topology

A single peer group topology is a PNNI network in which all nodes share PTSEs with all other nodes. As each node is brought up in a single peer group network, that node learns about all the other nodes, and the other nodes learn about the new node. All nodes are capable of determining routes to all other nodes within the single peer group. Figure 1-1shows an example single peer group topology.

 

Cisco PNNI Network Planning Guide for MGX and SES Products, Release 5

1-2

Part Number OL-3847-01 Rev. D0, April, 2004

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Contents Corporate Headquarters Text Part Number OL-3847-01 Rev. D0Copyright 2003, Cisco Systems, Inc All rights reserved N T E N T S IiiCompatible Standards Worksheets Part Number OL-3847-01 Rev. D0, April G U R E S ViiViii B L E S Part Number OL-3847-01 Rev. D0, April Audience ObjectivesOrganization Conventions XiiRelated Documentation DocumentationDocumentation Notes for the April 2004 Product Releases XiiiTechnical Manual Order of Use XivTechnical Manual Titles and Descriptions TermsXvi Xvii Xviii Xix Reference Guides Xxi Document Title Description XxiiXxiii Xxiv Xxv Xxvi Ordering Documentation Obtaining DocumentationCisco.com XxviiChapter Changes Changes to This DocumentXxviii Cisco TAC Website Obtaining Technical AssistanceDocumentation Feedback Opening a TAC CaseTAC Case Priority Definitions Obtaining Additional Publications and InformationXxx Xxxi Xxxii Introduction to Pnni Pnni Network DatabaseSingle Peer Group Topology Hierarchical Pnni Network Topology Example Single Peer Group TopologyPeer group Ppeer Peer Group Leaders Simple Node RepresentationComplex Node Representation Simple Node RepresentationBorder Nodes Pnni Internetworking with AiniHierarchical Pnni Network Benefits Pnni Internetworking with Iisp Example Pnni Internetworking with Aini TopologyPart Number OL-3847-01 Rev. D0, April Specifications Compatible StandardsPXM1E PXM45Capabilities PXM45/BCapabilities SES SESSVC Connection Limit AdjustmentsConnection Type Switch Connections CWM Endpoints DAX SpvcParallel Links Between Adjacent Switches Install Redundant Hardware in SwitchesPhysical Network Planning Multiple Links to an External Network Planning Guidelines for Individual Peer GroupsMultiple Links Between Adjacent Peer Groups Multiple Paths Between Network NodesPlanning Guidelines for Peer Group Leaders Planning Guidelines for Hierarchical NetworksPlanning Guidelines for Border Nodes Part Number OL-3847-01 Rev. D0, April Address and Closed User Group Planning Address Planning OverviewPnni Addressing Example Planning Address Configuration Settings Selecting an ATM Address FormatSupported Address Formats ESI SEL IDP DSPATM Field Description Default Values Guidelines for Selecting an Address FormatCategory Type Authorities Selecting a Pnni LevelAddress Registration Authorities DCC4shows an example topology of a Pnni MPG WAN Part Number OL-3847-01 Rev. D0, April Length Level Peer Group ID Portion of ATM Address BytesDefault Peer Group ID Selecting the Pnni Peer Group IDSelecting the ATM Address 20-byte Node AddressSelecting the Spvc Address Prefix Selecting the Ilmi Address PrefixPlanning Address Prefixes for Aini and Iisp Links Selecting Static Addresses for UNI Ports Additional Guidelines for Creating an Address PlanClosed User Group Overview Closed User Group ExampleSelecting an Interlock Code Planning CUG Configuration SettingsSelecting an Index Selecting Internal CUG Access Options Selecting CPE AddressesSelecting External CUG Access Options Specifying a Preferential CUGSelecting a Default CUG Address WorksheetsCUG Part Number OL-3847-01 Rev. D0, April How MGX and SES Nodes Select Routes Administrative WeightLink and Route Metrics Cell Delay Variation Cell Transfer DelayAvailable Cell Rate Maximum Cell Rate Shortest Path Table RoutingShortest Path Tables CTD CDV Class of Service TablesService Class Acronym Definition Guidelines Traffic MetricHow SVCs and SVPs use the SPTs How SPVCs and SPVPs use the SPTsOn-Demand Routing How MGX and SES Nodes Select LinksLoad Balancing for SPT and On-Demand Routing Preferred Routing Additional Routing Features in MGX and SES NodesService CLR0+12Priority Routing GroomingBlocking Pass-Through Connections Soft ReroutingPriority Bumping Nodal Point-to-Multipoint Branch RestrictionAXSM-E AXSM/AAXSM/B AXSM-XGFarthest Node Branching Part Number OL-3847-01 Rev. D0, April Aini ABRAesa Ansi APSCTD P2MPCBR IN-2DIN CUGCWM IN-3IN-4 MGX SES PGLPnni IN-5IN-6 TAC UBRUNI IN-7IN-8
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