Specifications

CHAPTER

3-1

Cisco IGX 8400 Series Provisioning Guide, Release 9.3.3 and Later Releases

OL-1166-04

Cisco IGX 8400 Series Nodes

In an IGX-only network, IGX nodes function as both network backbones and network access points. In

a mixed network, an IGX node can perform a variety of functions, including traffic routing and

bandwidth optimization, network administration and synchronization, and job management.

For information about the BPX, see Chapter 1, “The BPX Switch: Functional Overview,” in the

Cisco BPX 8600 Series Installation and Configuration guide.

Functional Overview

In a network, a node represents a chassis or other hardware point where network traffic is switched or

routed to the next node. Because the IGX WAN switch can handle many different types of traffic, the

IGX chassis can function as a node in many different networking environments. In addition, the modular

design of the chassis features removable service modules that can provision the node for different

networking technologies, so that the IGX node can function as a node in multiple networks

simultaneously, such as a Frame Relay network and an ATM network.

For example, an IGX node can service an ATM network through a UXM or UXM-E service module

installed in slot 3, while a UFM service module in slot 4 allows the IGX node to participate in a FR

network. Interworking between different networking technologies also allows the two networks to be

functionally attached.

In one of the most common network designs using the IGX, the IGX node functions as an edge switch

for the network, with an attached edge router handling routing of traffic coming into the network

attached to the IGX. With an installed URM card, this IP routing can be handled within the IGX chassis,

eliminating the need for a separate external router.

Understanding Network Synchronization

Available clock sources are defined within the network as primary (p), secondary (s), or tertiary (t). Each

trunk that can pass clock synchronization is defined. Each network node’s clock is locked to the

highest-level clock source available. If multiple, equal clock sources are available, each node chooses

the closest one (measured in number of hops).

If there is no primary, secondary, or tertiary clock source defined or working in a network, then the

internal oscillator of one node is automatically selected as the active network clock source.