Specifications

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Cisco MGX 8850 (PXM45) and MGX 8950 Software Configuration Guide
Release 3, Part Number 78-14788-01 Rev. C0, January 2004
Chapter 1 Preparing for Configuration
Collecting Information
ATM Addressing Plan
An ATM network addressing plan is critical for successful operation of the Cisco MGX 8850 and the
Cisco MGX 8950 switches in an ATM network. Both MPLS and PNNI networks require unique ATM
addresses on each switch. However, the PNNI protocol uses structured network addresses to logically
group network devices and determine routes between devices. For PNNI networks, an ATM address plan
is required.
PNNI network addressing is described in the Cisco MGX and SES PNNI Network Planning Guide.
IP Addressing Plan
An IP network addressing plan is required for switch management. IP network addressing is described
in “Guidelines for Creating an IP Address Plan,” later in this chapter.
Administrator Data
In most cases, more than one administrator will manage the switch. The Cisco MGX 8850 and the Cisco
MGX 8950 switches support multiple administrators and several different administration levels. As part
of the planning process, you might want to identify who will be managing the switch and at what level.
You can learn more about managing administrators by reading the “Configuring User Access” section in
Chapter 2, “Configuring General Switch Features.”
Network Clock Source Plan
Clock synchronization in an ATM network is very important. If two switches have trouble synchronizing
their communications, traffic between the switches may have excessive errors or line failures. MGX
switches support two methods of network clock synchronization:
• manual
• network clock distribution protocol (NCDP)
Both of these methods of clock synchronization are described in the sections that follow.
Note Manual clock configuration and NCDP configuration operate independently of one another. This means
that you can configure both versions of network clock sourcing on your network. However, only one
version can be enabled at a time. You cannot run your manual network clock configuration on your
network while NCDP is running, and vice-versa. However, both configurations are stored in the disk
database. Therefore, if you disable NCDP, the network reverts back to your original manual network
clock configuration. If you enable NCDP on that same network at a later point, the network will revert
back to the original NCDP configuration.
Planning for Manual Clock Synchronization
In manual clock source configurations, you need to configure a primary and secondary clock source,
which are distributed throughout the network. The secondary clock source takes over if the primary clock
source fails. You can configure a network setup with one master clock source, or with a secondary to
ensure better network clock stability. The secondary master clock source takes over if the primary master
clock source Figure 1-5 shows an example network clock source topology.