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
IMA support on PXM1E
The Cisco MGX 8850 and the Cisco MGX 8950 switches support many of the most common ATM
configuration parameters. To successfully configure lines and trunks, be sure that the configuration
settings used on the switch match the configuration settings used at the other end of the line or trunk. In
some cases, options you want to use at one end of the trunk are not supported at the other end. In these
situations, change your configuration plan to use settings that are supported at both ends.
Chapter 3, “Preparing AXSM Cards and Lines for Communication,” describes how to configure physical
layer line communications. Chapter 6, “Provisioning AXSM Communication Links,” describes how to
configure ATM ports.
IMA support on PXM1E
The AXSME-32-T1-E1 card supports IMA (I inverse Multiplexing for ATM) 1.0 and 1.1 on up to 32 T1
or E1 ports. The IMA feature enables multiple T1 or E1 lines to be grouped into a single high-speed ATM
port.
The advantage of the IMA feature is that you do not need T3/E3 circuits to support high bandwidth on
your switch. T1 IMA links support up to 12 Mbps, and E1 IMA links support up to16 Mbps.
If IMA is disabled on the AXSME-32-T1-E1 each T1 or E1 interface can be configured as a single port
running at full line rate.
When IMA is enabled on the AXSME-32-T1-E1 a configured group of T1 or E1 lines can support one
T1 or E1 port. A single IMA group can support up to 16 T1 or E1 links. Multiple IMA ports of any
configuration are supported per card. For example, you can have 4 IMA Groups with 4 links each.. At
the extremes, you can have 16 Groups with 1 link each or one Group with 16 links. If a T1/E1 line in an
IMA group fails, the IMA port automatically adjusts to continue operation over the remaining lines.
Note Each T1/E1 or IMA port supports only one T1 or E1 line at a time.
Note During AXSME switchovers, configured IMA groups are not operational to carry data. There will be a
delay until the IMA groups become functional, and the length of this delay depends on the transmission
delay between the IMA endpoints. Traffic loss can be around 3 seconds, and connections may be
re-routed.
To configure IMA links on an AXSME-32-T1-E1 card, refer to the “Cisco AXSM Software
Configuration Guide and Command Reference for the MGX 8850 (PXM45) and the MGX 8950”
Planning for Card and Line Redundancy
Card redundancy is a feature that associates two cards, so that if one card fails, the other card assumes
operation. Processor Switch Module 45 (PXM45) card redundancy is preconfigured on the Cisco
MGX 8850 and the Cisco MGX 8950 switches for PXM45 and PXM45/B cards. If PXM45 cards and
their associated back cards are inserted in slots 7 and 8, they will automatically operate as redundant
cards. One card assumes the active role, and the other card operates in standby mode.