Cisco Systems uBR7200 Series manual Statistic Description, Mac Id

Chapter 4 Troubleshooting the System

Troubleshooting Using Cable Flap Lists

Table 4-20 Flap List Statistics Description

Statistic	Description
MAC ID	This is the MAC-layer address of a cable modem. The first six digits indicate the vendor ID of
	the cable modem manufacturer, followed by six digits indicating a unique host address. Each
	cable modem's MAC address is unique.
Cable IF	This is the physical upstream interface on the Cisco uBR7200. It denotes the cable modem card
	slot number, the downstream port number on the RF line card and the upstream port number on
	the same cable modem card. The flap list data can be sorted based on the upstream port number
	which is useful when isolating reverse path problems unique to certain combining groups.
Insertions	Link insertion is the process whereby a modem performs an initial maintenance procedure to
	establish link with the CMTS. The Ins column is the flapping modem’s insertion count and
	indicates the number of times the RF link was abnormally re-established. An abnormality is
	detected when the time between link re-establishment attempts is less than the user-configurable
	parameter.
	Normal modem activity follows the sequence below.
	• The initial link insertion is followed by a keepalive loop between the CMTS and cable
		modem and is called station maintenance.
	•	Power-on
	•	Initial maintenance
	•	Station maintenance
	•	Power-off
	When the link is broken, initial maintenance is repeated to re-establish the link.
	Initial maintenance		@ Time T1
	Station maintenance
	Init maintenance		@ Time T2
	The Ins and Flap counters in the flap list are incremented whenever T2 – T1 < N where N is the
	insertion-time parameter configured in <cable flap-listinsertion-time>.Default value for this
	parameter is TBD seconds.
	A high Ins number indicates:
	• Intermittent downstream sync loss
	• DHCP or modem registration problems

Cisco uBR7200 Series Universal Broadband Router Software Configuration Guide

4-38 78-5897-01