Cisco BPX 8600 Series, Руководство по установке и настройке

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Cisco BPX 8600 Series Installation and Configuration
Release 9.3.0, Part Number 78-10674-01 Rev. D0, July 2001
Chapter 21 Configuring ATM Connections
ATM Command List
In releases previous to Release 9.1.07, when connections are derouted, the CPE does not receive Abit
notifications. In Release 9.1.07 on BPX, the Send Abit on Deroute feature was developed, which
allowed the Abit = 0 to be sent immediately when a connection is derouted. (This was specified by the
cnfnodeparm
parameter Send Abit immediately parameter.)
To further enhance the Send Abit on Deroute feature in Release 9.1.07, the Early Abit Notification on
ILMI/LMI Using Configurable Timer feature was implemented in Release 9.2 to allow the network
administrator to configure the node as to when Abit = 0 is sent out if a connection is derouted and not
rerouted quickly. This feature allows you to specify when Abit notifications will be sent at Frame Relay
and ATM ports, and at feeder trunks in a tiered network architecture that supports the ILMI/LMI
interface. In a tiered network, the Abit information is used by the feeder nodes such as MGX 8220
(AXIS) which then relays the Abit information to the CPE.
Performance Considerations
The status update messages are throttled at the rate of one message per second. Each message can be
used to specify the conditioning information on a maximum of 47 connections. It may take on the
order of minutes for the ILMI/LMI manager to process the Abit status when there is a large number of
connections.
There are two factors in performance:
• System performance
System performance is affected by the value of the time interval. In a network where connections
are normally derouted and rerouted quickly before the bucket timer expires, the performance
impact is very small. Only when the timer expires, then looping through all LCONs and sending
update messages will take up some CPU time which is estimated to be smaller than 1 percent.
•
Reroute time
Reroute time is not affected if LMI/ILMI is running on the controller card. When the protocol is
implemented on the line cards and feeder trunk cards, some additional Abit status communication
between them and controller card may delay the reroute process.
Specifically, on the BPX, if the BXM runs LMI/ILMI, the BCC has to send Abit update to the card.
These messages will be throttled. When this happens, the estimated time to reroute all 12K connections
increases no more than 5 percent.
For the IGX, enabling the Sending Abit Notification using Configurable Timer feature may impact
performance if many connections end at Frame Relay cards. This is due to the restricted format of
interface between NPM and Frame Relay cards.
ATM Command List
Table 21-15 ATM Connection Commands
Mnemonic Description
addcon Add connection
clrchstats Clear channel statistics
cnfabrparm Configure ABR parameters (applies to BXM)
cnfatmcls Configure ATM class
cnfcdparm Configure channel statistic level on UXM/BXM
cards