3Com 7600 manual 13-6CHAPTER 13 Traffic Management in the ATM Network

13-6CHAPTER 13: TRAFFIC MANAGEMENT IN THE ATM NETWORK

Flow Rate Traffic Management in the 7600 Card operates with both EFCI based and Adjustment Explicit Rate (ER) based flow control methods.

Transmission Rate The data transmission rate is controlled by means of rate tables called Profiles profiles. Depending on the information received in the returning RM cells

the data transmission rate is indexed up or down in the table. Each table has an upper and lower rate limit according to need. A set of 32 tables is pre-loaded into the system and is designed to cover all requirements of the network. The profiles are identified by their numbers. Please see the manufacturer for the characteristics of each profile.

Dual-Rate Mechanism A dual-rate mechanism is used which depends on whether a single VC is in use or multiple VCs are in use. For a single VC the full rate of 155 Mbps is used; for multiple VCs the maximum rate is set to one-half the full rate.

Static and Dynamic In the 7600 Card there are two types of Traffic Management: static and TM dynamic. The static TM is essentially the dual-rate mechanism described

in the previous section. The dynamic TM is the ABR feedback system described in the previous sections. The dynamic TM can be enabled and disabled by the LMA commands. When the dynamic TM is disabled, the static TM continues to operate.

TM Remote Client The TM system works independently for each ATM connection. For Database certain remote clients (LECs) it is desirable to set up special TM

characteristics which are used when communicating with it. For this purpose the 7600 Card maintains a database which holds the characteristics of each such connection including:

QEntry index

QTM enable/disable status

QConnection type

QATM address of the remote LEC

QProfile used when communicating with the remote LEC

QTM rate

The database contents can be displayed on the Management terminal and entries can be added and removed.