3com 7600 Benutzerhandbuch
13-6
C
HAPTER
13: T
RAFFIC
M
ANAGEMENT
IN
THE
ATM N
ETWORK
Flow Rate
Adjustment
Traffic Management in the 7600 Card operates with both EFCI based and
Explicit Rate (ER) based flow control methods.
Explicit Rate (ER) based flow control methods.
Transmission Rate
Profiles
The data transmission rate is controlled by means of rate tables called
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.
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.
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
TM
In the 7600 Card there are two types of Traffic Management: static and
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.
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
Database
The TM system works independently for each ATM connection. For
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:
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:
Q
Entry index
Q
TM enable/disable status
Q
Connection type
Q
ATM address of the remote LEC
Q
Profile used when communicating with the remote LEC
Q
TM rate
The database contents can be displayed on the Management terminal
and entries can be added and removed.
and entries can be added and removed.
abtthgde.book Page 6 Tuesday, June 23, 1998 10:29 AM