Installation and Operation Manual
Chapter
1 Introduction
ACE-3105, ACE-3205 Ver. 5.2
Functional Description
1-19
•
VBR1 shaped – PCR, CDVT, SCR and MBS
•
UBR+ – PCR, CDVT and MDCR
•
ACE-3105, ACE-3205 has a built-in shaper, based on the single/dual leaky
bucket protocol.
•
PCR/SCR granularity in the worst case is 0.39%
•
Minimum PCR/SCR supported is 100 cells/second
•
Recommended CDVT values are displayed in the relevant Traffic Descriptor
(TD) configuration screen (CDVT values cannot be enforced accurately).
ATM Cell Scheduling
Each port's egress ATM cell traffic is hierarchically matched to four strict-priority
queues, and the traffic is transmitted according to these four outbound queue
levels of priority:
•
First priority queue – CBR-shaped and CBR-unshaped cells are transmitted
first
•
Second priority queue – VBR cells
•
Third priority queue – UBR+ cells
•
Fourth priority queue – UBR cells are transmitted last.
Figure
1-14. ATM Queues Priority
ATM Policing
The ATM policing function defines which non-conformant ATM cells should be
discarded, tagged or counted by ACE-3105, ACE-3205, per user configuration.
The following policing modes are supported according to ATMF TM4.1:
•
CBR.1
•
VBR.1
•
VBR.2
•
VBR.3
•
UBR.1
•
UBR.2
The policing is configurable per a receive channel. Multiple channels can be
mapped to a single policing policy (group policing).
The granularity of the CDVT is 10ns. The minimum CDVT depends upon the port
type:
