•
Cells with the same CoS bits are bundled together. This means all the cells in a bundle
belong to the same class of service.
•
As alluded to in the previous rules, several triggers cause early packet transmission,
meaning that the packet is transmitted before the number of cells received is equal to
the value configured with the cell-bundle-size statement. These triggers are as follows:
•
The next cell is of type CBR or RTVBR.
•
The next cell has a different CLP bit.
•
The next cell has different CoS bits.
•
The 125-microsecond timer expires.
CoS-based cell bundling optimizes the release of a bundle by sending out the cell that
triggers early packet transmission as a single-cell packet. This means that when a cell
triggers early packet transmission, that cell is not bundled. Consequently, certain input
data patterns might cause primarily single-cell packets to be transmitted. For example,
say the output interface receives a steady pattern of two cells from a non-RTVBR queue,
followed by two cells from a UBR queue. In this case, all transmitted packets contain a
single cell because the first cell triggers a transition and is transmitted by itself. The
second cell is also transmitted by itself because the third cell triggers another transition,
and so on. This effect might not be dramatic with a mix of traffic; it is most evident with
steady traffic patterns, as generated by ATM test equipment programmed to emit regular
sequences of CoS queue transitions.
Copyright © 2017, Juniper Networks, Inc.190
ACX Series Universal Access Router Configuration Guide
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