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Appendix K
CDM-760 Advanced High-Speed Trunking Modem
K.3.2
Prioritization
Prioritization of traffic is a method of assigning various value levels to a particular classification
rule. Prioritization ensures that the packets/frames are "ordered" such that the highest level of
protection is provided to the most valuable traffic.
The CDM-760 offers eight priority levels (Table K-2), with Level 1 being the highest priority and
Level 8 the lowest priority.
K.3.3
Drain
Once you classify and prioritize the packets or frames, you need to determine how to drain the
traffic. Does your network require you to pass all high level traffic in a strict priority manner
such that lower priority traffic could be "starved" in times of overdriving the WAN bandwidth?
Or, can determinations be made about the maximum and minimum levels of service you can
accept on a per classification rule basis?
The CDM-760 Packet Processor provides a number of choices. You may select from three top-
level QoS drain algorithms:
•
Max/Priority
K.3.3.1 Max/Priority Mode
Max/Priority QoS mode is commonly used in ACM circuits in conjunction with Weighting (see
Sect. K.4).
In Max/Priority mode, every classification rule is assigned a "not to exceed" Maximum Data Rate
and a Priority Level. You may assign up to 32 classification rules using any combination of the
classifiers listed in Table K-2.
If you do not need to limit the total traffic that can be assigned to a particular rule, then you
may set the Maximum Data Rate to a number that is excessively large, e.g. 999999 kbps.
In Max/Priority mode, the highest priority level traffic (i.e., Priority Level 1) will be drained until
empty or until the Maximum Data Rate is met for all Priority Level 1 classification rules before
attempting to drain any lower-priority level (i.e., Priority Level 2) classification rules. If, at any
Order Precedence
Classifier
6
Destination IP/Mask
7
Source Ports
8 (Last)
Destination Ports
Table K-2. Rule Priorities
Priority Level
1
Highest Priority
2
Second Highest Priority
3
Third Highest Priority
4 – 7
Fourth through Seventh Priorities
8
•
Min/Max
K–3
Rank
Lowest Priority
•
DiffServ
Revision 4
MN-CDM760
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