Modem Installation And Maintenance Practice

Section 5, User Interface - Menu Descriptions
61179605L5-5B 5-15
Strict Prioritization
There are four available virtual circuits (VCs) per SHDSL loop that can be prioritized on a
strict prioritization basis. This means that any available high priority VC traffic gets queued
into the ATM/SHDSL pipe first followed by traffic at the next highest priority class, and so on,
to the lowest priority class (see Figure 5-10). If a priority class contains no elements, it is
bypassed but always considered for the next queueing sequence. Prioritization only applies to
egress traffic of the subscriber (SHDSL) ports.
As described above Four VCs can be configured on each SHDSL port. There are four priority
settings: High = CBR, MidH = VBRrt, MidL = VBR, and Low = UBR. There are no rate settings
for the cbr, vbrrt, and vbr configurations, therefore, these ATM Class of Service (COS) prior-
ities have been redefined as High, MidH, MidL, and Low priorities.
Figure 5-10. Strict Prioritization Concept Diagram
Total Access 1240
SHDSL
Loop Bandwidth
VC
Strict Prioritization
Port 12 Vlan 515 VC 0/38
Port 12 Vlan 514 VC 0/37 Port 12 Vlan 513 VC 0/36 Port 12 Vlan 512 VC 0/35
Ethernet
Egress
Ingress
SHDSL ports 1-24
SHDSL Port 12
High Priority
MidHigh Priority MidLow Priority
Low Priority
Vlan 101
Vlan 102
Vlan 123
Vlan 124
Port 1 Port 23
Port 24
Port 12
Port 2
Egress
Ingress