Limitations For Cos On Ppp Interfaces; Guidelines For Configuring Cos On Ppp And Mlppp Interfaces - Juniper ACX1000 Configuration Manual

Limitations for CoS on PPP Interfaces

Guidelines for Configuring CoS on PPP and MLPPP Interfaces

Copyright © 2017, Juniper Networks, Inc.
equals 36 is not a power of 2, the lower fill-level is internally adjusted to convert it to
be a number exponentially raised to 2.
When fragmentation-map is configured, the forwarding-class carrying the multi-class
0 traffic must be assigned the highest priority and the forwarding-class carrying the
multi-class 3 traffic must be assigned the lowest priority. Such a configuration is
necessary because of the NPU design.
The following restrictions apply for configuring CoS on PPP interfaces on ACX Series
routers:
The distribution of excess rate between 2 or more queues that contain the same priority
occurs on a first-come, first-served basis. For example, consider two Queues configured
as follows:
Q1 : Transmit-rate = 10%, Shaping-rate = 20%
Q2 : Transmit-rate = 10%, Shaping-rate = 30% on same priority
The excess rate for Q1 = (20 - 10) = 10%
The excess rate for Q2 = (30 - 10) = 20%
The excess rate distribution between Q1 and Q2 does not follow the same ratio but
packets in these queues are served in first-come, first-served manner. The shaping
rate continues to be honored in such a scenario.
Keep the following points in mind when you configure CoS on PPP and MLPPP interfaces:
You can configure only the any option with the
class-of-service schedulers scheduler-name drop-profile-map]
the protocol type for the specified scheduler. You cannot specify the TCP or non-TCP
protocol types.
CoS functionalities for fractional T1 and E1 interfaces are not supported. CoS is
supported only for full T1 and E1 interfaces.
Weighted fair queuing (WFQ) shaping and scheduling model is not supported. Instead
of WFQ, CIR-EIR model is supported to handle shaping and scheduling requirements.
Percentage-based rate configuration is not supported for MLPPP LSQ interfaces; only
absolute rate configration in bps is supported.
Auto-adjustment of shaping and scheduling rates with the addition or deletion of T1/E1
links is not supported. All the limitations applicable for CoS on ACX routers apply for
PPP interfaces.
All the policer limitations on ACX routers for Gigabit Ethernet interfaces are valid for
PPP interfaces. This restriction includes ingress and egress policers. Because these
limitations are chassis-wide, they are also effective for PPP interfaces.
Chapter 27: Configuring Class of Service
statement at the
protocol
hierarchy level to specify
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