Configuring Multiclass Mlppp On Lsq Interfaces - Juniper ACX1000 Configuration Manual

ACX Series Universal Access Router Configuration Guide

Configuring Multiclass MLPPP on LSQ Interfaces

518
Configuring the Minimum Number of Active Links on Multilink and Link Services Logical
Interfaces on page 515
Configuring MRRU on Multilink and Link Services Logical Interfaces on page 516
Configuring DLCIs on Link Services Logical Interfaces
For link services LSQ (
lsq-
multiclass MLPPP (MCML). If you do not configure MCML, fragments from different
classes cannot be interleaved. All fragments for a single packet must be sent before the
fragments from another packet are sent. Nonfragmented packets can be interleaved
between fragments of another packet to reduce latency seen by nonfragmented packets.
In effect, latency-sensitive traffic is encapsulated as regular PPP traffic, and bulk traffic
is encapsulated as multilink traffic. This model works as long as there is a single class of
latency-sensitive traffic, and there is no high-priority traffic that takes precedence over
latency-sensitive traffic. This approach to LFI, used on the Link Services PIC, supports
only two levels of traffic priority, which is not sufficient to carry the four-to-eight forwarding
classes that are supported by M Series and T Series routers. For more information about
the Link Services PIC support of LFI, see Configuring Delay-Sensitive Packet Interleaving
on Link Services Logical Interfaces.
NOTE: ACX Series routers do not support link fragmentation interleaving
(LFI).
For link services LSQ interfaces only, you can configure MCML, as defined in RFC 2686,
The Multi-Class Extension to Multi-Link PPP. MCML makes it possible to have multiple
classes of latency-sensitive traffic that are carried over a single multilink bundle with
bulk traffic. In effect, MCML allows different classes of traffic to have different latency
guarantees. With MCML, you can map each forwarding class into a separate multilink
class, thus preserving priority and latency guarantees.
NOTE: Configuring both LFI and MCML on the same bundle is not necessary,
nor is it supported, because multiclass MLPPP represents a superset of
functionality. When you configure multiclass MLPPP, LFI is automatically
enabled.
The Junos OS implementation of MCML does not support compression of
common header bytes, which is referred to in RFC 2686 as "prefix elision."
MCML greatly simplifies packet ordering issues that occur when multiple links are used.
Without MCML, all voice traffic belonging to a single flow is hashed to a single link to
avoid packet ordering issues. With MCML, you can assign voice traffic to a high-priority
class, and you can use multiple links. For more information about voice services support
on link services IQ interfaces (
) interfaces with MLPPP encapsulation, you can configure
), see Configuring Services Interfaces for Voice Services.
lsq
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