CoS on ATM Interfaces Overview
The ATM2 intelligent queuing (IQ) interface allows multiple IP queues into each virtual circuit (VC). On Juniper Networks M Series Multiservice Edge Routers (except the M320 router), a VC tunnel can support four class-of-service (CoS) queues. On M320 routers and T Series Core Routers, for all ATM2 IQ PICs except the OC48 PIC, a VC tunnel can support eight CoS queues. Within a VC tunnel, the weighted round-robin (WRR) algorithm schedules the cell transmission of each queue. You can configure the queue admission policies, such as early packet discard (EPD) or weighted random early detection (WRED), to control the queue size during congestion.
For information about CoS components that apply generally to all interfaces, see Understanding How Class of Service Manages Congestion and Controls Service Levels in the Network. For general information about configuring ATM interfaces, see the Junos OS Network Interfaces Library for Routing Devices.
To configure ATM2 IQ VC tunnel CoS components, include the following
statements at the [edit interfaces at-fpc/pic/port] hierarchy
level:
[edit chassis fpc slot-number pic pic-number] max-queues-per-interface number; [edit interfaces at-fpc/pic/port] atm-options { linear-red-profiles profile-name { high-plp-max-threshold percent; low-plp-max-threshold percent; queue-depth cells high-plp-threshold percentlow-plp-threshold percent; } plp-to-clp; scheduler-maps map-name { forwarding-class class-name { epd-threshold cells plp1 cells; linear-red-profile profile-name; priority (high | low); transmit-weight (cells number | percent number); } vc-cos-mode (alternate | strict); } } unit logical-unit-number { atm-scheduler-map (map-name | default); family family { address address { destination address; } } plp-to-clp; shaping { (cbr rate | rtvbr peak rate sustained rate burst length |vbr peak rate sustained rate burst length); } vci vpi-identifier.vci-identifier; }