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Enabling Eight Queues on ATM2 IQ Interfaces

By default, ATM2 IQ PICs on T-series and M320 platforms are restricted to a maximum of four egress queues per interface. You can enable eight egress queues on ATM2 IQ interfaces by including the max-queues-per-interface statement at the [edit chassis fpc slot-number pic pic-number] hierarchy level:



[edit chassis fpc slot-number pic pic-number]

max-queues-per-interface (4 | 8);

The numerical value can be 4 or 8.

If you include the max-queues-per-interface statement, all ports on the ATM2 IQ PIC use the configured maximum.

When you include the max-queues-per-interface statement and commit the configuration, all physical interfaces on the ATM2 IQ PIC are deleted and re-added. Also, the PIC is taken offline and then brought back online immediately. You do not need to manually take the PIC offline and online. You should change modes between four queues and eight queues only when there is no active traffic going to the ATM2 IQ PIC.

For general information about configuring up to eight forwarding classes and queues on PICs other than ATM2 IQ PICs, see Configuring Up to Eight Forwarding Classes.

Note: When you are considering enabling eight queues on an ATM2 IQ interface, you should note the following:

ATM2 IQ interfaces using Layer 2 circuit trunk transport mode support only four CoS queues.
ATM2 IQ interfaces with MLPPP encapsulation support only four CoS queues.
You can configure only four RED profiles for the eight queues. Thus, queue 0 and queue 4 share a single RED profile, as do queue 1 and queue 5, queue 2 and queue 6, and queue 3 and queue 7. There is no restriction on EPD threshold per queue.
The default chassis scheduler allocates resources for queue 0 through queue 3, with 25 percent of the bandwidth allocated to each queue. When you configure the chassis to use more than four queues, you must configure and apply a custom chassis scheduler to override the default. To apply a custom chassis scheduler, include the scheduler-map-chassis statement at the [edit class-of-service interfaces at-fpc/pic/*] hierarchy level. For more information about configuring and applying a custom chassis scheduler, see Associating the Scheduler Map with the Packet Forwarding Component Queues.

Example: Enabling Eight Queues on ATM2 IQ Interfaces

In Figure 21, Router A generates IP packets with different IP precedence settings. Router B is an M320 or T-series platform with two ATM2 IQ interfaces. On Router B, interface at-6/1/0 receives traffic from Router A, while interface at-0/1/0 sends traffic to Router C. This example shows the CoS configuration for Router B.

Figure 21: Example Topology for Router with Eight Queues

Image g015530.gif

On Router B:



[edit chassis]
fpc 0 {


pic 1 {
max-queues-per-interface 8;
}


}
fpc 6 {


pic 1 {
max-queues-per-interface 8;
}


}
 
[edit interfaces]
at-0/1/0 {


atm-options {


linear-red-profiles {
red_1 queue-depth 1k high-plp-threshold 50 low-plp-threshold
80;
red_2 queue-depth 2k high-plp-threshold 40 low-plp-threshold
70;
red_3 queue-depth 3k high-plp-threshold 30 low-plp-threshold
60;
red_4 queue-depth 4k high-plp-threshold 20 low-plp-threshold
50;
}




scheduler-maps {


sch_red {
vc-cos-mode strict;


forwarding-class fc_q0 {
priority high;
transmit-weight percent 5;
linear-red-profile red_1;
}




forwarding-class fc_q1 {
priority low;
transmit-weight percent 10;
linear-red-profile red_2;
}




forwarding-class fc_q2 {
priority low;
transmit-weight percent 15;
linear-red-profile red_3;
}




forwarding-class fc_q3 {
priority low;
transmit-weight percent 20;
linear-red-profile red_4;
}




forwarding-class fc_q4 {
priority low;
transmit-weight percent 5;
linear-red-profile red_1;
}




forwarding-class fc_q5 {
priority low;
transmit-weight percent 10;
linear-red-profile red_2;
}




forwarding-class fc_q6 {
priority low;
transmit-weight percent 15;
linear-red-profile red_3;
}




forwarding-class fc_q7 {
priority low;
transmit-weight percent 20;
linear-red-profile red_4;
}


}




sch_epd {
vc-cos-mode alternate;


forwarding-class fc_q0 {
priority high;
transmit-weight percent 5;
epd-threshold 1024;
}




forwarding-class fc_q1 {
priority low;
transmit-weight percent 10;
epd-threshold 2048;
}




forwarding-class fc_q2 {
priority low;
transmit-weight percent 15;
epd-threshold 3072;
}




forwarding-class fc_q3 {
priority low;
transmit-weight percent 20;
epd-threshold 4096;
}




forwarding-class fc_q4 {
priority low;
transmit-weight percent 5;
epd-threshold 2048;
}




forwarding-class fc_q5 {
priority low;
transmit-weight percent 10;
epd-threshold 3072;
}




forwarding-class fc_q6 {
priority low;
transmit-weight percent 15;
epd-threshold 4096;
}




forwarding-class fc_q7 {
priority low;
transmit-weight percent 20;
epd-threshold 5120;
}


}


}


}




atm-options {
vpi 0;
}




unit 0 {
vci 0.100;


shaping {
cbr 1920000;
}


atm-scheduler-map sch_red;


family inet {
address 172.16.0.1/24;
}


}




unit 1 {
vci 0.101;


shaping {
vbr peak 1m sustained 384k burst 256;
}


atm-scheduler-map sch_epd;


family inet {
address 172.16.1.1/24;
}


}


}
at-6/1/0 {


atm-options {
vpi 0;
}




unit 0 {
vci 0.100;


family inet {
address 10.10.0.1/24;
}


}




unit 1 {
vci 0.101;


family inet {
address 10.10.1.1/24;
}


}


}
 
[edit class-of-service]
classifiers {


inet-precedence inet_classifier {


forwarding-class fc_q0 {
loss-priority low code-points 000;
}




forwarding-class fc_q1 {
loss-priority low code-points 001;
}




forwarding-class fc_q2 {
loss-priority low code-points 010;
}




forwarding-class fc_q3 {
loss-priority low code-points 011;
}




forwarding-class fc_q4 {
loss-priority low code-points 100;
}




forwarding-class fc_q5 {
loss-priority low code-points 101;
}




forwarding-class fc_q6 {
loss-priority low code-points 110;
}




forwarding-class fc_q7 {
loss-priority low code-points 111;
}


}




forwarding-classes {
queue 0 fc_q0;
queue 1 fc_q1;
queue 2 fc_q2;
queue 3 fc_q3;
queue 4 fc_q4;
queue 5 fc_q5;
queue 6 fc_q6;
queue 7 fc_q7;
}




interfaces {


at-6/1/0 {


unit * {


classifiers {
inet-precedence inet_classifier;
}


}


}


}


}
[edit routing-options]
static {


route 10.10.20.2/32 {
next-hop at-0/1/0.0;
retain;
no-readvertise;
}




route 10.10.1.2/32 {
next-hop at-0/1/0.1;
retain;
no-readvertise;
}


}

Verifying the Configuration

To see the results of this configuration, you can issue the following operational mode commands:

show interfaces at-0/1/0 extensive
show interfaces queue at-0/1/0
show class-of-service forwarding-class

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