1. Juniper qos
JNCIA

2. QOS? Converged networks supports various applications and flows.
Need to prioritize sensitive traffic
Intserv, diffserv

3. Main QOS building blocks
Classification
Marking
Congestion management
Congestion avoidance
Traffic policing and shaping
Link efficiency
Congestion avoidance and Link effeciency

4. Diffserv – L2 Priority Code Point (PCP) for Ethernet encapsulation PCP
Acronym
Traffic Types 1
0 (lowest) BK
Background BE
Best Effort 2 EE
Excellent Effort 3 CA
Critical Applications 4 VI
Video, < 100 ms latency and jitter 5 VO
Voice, < 10 ms latency and jitter 6 IC
Internetwork Control 7
7 (highest) NC
Network Control

5. DIFFSERV – L3

6. DSCP Class
DSCP (bin)
DSCP (dec)
IP precedence
ToS (dec)
none
cs1
1000 8 1 32
af11
1010 10 40
af12
1100 12 48
af13
1110 14 56
cs2
10000 16 2 64
af21
10010 18 72
af22
10100 20 80
af23
10110 22 88
cs3
11000 24 3 96
af31
11010 26
104
af32
11100 28
112
af33
11110 30
120
cs4
100000 4
128
af41
100010 34
136
af42
100100 36
144
af43
100110 38
152
cs5
101000 5
160 ef
101110 46
184
cs6
110000 6
192
cs7
111000 7
224

7. Classification Match traffic and put it into proper queue
Firewall filters
show
from {
protocol [ udp tcp ];
port 5060; }
then {
forwarding-class cos-voice;
accept;

8. marking Rewrites DSCP value with a new one per forwarding class
Forwarding classes should be the same across whole network
There is no special meaning of particular classes
[edit class-of-service]
rewrite-rules {
dscp rewrite-dscps {
forwarding-class cos-voice {
loss-priority low code-points ef; }
forwarding-class cos-video {
loss-priority low code-points cs5;
forwarding-class cos-critical {
loss-priority low code-points af31;
forwarding-class cos-bulk {
loss-priority low code-points af11;
loss-priority high code-points cs1;

9. Congestion management
Queuing mechanisms
FIFO
WFQ
CBWFQ
CBWFQ + PQ = LLQ
CQ, PQ
WFQ gives each flow same BW. Lower weight = better priority. Weight depends on IP prec.

10. LLQ

11. Congestion avoidance RED WRED, CBWRED
Configured as drop-profile under [edit class-of-service schedulers scheduler-name]
Tail drop
RED – min and max threshold

12. Traffic shaping and policing
Single token bucket
Dual Token Bucket (single rate three color marker)
Dual rate token bucket (two rate three color marker)
[edit firewall]
three-color-policer 1m-cir {
two-rate {
committed-burst-size 3k;
committed-information-rate 1m;
peak-burst-size 3k;
peak-information-rate 2m; }

13. TWO RATE THREE COLOR MARKER
CIR (bps) = Bc/Tc
Default Tc = 125 ms

14. LAB
Task 1:
[ ] Mark and classify HTTP and ICMP traffic between C1 and C2.
[ ] Use DSCP EF for HTTP traffic and assign it to Queue1.
[ ] Use DSCP AF1x for ICMP traffic and assign it Queue2.
[ ] Verify your setting on C1 and C2 in Wireshark.
Task 2:
[ ] Assign to EF traffic 10% of BW and assign it
to strict priority queue.
[ ] Assign to AF traffic 30% of BW.
[ ] Use default BW assignment for NC and rest for BE.

15. root@JR1# show interfaces fe-0/0/3 unit 0 { description To-PC1;
show firewall
filter qos-marker {
term icmp {
from {
source-address {
/32; }
protocol icmp;
then {
forwarding-class expedited-forwarding;
accept;
term http {
destination-port 80;
forwarding-class assured-forwarding;
term default {
then accept;
show interfaces fe-0/0/3
unit 0 {
description To-PC1;
family inet {
filter {
input qos-marker; }
address /24;
show class-of-service
interfaces {
fe-0/0/3 {
classifiers {
dscp default;
rewrite-rules {

16. class-of-service {
interfaces {
fe-* {
scheduler-map http-icmp-qos; }
schedulers {
sched-ef {
transmit-rate percent 10;
buffer-size percent 10;
priority strict-high;
sched-af {
transmit-rate percent 30;
buffer-size percent 30;
priority high;
sched-be {
transmit-rate percent 55;
buffer-size percent 55;
sched-nc {
transmit-rate percent 5;
buffer-size percent 5;
class-of-service {
scheduler-maps {
http-icmp-qos {
forwarding-class network-control scheduler sched-nc;
forwarding-class best-effort scheduler sched-be;
forwarding-class assured-forwarding scheduler sched-af;
forwarding-class expedited-forwarding scheduler sched-ef; }

17. END