Lab 2. QoS - Priority Queuing

Priority queuing use 4 methods:

1. High. It’s the highest priority
2. Medium.  This is the second priority
3. Normal. This is the tird priority and by default traffic classified by this priority
4. Low. It’s the lowest priority

Let’s do practice

R1#

interface Loopback0

 ip address 1.1.1.1 255.255.255.255

 ip ospf 1 area 0

!

interface FastEthernet0/0

 ip address 12.12.12.1 255.255.255.0

 ip ospf 1 area 0

 no shut

R2#

interface Loopback0

 ip address 2.2.2.2 255.255.255.255

 ip ospf 1 area 0

!

interface FastEthernet0/0

 ip address 12.12.12.2 255.255.255.0

 ip ospf 1 area 0

 no shut

Let’s make example.

• All telnet will be set as high queue
• All http traffic will be set as medium queue
• All ping traffic will be set as normal queue
• Default traffic will be set as low queue

R1#

priority-list 1 protocol ip high tcp 23

priority-list 1 protocol ip medium tcp 80

priority-list 1 protocol ip normal list 100

priority-list 1 default low

!

access-list 100 permit icmp any any echo

access-list 100 permit icmp any any echo-reply

!

interface fa0/0

 priority-group 1

Verify the queuing priority

R1#show queueing priority

Current DLCI priority queue configuration:

Current priority queue configuration:

List   Queue  Args

1      low    default

1      high   protocol ip          tcp port telnet

1      medium protocol ip          tcp port www

1      normal protocol ip          list 100

Let’s debug if we already assign to right priority or not.

To avoid appear a lot of messages, let’s deactivate debug for cdp and keepalive

R1#

no cdp run

!

int f0/0

  no keepalive

Let’s do debug priority

R1(config-if)#do debug priority

Let’s test ping. It shoul go to normal priority

R1(config-if)#do ping 2.2.2.2 sour 1.1.1.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 24/40/56 ms

R1(config-if)#

*Mar  1 00:21:23.923: PQ: FastEthernet0/0: ip (s=1.1.1.1, d=2.2.2.2) -> normal

*Mar  1 00:21:23.923: PQ: FastEthernet0/0 output (Pk size/Q 114/2)

*Mar  1 00:21:23.979: PQ: FastEthernet0/0: ip (s=1.1.1.1, d=2.2.2.2) -> normal

*Mar  1 00:21:23.979: PQ: FastEthernet0/0 output (Pk size/Q 114/2)

*Mar  1 00:21:24.019: PQ: FastEthernet0/0: ip (s=1.1.1.1, d=2.2.2.2) -> normal

*Mar  1 00:21:24.019: PQ: FastEthernet0/0 output (Pk size/Q 114/2)

*Mar  1 00:21:24.051: PQ: FastEthernet0/0: ip (s=1.1.1.1, d=2.2.2.2) -> normal

*Mar  1 00:21:24.055: PQ: FastEthernet0/0 output (Pk size/Q 114/2)

*Mar  1 00:21:24.099: PQ: FastEthernet0/0: ip (s=1.1.1.1, d=2.2.2.2) -> normal

R1(config-if)#

*Mar  1 00:21:24.099: PQ: FastEthernet0/0 output (Pk size/Q 114/2)

Let’s do telnet. It should go to high priority

R1(config-if)#do telnet 2.2.2.2

Trying 2.2.2.2 ... Open

*Mar  1 00:23:57.191: PQ: FastEthernet0/0: ip (tcp 23) -> high

*Mar  1 00:23:57.195: PQ: FastEthernet0/0 output (Pk size/Q 60/0)

*Mar  1 00:23:57.275: PQ: FastEthernet0/0: ip (tcp 23) -> high

*Mar  1 00:23:57.275: PQ: FastEthernet0/0 output (Pk size/Q 60/0)

*Mar  1 00:23:57.279: PQ: FastEthernet0/0: ip (tcp 23) -> high

*Mar  1 00:23:57.283: PQ: FastEthernet0/0 output (Pk size/Q 63/0)

*Mar  1 00:23:57.287: PQ: FastEthernet0/0: ip (tcp 23) -> high

*Mar  1 00:23:57.287: PQ: FastEthernet0/0 output (Pk size/Q 60/0)