Configure QoS

Tasks Link to heading

• All Telnet traffic to 2.2.2.2 is set DSCP to 60.
• All Web traffic to 2.2.2.2 is set IP Precedence to 3.
• All other traffic is set DSCP to 40.

Answer:

• By default:

  • Ping traffic has DSCP = 0.
  • Telnet traffic has DSCP = 48 (0xc0 = 110 000) (CS6).
  • Web traffic has DSCP = 48 (0xc0 = 110 000) (CS6).

• Steps in configuring QoS:

  1. Identify traffic (access-list).
  2. Classify traffic to classes (class-map).
  3. Apply QoS policies to classes (policy-map).
  4. Put policies on interfaces (service-policy input/output).

Configuration Link to heading

hostname R1
no cdp run
int f0/0
    ip add 10.0.0.1 255.255.255.0
    no shut
ip route 2.2.2.0 255.255.255.0 10.0.0.2
ip access-list extended TELNET_TRAFFIC
    permit tcp any host 2.2.2.2 eq 23
ip access-list extended WEB_TRAFFIC
    permit tcp any host 2.2.2.2 eq 80
class-map TELNET
    match access-group name TELNET_TRAFFIC
class-map WEB
    match access-group name WEB_TRAFFIC
policy-map POLICY1
    class TELNET
        set dscp 60
    class WEB
        set ip precedence 3
    class class-default
        set dscp 40
int f0/0
    service-policy output POLICY1

hostname R2
no cdp run
int f0/0
    ip add 10.0.0.2 255.255.255.0
    no shut
int l0
    ip add 2.2.2.2 255.255.255.0
ip http server

Verification Link to heading

Test by using Wireshark to capture packets:

R1# telnet 2.2.2.2
Trying 2.2.2.2 ... Open

R1# telnet 2.2.2.2 80
Trying 2.2.2.2, 80 ... Open

R1# ping 2.2.2.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 20/20/20 ms

R1# show policy-map int f0/0
 FastEthernet0/0
  Service-policy output: POLICY1
    Class-map: TELNET (match-all)
      9 packets, 549 bytes
      5 minute offered rate 0000 bps, drop rate 0000 bps
      Match: access-group name TELNET_TRAFFIC
      QoS Set
        dscp 60
          Packets marked 9
    Class-map: WEB (match-all)
      7 packets, 420 bytes
      5 minute offered rate 0000 bps, drop rate 0000 bps
      Match: access-group name WEB_TRAFFIC
      QoS Set
        precedence 3
          Packets marked 7
    Class-map: class-default (match-any)
      50 packets, 3287 bytes
      5 minute offered rate 0000 bps, drop rate 0000 bps
      Match: any
      QoS Set
        dscp cs5
          Packets marked 5