QOS - GTS

TOPOLOGY: R2 ------ R3 ------ R1 ------ R4

GTS or generic traffic shaping. This predates MQC.
The LAB requirement here is to use GTS to limit the traffic flow to R4. Packets destined to R4 loopback (150.1.4.4) is allowed 16k and packets destined to R4 fa0/0 (155.1.148.4) is allowed only 8K.

I create two acls matching the required traffic flows on R1

access-list 100 permit ip any 155.1.148.0 0.0.0.255
access-list 101 permit ip any 150.1.4.0 0.0.0.255


I apply 2 traffic-shape commands to the fa0/0 interface on R1.

interface FastEthernet0/0
ip address 155.1.148.1 255.255.255.0
duplex half
traffic-shape group 100 8000 1000 2000 10
traffic-shape group 101 16000 1000 2000 10

I execute 2 pings: One from R3 to fa0/0 on R4, and one from R2 to lo0 on R4.

Router_3#ping 155.1.148.4 size 2000 repeat 1000 timeout 1
Router_2#ping 150.1.4.4 size 2000 repeat 1000 timeout 1

I then examine the traffic shaping with the following three commands on R1.

show traffic-shape
show traffic-shape statistics
show traffic-shape queue fa0/0


Router_1#show traffic-shape

Interface Fa0/0
Access Target Byte Sustain Excess Interval Increment Adapt
VC List Rate Limit bits/int bits/int (ms) (bytes) Active
- 100 8000 375 1000 2000 125 125 -
- 101 16000 375 1000 2000 62 125 -


Router_1#show traffic-shape queue fa0/0
Traffic queued in shaping queue on FastEthernet0/0
Traffic shape group: 100
Queueing strategy: weighted fair
Queueing Stats: 10/10/64/46 (size/max total/threshold/drops)
Conversations 1/1/16 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
Available Bandwidth 8 kilobits/sec

(depth/weight/total drops/no-buffer drops/interleaves) 10/4048/46/0/0
Conversation 1, linktype: ip, length: 1514
source: 155.1.13.3, destination: 155.1.148.4, id: 0x002B, ttl: 254, prot: 1


Traffic shape group: 101
Queueing strategy: weighted fair
Queueing Stats: 9/10/64/61 (size/max total/threshold/drops)
Conversations 1/1/16 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
Available Bandwidth 16 kilobits/sec

(depth/weight/total drops/no-buffer drops/interleaves) 9/4048/61/0/0
Conversation 5, linktype: ip, length: 1514
source: 155.1.23.2, destination: 150.1.4.4, id: 0x004E, ttl: 253, prot: 1


Lastly the show traffic-shape statistics command indicates the ping to R4 loopback is transmitting twice the amount of data in comparison to the ping to R4 fa0/0 interface.

Router_1#show traffic-shape stat
Acc. Queue Packets Bytes Packets Bytes Shaping
I/F List Depth Delayed Delayed Active
Fa0/0 100 10 98 130592 92 128508 yes
Fa0/0 101 10 277 329510 254 309188 yes



GTS can also be applied to the interface as a whole with the traffic-shape rate command. For example.

int fa0/0
traffic-shape rate 128000 8000 8000 100