The goal of my lab is to test and prove the effect of QoS between a central site and a remote site. It simulates the case of a customer where I have to configure QoS. The link between the central site and the remote site is normaly a SDSL 2 Mb/s, but in my lab it is a simple 100Mb ethernet link. However the 2 Mb/s bitrate is between the operator's routers and not between the custmer's equipments. That's why I want to create the bottleneck on the customer's routers and to adjust the bitrate to 2 Mb/s, in order to be able to do QoS prioritization.
The customer uses GRE tunnels between central and remote sites to do dynamic routing.
On GRE tunnel, you can only use Traffic shaping to use CBWFQ (hierarchical service policy).
For the lab, the speed of the routers (Cisco 1721) is set to 100 Mb/s.
The soft Wan killer is used to saturate the link : always UDP discard
First of all, I would like to show how the voice is altered without QoS.
Wan killer is used with a bandwidth of 100000 kb/s, a size of packet of 1440 bytes.
Until 17 % of flooding (17 Mb/s) the phone call quality is OK (in the same direction than the flooding). The note given by the cisco 7960 is 4.500 which is excellent, despite the 2 Mb/s shapping.
Here is a show of the Fa 0 interface on R2 :
R2#sh int fa 0
FastEthernet0 is up, line protocol is up
Hardware is PQUICC_FEC, address is 0013.199e.2d0d (bia 0013.199e.2d0d)
MTU 1500 bytes, BW 100000 Kbit, DLY 1000 usec,
reliability 255/255, txload 6/255, rxload 44/255
Encapsulation 802.1Q Virtual LAN, Vlan ID 1., loopback not set
Full-duplex, 100Mb/s, 100BaseTX/FX
Input queue: 23/75/4/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
30 second input rate 17575000 bits/sec, 1747 packets/sec
30 second output rate 2374000 bits/sec, 429 packets/sec
Here is a show of the Tunnel GRE interface :
R2#sh int tu 1
Tunnel1 is up, line protocol is up
Hardware is Tunnel
Internet address is 172.16.0.2/24
MTU 1514 bytes, BW 2000 Kbit, DLY 500000 usec,
reliability 255/255, txload 255/255, rxload 44/255
Encapsulation TUNNEL, loopback not set
Tunnel source 192.168.0.2 (FastEthernet0.1), destination 192.168.0.1
Tunnel protocol/transport GRE/IP, key disabled, sequencing disabled
Tunnel TTL 255
Checksumming of packets disabled, fast tunneling enabled
Tunnel transmit bandwidth 8000 (kbps)
Tunnel receive bandwidth 8000 (kbps)
Input queue: 3/75/0/0 (size/max/drops/flushes); Total output drops: 49074
Queueing strategy: fifo
Output queue: 0/0 (size/max)
30 second input rate 352000 bits/sec, 214 packets/sec
30 second output rate 2000000 bits/sec, 214 packets/sec
Here are the shapper statistics :
R2#sh policy-map interface
Service-policy output: shape
Class-map: class-default (match-any)
76719 packets, 106314226 bytes
30 second offered rate 17024000 bps, drop rate 14388000 bps
Target/Average Byte Sustain Excess Interval Increment
Rate Limit bits/int bits/int (ms) (bytes)
2000000/2000000 12500 50000 50000 25 6250
Adapt Queue Packets Bytes Packets Bytes Shaping
Active Depth Delayed Delayed Active
- 64 10816 12335322 10816 12335322 yes
Traffic shaping is active and a lot of packet are drop. Why is the phone call quality not affected ???
At this step, no queuing tool is used by the shapper, it is in Fifo mode I guess. Fair-queuing is not activated on the class-default where the shapping is configured.
I don't understand why the voice, which has a bitrate of 80ko/s approximatively and is in competition with an 17 Mb/s UDP flooding stream, can be unaffected ???
Is there something I forgot ?
I would appreciate your help on this, thank you.