What do source and destination stand for in QoS settings

Question

I have had to deal with QoS several times but in this modem I have this complex options page:

Interface:
Protocol:
Src IP:
Src Mask:
Dest IP:
Dest Mask:
Src Port:
Dest Port:
Speed (kb/s): 

I have selected Internet for interface option and TCP/UDP for protocol option. The other options have text areas to fill out. I don't know how to slow down a specific IP with these options. I tried several combinations but couldn't figure it out. I couldn't find any information about source and destination on the Internet.

Answer 1

The various options you listed (except speed) let you identify the traffic that will be affected by the QoS rule. The values you should provide will depend on your specific requirements.

For example, if you wanted to affect only traffic sent by a device at IP address 10.0.0.1 from port 5000 to port 80 on the device at IP 172.16.0.2 the fields you're inquiring about would look like this:

Src IP: 10.0.0.1
Src Mask: 255.255.255.255
Dest IP: 172.16.0.2
Dest Mask: 255.255.255.255
Src Port: 5000
Dest Port: 80

Note: Most devices treat a wildcard mask of 255 as requiring the corresponding octet in the IP address to match exactly. Therefore 255.255.255.255 means the entire IP address would have to match before the rule applies but the mask 255.255.0.0 would mean the rule applies as long as the first two octets match. Check your product's documentation for its specific requirements.

To have the rule affect all traffic from your local network of 10.0.0.1/24 destined to any IP address in the world you'd use:

Src IP: 10.0.0.1
Src Mask: 255.255.255.0
Dest IP: 1.1.1.1 (this value wouldn't matter)
Dest Mask: 0.0.0.0 (this means any address will match)
Src Port: ?
Dest Port: ?

I don't know what values your device accepts in the Source & Destination Port fields when they should match all ports. Your manual or the device's online help should explain this.

More Information

• Wildcard masks