Conditional Rate Limiting?

[trmg]

Hey All,

Is it possible to set up EEM (or something) to apply rate limits under certain conditions, and when those conditions no longer exist to remove the rate limits?

I bought a netTALK Duo (similar to MagicJack but no computer required) and want to configure my router (Cisco 871 running IOS 12.4(24)T) so that voice traffic isn't trampled when there is high WAN utilization.

I have outgoing QoS set up, which was very easy. The problem now is policing incoming traffic. I don't want to set up static rate limits because then the bandwidth I set aside for VoIP will be reserved whether or not there is a call in place. I want to be able to use the additional bandwidth when the phone isn't being used.

Would it be possible to have EEM (or something) apply rate-limit rules when there is voice traffic to the netTALK device and remove the rate-limit rules when there is no voice traffic?

Hopefully I'm not too crazy!

 

[dgrizzard]

The problem is QoS only works in an outbound fashion. In other words your ISP would have to apply the QoS policy on their outbound interface going to your connection.

The reason is the way access-lists/qos/etc are applied to traffic. They are applied not before the traffic enters the router (would be impossible if you think about it), it applies it before it routes the traffic out the outbound interface. So if you apply that, then you could not apply QoS or traffic shaping to inbound traffic on your router, since it will already have passed in and congested your WAN connection by the time it hits the router.

Another way to think about it is the way you have your current QoS setup. You have that setup on your WAN interface. So traffic enters your LAN/ethernet interface, and then before it goes out the WAN interface it is prioritized depending on traffic conditions.

 

[trmg]

I understand why QoS can't be applied to incoming traffic. I was just hoping that there was a way to dynamically rate limit traffic. I've been successful with setting up static rate limit rules, but they are just that...static...and aren't necessary 24/7/365.

I suppose I could buy a second router and place it between my existing router and my ISP to perform QoS on "outbound" traffic to my existing router (and thus performing QoS on "inbound" traffic from the 'net), but that's not very cost effective, haha.