We have 2-T1 that are being used for Internet Access. During most of the day the BW is almost at 100% due to mainly SMTP (Attachments), FTP traffic, which results in pretty bad HTTP performance.
As a first step i enabled WFQ on the serial interface, which should help in giving preference to low-volume traffic.
I want to implement the below also but wanted to get input, if they would be useful
1. Use Class\Policy Maps to identify SMTP,FTP traffic and then police the outbound rate, so that this traffic doesn't take 100% Interface BW.
2. Can the same Policy Maps (as above) be used to rate-limit inbound traffic also ?
3. Is the service-policy command applied to the Physical Interface Or to the Sub-Interface (configured with the actual IP) ?
4. Is there a way to identify File Transfers over HTTP as opposed to regular HTTP HTML Browsing using NBAR ?
5. If I want to rate-limit SMTP\FTP traffic, only when the interface is fully congested , how can I do that ? (Using Custom Queuing ?)
"In your config, class-default is going to get rest of available bandwidth?" Don't believe it will get the rest, but will compete with the other defined classes. Which leads to your next question.
"And that will establish the ratio of how the packets are going to be serviced?" Not clear exactly how the ratio is established.
Reason I didn't define a bandwidth percentage within class-default with FQ active, it hasn't been clear to me whether it controls bandwidth ratios or provides a floor for the FQ flows, at least on non-7500 platforms. See the section "Understand Platform Differences" within http://www.cisco.com/en/US/tech/tk39/tk48/technologies_tech_note09186a00800fe2c1.shtml#platform.
What's important in this configuration example is restricting FTP flows to just one queue with a minimal bandwidth guarantee.
If it's important to really set the class-default bandwidth (and its bandwidth ratio to other classes, and sometimes it is), I then use FIFO for the class, just as all the other classes are doing (on non-7500s).
Getting bandwidth hogs deprioritized (e.g. FTP), getting critical traffic prioritized (e.g. VoIP) and using FQ for everything else usually works well in most cases.