[c-nsp] prioritize VoIP and Skype traffic in office routers

[Martin T]

I would like to improve packet processing prioritization in case of
temporary congestions in my gateways(Cisco 1842,
C1841-ADVIPSERVICESK9-M) which are serving two small offices in
different cities. My ISP(same for both offices) does not support RSVP
so I can't make any RSVP requests. In addition, they do not support
prioritization based on DSCP or TOS field values. VoIP gateways are
located in office LAN's.

So far I have came up with following ideas:

1) Process packets passing the router using CEF("ip cef" in global
configuration mode). Should I consider changing the load-sharing
algorithm? At the moment I use "universal" load-sharing algorithm for
CEF.

2) Change interface queuing strategy(currently it's FIFO) for all Fast
Ethernet interfaces in gateways. There are many possibilities like
Custom Queuing, CBWFQ, Priority Queuing. "Priority Queuing" seems to
be especially appealing in this scenario- Skype and VoIP traffic would
have the highest priority and there isn't a worry that they could take
all of the available bandwidth. Any opinions here? Is Priority Queuing
a smart decision here?

3) use WRED


For classifying traffic I would use NBAR for
Skype(http://www.cisco.com/en/US/docs/ios/12_4t/qos/configuration/guide/qsnbarrm.html)
and transport layer protocol + port numbers for VoIP.

Which interface buffer queuing would be the best in described
scenario? Are all three methods reasonable?

PS if any additional information is needed, feel free to ask!

regards,
martin