hi all, i have taken DSL connections from an ISP, consider 2 sites. Both are using ADSL connection terminated on their Fas 0/1 interfaces. The circuit taken is of 256 kpbs. now at each site we have a server that needs to be guaranteed 50% of bandwidth, now this is what i have done
configure interface bandwidth
int fas 0/1
service-policy output server
now here is the confusion, this qos will work only if there is congestion right ? so when there will be congestion of a 100mbps link ?? coz the circuit is 256 kpbs from DSL MODEM to ISP, the link from Fas 0/1 to MODEM is 100mbps, so router will send traffic at 100mbps to Modem right ? but when i issue the command
sh int fas 0/1
to see the load, it never exceeds 270-280 kpbs, so is the flow control between fas 0/1 and modem is limiting the traffic ?
To keep it simple, how shall i apply qos to Fas 0/1 in my case ?? CBWFQ will work when there is congestion its very difficult that 100mbps gets congested
i hope you understand what i am trying to ask,
kindly guide me through this
As both Paolo and Mohamed correctly note, the key is a CBWFQ parent shaper that will limit your outbound FastEthernet to 256 Kbps. Within the child policy, you'll provide a class that guarantees the minimal bandwidth for your server.
e.g. (syntax likely incorrect)
ip access-list extended special_server
permit ip host x.x.x.x any
match access-list special_server
bandwidth percentage 50
interface fastethernet 1
service-policy output parent_shaper
The problem with config example is that won't work, because as the original posted, the 100mb interface is never congested.
The solution is using so called hierarchical policy, shape to the uplink value as needed, then apply llq or whatelse is desired.
See for example
Hope this helps, please rate post if it does!