QoS Cisco Routers
Posted on 2010-01-07
Lots of basic questions on QoS...
Does a router only queue and prioritze packets during times of congestion or does applying the service policy to an interface ensure that all data filters through the queue (even if it isn't congested) to make sure all priority traffic is sent first?
What situations would you specify an input policy vs an output policy? Does this apply to packets that switch from one interface to another inside of the router? Example - A packet coming from LAN that is routed out through another interface.
If you are trying to apply a qos policy on an ethernet interface that is connected at 100Mb but is attached to say Metro Ethernet running at 10Mb. In addition to applying the service policy, Do you need to set the bandwidth lower on the interface (since the router is always going to try to send it 100Mb) for it to effectively prioritze the traffic?
Do routing protocols with precedence 6 and 7 need to be classified or does the router just automatically identify them and send them first?
If I specify to match dcsp cs5 in my class-map is it necessary to also match dscp ef? I'm guessing that cs5 will match anything by the first 3 bits rather than all 6.