by Olivier | Feb 27, 2010 | IOS, Lab, Non classé, QOS, Written Theory |
Here are also all supported markings after you have classified your traffic :
- IP Precendence (set ip precedence <<value>>)
- DSCP (set ip dscp <<value>>)
- QoS group (set ip precedence <<value>>)
- MPLS experimental bits (set mpls experimental <<value>>)
- Frame Relay DE bit (set fr-de)
- ATM CLP bit (set atm-clp)
by Olivier | Feb 27, 2010 | IOS, Lab, Non classé, QOS, Written Theory |
Here are all tools that we can use to classify the traffic under a class-map:
- ACL
- Existing markings ( CoS,IP Precedence,DSCP)
- QoS group
- Protocol (using NBAR)
- Traffic matching another class-map
- Mac-address (source or destination)
- Range of UDP ports
by Olivier | Feb 27, 2010 | IOS, Lab, Non classé, QOS, Written Theory |
Just as a reminder , CoS marking (Layer 2) doesn’t “survive” to Layer 3 as the route processor will remark it.
It is why the most of the time a Cos to DSCP rewriting policy must be applied on the input direction of the interface.
by Olivier | Feb 27, 2010 | IOS, Lab, Non classé, QOS, Written Theory |
Before enabling AutoQoS , take in mind the following pre-requisites :
- CEF must be enabled as AutoQoS relies on NBAR which is dependant of CEF.
- No Policy QoS can be attached to the interface
- The correct bandwidth statement must be set up on the interface
- An IP address must be configured on an interface if its speed is less than 768 Kbps
- The interface can’t be in a shutdown mode
You can the ask why IP Address is an mandatory element ?
It is simply because if your speed links is less than 768 Kbps , then AutoQoS will enable Multilink PPP (MLP)
by Olivier | Feb 27, 2010 | IOS, Lab, Non classé, QOS, Written Theory |
By default , a class-map will use the match-all criteria so it will tell that you must match all your conditions in your class-map before to classify the traffic .
If you want classify directly when at least one condition is met then use the criteria match-any.
Unclassified traffic will go in the default class.
by Olivier | Feb 25, 2010 | IOS, Lab, Non classé, QOS, Written Theory |
Shaping can be applied only in the outbound direction and doesn’t discard the traffic exceeding the rate limit automatically. Shaping will bufferize the queue until the bandwidth become available or in last action will drop exceeding packets.
Compared to Policing , shaping preserves the bandwidth and is recommended on lower bandwidth links.
Qos Shaping is also considered as an Traffic Conditioner
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