03-30-2008 11:54 PM - edited 03-03-2019 09:20 PM
Hi,all
Thanks in advance
Their is some confusion in qos configuration in mpls network.
One of my customer wants to deploy qos for bandwidth management in mpls network.
Scenario is like below.
MPLS sp provides 18 mb ethernet connection to customer.Bandwidth is controlled by MPLS sp.customer wants to reserve 16 mb for video traffic and remaining for data.But connection is comming on fastethernet port on 2811 router.I am plaaning to use CBLLQ.is it right solution or not?
03-31-2008 12:04 AM
Sandeep, Okay, but you need to ask the ISP to allow the QoS traffic over there MPLS network Thanks Goutam
03-31-2008 12:35 AM
The most critical to your design is shaper. There will be bottleneck on the ISP side, where ISP will not let more than 18Mb through, probably by policing. So what you need is create shaper on the output.
That is good news, since CBWFQ or CBWFQ+LLQ is not supported on the Ethernet itself very well, and almost not at all on subinterfaces.
Under shaper there should be a child map with all the policies.
So it will be like this:
PARENT: Shape average 18M
CHILD: class video
class data
It is a normal scenario, and you primarily to take care of your bottlenecks.
03-31-2008 01:25 AM
I agree with Pavlo that you need to use nested policies with the parent policy shaping the traffic and LLQ+ CBWFQ for prioritising the traffic
BTW, reserving 16MB out of 18 seems to be a bit too high for video. Recommendation for LLq is about 33% bandwidth
Narayan
03-31-2008 02:45 AM
thanks all of you for quick reply
But can i get some documentaion about nested policies under the parent policy, i mean can i get config example?
And what is meaning of "Recommendation for LLq is about 33% bandwidth"
03-31-2008 02:47 AM
one more question.
cisco 2811 router support CAR and GTS?
03-31-2008 03:11 AM
Have a look here
http://www.cisco.com/en/US/docs/ios/12_2/qos/configuration/guide/qcfmcli2.html#wp1022062
From the QoS SRND
Cisco Technical Marketing testing has shown a significant decrease in data application response times
when realtime traffic exceeds one-third of link bandwidth capacity. Extensive testing and customer
deployments have shown that a general best queuing practice is to limit the amount of strict priority
queuing to 33 percent of link capacity. This strict priority queuing rule is a conservative and safe design
ratio for merging realtime applications with data applications.
http://www.cisco.com/univercd/cc/td/doc/solution/esm/qossrnd.pdf
HTH
Narayan
03-31-2008 05:34 AM
There are two issues you need to address. First, what to do with the traffic you send to MPLS. Second, what happens to the traffic as it exits MPLS.
For the former, much as the other posters have also noted, a hierarchical shaper, with the parent's shaper configured for 18 Mbps, and the child's video class provided 16 Mbps, would often be the norm. If the video is not real-time, an ordinary CBWFQ class reservation of the necessary bandwidth usually works fine. If the video is real-time, e.g. video conferencing, LLQ is often the choice, but at these bandwidth levels, it's often not necessary.
e.g. (pseudo config)
policy-map parent
class class-default
shape 18 Mbps
policy-map child
class video
bandwidth 16 Mbps (or priority 16 Mbps)
class class-default
no fair-queue (FQ, on most platforms, seems to disturb non-LLQ bandwidth reservations)
fastethernet 0/0
service-policy output parent
The latter issue, what happens at MPLS egress, can be just as important. If your MPLS environment is multi-point, it's crucial too. If there are only two sites, your outbound policy, alone, might be all you need, but you still need to confirm what the MPLS provider does. For instance, they might rate-limit the MPLS egress bandwidth, and if their burst intervals differ from your shaper's, even though you both are configured for 18 Mbps, they might still drop some of your traffic.
If you're working with multi-point MPLS, then you need to consider how to obtain the bandwidth reservation you need within that environment which is very dependent on what the MPLS vendor offers. The latter is usually accomplished by usage of some type of CoS/QoS marking, for which the MPLS provider guarantees some service level for particular markings.
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