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QoS Cisco Routers
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.
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.
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Well your router will only "prioritize" packets when link is congested. However, if you have some sort of CAR setup on your circuit through your ISP they may have dedicated bandwidth reserved for certain classifications used to guarantee Voice or Video extra priority through their network. Like if it were a P2P or MPLS.
Policing won't prioritize, it CAN mark packets to be prioritized by an upstream device, but I don't think that's what you want.
If you want to prioritize, you can use LLQ. But it only works during congestion because that's the only time it's needed. If nothing is congested the packets will be sent as soon as they're received so you don't need to prioritize.
If you want to prioritize, you can use LLQ. But it only works during congestion because that's the only time it's needed. If nothing is congested the packets will be sent as soon as they're received so you don't need to prioritize.
ASKER
Well here is the policy I tried to put in place but I'm still having call quality issues at times. I guess what probably needs to be done is that I just need to reserve bandwidth for my voip calls. Can you reserve bandwidth by matching dscp markings or does it have to be done via an ACL?
class-map match-any voip
match dscp ef
match dscp cs5
match precedence 5
match dscp cs3
match dscp af31
match precedence 3
!
!
policy-map qospolicy
class voip
priority 2000
class class-default
fair-queue
!
! Heres the 10mb
interface FastEthernet0/1/1
bandwidth 10400
service-policy output qospolicy
Give us the output of:
show policy-map int fa0/1/1 out
We need to see if it is matching properly.
show policy-map int fa0/1/1 out
We need to see if it is matching properly.
ASKER
here is the output for show policy-map and show queue...If I have the bandwidth set to 10400kb and I am reserving 2000kb where is the rest of my bandwidth going? Available bandwidth shows 5800kb.
Service-policy output: qospolicy
Class-map: voip (match-any)
247456 packets, 53050903 bytes
5 minute offered rate 386000 bps, drop rate 0 bps
Match: dscp ef
234151 packets, 50090374 bytes
5 minute rate 377000 bps
Match: dscp cs5
219 packets, 111892 bytes
5 minute rate 0 bps
Match: precedence 5
0 packets, 0 bytes
5 minute rate 0 bps
Match: dscp cs3
12713 packets, 2590342 bytes
5 minute rate 2000 bps
Match: dscp af31
373 packets, 258295 bytes
5 minute rate 1000 bps
Match: precedence 3
0 packets, 0 bytes
5 minute rate 0 bps
Queueing
Strict Priority
Output Queue: Conversation 264
Bandwidth 2000 (kbps) Burst 50000 (Bytes)
(pkts matched/bytes matched) 1/404
(total drops/bytes drops) 0/0
Class-map: class-default (match-any)
693368 packets, 210938567 bytes
5 minute offered rate 1368000 bps, drop rate 0 bps
Match: any
Queueing
Flow Based Fair Queueing
Maximum Number of Hashed Queues 256
(total queued/total drops/no-buffer drops) 0/0/0
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: Class-based queueing
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/1/256 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
Available Bandwidth 5800 kilobits/sec
The rest will go to the class-default. Your packets are being matched and forwarded appropriately. So this is for voice traffic? You should be able to use less matching, do you know what the packets are actually marked with?
What issues are you having exactly?
What issues are you having exactly?
ASKER
That is why I asked the last question on there...
If I specify to match dcsp cs5 in my class-map is it necessary to also match dscp ef or precedence 5? Or is cs5 an all inclusive kind of thing?
I have audible packet loss on calls but I will get it figured out in time as I am just now getting the QoS policy put in place on our network and until I get all of my equipment tagging the packets its hard to say where its coming from.
If I specify to match dcsp cs5 in my class-map is it necessary to also match dscp ef or precedence 5? Or is cs5 an all inclusive kind of thing?
I have audible packet loss on calls but I will get it figured out in time as I am just now getting the QoS policy put in place on our network and until I get all of my equipment tagging the packets its hard to say where its coming from.
What kind of router are you running this policy on? You could also match based on protocol, like SIP or H323, or even RTP. This might be beneficial, instead of trying to mark everything.
You should only need to match ef, that should be the marking your phones are using. Here's my QoS policy:
class-map match-any PRIORITY
description This is all the traffic that gets priority.
match protocol sip
match protocol rtcp
match protocol rtp audio
match protocol skinny
match protocol skype
match protocol dns
!
policy-map QoS_OUT
class PRIORITY
priority 200
You should only need to match ef, that should be the marking your phones are using. Here's my QoS policy:
class-map match-any PRIORITY
description This is all the traffic that gets priority.
match protocol sip
match protocol rtcp
match protocol rtp audio
match protocol skinny
match protocol skype
match protocol dns
!
policy-map QoS_OUT
class PRIORITY
priority 200
ASKER
thanks for the help
ASKER