02-25-2009 07:35 AM - edited 03-04-2019 03:42 AM
Hello Experts,
Need your inputs:
I have a Cisco 3825 runnnit IOS version:
c3825-spservicesk9-mz.124-12c.bin
configured with Gigabit ethernet 0/1 as the WAN interface. The configs are as follows:
class-map match-any Multimedia
match ip dscp ef
class-map match-any Interactive
match ip dscp cs3
match ip dscp af31
match ip dscp af32
match ip dscp af33
class-map match-any MissionCritical
match ip dscp cs4
match ip dscp af41
match ip dscp af42
match ip dscp af43
!
!
policy-map PrimaryQueues
class Multimedia
priority 1024
class MissionCritical
bandwidth 11008
random-detect dscp-based
class Interactive
bandwidth 256
random-detect dscp-based
class class-default
set dscp default
fair-queue
random-detect dscp-based
policy-map PrimaryQOSOUT
class class-default
shape average 16384000
service-policy PrimaryQueues
interface GigabitEthernet0/1
bandwidth 16384
ip address 192.168.93.14 255.255.255.252
ip nbar protocol-discovery
load-interval 30
duplex full
speed 100
media-type rj45
no keepalive
no cdp enable
service-policy output PrimaryQOSOUT
Will the configuration suffice for QoS or since i'm having gigabit ethernet as my WAN interface, I will need to tweak the transmit ring setting to ensure QoS kicks in. I thought the QoS will kick in once the traffic reaches 70% of 16Mb.
Thanks in advance.
02-25-2009 09:41 AM
Hello.
Your configuration looks good and should work. You should not need to change your hardware queue as when you configure the service-policy on the interface the router automatically shortens it. You can check with the command below
R1#show controllers s2/0
â¦â¦â¦â¦â¦â¦â¦â¦â¦â¦â¦â¦â¦â¦..
tx_underrun_err=0, tx_soft_underrun_err=0, tx_limited=0(16)
QoS kicks in as soon as the hardware queue is full. At other times with no congestion QoS doesn't do anything as it doesn't need to.
Only other thing I would like to mention is that you haven't given your class-default a bandwidth setting. This means that your class-default won't get the rest of the bandwidth, instead the un-allocated bandwidth will be shared amoungst the other queues. So, one might think that the class-default might get 4MB but you'll find that bandwidth will be shared out so the class-default in times of congestion might only get 1MB.
Simon
02-25-2009 10:23 AM
"Only other thing I would like to mention is that you haven't given your class-default a bandwidth setting."
If you refer to the child policy's class-default, it's using FQ for which, on most platforms and most router IOSs, you can't configure bandwidth unless you don't want FQ.
02-25-2009 10:15 AM
"Will the configuration suffice for QoS or since i'm having gigabit ethernet as my WAN interface . . ."
Can't say, not enough information.
". . . I will need to tweak the transmit ring setting to ensure QoS kicks in."
You may although don't see any tunning on the gig interface.
"I thought the QoS will kick in once the traffic reaches 70% of 16Mb."
Why do you think that? QoS should kick in when shaper delays packets. When shaper delays packets depends much on Bc and Tc not just bandwidth.
PS:
When working with WAN Ethernet, you might need to set shaper slower than nomimal bandwidth if you need to account for L2 overhead.
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