From: Stefaan Vander Rasieren (svanderr@cisco.com)
Date: Mon Feb 26 2007 - 10:25:06 ART
Luca,
The reason is because the subinterface simply does not know when the
queueing should kick in. When you apply queueing on a main interface,
then it is the transmit ring (final fifo queue before sending the packet
on the wire) which will signal IOS that it is full, i.e. that the
interface is congested, and that the configured queuing strategy should
kick in.
A subinterface does not get this kind of feedback from the transmit ring
of the main interface it belongs to. Therefore, one needs to create an
artificial backpressure mechanism which will tell the subinterface when
its differentiated queueing needs to kick in. The only way to do this,
is with traffic shaping. Traffic shaping will tell how much bandwidth
is available, and will provide some buffering in case the traffic
exceeds the configured CIR.
So your statement is not 100% complete, saying that you need a parent
and child policy-map for queueing to work on a subinterface. The parent
policy should also shape in a class (e.g. class-default) and then you
can apply a child polciy with queueing in this shaped class.
Hope it makes some sense,
Stef
Bit Gossip wrote:
> Thank you for the article, it is very interesting.
>
> But the logic is really very contorted .....
>
> Subinterfaces in general dont support queueing
> but if the queue is applied via a child policy attached to a parent
> policy which is in turn attached to a subinterface, then it works
>
> Why are things so complex :-(
>
> Luca.
>
>
> On Mon, 2007-01-29 at 02:20, Victor Cappuccio wrote:
>
>> If you want to do it using New Style IOS MQC :D
>> then look here:
>> http://www.cisco.com/warp/public/105/qos_subint.html
>> it says that:
>>
>> Cisco IOS logical interfaces do not inherently support a state of congestion and do not support the direct application of a service policy that applies a queueing method. Instead, you first need to apply shaping to the subinterface using either generic traffic shaping (GTS) or class-based shaping.
>>
>> Configuration Steps:
>>
>> Applying a Hierarchical Policy
>>
>> Follow these steps to apply a hierarchical policy:
>>
>> 1.
>>
>> Create a child or lower-level policy that configures a queueing mechanism. In the example below, we configure LLQ using the priority command and CBWFQ using the bandwidth command. Refer to Congestion Management Overview for more information.
>>
>> policy-map child
>> class voice
>> priority 512
>>
>> 2.
>>
>> Create a parent or top-level policy that applies class-based shaping. Apply the child policy as a command under the parent policy since the admission control for the child class is done based on the shaping rate for the parent class.
>>
>> policy-map parent
>> class class-default
>> shape average 2000000
>> service-policy child
>>
>> 3.
>>
>> Apply the parent policy to the subinterface.
>>
>> interface ethernet0/0.1
>> service-policy parent
>>
>>
>> R3 S0.23 --- Fr -- R2
>>
>> R3(config)#class-map voice
>> R3(config-cmap)#ma ip dscp ef
>> R3(config-cmap)#exit
>>
>> R3(config)#policy-map child
>> R3(config-pmap)#class voice
>> R3(config-pmap-c)#priority 512
>> R3(config-pmap-c)#
>> R3(config-pmap-c)#policy-map parent
>> R3(config-pmap)#class class-default
>> R3(config-pmap-c)#shape average 512000
>> R3(config-pmap-c)#service-policy child
>>
>>
>> R3(config-pmap-c)#int s0.23
>> R3(config-subif)#ser out parent
>> R3(config-subif)#do show frame-relay map
>> Serial0.23 (up): point-to-point dlci, dlci 302(0x12E,0x48E0), broadcast
>> status defined, active
>> R3(config-subif)#do show policy-map inter s0.23
>>
>> Serial0.23
>>
>> Service-policy output: parent
>>
>> Class-map: class-default (match-any)
>> 0 packets, 0 bytes
>> 5 minute offered rate 0 bps, drop rate 0 bps
>> Match: any
>> Traffic Shaping
>> Target/Average Byte Sustain Excess Interval Increment
>> Rate Limit bits/int bits/int (ms) (bytes)
>> 2000000/2000000 12500 50000 50000 25 6250
>>
>> Adapt Queue Packets Bytes Packets Bytes Shaping
>> Active Depth Delayed Delayed Active
>> - 0 0 0 0 0 no
>>
>> Service-policy : child
>>
>> Class-map: voice (match-all)
>> 0 packets, 0 bytes
>> 5 minute offered rate 0 bps, drop rate 0 bps
>> Match: ip dscp ef
>> Queueing
>> Strict Priority
>> Output Queue: Conversation 72
>> Bandwidth 512 (kbps) Burst 12800 (Bytes)
>> (pkts matched/bytes matched) 0/0
>> (total drops/bytes drops) 0/0
>>
>> Class-map: class-default (match-any)
>> 0 packets, 0 bytes
>> 5 minute offered rate 0 bps, drop rate 0 bps
>> Match: any
>> R3(config-subif)#
>> R3(config-subif)#do show frame-relay pvc 302
>>
>> PVC Statistics for interface Serial0 (Frame Relay DTE)
>>
>> DLCI = 302, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial0.23
>>
>> input pkts 163269 output pkts 119204 in bytes 14618202
>> out bytes 12180126 dropped pkts 0 in pkts dropped 0
>> out pkts dropped 0 out bytes dropped 0
>> in FECN pkts 0 in BECN pkts 0 out FECN pkts 0
>> out BECN pkts 0 in DE pkts 0 out DE pkts 0
>> out bcast pkts 85659 out bcast bytes 10166564
>> 5 minute input rate 0 bits/sec, 0 packets/sec
>> 5 minute output rate 0 bits/sec, 0 packets/sec
>> pvc create time 1w1d, last time pvc status changed 1w1d
>>
>> I found this link for Subinterface http://www.cisco.com/warp/public/63/idb_limit.html
>>
>> Verification:
>>
>>
>> R3(config-pmap-c)#do ping
>> Protocol [ip]:
>> Target IP address: 192.168.23.2
>> Repeat count [5]: 1486
>> Datagram size [100]: 100
>> Timeout in seconds [2]: 0
>> Extended commands [n]: y
>> Source address or interface:
>> Type of service [0]: 0Xb8 !! SET EF BIT
>> Set DF bit in IP header? [no]:
>> Validate reply data? [no]:
>> Data pattern [0xABCD]:
>> Loose, Strict, Record, Timestamp, Verbose[none]:
>> Sweep range of sizes [n]:
>> Type escape sequence to abort.
>> Sending 512000, 100-byte ICMP Echos to 192.168.23.2, timeout is 0 seconds:
>> ......................................................................
>> ......................................................................
>> ......................................................................
>> ......................................................................
>> ......................................................................
>> ......................................................................
>> ......................................................................
>> ......................................................................
>> ......................................................................
>> ......................................................................
>> ......................................................................
>> ......................................................................
>> ......................................................................
>> ......................................................................
>> ......................................................................
>> ......................................................................
>> ......................................................................
>> ......................................................................
>> Success rate is 0 percent (0/1486)
>> R3(config-pmap-c)#do show policy-map int s0.23
>>
>> Serial0.23
>>
>> Service-policy output: parent
>>
>> Class-map: class-default (match-any)
>> 1518 packets, 159496 bytes
>> 5 minute offered rate 4000 bps, drop rate 0 bps
>> Match: any
>> Traffic Shaping
>> Target/Average Byte Sustain Excess Interval Increment
>> Rate Limit bits/int bits/int (ms) (bytes)
>> 512000/512000 3200 12800 12800 25 1600
>>
>> Adapt Queue Packets Bytes Packets Bytes Shaping
>> Active Depth Delayed Delayed Active
>> - 0 1518 159496 0 0 no
>>
>> Service-policy : child
>>
>> Class-map: voice (match-all)
>> 1486 packets, 154544 bytes <<<<<<<<<<<<<<<<<<<<<<<<<<< See there?
>> 5 minute offered rate 4000 bps, drop rate 0 bps
>> Match: ip dscp ef
>> Queueing
>> Strict Priority
>> Output Queue: Conversation 72
>> Bandwidth 512 (kbps) Burst 12800 (Bytes)
>> (pkts matched/bytes matched) 0/0
>> (total drops/bytes drops) 0/0
>>
>> Class-map: class-default (match-any)
>> 32 packets, 4952 bytes
>> 5 minute offered rate 0 bps, drop rate 0 bps
>> Match: any
>> R3(config-pmap-c)#
>>
>>
>>
>> -----Mensaje original-----
>> De: nobody@groupstudy.com en nombre de Edison Ortiz
>> Enviado el: dom 28/01/2007 13:51
>> Para: Bit Gossip
>> CC: ccielab
>> Asunto: Re: policing and wfq with mqc
>>
>> There are 2 ways:
>>
>> 1) show frame pvc 221
>>
>> 2) show policy-map interface
>>
>> On 1/28/07, Bit Gossip <bit.gossip@chello.nl> wrote:
>>
>>> My task requires to configure a certain service-policy to do policing
>>> and wfq between r2 and r1 which are connected via a fr pvc attached to a
>>> serial interface s4/0.221.
>>> I have found 2 approches; are they both correct?
>>> For the second one I dont know how to show and monitor the
>>> service-policy!
>>> BTW: it is not possible to attach the service-policy to the sub-if
>>> because wfq is not supported for sub-if
>>> Thanks,
>>> Luca.
>>>
>>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>
>>> - attach the policy to s4/0
>>>
>>> interface Serial4/0
>>> service-policy output S6
>>> ...
>>>
>>>
>>> in this case I can easily show the effect and monitor the counters:
>>>
>>>
>>> r2#show policy-map int s4/0
>>>
>>> Serial4/0
>>>
>>> Service-policy output: S6
>>>
>>> Class-map: S6-2 (match-all)
>>> 0 packets, 0 bytes
>>> 30 second offered rate 0 bps, drop rate 0 bps
>>> Match: access-group name S6-2
>>> police:
>>>
>>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>>
>>> - attach the policy to dlci 221
>>>
>>> interface Serial4/0
>>> bandwidth 115200
>>> no ip address
>>> encapsulation frame-relay
>>> load-interval 30
>>> serial restart-delay 0
>>> no frame-relay inverse-arp
>>> !
>>> interface Serial4/0.221 point-to-point
>>> bandwidth 64
>>> ip address 10.1.122.2 255.255.255.0
>>> frame-relay interface-dlci 221
>>> class S6
>>>
>>> map-class frame-relay S6
>>> service-policy output S6
>>>
>>>
>>> But in this case I dont know how to monitor it?
>>> r2# show policy-map interface s4/0
>>>
>>> r2#
>>>
>>> _______________________________________________________________________
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>>>
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>
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