Vaibhava Varma Sun, 05/16/2010 - 08:17
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Hi There


Can you give a little more description of your exact requirements ?


I think If the requirement is for the SP not to intervene then Short Pipe Mode Deployment within SP Core will conform to CE Domain QoS as the Egress Edge Scheduling /Discard is based on the DSCP value of the IP Packet receivd at the Ingress as its unchanged during the MPLS2IP translation.


But still inside SP Network the Packet will be treated according to the IP DSCP/MPLS EXP Translation happeing in the IP2MPLS transformation of the Packet received at the Ingress. So from my understanding what we can control is at the Ingress by sending the packets marked with our choice of IPP/DSCP and then let SP impose the EXP during the IP2MPLS translation based on CE DSCP Value in the IP Packet.


Regards

Vaibhava Varma

Just Kennie Sun, 05/16/2010 - 09:23
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Thanks Varma,


   Got some clue from what you sence, but I still need to clearify, are u saying after marking mi packet wit DSCP value, I still have to rely on the SP to inpose the EXP bit during the IP to MPLS translation, is there no way around this ?????

Also, can you paste a detailed and comprehensive link for me to read it up

  Thanks man.

Vaibhava Varma Sun, 05/16/2010 - 09:48
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Hi Kenni


Yes we have to rely on ISP as it has the control during IP2MPLS condition for the EXP imposition and  from my understanding there is no way around this as during IP2MPLS Transition there are two choices on EXP Impostion during IP2MPLS condition


1. Automatically the IPP(0-7) of Packet is mapped  to EXP (0-7) on both the bottom and top label if there is no explicit marking and classification happening on the Ingress PE-CE Link.


2..We need to specifiy to SP that we want a particular QoS Treatement for your VPN Traffic despite of the Ingress IPP and in that

case SP will manually set the EXP matching your requirements by doing a match any on the Ingress PE-CE Link but again that invloves SP. This is a more like a Virtual Leased Line Services concept for Layer 2 VPNs whereby all your VPN traffic is carried with a particular QoS treatment end to end in SP Core.


Sorry but I do not havre any links as such but you can read "MPLS Configuration on Cisco IOS Softwares "Book by Lancy Lobo and Umesh Lakshman. I find it good on explaining things.


Regards

Vaibhava Varma

Just Kennie Sun, 05/16/2010 - 10:20
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Thanks once again Varma,

  Getting better now, I want to review your two scenerios.

1.1. Automatically the IPP(0-7) of Packet is mapped  to EXP (0-7) on both  the bottom and top label if there is no explicit marking and  classification happening on the Ingress PE-CE Link.


---> Since IPP is automatically mapped to EXP during the translation, can I simply do the classification and marking from my side, and instruct the SP to leave my traffic the way it is, will this suffice ???

2..We need to specifiy to SP that we want a particular QoS Treatement  for your VPN Traffic despite of the Ingress IPP and in that

case  SP will manually set the EXP matching your requirements by doing a match  any on the Ingress PE-CE Link but again that invloves SP. This is a  more like a Virtual Leased Line Services concept for Layer 2 VPNs  whereby all your VPN traffic is carried with a particular QoS treatment  end to end in SP Core.

------> Here are looking at three areas the traffic will tranverse. CE to PE, PE to PE, and PE to CE.

    Will the QoS treatment done by the SP through their PE to PE still carry on to PE to CE (as IPP), please explain the diff QoS on each path and whose responsibility....me or SP?

Vaibhava Varma Sun, 05/16/2010 - 11:55
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Hi Kenni


As you said there are 3 Sections to look at for QoS as packet traverses from Ingress to Egress. At the Ingress ISP can rely on automatic EXP impostion/Manual Impostion.If its Automatic then its CE Responsibility,but if ISP is setting it up manually its his responsibility.Within the Core its all SPs responsibility and it has no changes on the IPP/DSCP of packet, the QoS within ISP Core is based on EXP. At the Egress there are different options available and its SP responsibility. SP QoS is classified into 3 different QoS Schemes.


The IPP/DSCP of the packet is always preserved across the SP Core and its at the Egress the fate of IPP/DSCP is decided based upon the QoS Scheme SP is using.


SPs offer QoS in 3 ways:


Unfiorm Mode - The Scheduling/Discard behaviuor at the Egress PE-CE Link is based on EXP (of the packet arriving at its Ingress Core Link on the Egress PE router) and hence the IPP/DSCP will not be preserved in this case (same as of the original packet at the Ingress) becuase SP sets it manually to macth the EXP received so the scheduling/discard behaviour can be appropriately applied. Here the SP and CE are 2 different QoS domains and SP is extending its QoS Domian till CE and most common for SP Managed CE VPN setups.


Short Pipe Mode - The Scheduling/Discard behaviuor at the Egress PE-CE Link is based on the original DSCP of the packet. Here the IPP/DSCP is preserved in this case( same as of the original packet at the Ingress). This mode is the one which conforms to CE Domain QoS as at ISP Egress Packets get Treatment according to their IPP/DSCP the same way as a CE Router will do.


Long Pipe Mode (Pipe commonly) -The Scheduling/Discard behaviuor at the Egress PE-CE Link is based upon the EXP of the packet arriving at its Ingress Core Link on the Egress PE router,. Here also the IPP/DSCP is preserved in this case (same as of the original packet at the Ingress )but at ISP Egress Packets get Treatment according to their EXP the same way an ISP will do in its core . This is suitable for Carrier Supporting Career scenario.wherein one ISP serves another ISP as Customer.


The answer to both of your questions from my understanding is SP Short Pipe Mode wherein CE Domain QoS is preserved at the ISP Egress Edge PE-CE Link. Remember that whatever is happeing in the SP Core is not relevant to IPP/DSCP except Uniform Mode. The IPP/DSCP is always preserved except Unform Mode and Customer can always tell the SP what is their QoS requirement to get the required solution.


Regards

Vaibhava Varma

Just Kennie Sun, 05/16/2010 - 12:57
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Varma,

   Thanks so much. You made my day.

  As  you said. I think what I need is the shorp pipe mode. But as the customer now, how do I get make the SP adopt the mode for me? What needs to be done in terms of hardware, infrastructure and configuration ??? How do I know I am truly on that mode.

Vaibhava Varma Sun, 05/16/2010 - 14:15
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Hi Kennie



Glad to hear that its helpful for you.SPs have their core already provisioned for these different QoS Services they offer to their Customers and all need to be done as a Customer is just ask the SP to provision your VPN with your QoS requirements and they will come up with that. SPs core is pre-provisioned . All it will take is to provision the PE-CE Link for the VRF to be configured with right QoS maps.


SPs also understand when the Customer goes and asks them for QoS and if its not managed CPE solution, Short Pipe Mode is the default choice.

This will help checking with SP for your QoS requirements.Generally QoS is provided as CAR(Commited Access Rate) values in Kbps/Mbps mixed with the different SLA levels for Packet Drops and Delay.


For verifying that the right QoS is applied is a tough question from Customer Standpoint of view as mostly the QoS Logic comes from SP end.  But here are a couple we can do.


1. During congestion no traffic should drop for Priority Class Traffic such as Voice.

2. Do an extneded ping between two CEs with the ToS bits set to match the different class of traffic and verify using Policy Maps that we are receiving the same IPP/DSCP as we sent from site to another. This surely confirms our IPP /DSCP is preserved and its not Unform Mode.

3. Can ask SP to provide us their PE-CE QoS config and look at the Egress QoS config there.


For a Customer Hardware should be fine for any Cisco ISR for CE, IPVoice IOS as most enterprise are adopting to VoIP and thats the Prima for QoS,.

Configurations from CE standpoint will be to create Class Maps and Policy Maps(with appropriate Scheduling/Discard  as per the requirements) and applying it to CE-PE Link.


I think you can easily get reference from some good books dealing in QoS who will help you with the detailed configurations. Not remembering any right now but Googling it and should give good pointers.


Hope it helps you !


Regards

Vaibhava Varma

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