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MPLS to IP QOS tagging and MPLS tagging

Level 1
Level 1

I am trying to figure out how to make sure that packets that are supposed to be applied to QoS policies are being tagging going from the MPLS network to IP ( ie the cloud to the CPE).  I would also appreciate any guidance on how to implement mpls in the cloud.

The drawing is extremely rudimentary but it gives the general idea.

What is being seen now is the packet is tagged properly from the CPE in regards to the QoS policy but when it is being returned from the cloud it is not because the MPLS header is in the way.

Again, any help or guidance is appreciated.

Thank you.


6 Replies 6

Mahesh Gohil
Level 7
Level 7

Hello Lynne,

This kind of issue arise when there is no mapping between mpls exp and precedence/dscp.

Can you confirm whether "mls qos" (required) is globally enabled on our router.

Regarding mpls implementation...unfortunately i do not have visio and not able to open files shared by you.

If you can share some ppt will be helpful to guide you



Level 1
Level 1

Hello Lynne,

that depends on how's the provider network configured.

Is the provider supposed to support your QoS marking? Are they providing any guaranteed bandwidth for the different DSCPs?

As a rule of thumb, if you didn't pay for any Qos SLA, they'll simply mark down to 0 everything.

Check with them what they do with marked traffic and, if case they are supposed to honour the marking, open a case with them.

Hope it helps,


I looked to do a "sh mls qos" on a router running c7200-p-mz.124-21.bin" and I do not see it as an option.

sh mls ?
  rp  rp

XXXX#sh mls rp ?
  interface   fcp interface status and configuration
  ip          ip
  ipx         ipx
  vtp-domain  vtp-domain
  |           Output modifiers

If a router has it on would it be an option to run the "sh mls qos" command.

In my configuration I host the MPLS environment on our routers. i am not the carrier though for the circuits.    I will check with our carriers as to what they are doing.

I also want to set things up so the tags stay both within our mpls network and when they are sent out and back to IP to the customer.

I apologize in being so uneducated when it comes to this.  I am just starting to really learn about this aspect of QoS and how it works with MPLS to IP network.

Thank you.

I have added a word doc that shows a picture of the visio.

Thank you.

Hello ,

I am not clear as you are taking care of ce routers or the mpls cloud..anyway i am not sure whether mls wos is suppoted on

the ios you are running. If it is supported then it should support command also.

Anyway to run mpls on the diagram you provided is simple one.. below are few bullet piont.

Lets divide routers in below category

Pe(edge routers)--where ce are connected

P--unnamed routers in your diagram--core routers

> Run MPLS between Edge routers (where CE connected via. VRF) and P routers

> Run MP-BGP between edge routers

    > If you have decided to go for RR like structure..every PE will be meshaed to RR only. As per your diagram you have only

       Two edge routers so just run mp-bgp between these two PE routers

>Run mpls between core routers.

> Create vrf,address-family per customer at PE and redistribute connected routes in address-family..

  Additionally you can redistribute any static/dynamic protocol if you are running it between pe and ce routers.

Regarding qos tagging.

When packet enters mpls domain the ip packet's qos marking (from tos bits) will be copied by default to mpls exp bit if provider

is not overridding this on top label...and it will be available at egress PE if P routers are not overridding this behavior....

The same is copied back to ip packet (if exp is trusted via. mls qos and provider is not manipulating it)..Well this is a vast topic and there are

lot of details..

Hope this is helpful



Luc De Ghein
Cisco Employee
Cisco Employee

Hi Lynne,

Have a look at this link:

(The link is on VPN QOS design, but the same principles apply when there is no VPNs in the MPLS network.)

The section on "MPLS DiffServ Tunneling Modes" should be interesting to you.

It sounds to me that you'd like to implement the uniform mode, because you'd like to copy the value of the

EXP bits (now called the Traffic Class bits) into the DSCP of the IP header.