MPLS & CoS

[marshyrob]

Can any help with a MPLS CoS configuration that i need to understand as im a little new to all this.

We currently have a LAN configured to trust DSCP for IPT and have all the CoS setup correctly (so ive been told) on all the switchports that provide IPT. We have the uplinks to the WAN routers configured with the same trust commands as the swtich ports.

I need to understand if we need to make any changes to our routers that peer with the BT routers to pass "marked packets" to it. We have not configured anything on the routers themselves jsut the LAN. Im just a bit concerned that we wont be utilising the CoS in the MPLS cloud because we are not passing the marked packets onto the BT routers because of a configuration issue our end. Or does the router keep the markings on the packets by default?

Can anyone shed any light on this?

Thanks

 

[plshlpme]

if you dont have any policy's/route maps/rate-limits on the router then it will not strip the cos values and the bt routers will route them properly.

now does BT provide and manage a CE edge device for you?
because if so they will have an outbound policy map set that should be set up based on what you originally requested from them...

 

[marshyrob]

hi plshlpme

Thanks for the reply i appreciate it.

We manage our own CE router and they obviously manage the PE, we have a 2mb Serial connection to the PE.

We do however have a policy map on that outbound connection relating to other applications, so im presuming its going to adhere to that map.

The map allows certain traffic percentages of bandwidth via policing it. All GOLD data has 60% bandwidth, this is where the telephony traffic would fall into, so will this change the CoS settings/markings?

Thanks in advance

Rob

 

[plshlpme]

do you have some sort of route map on the router to convert your cos values to the dscp values that BT uses?

you will have to work with them on this one most likely..

i have ces with BT as well and we use precedence on the lan and wan.. this was set up ahead of time and BT builds their policy accordinly.

we use prec 5 for voice and we use llq for the voice class to ensure its prioritized.

you may just want to give them a call and ask them if they see packets incrementing on the nrt (voice) class and if not ask for a copy of their policy so that you can ensure your sending them what they want...