Enterprise QoS Solution Reference Network Design Guide
Enterprise QoS Solution Reference Network Design Guide
Enterprise QoS Solution Reference Network Design Guide
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Chapter 5 MPLS VPN <strong>QoS</strong> <strong>Design</strong><br />
Version 3.3<br />
Provider-Edge <strong>QoS</strong> Considerations<br />
bandwidth percent 15 ! Video class gets 15% CBWFQ<br />
class QOSGROUP1<br />
bandwidth percent 5 ! Bulk class gets 5% CBWFQ<br />
random-detect discard-class-based ! DC-Based WRED is enabled<br />
random-detect discard-class 0 30 40 10 ! DC 0 is tuned for WRED<br />
random-detect discard-class 1 20 40 10 ! DC 1 is tuned for WRED<br />
class QOSGROUP0<br />
bandwidth percent 25 ! Best Effort class gets 25% CBWFQ<br />
random-detect discard-class-based ! DC-Based WRED is enabled<br />
random-detect discard-class 0 30 40 10 ! DC 0 is tuned for WRED<br />
random-detect discard-class 1 20 40 10 ! DC 1 is tuned for WRED<br />
!<br />
!<br />
policy-map PE-CE-SHAPING-QUEUING ! Customer has 3 Mbps CIR over FE<br />
class class-default<br />
shape average 3000000 ! Shaping policy for 3 Mbps CIR<br />
service-policy PE-CE-QUEUING ! Nested queuing policy<br />
!<br />
interface ATM2/0<br />
no ip address<br />
no atm ilmi-keepalive<br />
!<br />
interface ATM2/0.1 point-to-point<br />
description ATM-OC3 TO MPLS VPN CORE ! Link to/from MPLS VPN Core<br />
ip address 20.2.34.4 255.255.255.0<br />
pvc 0/304<br />
vbr-nrt 149760 149760<br />
service-policy input MPLSEXP-QOSGROUP-DISCARDCLASS ! MPLS EXP to QG/DC<br />
!<br />
tag-switching ip<br />
!<br />
!<br />
interface FastEthernet1/0<br />
description FE TO CUSTOMER RED CE ! Link to/from CE<br />
ip vrf forwarding RED<br />
ip address 10.1.12.2 255.255.255.0<br />
service-policy input PIPE-MARKING ! Pipe marking policy<br />
service-policy output PE-CE-SHAPING-QUEUING ! Shaping/Queuing policy<br />
!<br />
Verification commands:<br />
Pipe Mode with an Explicit Null LSP<br />
show policy<br />
show policy interface<br />
When CEs are provider managed, some providers prefer to offload the ingress MPLS EXP marking of<br />
customer traffic from the PE and push these policies out to the ingress interface of the CE. However,<br />
because the CE-to-PE link is regular IP (not MPLS), a difficulty arises as to how to set the provider’s<br />
marking without affecting the IP DiffServ markings that the customer has set (because, again, these are<br />
to be preserved and untouched through the MPLS VPN cloud in Pipe Mode operation). Therefore, a<br />
solution to this scenario was introduced in Cisco IOS Release 12.2(13)T, with the Pipe Mode MPLS<br />
DiffServ tunneling with an Explicit Null LSP feature.<br />
This feature prepends an Explicit Null LSP label for customer traffic headed from the CE to the PE. This<br />
label is not used for MPLS switching; it is used only to preserve the provider’s MPLS EXP markings<br />
over the CE-to-PE link. On the PE, the MPLS EXP values are copied to regular MPLS labels that are<br />
pushed onto the packet (which are used for MPLS switching), and the explicit null label is discarded.<br />
<strong>Enterprise</strong> <strong>QoS</strong> <strong>Solution</strong> <strong>Reference</strong> <strong>Network</strong> <strong>Design</strong> <strong>Guide</strong><br />
5-29
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