Uniform Mode - Cisco WS-SUP32-GE-3B - Supervisor Engine 32 Software Configuration Manual

MPLS DiffServ Tunneling Modes
Figure 39-2
DSCP
Short Pipe mode functions as follows:
1.
2.
3.
4.
5.
6.
7.
8.
9.
For additional information, see "MPLS DiffServ Tunneling Modes" at this URL:
http://www.cisco.com/en/US/docs/ios/12_2t/12_2t13/feature/guide/ftdtmode.html
Short Pipe Mode Restrictions and Guidelines
The following restriction applies to Short Pipe mode:
•

Uniform Mode

In Uniform mode, packets are treated uniformly in the IP and MPLS networks; that is, the IP precedence
value and the MPLS EXP bits always correspond to the same PHB. Whenever a router changes or
recolors the PHB of a packet, that change must be propagated to all encapsulation markings. The
propagation is performed by a router only when a PHB is added or exposed due to label imposition or
Catalyst Supervisor Engine 32 PISA Cisco IOS Software Configuration Guide, Release 12.2ZY
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Short Pipe Mode Operation with VPNs
PE1
CE1
MPLS
EXP 5
MPLS
EXP 5
DSCP
1 1
1 2 3
CE1 transmits an IP packet to PE1 with an IP DSCP value of 1.
PE1 sets the MPLS EXP field to 5 in the imposed label entries.
PE1 transmits the packet to P1.
P1 sets the MPLS EXP field value to 5 in the swapped label entry.
P1 transmits the packet to P2.
P2 pops the IGP label entry.
P2 transmits the packet to PE2.
PE2 pops the BGP label.
PE2 transmits the packet to CE2, but does QoS based on the IP DSCP value.
Short Pipe mode is not supported if the MPLS-to-IP egress interface is EoMPLS (the adjacency has
the end of marker (EOM) bit set).
P1 P2
MPLS
EXP 5
MPLS MPLS
EXP 5 EXP 5
DSCP DSCP
1 1
4 5 6 7
Chapter 39 Configuring MPLS QoS
PE2
CE2
DSCP DSCP
1 1
8 9
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