Short Pipe Mode - Cisco 7604 Configuration Manual

MPLS DiffServ Tunneling Modes
MPLS DiffServ Tunneling Modes
Tunneling provides QoS the ability to be transparent from one edge of a network to the other edge of the
network. A tunnel starts where there is label imposition. A tunnel ends where there is label disposition;
that is, where the label is removed from the stack, and the packet goes out as an MPLS packet with a
different per-hop behavior (PHB) layer underneath or as an IP packet with the IP PHB layer.
For the PFC3BXL or PFC3B, there are two ways to forward packets through a network:
•
•
Both tunneling modes affect the behavior of edge and penultimate label switching routers (LSRs) where
labels are put onto packets and removed from packets. They do not affect label swapping at intermediate
routers. A service provider can choose different types of tunneling modes for each customer.
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

Short pipe mode is used when the customer and service provider are in different DiffServ domains. It
allows the service provider to enforce its own DiffServ policy while preserving customer DiffServ
information, which provides a DiffServ transparency through the service provider network.
QoS policies implemented in the core do not propagate to the packet ToS byte. The classification based
on MPLS EXP value ends at the customer-facing egress PE interface; classification at the
customer-facing egress PE interface is based on the original IP packet header and not the MPLS header.
The presence of an egress IP policy (based on the customer's PHB marking and not on the provider's
Note
PHB marking) automatically implies the Short Pipe mode.
Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
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Short Pipe mode—In Short Pipe mode, the egress PE router uses the original packet marking instead
of the marking used by the intermediate provider (P) routers. EXP marking does not propagate to
the packet ToS byte.
For a description of this mode, see the
For the configuration information, see the
Uniform mode—In Uniform mode, the marking in the IP packet may be manipulated to reflect the
service provider's QoS marking in the core. This mode provides consistent QoS classification and
marking throughout the network including CE and core routers. EXP marking is propagated to the
underlying ToS byte.
For a description, see the "Uniform Mode" section on page
For the configuration procedure, see the
Chapter 42 Configuring PFC3BXL or PFC3B Mode MPLS QoS
"Short Pipe Mode" section on page
"Configuring Short Pipe Mode" section on page
42-33.
"Configuring Uniform Mode" section on page
42-32.
42-35.
42-40.
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