DiffServ Support in MPLS Networks

1
DiffServ Support in MPLS Networks

• References
• Juniper white paper
• Supporting Differentiated Service Classes
  Multiprotocol Label Switching (MPLS)
• IETF RFC3270
• Multiprotocol Label Switching (MPLS) Support of
  Differentiated Services

2
DiffServ Enabled MPLS

• DiffServ traffic now follows an LSP directed path
  rather than connectionless IP paths
• More predictable in terms of resource consumption
  and less over provisioning
• Resources associated with an LSP can be reserved
  to provide highly predictable services

3
DiffServ Enabled MPLS

• Two types of DiffServ enabled LSPs
• EXP Inferred LSP (E-LSP) the class information
  is in the EXP sub-field of the MPLS shim header
• Label only inferred LSP (L-LSP) the class
  information is implied by the label value

4
DiffServ Enabled MPLS

• An example of an E-LSP

5
DiffServ Enabled MPLS

• An example of an E-LSP

6
DiffServ Enabled MPLS

• Benefits of E-LSP
• The operation of DiffServ over MPLS using E-LSPs
  is similar to the operation of DiffServ over
  native IP packets in the core.
• Assuming a default PHB-to-EXP mapping, E-LSPs are
  supported by existing signaling and label
  distribution protocols without modification
• Reducing the total number of LSPs
• Limitations of E-LSP
• When an existing E-LSP is preempted, all service
  classes are preempted
• Traffic engineering at aggregate level not per
  class level
• Limited to 8 classes

7
DiffServ Enabled MPLS

• An example of L-LSPs

8
DiffServ Enabled MPLS

• Benefits of L-LSP
• Better capability in supporting guaranteed
  services
• Allowing per class based traffic engineering
• Allowing LSP established across an ATM network
• May support more than 8 classes
• Limitations of L-LSP
• Dynamic creating of an L-LSP is not supported by
  the existing label distribution protocols
• Manual configuration can be complex and time
  consuming
• Adding complexity to network management to
  support higher number of LSPs