TMPLS Background

1
TMPLS Background

• Stewart Bryant
• stbryant_at_cisco.com

2
T-MPLS

• T-MPLS was liaised to IETF after it was consented
  by the ITU.
• Product of ITU-T SG15 Q12 - G.8110(.1), G.8112,
  G.8121, G.8131
• T-MPLS is essentially an Ethernet PW, running
  over MPLS PSN, running over Ethernet
• OAM is G.8114/Y.1373 a derivative of Y.1711,
  currently in AAP (restricted last call)
• Existing definition is statically - centrally -
  configured however ITU looking at developing a
  control plane
• Normative text is a complete re-definition of the
  protocol using specialist ITU language and formal
  notation.

3
TMPLS MPLS Disjoint?

• ITU SG15 experts claim that MPLS and T-MPLS will
  always be configured to be in disjoint layers in
  the network and that this is sufficient.
• Goal is to be able to transport T-MPLS on
  existing equipment via the use of MPLS codepoint.
  
• Disjoint layers claimed as TMPLS is "below MPLS"
• Claimed no need for different codepoint as no
  intentions for interoperability (However ITU
  interoperability contributions have been
  presented in SG15 )

4
IETF Concerns

• Liaison statements have been exchanged and
  various IAB/IESG/WG chairs have attended a number
  of ITU SG15 meetings in person expressing
  concerns about T-MPLS.
• IETF is concerned that T-MPLS, or a development
  of T-MPLS will break MPLS or an IETF development
  of MPLS.
• Issue is shared code point for different
  specification of the functionality and
  attributes. Excellent opportunity for collision.
• Experience tells us that initial limited
  functionality never remains limited.
• Massive interoperability issues could ensue
• Work plan includes incorporating new PW types
  that duplicate existing IETF PWE
• Further discussion will take place in PWE3 this
  afternoon.