Circuit Emulation Over Transport BOF (ceot)
Tuesday, December 12 at 1700-1800
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CHAIRS: Luca Martini <luca@level3.net>
Chris Liljenstolpe <chris@cw.net>
DESCRIPTION:
SPs are focused on providing services for customer transport of layer
1 and layer 2 (bit-based and frame-based) payloads over a unified
infrastructure. These services, often referred to as transparent
transport, includes the transport of Ethernet, ATM and Frame Relay as
well as methods for transporting time division multiplexed (TDM)
digital signals (SONET circuit emulation) over a packet-oriented
network.
The Objectives of this BOF are :
Present some problems to be solved: Layer 1/2 Circuit emulation service,
and Legacy core circuit transport across new transport technologies.
Assess the viability of of pursuing standardization work within the
IETF.
Discuss , and obtain agreement on the two proposed WG charter.
READING MATERIAL:
draft-martini-l2circuit-trans-mpls-04.txt
draft-kompella-mpls-l2vpn-02.txt
draft-stdenis-ms-over-mpls-00.txt
draft-malis-sonet-ces-mpls-01.txt
draft draft-white-sonet-format-rtp-00.txt
draft-boyle-sts-ip-00.txt
AGENDA:
* Agenda Bashing - co-Chairs ( 5 minutes )
* Legacy Circuit Emulation over transport. ( 10 minutes )
* Layer 2 VPNs service over transport. ( 10 minutes )
* CEOT Charter review ( 25 minutes )
* Where do we go from here. ( 10 minutes )
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Background
Service providers (SP) offering digital transport services are
seeking to unify transport of multiple services across a common
packet switched network. Examples of digital transport services
include transport of IP packets, Ethernet frames, ATM cells, Frame
Relay frames, and time division multiplexed (TDM) digital signals.
In the past this has been achieved by defining interworking functions
between each type of digital transport service and the transport
technology used in the packet switch network. The benefit to the
service provider is that all aspects of the service including quality
of service (QoS), encapsulation of protocol data units (PDU), and
management and control interworking function. The downside is that
this approach is often complex, time consuming, and costly to
implement.
An alternative approach is to use tunnels to transparently transport
digital services across a packet switched network. There are many
proprietary service specific implementations in the market that use
this approach. Under this approach no strict interworking function
is required between the digital transport service and the transport
technology used in the packet switch network. The packet switched
network can transparently transport PDUs for any service without
knowledge of the service being transported.
Transparent Transport
The basic idea behind transparent transport is to create "virtual
wires" across a packet switched network by encapsulating service-
specific Packet Data Units ( PDUs) arriving at an ingress logical
port and transporting them across a tunnel to an egress device. At
the egress device the encapsulation header is extracted and used to
determine the outgoing logical interface. The PDUs are then sent on
the egress logical interface.
From the customer perspective the virtual wire is perceived as an
unshared connection using the native digital service transport
format. The customer is not exposed to the underlying technology
used in the packet switched network. The service provider is able to
offer multiple services across a common packet network without
complex interworking functions.
Transparent transport requires the edge devices providing service
interfaces to use common service-specific techniques for
encapsulating PDUs, passing service status information, and
performing link monitoring across the tunnel.
Common Status and Control Plane
Some form of network control is required to create and manage tunnels
across the packet switched network and coordinate service-specific
information between the edge devices. This control may be provided
through a command line interface, a network management protocol, or a
dynamic signalling or routing protocol.
The protocols used for tunnel management depend on the type of packet
switch network deployed by the carrier. For example, LDP or RSVP-TE
may be used to create and manage tunnels across a packet switched
network based on MPLS.
New protocols or modifications to existing protocols are required to
coordinate service-specific information between edge devices. More
than one protocol may prove viable for coordinating service-specific
information. For example, BGP or LDP may be modified for this
purpose.
Purpose
The purpose of the BOF is to assess the viability of pursuing
standardization work within the IETF for these new transport
technologies. If this work is determined to be viable, a CEOT
working
groups is envisioned to carry out the process. The working group
will focus on development of a common status and control plane for
the end to end tunnel, and common techniques for encapsulating
service-specific PDUs. This BOF will focus on discussion of the
CEOT WG , and its requirements.
WG Preliminary Objectives
Specify statistics and other network management information needed
for tunnel operation. For example, to be able to determine when a
circuit's up/down state has changed.
Specify the mechanisms that are needed to distribute the end to end
setup information for the circuit being transported.
Specify the mechanisms that will service providers to extend the
emulated circuit to be transported across multiple service provider
networks ( NNI interface ).
Specify the security mechanisms to be used to protect the control of
the CEOT technology at the NNI interface.
Specify end to end circuit status signaling methods.
Specify methods for integrating end to end tunnel signaling
information, and diffserv information with the transporting network.
Specify methods to communicate timing across the transport network.