Generalized MPLS(GMPLS)
Generalized MPLS
a. What is "Generalized MPLS" or "GMPLS"
From "Generalized Multi-Protocol Label Switching Architecture" "Generalized MPLS extends MPLS to encompass time-division (e.g. SONET ADMs), wavelength (optical lambdas) and spatial switching (e.g. incoming port or fiber to outgoing port or fiber)."
GMPLS represents a natural extension of MPLS to allow MPLS to be used as the control mechanism for configuring not only packet-based paths, but also paths in non-packet based devices such as optical switches, TDM muxes, and SONET/ADMs.
For an overview of GMPLS, see Generalized Multiprotocol Label Switching: An Overview of Routing and Management Enhancements
b. What are the components of GMPLS?
GMPLS introduces a new protocol called the "Link Management Protocol" or LMP. LMP runs between adjacent nodes and is responsible for establishing control channel connectivity as well as failure detection. LMP also verifies connectivity between channels.
Additionally, the IETF's "Common Control and Measurement Plane" working group (ccamp) is working on defining extensions to interior gateway routing protocols such as OSPF and IS-IS to enable them to support GMPLS operation.
c. What are the features of GMPLS?
GMPLS supports several features including:
Link Bundling - the grouping of multiple, independent physical links into a single logical link
Link Hierarchy - the issuing of a suite of labels to support the various requirements of physical and logical devices across a given path
Unnumbered Links - the ability to configure paths without requiring an IP address on every physical or logical interface
Constraint Based Routing - the ability to automatically provision additional bandwidth, or change forwarding behavior based on network conditions such as congestion or demands for additional bandwidth
d. What are the "Peer" and "Overlay" models?
GMPLS supports two methods of operation, peer and overlay. In the peer model, all devices in a given domain share the same control plane. This provides true integration between optical switches and routers. Routers have visibility into the optical topology and routers peer with optical switches. In the overlay model, the optical and routed (IP) layers are separated, with minimal interaction. Think of the overlay model as the equivalent of today's ATM and IP networks, where there is no direct connection between the ATM layer and the IP routing layer.
The peer model is inherently simpler and more scalable, but the overlay model provides fault isolation and separate control mechanisms for the physical and routed network layers, which may be more attractive to some network operators.
e. What is the "Optical Internetworking Forum"?
The Optical Internetworking Forum (OIF) is an open industry organization of equipment manufacturers, telecom service providers and end users dedicated to promote the global development of optical internetworking products and foster the development and deployment of interoperable products and services for data switching and routing using optical networking technologies.
An Introduction to the Optical Internetworking Forum White Paper can be found at http://www.oiforum.com/
f. Where can I get more information on GMPLS?
For information about GMPLS standards development, visit the IETF Common Control and Measurement Plane (CCAMPP) working group web page at http://www.ietf.org/html.charters/ccamp-charter.html as well as the White Papers section of this web site.
a. What is "Generalized MPLS" or "GMPLS"
From "Generalized Multi-Protocol Label Switching Architecture" "Generalized MPLS extends MPLS to encompass time-division (e.g. SONET ADMs), wavelength (optical lambdas) and spatial switching (e.g. incoming port or fiber to outgoing port or fiber)."
GMPLS represents a natural extension of MPLS to allow MPLS to be used as the control mechanism for configuring not only packet-based paths, but also paths in non-packet based devices such as optical switches, TDM muxes, and SONET/ADMs.
For an overview of GMPLS, see Generalized Multiprotocol Label Switching: An Overview of Routing and Management Enhancements
b. What are the components of GMPLS?
GMPLS introduces a new protocol called the "Link Management Protocol" or LMP. LMP runs between adjacent nodes and is responsible for establishing control channel connectivity as well as failure detection. LMP also verifies connectivity between channels.
Additionally, the IETF's "Common Control and Measurement Plane" working group (ccamp) is working on defining extensions to interior gateway routing protocols such as OSPF and IS-IS to enable them to support GMPLS operation.
c. What are the features of GMPLS?
GMPLS supports several features including:
Link Bundling - the grouping of multiple, independent physical links into a single logical link
Link Hierarchy - the issuing of a suite of labels to support the various requirements of physical and logical devices across a given path
Unnumbered Links - the ability to configure paths without requiring an IP address on every physical or logical interface
Constraint Based Routing - the ability to automatically provision additional bandwidth, or change forwarding behavior based on network conditions such as congestion or demands for additional bandwidth
d. What are the "Peer" and "Overlay" models?
GMPLS supports two methods of operation, peer and overlay. In the peer model, all devices in a given domain share the same control plane. This provides true integration between optical switches and routers. Routers have visibility into the optical topology and routers peer with optical switches. In the overlay model, the optical and routed (IP) layers are separated, with minimal interaction. Think of the overlay model as the equivalent of today's ATM and IP networks, where there is no direct connection between the ATM layer and the IP routing layer.
The peer model is inherently simpler and more scalable, but the overlay model provides fault isolation and separate control mechanisms for the physical and routed network layers, which may be more attractive to some network operators.
e. What is the "Optical Internetworking Forum"?
The Optical Internetworking Forum (OIF) is an open industry organization of equipment manufacturers, telecom service providers and end users dedicated to promote the global development of optical internetworking products and foster the development and deployment of interoperable products and services for data switching and routing using optical networking technologies.
An Introduction to the Optical Internetworking Forum White Paper can be found at http://www.oiforum.com/
f. Where can I get more information on GMPLS?
For information about GMPLS standards development, visit the IETF Common Control and Measurement Plane (CCAMPP) working group web page at http://www.ietf.org/html.charters/ccamp-charter.html as well as the White Papers section of this web site.
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