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ASTN/ASON and GMPLS Overview and Comparison. By, Kishore Kasi Udayashankar Kaveriappa Muddiyada K. Motivations Complex process of provisioning of end-to-end transport service Heterogeneous transport networks Automation of end-to-end provisioning Ability to offer more service
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ASTN/ASON and GMPLS Overview and Comparison • By, • Kishore Kasi Udayashankar • Kaveriappa Muddiyada K
Motivations • Complex process of provisioning of end-to-end transport service • Heterogeneous transport networks • Automation of end-to-end provisioning • Ability to offer more service • Directly integrate IP clients over WDM
How? • “intelligence” into the control plane of OTN • automatic and seamless circuit provisioning • unified control binding technologies • Benefits? • cost reduction and better quality of network operation • simplified and rapid network configuration • switched services and dynamic bandwidth assignment
ASTN/ASON • ITU-T Recommendation G.805/G.8080 • Architecture that defines the components and interactions between components • Distributed control plane • Task of control planes • Call and connection control • Path control based on network state • Discovery for self configuration
ASTN/ASON (Continued…) • Protocols must support multi-layer, multi-vendor network • Layering • Administrative partitioning • Operational partitioning • Types of interfaces in the control plane
GMPLS • Unified control plane for packet and circuit switching technologies • Four interfaces. • Interface Switching Capability • No NNIs.
GMPLS (Continued…) • Extension of routing protocols • OSPF-TE and ISIS-TE • Signaling protocols, RSVP-TE and CR-LDP • Label Switched Paths (LSP)
Multi-layer Resource Model Representation In GMPLS • Basic topology abstraction is TE link • Link interface can support one or more interface switching types defined • Interface Switching Capability (ISC) • ISC descriptor describes related TE properties • A particular resource on a link is represented by a label
In GMPLS (Continued...) • Basic service abstraction is a LSP • Concept of hierarchical LSP • LSP in server region represented as TE link or Forwarding adjacency in client region • Client LSP routed over a TE link == tunneled within a server LSP
Multi-layer Resource Model Representation • In ASON • ISC concept has been reduced • Optical part of OTN hierarchy is mapped to LSC • Digital path layers of OTN and SDH hierarchy is mapped to TDM
In ASON (Continued…) • Transport networks functional model G.805 • Client/server association between adjacent layers • Each layer partitioned to reflect internal structure
In ASON (Continued…) • Partitioning concepts • Starting from the smallest indivisible subnetwork • Contained and containing subnetwork • Contained subnetwork cannot provide connectivity not available in containing subnetwork • Ports on boundary of containing subnetworks and interconnection capability are represented by contained subnetworks
In ASON (Continued…) • Partitioning concepts (contd…)
In ASON (Continued…) • Layering concepts • Layer networks in a client-server model • Termination and Adaptation Functions • Topology and connectivity not visible to client
Overview of MPLS/GMPLS Concepts • Forward Equivalence Class • Label • LSR • LSP • Label allocation • Next Hop Label Forwarding Entry (NHLFE) • Route selection
From: Dr. Harry Perros, Connection Oriented Networks (CSC 576), Fall ‘06
From: Dr. Harry Perros, Connection Oriented Networks (CSC 576), Fall ‘06
Control Plane Architecture • In GMPLS • Peer model • Overlay model • Augmented model
Control Plane Architecture • In ASON • Protocol neutral way • Support various transport infrastructure • Applicable irrespective of control plane that has been subdivided into domains
In ASON (Continued…) • General model of policy • System is a collection of components • System boundary • Nested system boundaries • Policy port as filters
In ASON (Continued…) • General model of federation • Creation, deletion and maintenance of connections across multiple domains • Community of domains • Domains cooperate for connection management • Joint Federation Model and Cooperative model
In ASON (Continued…) Cooperative Model Joint federation Model
In ASON (Continued…) • Architectural components • Connection controller (CC) component • Routing controller (RC) component • Link resource manager component • Traffic policing (TP) component • Call controller component • Discovery agent (DA)
GMPLS Control Plane, Policy-based Management and Information Modeling • Policy based Management (PBM) • Improve collaboration between management and GMPLS control plane. • Extending Policy Core Information models (PCIM) with policy events. • Diverse local and global decision logic distributed among multiple network elements and network layers.
Discussion Items • Advantages and Features. • Types of GMPLS policies and actions – few examples • Control plane and PBM architecture. • GMPLS managed entities • Two uses cases to explain PBM in GMPLS
Advantages • Dynamic, flexible and cooperative interworking • Traffic engineering (TE) capabilities brought by GMPLS. • Improve operational efficiency. • New services requires complex and dynamic configurations of network resources. • Avoid configuring node-by-node and consider entire network domain as a whole. • Increase automation by using rule sets.
Features • Standardized operational processes in multi-vendor environments. • Policy rule - Network operator has control over state changes for a given network function. • Adapting and changing behavior at runtime. • Translating SLA, network and management areas (eg. Routing, configuration, fault management) into policies. • Adding/deleting/modifying policies in policy repository.
PBM Framework Policy based admission control. Policy Information Models “Policies are used to control the state that a managed object is in at any given time; the state itself is modeled using an information model”. Policy core Information Model (PCIM), MIB, PIB. Policy rule – It is a binding of a set of policy actions to a set of policy conditions. Features (Continued…)
Policies and Policy Actions • Admission Control Policy • Call/connection admission action, Call/connection Rejection Action. • Signaling Control Policy • Signaling recovery action • TE Routing Policy • Link State Advertisement action, Manage TE Info action • Path Computation and Selection Policy • Path computation action, Link Type selection action • Load Distribution Policy • Load distribution action • Recovery related policies……
Need for a separate Control Plane (CP) Fundamental principles of GMPLS CP Separating protocol generic and application specific mechanisms. TE Link as a unique application specific entity. Two-stage OSPF architecture and database. TE Link – resource aggregates that are encoded as links with TE attributes. OSPF-TE with opaque LSA capabilities along with topology LSA distribution. Control Plane and PBM Architecture
GMPLS Managed Entities • Features of NOBEL Information Model. • Specifies managed entities and represents control plane (CP) • Components, capabilities, interworking of CP components. • CP Element represents a control plane instance hosted by a CP node. • Separate instances of managed entities for control plane and transport plane entities.
Use Case 1 • Combined call and connection setup via User Network Interface (UNI). • Considering circuit switch capable GMPLS network. • SLA/SLS information installed in policy and service admission repository. • Global call admission directives in global Call admission policy decision point (PDP) downloaded by policy execution point (PEP). • Local and node specific connection admission policies in global connection admission PDP.
Description [1] connection request using call setup messages over UNI [1b] comparing client id and port with call admission directives, does not match. [2a] call level parameters translate into network resource related requirements and evaluated by LPDP. [2b] requirements verified against general connection admission policy [3] May be asked to renegotiate due to network or node limitation
Continued… [4] connection setup is delegated to TEC which checks against path selection policy rules with LPDP [5] signaling controller (SgC) requests LPDP to check against signaling control policy rules. [6] ingress node signals modified call setup request.
Use Case 2 • Event Driven TE Policy action for TE link utilization threshold crossing event. • Emits threshold crossing alert (TSA). • use case example - Predefined percentage (say 85%) of the current forwarding adjacency (FA) packet switched connection (PSC) link unreserved bandwidth is consumed. • TE link utilization thresholds are set. • TE Control action – • New FA PSC LSP • New FA TDM LSP eg. At the server layer.
Description [1a] TE link emits TCA to TEC, internal signal. [1b] TE link emits TCA to Management Plane (MP), CP-MP interaction notification. [2] TEC requests PEP to invoke event policy rule. [3] PEP forwards decision request to PDP (local, global or both) [3a],[3b] LPDP evaluates load-distribution action policy rule. If it does not succeed, create LSP create action policy is evaluated with global PDP.
Continued… [4] LPDP evaluates path computation/selection policy rules and delegates TEC to enforce policy decisions. [5] TEC triggers SgC for setup of server layer. [6] If success, TEC will check LSA update policy and Information dissemination policy to initiate LSA update. [7]. TEC updated TEDB with new FA-LSP and notifies MP about result of policy decision [8a] [8b] TE Link emits state change notification to inform MP.
Bibliography • G.805 ITU-T specification • G.8080 ITU-T specification • ASON Current status of standardization work, B. Zeuner, G. Lehr, Deutsche Telekom • ASON and GMPLS – The battle of optical control plane • Data connection limited. • Control plane for Optical networks: The ASON Approach, Andrzej Jajszczyk, AGH University of science and technology, Krakow, Poland • ASON and GMPLS – Overview and Comparision, S. Tomic, B. Statovci-Halimi, A. Halimi • GMPLS Control Plane, policy based management, and information Modelling, H.Lonsethagen, et. al.