Astn/Ason and Gmpls Overview and Comparison: By, Kishore Kasi Udayashankar Kaveriappa Muddiyada K
Astn/Ason and Gmpls Overview and Comparison: By, Kishore Kasi Udayashankar Kaveriappa Muddiyada K
Astn/Ason and Gmpls Overview and Comparison: By, Kishore Kasi Udayashankar Kaveriappa Muddiyada K
By,
KishoreKasiUdayashankar
KaveriappaMuddiyadaK
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)
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
In ASON (Continued)
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
In ASON (Continued)
From: Dr. Harry Perros, Connection Oriented Networks (CSC 576), Fall 06
From: Dr. Harry Perros, Connection Oriented Networks (CSC 576), Fall 06
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)
Joint federation Model
Cooperative 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)
Discussion Items
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.
Features (Continued)
PBM Framework
Policy based admission control.
TE Routing Policy
Link State Advertisement action, Manage TE Info action
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), CPMP 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.