from pos to gfp - abstract - dfn

From PoS to GFP - Abstract

Thomas Hagmeister (Alcatel)

In multilayer networks for data and optical networks the traditionalinterconnection is facilitated today with PoS (Packet over SDH/Sonet)interfaces on the routers connected to the SDH/Sonet interfaces of theoptical networking equipment. This way of interfacing is state of the arttoday and combines some advantages of the data and optical network nodes,but has certain limitations in terms of networking costs and flexibility.With the standardization of GfP (Generic Framing Procedure) and LCAS (LinkCapacity Adjustment Scheme) the interfacing between the data and opticalnetwork could be based on Ethernet at lower costs and with the flexibilityof virtual concatenation. The presentation will exploit this new way ofinterfacing addressing furthermore the additional optimisation forflexibility using VLAN tag based traffic alignement and for provisioningusing the GMPLS based control plane approach.

All rights reserved © 2005, Alcatel

Viola Workshop April 2005ALCATEL Optical Networks Division

Thomas Hagmeister / 2005-04-27

From POS To GFP

All rights reserved © 2005, AlcatelOND Product Strategy – POS2GFP / 2005-04-27 - 2 -

Motivation

Today Tomorrow

Improve the efficiency of data transportImprove the efficiency of data transport

InterfaceTechnology

OverallNetwork

Cost

POS GFP/VCAT/LCAS Layer 2

Inefficient useof transmission

resources


resources


Motivation

Today Tomorrow


InterfaceTechnology

OverallNetwork

Cost



resources


resourcesOptimized useof transmission

resources

Optimized useof transmission

resources


Motivation

Today Tomorrow


InterfaceTechnology

OverallNetwork

Cost



resources


resourcesOptimized useof transmission

resources

Optimized useof transmission

resourcesOptimizedInterfacingOptimizedInterfacing


IP/MPLS Router Interfaces Over Transport

TransportNode

Router Router Router

TransportNode

TransportNode

Possible Interfacings between Routers and Transport Nodes

! POS interfacing! POS-channelized interfacing! Ethernet/VLAN interfacing


POS Interfacing

Individual POS ports per link! Currently deployed solution! SDH/SONET alarms can be used to trigger fast IP/MPLS rerouting in

case of failures– Drawback: inefficient in case of many low capacity links

TransportNodeRouter IP Links

VC-4-ncchannelsSeparate

physical ports


POS Interfacing (Channelized)

Easiest way, no technology change in Routers and Transportnetwork

+ Reduction of POS interfaces by grooming of IP links– Interfaces very expensive, not widely deployed

Router IP Links

VC-4-ncchannelsSingle channelized

physical port

TransportNode


Disadvantages of POS Interfaces

Drawbacks! Limited granularity, poor scalability of used transport entities,

combinations of different channel sizes / concatenation levels notavailable" granularity only in factors of 4 (155 Mbps, 622 Mbps, 2.5 Gbps, ...)" Contiguous Concatenation wastes transport resources" missing implementation of Virtual Concatenation (RFC3255)

! Proprietary usage of the SDH overhead " “invalid” SDH signals" frequently resulting in WDM ptp connections

Conclusions# POS interfaces (both types) are not efficient as interfacing solution# Advanced technologies to be introduced


Introduction of Advanced Technologies

Three mechanisms

Generic Framing Procedure (GFP)!Efficient mapping mechanism for packets

Virtual concatenation (VCAT)!Efficient use of SDH payload capacity!Granularity: n * VC-4!Decoupling of service and line bit rates

Link Capacity Adjustment Scheme (LCAS)!Dynamic increase or decrease of used transport resources


! VLAN tags are introduced segregating traffic to different destinations! An Ethernet/VLAN capable L2 function in the transport node

separates the IP links and maps each into a VC-4-xv channel ofadequate size

! Ethernet OAM is necessary to support fast IP/MPLS rerouting in caseof failures

Ethernet/VLAN Interfacing

The Router assigns several IP links to GbE/10GbE interfaces

Router IP Links

VC-4-xvchannels

VLANs

GbE/10GbE

TransportNode


Ethernet/VLAN Interfacing

!Prerequisite$ Core routers must be able to use VLAN as logical interface definition on

the trunk side+ Pros

$ Decoupling of IP link speeds and physical interfaces (cost savings)$ IP links dynamically share the available Ethernet bandwidth

(compensation of traffic variations)$ Major brand core routers support VLAN subinterfaces on GbE$ Introduction of L2 functions is a consequent enhancement of the

transport node technology

Eth/VLANL2

function

Transport Node

GFPVCATLCAS

SDHMatrix


Further Evolution - Multilayer GMPLS

! Multilayer Control Plane! Automatic Multilayer Resource Control! Advanced Reservation! Multilayer Bandwidth on Demand

ASON/GMPLS

Transmission Network

ASON/GMPLS

Ethernet

Router

Transport Node


Summary

Interfaces between IP core routers today usually are POS! Approved network design

Limitations, in particular when links pass a transport network! Cost efficient only with few well filled high-speed interfaces! Inefficient when many links are only partially filled! In principle, today only one IP link per physical port

Alternatives! Interface technology with 1 or 10 GbEthernet! Efficient transport capacity mapping with GFP/VCAT/LCAS! L2 function for further optimization! One port – several destinations

Efficient Multilayer Control with ASON/GMPLS


www.alcatel.com

Thomas Hagmeister

Thank You ...


Generic Framing Procedure (GFP)

Generic mechanism to carry packets over any fixed rate (TDM)channels

Variants! Frame mapped (GFP-F): individual client PDUs mapped into GFP frames,

bandwidth efficient! Transparent mapped (GFP-T): mapping based on characters, minimum

latency

ITU-T G.7041

Ethernet otherIP/PPP

Payload dependent (client specific) GFP sublayerPayload independent GFP sublayer

OTH ODUk pathSDH VC-n path other


Virtual Concatenation (VCAT)

Concatenation: several containers (e.g. VC-4) are bundled in a waythat their transmission capacity can be used as one single entity! Higher bandwidth for signals than VC-4 possible! More efficient use of SDH payload capacity

Virtual concatenation: containers are concatenated only inconcatenation endpoints (VCAT ports), through the network containersof a VCAT group can follow different paths! Supporting adjustable connection bandwidth! Decoupling of service and line bit rate! Prerequisite for LCAS

ITU-T G.707, G.709


Link Capacity Adjustment Scheme (LCAS)

User-plane handshake protocol between VCAT ports hitless capacity modifications (add, remove) hardware/firmware based protocol protocol runs over path overhead in (VC-n) trails within VCAT group prerequisite: connection management (NMS, ASON/GMPLS) has

set-up the network connection(s)! LCAS doesn’t set up additional or tear down existing connections! LCAS controls traffic flow over the set of VCAT trails;

traffic flows over set of fault free trails

ITU-T G.7042

from pos to gfp - abstract - dfn

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