From PoS to GFP - Abstract - DFN
Transcript of 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
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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
Inefficient useof transmission
resources
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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
Inefficient useof transmission
resourcesOptimized useof transmission
resources
Optimized useof transmission
resources
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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
Inefficient useof transmission
resourcesOptimized useof transmission
resources
Optimized useof transmission
resourcesOptimizedInterfacingOptimizedInterfacing
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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
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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
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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
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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
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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
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! 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
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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
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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
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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
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www.alcatel.com
Thomas Hagmeister
Thank You ...
All rights reserved © 2005, Alcatel
Annex (From POS To GFP)
Viola Workshop April 2005
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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
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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
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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