From PoS to GFP - Abstract Thomas Hagmeister (Alcatel)

Transcription

1 From PoS to GFP - Abstract Thomas Hagmeister (Alcatel) In multilayer networks for data and optical networks the traditional interconnection is facilitated today with PoS (Packet over SDH/Sonet) interfaces on the routers connected to the SDH/Sonet interfaces of the optical networking equipment. This way of interfacing is state of the art today 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 (Link Capacity Adjustment Scheme) the interfacing between the data and optical network could be based on Ethernet at lower costs and with the flexibility of virtual concatenation. The presentation will exploit this new way of interfacing addressing furthermore the additional optimisation for flexibility using VLAN tag based traffic alignement and for provisioning using the GMPLS based control plane approach.

2 Viola Workshop April 2005 ALCATEL Optical Networks Division From POS To GFP Thomas Hagmeister /

3 Motivation Page 2 Improve the efficiency of data transport Overall Network Cost Inefficient use of transmission resources Today Tomorrow Interface Technology POS GFP/VCAT/LCAS Layer 2 OND Product Strategy POS2GFP /

4 Motivation Page 3 Improve the efficiency of data transport Overall Network Cost Inefficient use of transmission resources Optimized use of transmission resources Today Tomorrow Interface Technology POS GFP/VCAT/LCAS Layer 2 OND Product Strategy POS2GFP /

5 Motivation Page 4 Improve the efficiency of data transport Overall Network Cost Inefficient use of transmission resources Today Optimized use of transmission resources Optimized Interfacing Tomorrow Interface Technology POS GFP/VCAT/LCAS Layer 2 OND Product Strategy POS2GFP /

6 IP/MPLS Router Interfaces Over Transport Page 5 Possible Interfacings between Routers and Transport Nodes Router Router Router Transport Node Transport Node Transport Node! POS interfacing! POS-channelized interfacing! Ethernet/VLAN interfacing OND Product Strategy POS2GFP /

7 POS Interfacing Page 6 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 Router IP Links Transport Node Separate physical ports VC-4-nc channels OND Product Strategy POS2GFP /

8 POS Interfacing (Channelized) Page 7 Easiest way, no technology change in Routers and Transport network Router IP Links Transport Node Single channelized physical port VC-4-nc channels + Reduction of POS interfaces by grooming of IP links Interfaces very expensive, not widely deployed OND Product Strategy POS2GFP /

9 Disadvantages of POS Interfaces Page 8 Drawbacks! Limited granularity, poor scalability of used transport entities, combinations of different channel sizes / concatenation levels not available " 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 OND Product Strategy POS2GFP /

10 Introduction of Advanced Technologies Page 9 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 OND Product Strategy POS2GFP /

11 Ethernet/VLAN Interfacing Page 10 The Router assigns several IP links to GbE/10GbE interfaces Router IP Links VLANs Transport Node GbE/ 10GbE VC-4-xv channels! 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 of adequate size! Ethernet OAM is necessary to support fast IP/MPLS rerouting in case of failures OND Product Strategy POS2GFP /

12 Ethernet/VLAN Interfacing Page 11 Transport Node Eth/VLAN L2 function GFP VCAT LCAS SDH Matrix! 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 OND Product Strategy POS2GFP /

13 Further Evolution - Multilayer GMPLS Page 12 ASON/GMPLS Ethernet ASON/GMPLS Transmission Network Transport Node Router! Multilayer Control Plane! Automatic Multilayer Resource Control! Advanced Reservation! Multilayer Bandwidth on Demand OND Product Strategy POS2GFP /

14 Summary Interfaces between IP core routers today usually are POS! Approved network design Page 13 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 OND Product Strategy POS2GFP /

15 Page 14 Thank You... Thomas Hagmeister OND Product Strategy POS2GFP /

16 Annex (From POS To GFP) Viola Workshop April 2005

17 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 Page 16 Ethernet IP/PPP other Payload dependent (client specific) GFP sublayer Payload independent GFP sublayer SDH VC-n path OTH ODUk path other OND Product Strategy POS2GFP /

18 Virtual Concatenation (VCAT) Page 17 Concatenation: several containers (e.g. VC-4) are bundled in a way that 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 in concatenation endpoints (VCAT ports), through the network containers of 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 OND Product Strategy POS2GFP /

19 Link Capacity Adjustment Scheme (LCAS) Page 18 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 OND Product Strategy POS2GFP /