Redefining P-OTS

Packet-optical transport systems (P-OTS) are moving from the metro and into the network core, and Heavy Reading believes that 2010 will be a big year for this emerging product segment. Over the past several months, we've researched the core P-OTS opportunity and published the findings in a new Heavy Reading report entitled "The Core Packet-Optical Transport Evolution."

With a host of equipment suppliers now targeting core P-OTS applications, we have refined the Heavy Reading core P-OTS definition. Our criteria include the following:

  • WDM transport and wavelength-level switching with a core/backbone DWDM focus. This means the DWDM system must transmit at least 1,000 km without regeneration, with 80 channels of DWDM and integrated ROADM.
  • Integrated optical crossconnect. We believe operators will require at least 1 Tbit/s of switching capacity today and want systems that scale to multiple terabits of switching capacity in the future.
  • Full support for Sonet/SDH.
  • OTN and Ethernet switching. On the OTN side, we see strong momentum building for the new ODU0-level switching, which is highly efficient for Gigabit Ethernet traffic. Operators are also interested in the ODUflex standard, which is a more flexible container for OTN. On the Ethernet side, we believe that connection-oriented Ethernet is required.
  • ASON/GMPLS optical control plane. The control plane is required for building mesh networks, similar to what first-generation optical crossconnects can do in core networks today.
  • Transport-class network element. This new equipment must be as reliable and resilient as current DWDM and optical crossconnect systems.

Our definition will continue to be refined as the new segment takes shape, and as operators refine their own requirements for these new devices. As of the end of 2009, no vendor was shipping a product that met all of Heavy Reading's requirements – though many were trying. We believe those closest to market are the Ciena Corp. (NYSE: CIEN) 5430/5410 RSS, startup Cyan Optics Inc. Z77, Hitachi Ltd. (NYSE: HIT; Paris: PHA) AMN 6400, Huawei Technologies Co. Ltd. OSN 8800, Tellabs Inc. (Nasdaq: TLAB; Frankfurt: BTLA) 7100 HCSS, and Alcatel-Lucent (NYSE: ALU)'s much rumored, but not publicly disclosed, next-generation core switch.

Of these vendors on the short list, most need to commercialize their large-scale (terabit and multi-terabit) OTN optical switch fabrics. Huawei, meanwhile, is already shipping a large-scale OTN/DWDM product (the OSN 8800), but has yet to introduce a packet switching fabric on this platform. Cyan Optics is very close, with its commercially shipping Z77 product. Still, Cyan has yet to add ODU0 switching to the Z77 – something we believe will be a key requirement in core P-OTS RFPs.

— Sterling Perrin, Senior Analyst, Heavy Reading

For more information about Heavy Reading's "The Core Packet-Optical Transport Evolution," or to request a free executive summary of this report, please contact:

HSalemi 12/5/2012 | 4:44:20 PM
re: Redefining P-OTS There was a lot of talk long time ago (~15 years) about VCAT/LCAS to enable capability of flexible pipes via SONET/SDH networks. It took a long time, and looks like a very limited deployement (if I am not mistaken!).

Would ODUFlex be any different? Why?
mvissers 12/5/2012 | 4:44:18 PM
re: Redefining P-OTS

ODUflex is being added to the next version of OTN line port devices. Once those new line ports are added to the OTN systems the network is capable to support switched ODUflex connections.

Note that the new OTU4 and OTU3e2 line ports treat ODUk (k=0,1,2,2e,3) signals as specific bit rate versions of the generic ODUflex signals; i.e. all those ODUk/ODUflex signals are mapped into the HO ODU4 and HO ODU3e2 by means of the new Generic Mapping Procedure (GMP). GMP is a generalized asynchronous mapping technology that is agnostic of the bit rates of the client and server signals. You only need to configure the bit rate and tolerance of the LO ODU signal and the tributary slots in which it is transported in the line port to have the GMP process perform its task to map/demap this LO ODU signal into/from the HO ODU tributary slots. This programmability also enables the hitless resizing of the ODUflex connections when such ODUflex connection carries GFP-F encapsulated packet streams (e.g. Ethernet, IP, MPLS).

The traditional Asynchronous Mapping Procedure (AMP) supported in today's OTU2 and OTU3 line ports is complemented with the new GMP process, enabling support of ODU0, ODU2e and ODUflex signals by those line ports.

GMP is also the mapping procedure used to map new sub-2.5G CBR clients (e.g. 1GE, STM-1/4, FC-100/200, CPRI Opt. 1/2/3, ..) into ODU0/ODU1, and to map 40GE and 100GE into ODU3 and ODU4.

Other new CBR clients (e.g. FC-400/800, CPRI Opt. 4/5/6, 3G SDI, ...) are mapped into an ODUflex using the very simple Bitsynchronous Mapping Procedure (BMP), which wraps the ODUflex around the CBR client.

ODUk and ODUflex will also used to carry Ethernet VLANs, MPLS(-TP) LSPs and PWs and IP/IPVPNs via GFP-F encapsulation between L2 PE and L3 PE switching fabrics in either L2 or L3 PE nodes, or embedded in the OTN XC nodes. Those ODUk/ODUflex connections act as tunnels (OTN (sub) Lambda Switched Paths (OTN sLSP/LSP) with GMPLS control) for those packet service layer signals. Use of ODUflex connections between two L2/L3 PE fabrics allows to resize those sLSP tunnels when bandwidth demand grows.

OTN (s)LSP type tunnels are economical when tunnel bandwidth is larger than 0.4G. Below 0.4G MPLS(-TP) Label Switched Path (MPLS LSP) type tunnels are more economical. OTN sLSP and OTN LSP connections are both supported by the LO ODU layer in the OTN. L2 and L3 PE node ports with OTN sLSP/LSP endpoints are connected to the OTN via OTUk (k=2,3,4) Inter Domain Interfaces (IrDI) specified in G.709V3. The OTU3/4 IrDIs use the same multi-lane interfaces as 40GE/100GE.

The ODUflex and its enabling GMP technology are at the core of the next gen OTN technology, and will be used as basis for any future circuit based transport network. With those technologies circuit networks combine the traditional high performance connections with pseudowire like bandwidth flexibility.

ODUflex/GMP are technologies used in the core of the OTN enabling support for any service rate. VCAT/LCAS are technologies used at the edge of the SDH network to support service rates that the core did not support.

ODUflex will as such be very different from VCAT/LCAS.


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