Choose your own path to the most efficient IP network
The economic recession has just about everyone trying to figure out how to cut costs—at home, at the office and in the network. To reduce the cost per transported bit, some industry players say all you have to do is build a network made up of lots of IP routers and dumb optical pipes. Just converge all services onto an all-IP infrastructure. You get a lower-cost network that's easier to maintain than legacy SONET/SDH and WDM networks, right? Not quite.
There is no one-size-fits-all solution. Networks deliver multiple services, so shouldn't you be able to pick the technology—from WDM, OTN and SONET/SDH to Ethernet, MPLS and IP—that works best for any given network function? An integrated packet/optical transport platform residing beneath an IP infrastructure lets you do just that and in most cases reduces the total cost of ownership (TCO) of the IP network. Exactly how much cost an integrated packet/optical transport platform can save you depends on many factors, including service mix, density of services and network topology.
Sure, core IP networks are very flexible, and they do support enhanced service features. However, they also come with higher TCO, primarily because compared with the same IP network supported with a packet/optical solution underneath it, they require:
- greater router and port requirements,
- the need for more network capacity (private line services and those with guaranteed bandwidth requirements consume more IP-network capacity than they do on a TDM network),
- longer restoration times,
- higher latency, and often
- less redundancy.
Because an IP router-based network has the same OSI layers as circuit-switched networks, the only real changes convergence brings about are where you put the network intelligence and which layers address which network functions. Unfortunately, few people have focused on which layer is best suited for each network function.
Optical transport solutions can offload any traffic from the routers that Carrier Ethernet and optical facilities can handle equally well, at a much lower cost per bit. Routers continue to handle Layer-3 service features. By traversing packet optical layers, many services can take advantage of the lower latency, faster switch times and more deterministic performance.
For example, the Tellabs® 7100 Optical Transport System integrates in a single platform an intelligent services layer and a dynamic optical layer. The intelligent services layer combines Ethernet, video, SAN, OTN, and SONET/SDH service types onto 10 Gbps, 40 Gbps and, eventually, 100 Gbps optical wavelengths. You pick only the hardware modules for the services you need. The dynamic optical layer is a reconfigurable, expandable optical switching layer. The same fiber infrastructure handles additional connections and higher-bandwidth wavelengths, with no impact to existing services. By using DWDM, ROADMs and dynamic control plane technologies, this layer provides the approach with the lowest capital expense and operating expense to multiservice transport and delivery.
This integrated packet-optical approach offers other benefits, too, including:
- nearly unlimited bandwidth expansion
- reduced costs—less hardware means lower space, power and cooling requirements
- fewer network elements to manage
- less cabling between network elements
- fewer interoperability issues
So take advantage of IP—where IP makes sense—but rely on other technologies where they're a better fit. After all, shouldn't you get to choose, rather than having the technology choose for you?
There are many acronyms in my post, so here's a quick glossary:
- DWDM: Dense Wavelength Division Multiplexing
- Gbps: Gigabit per second
- IP: Internet Protocol
- MPLS: Multi Protocol Label Switching
- OSI: Open Systems Interconnection
- OTN: Optical Transport Network
- ROADM: Reconfigurable Optical Add Drop Multiplexer
- SAN: Storage Area Network
- SDH: Synchronous Digital Hierarchy
- SONET: Synchronous Optical Network
- TDM: Time Division Multiplexing
- WDM: Wavelength Division Multiplexing
