Juniper's Packet-Optical Spells M-P-L-S
Juniper, which paired up with Nokia Networks for its packet-optical plans, envisions a core network where Multiprotocol Label Switching (MPLS) label-switched paths (LSPs) aren't determined on the fly by routers, but are provisioned through the network core just as wavelengths are today.
"You make the MPLS layer the transport layer. That's where I think the packet-optical discussions are going," Juniper senior director Luc Ceuppens tells Light Reading.
And he's not talking about MPLS-TP. In Juniper's thinking, MPLS-TP comes into play in an all-OTN network, when large ODU payloads are being shunted around. Juniper is talking about more finely grained units of traffic, carried over the optical transport network via MPLS.
It's not a popular view. Many companies see packet-optical transport systems (P-OTS) and converged packet-optical networks as a way to use fewer router ports in the network core. Verizon Communications Inc. (NYSE: VZ) went so far as to ask the industry to create new long-haul optical boxes that could let traffic sometimes bypass router ports, and Alcatel-Lucent has crafted a packet-optical strategy along those lines. (See Verizon Rethinks Long Haul and AlcaLu Makes Its Packet-Optical Move .)
These companies argue that a majority of the traffic going through a router doesn't need to be processed, because its destination is farther along in the network. So, why not pack that "express" traffic into wavelengths that skip the router?
Guess what: Juniper doesn't see so much of a need to bypass routers. "We believe a lot of the bypass cases are corner cases," Ceuppens says.
He says router bypass might work at an Internet exchange point, which deals in huge chunks of aggregated traffic. But he argues it's less efficient in most cases, "when you have tens of thousands of LSPs on the network" all headed to different destinations. Router bypass, in that case, would "end up adding wavelengths that are then not filled in the most efficient way." The result: What you save in router ports would be spent adding more P-OTS ports.
(Juniper claims to have a study that verifies this; look for the results to come soon, Ceuppens says.)
To Juniper, the real benefit of packet-optical convergence is that MPLS, once married to the optical network, could be made more deterministic. The network could provision MPLS connections the way wavelengths are provisioned.
"Very often, when we talk to our customers, they bring this up," Ceuppens says. "They like the MPLS network, but they want the manageability they have in their TDM networks."
Whether this idea takes off might depend on how many carriers Juniper can convince. Verizon is dead-set certain that it can save money by using P-OTS to bypass routers some of the time, and much of the industry seems to back that notion, according to Heavy Reading analyst Sterling Perrin.
"Operators tell us 60 percent of router traffic is transit," says Perrin. "There's a belief that stuff going through the router doesn't need to go through the router -- and that routers are more expensive than transport equipment."
Another factor to consider is that MPLS-TP, which would provide some of the determinism Ceuppens is talking about, appears to be gaining popularity as Provider Backbone Bridging - Traffic Engineering (PBB-TE) loses ground. "We are seeing things jelling around MPLS-TP right now for carrier-oriented Ethernet," Perrin says. (See MPLS-TP vs. PBB-TE.)
Ceuppens says the argument between the two comes down to where a carrier wants to do its switching: in routers (Juniper's MPLS case) or in optical transport (the OTN case that more of the industry seems to be pursuing).
They aren't mutually exclusive cases, and Ceuppens sees reason for the industry to develop a box that does both, switching either MPLS or OTN traffic natively as it arrives. That would be a P-OTS, of course -- although Ceuppens thinks such a box should be defined by having a single switch fabric that handles both traffic types natively.
Important point: Juniper and NSN have announced no such system, nor have they even said they intend to develop a P-OTS: Ceuppens declined to comment on any P-OTS plans. It's worth noting, though, that Juniper has invested in P-OTS startup Cyan Optics Inc. (See Cyan Plays God With Optical.)
— Craig Matsumoto, West Coast Editor, Light Reading
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