The Chinese equipment maker showcased a prototype optical switch at this year's OFC/NFOEC that can scale to 10 Petabit.
"Although the numbers [400,000 lasers] appear quite staggering, they point to a need for photonic integration"
Reg Wilcox, Huawei
Huawei has demonstrated a concept Petabit Packet Cross Connect (PPXC), a switching platform to meet future metro and data centre requirements. The demonstrator is not expected to be a commercial product before 2017.
Current platforms have switching capacities of several Terabits. Yet Huawei believes a one thousand-fold increase in switching capacity will be needed. Fibre capacity will be filled to 20 and eventually 50 Terabits using higher-order modulation schemes and flexible spectrum. This will add up to a Petabit (one million Gigabits) per site, assuming 200 switched fibres at busy network exchanges.
"We are not saying we will introduce a 10 Petabit product in five years' time, although the technology is capable of that," says Reg Wilcox, vice president of network marketing and product management at Huawei. "We will size it to what we deem the market needs at that time."
Source: Huawei
The PPXC uses optical burst transmission to implement the switching. Such burst transmission uses ultra-fast switching lasers, each set to a particular wavelength in nanoseconds. Like Intune Networks’ Verisma iVX8000 optical packet switching and transport system, each wavelength is assigned to a particular destination port. As OTN traffic or packets arrive, they are assigned a wavelength before being sent to a destination port.
Huawei's switch demonstration linked two Huawei OSN8800 32-slot platforms, each with an Optical Transport Network (OTN) switching capacity of 2.56 Terabit-per-second (Tbps), to either side of the core optical switch, to implement what is known as a three-stage Clos switching matrix.
With each OSN8800, half the slots are for inter-machine trunks to the core optical switch, the middle stage of the Clos switch. "The other half [of the OSN8800] would be dedicated to whatever services you want to have: Gigabit Ethernet, 10 Gigabit Ethernet; whatever traffic you want riding over OTN," says Wilcox.
The core optical switch implements an 80x80 matrix using 80 wavelengths, each operating at 25Gbps. The 80x80 matrix is surrounded by MxM fast optical switches to implement a larger 320x320 matrix that has an 8 Terabit capacity. It is these larger matrices - 'switch planes' - that are stacked to achieve 10 Petabit. The PPXC grooms traffic starting at 1 Gigabit rates and can switch 100Gbps and even higher speed incoming wavelengths in future.
Oclaro provided Huawei with the ultra-fast lasers for the demonstrator. The laser - a digital supermode-distributed Bragg reflector (DS-DBR) - has an electro-optic tuning mechanism, says Robert Blum, director of product marketing for Oclaro's photonic component. Here current is applied to the grating to set the laser's wavelength. The resulting tuning speed is in nanoseconds although Oclaro will not say the exact switching speed specified for the switch.
Each switch plane uses 4x80 or 320, 25Gbps lasers. A 10 Petabit switch requires 400,000 (320x1250) lasers. "Although the numbers appear quite staggering, they point to a need for photonic integration," says Wilcox. Huawei recently acquired photonic integration specialist CIP Technologies.
The demonstration highlighted the PPXC switching OTN traffic but Wilcox stresses that the architecture is cell-based and can support all packet types: "We are flexible in the technology as the world evolves to all-packet.” The design is therefore also suited to large data centres to switch traffic between servers and for linking aggregation routers. "It is applicable in the data centre as a flattened [switch] architecture," says Wilcox.
Huawei claims the Petabit switch will deliver other benefits besides scalability. "Rough estimates comparing this device to OTN switches, MPLS switches and routers yields savings of greater than 60% on power, anywhere from 15-80% on footprint and at least a halving of fibre interconnect," says Wilcox.
Meanwhile Oclaro says Huawei is not the only vendor interested in the technology. "We have seen quite some interest recently in this area [of optical burst transmission]." says Oclaro's Blum. "I wouldn't be surprised if other companies make announcements in this space."
Further reading:
- OFC/ NFOEC 2012 paper: An Optical Burst Switching Fabric of Multi-Granularity for Petabit/s Multi-Chassis Switches and Routers