Nokia's 4.8-terabit FP5 packet-processing chipset

Part 1: IP routing: Nokia's latest FP5 and router platforms 

Nokia has unveiled its latest packet-processing silicon that will be the mainstay of its IP router platforms for years to come.

The FP5 chipset is rated at 4.8 terabits-per-second (Tbps), a twelvefold improvement in Nokia’s packet-processing silicon performance in a decade. (See chart.)

Source: Nokia, Gazettabyte

Communications service provider (CSP) BT says Nokia’s 7750 router platforms equipped with the FP5 chipset will deliver every use case it needs for its Multi Service Edge; from core routing, MPLS-VPN, broadband network gateways (BNG), to mobile backhaul and Ethernet.

The FP5 announcement comes four years after Nokia unveiled its existing flagship router chipset, the FP4. The FP4 was announced as a 2.4Tbps chipset but Nokia upgraded its packet-processing rating to 3Tbps.

Heidi Adams

“We announced what we knew but then, through subsequent development and testing, the performance ended up at 3Tbps,” says Heidi Adams, head of IP and optical networks marketing at Nokia.

The FP5 may also exceed its initial 4.8Tbps rating.

Nokia will use the FP5 to upgrade its existing platforms and power new router products; it will not license the chipset nor will it offer it for use in open router platforms.

Nokia’s chipset evolution

At the heart of Nokia’s router silicon is a 2D array of packet processing cores.

The FP3, announced in 2011 by Alcatel-Lucent (acquired by Nokia in 2016), used 288 packet processing cores arranged in a 32x9 array. Each row of cores acted as a packet-processing pipeline that could be partitioned to perform independent tasks. The array’s columns performed table look-ups and each column could be assigned several tasks.

Nokia didn’t detail how the FP4 upgraded the array of cores. But the performance enhancement was significant; the FP4 delivers a 7.5x improvement in packet processing performance compared to the FP3.

The 16nm CMOS FP4 chipset includes a traffic manager (q-chip), packet processor (p-chip), the t-chip that interfaces to the router fabric, and what was then a new chip, the e-chip.

The e-chip acts as a media access controller (MAC) that parcels data from the router’s client-side pluggable optical modules for the p-chip.

Nokia even designed memory for the FP4 whereby instructions can be implemented during memory access and the memory can be allocated to perform different types of look-up and buffering, depending on requirements.

To maximise the memory’s performance, Nokia used advanced packaging for the FP4’s p-chip and q-chip. The resulting 2.5D-packaged p-chip comprises the packet processor die and stacks of memory. The q-chip is also a multi-chip module containing RISC processors and buffering memory.

The FP4 uses 56Gbps PAM-4 serialiser-deserialiser (serdes) interfaces, technology that Nokia secured from Broadcom.

FP5’s features

The FP5 builds on the major architectural upgrade undertaken with the FP4.

Using a 7nm CMOS process technology, Nokia’s FP5 designers have combined on-chip what were two separate FP4 chips: the packet processor (p-chip) and traffic manager (q-chip).

The FP5 chipset consumes a quarter of the power of the FP4 in terms of watts-per-gigabit (0.1W/Gig for the FP5 compared to the FP4’s 0.4W/Gig).

Consolidating two chips into one accounts for part of the power savings. Using 112Gbps serdes and a more advanced CMOS process are other factors.

Nokia has also added encryption hardware blocks to the chip’s ports. The hardware blocks implement the MACsec algorithm and can also encrypt layer 2.5 and layer 3 traffic.

The chipset can handle packet flows as large as 1.6 terabits. “We don’t have any physical interfaces that support flows at that rate,” says Adams. “It’s an indicator that the chipset is ready for much more.”

The e-chip, which Nokia describes as a tremendously important device, has also been upgraded. As well as the MAC function, it acts as an early-stage packet processor, performing pre-processing and pre-classification tasks on the traffic.

The e-chip also performs pre-buffering for the packer processor. Using multiple such devices allows the line card to expand the forwarding limit of the FP5’s packet processor. This enables Nokia’s routers to perform what it calls intelligent aggregation (IA). “We can bring in more traffic, increase the number of ingress ports even if those ports start to get fully loaded, because of the chipset architecture being fully buffered,” says Adams. “The result is a 30 per cent uplift in the stated capacity numbers.”

The FP5 chipset has been taped out and the silicon is being tested in Nokia’s lab.

Router platforms

IP core routers are tasked with moving large amounts of IP traffic across a network backbone. IP edge routers, in contrast, typically aggregate a variety of services such as mobile transport, residential traffic or act as gateways.

Source: Nokia, Gazettabyte

The platforms that will use the FP5 are classified by Nokia as edge routers. “The boundaries have blurred,” says Adams. “It is more important to look at how applications are deployed and what the requirements are.”

The platforms using the FP5 are the existing 7750 SR-14s and 7750-SR7s routers that were announced with the launch of the FP4.

These chassis were designed to accommodate Nokia’s current and next-generation router cards. “This allows operators to retain the same chassis and support a mix of FP4 and FP5 cards, growing into them gradually,” says Adams.

Nokia has announced three other platforms: two mid-range platforms, the 7750 SR2-se and the 7750 SR1-se, and the 7750 SR-1 that will be available in six variants. “They [the SR-1 boxes] are going to be available in a range of configurations and different port speeds,” says Adams.

Platforms using the FP5 chipset will ship in the first half of 2022, starting with the SR-1.

Nokia also announced an FP5 expandable media adaptor (XMA) line card for the non-fixed platforms (the 7750 SR-14s/ SR-7s and SR-2se). The card supports 36 pluggable slots and with 400 Gigabit Ethernet (GbE) has a capacity of 14.4Tbps full-duplex or 19.2Tbps in intelligent aggregation mode.

The card will also support 400ZR and ZR+ coherent modules and is ready for 800GbE pluggables that will double the card’s capacity ratings.

Nokia says the FP5 improves the throughput of the XMA card by a factor of three: Nokia’s 4.8Tbps XMA (12Tbps IA) uses four FP4 chipsets while the latest 14.4Tbps (19.2Tbps IA) XMA uses six FP5 chipsets.

Custom silicon versus disaggregated designs

Nokia says the benefits of having its own chipset justify the intellectual effort and development expense, even when advanced merchant silicon is available and certain CSPs are embracing open disaggregated routers.

“We feel there is a need in the industry for platforms based on this kind of technology,” says Adams.

What is important is the total cost of ownership and that Nokia’s systems are deployed in critical networks where resiliency, reliability, the feature set and network security are all critical, says Adams.

Nokia also points to the progress it has made since the launch of the FP4. “We have secured 350 projects, two-thirds of which were new footprints or competitive displacements,” says Adams. Nokia’s IP revenues in 2020 were $3.2 billion.

That said, Nokia also partners with merchant silicon vendors: the 7250 IXR interconnect router uses merchant silicon, for example.

“If I look at disaggregation, absolutely, it is an interesting area,” says Adams. “But I think it is very early days.”

Neil McRae, managing director and chief architect at BT, says that while some operators are looking at disaggregated software and hardware, BT doesn’t believe this is necessarily the best solution in terms of performance, reliability or cost.

Neil McRae

“Increasingly, the ratio of capital investment in core networking is moving towards optical transceivers than router silicon,” says McRae. “But to get the most out of the network and the router, using custom silicon for the most demanding cases still delivers the best outcomes.

“In our live network but also in our testing, the integrated solution is more reliable, easier to operate and a significant improvement from a total cost of ownership point of view,” says McRae.

BT says it will be able to scale interfaces on the 7750 from 1-400Gbs using the FP5 and Nokia’s SR-OS routing networking software.

BT also highlights the importance of reliability under demand, pointing out how the CSP’s traffic has doubled during the pandemic without impacting its customers.

“Nokia’s understanding of how the underlying silicon is going to react in different situations gives them a significant advantage in building the software on top that performs in challenging situations,” says McRae.

Chip Strategy

Nokia says that were it to sell its FP5 silicon as a standalone product, it would enter a very different design environment.

“You are designing to the requirements of multiple customers versus designing for your systems,” says Adams.

Nokia's belief is that there is strong demand for platforms designed to purpose.

“We are staying true to that strategy,” says Adams.