Market Leader Programs
5G Transport - A 2023 Heavy Reading Survey
2023 Open RAN Operator Survey
Coherent Optics at 100G, 400G, and Beyond
Open RAN Platforms and Architectures Operator Survey
Cloud Native 5G Core Operator Survey
Bridging the Digital Divide
5G Network Slicing Operator Survey
Open, Automated & Programmable Transport
The Journey to Cloud Native
Remember that BT is the only substantive carrier to consider deploying PBT (for the moment). And originally they intended to use it only in the backhaul network to deliver three specific features:
- Had to be based on Ethernet to allow them to deploy the Ethernet DSLAMs (called MSANs) that are an integral component of 21CN.
- Had to allow a scalable encapsulation scheme in order to enable BT Wholesale to carry multiple retail ISP traffic streams in separate logical pathways across the same backhaul link. This is a feature of the UK retail/wholesale model, and itGÇÖs one reason that ATM has been used in this part of the network historically. (Note the other is supposedly QoS, but this was always a red herring).
- Had to be cheap enough to scare the willies out of Cisco, Juniper and Alcatel, who were, and are still, all pushing VPLS solutions to BT. After all, theyGÇÖve only invested a few man-decades of development and test effort in MPLS/VPLS so itGÇÖd be nice if carriers keep deploying it.
Luckily Nortel stumbled across the BT requirement (while they were trying to convince BT to look at their platform for the 21CN iNode) and was willing to eat margin on those PBT boxes in order to stay engaged in BT 21CN, and to establish the myth that PBT is "cheaper" than MPLS. In fact an Ethernet box without a control plane will be slightly cheaper than a similar box with a control plane, but not so much cheaper that it will ever make up for the horrendous increase in operational costs a carrier would face if they deployed the box beyond a very limited scope. Remember, you need to save $5 of CapEx for every $1 of annual OpEx that you add GÇô and thatGÇÖs a very lenient view of the equation.
Meanwhile Nortel started making lots of noise about PBT, and tried to find another carrier to deploy it. A few carriers showed some interest, and there was a real incentive for those carriers to tell the world they were looking at PBT because they wanted to scare Cisco, Juniper and Alcatel too! How else can you get vendors who are retaining 70+ points of margin to cut their prices? Hey GÇô those carriers never need to really deploy PBT, they just have to say they might and they get another ten points of discount from their existing supplier!
But for any carrier to use PBT beyond the relatively modest scope that BT was considering, PBT needs a control plane. Without it PBT is just an encapsulation (plus some OAM that's built into carrier Ethernet anyway, but needs a labelling scheme to hook onto). Add a control plane to PBT and GÇô good grief GÇô where did that cost saving go!
So by getting out of hand thereGÇÖs a danger that some carriers may now really deploy PBT, because theyGÇÖll fall for the hype. And if the hype continues it means that a whole set of vendors who claim to be GÇ£technology agnosticGÇ¥ will end up supporting both techniques. Please donGÇÖt confuse this with GÇ£survival of the fittestGÇ¥. MPLS already beat ATM and has been proven to work and scale.
If carriers think that MPLS vendors are charging too much for their boxes, then thatGÇÖs the problem that needs to be fixed.