Ethernet equipment

Vendors Clash Over PBT

PBT (Provider Backbone Transport) has solidified its reputation as the telecom industry's most controversial technology, with its supporters and detractors jostling for the chance to talk up or shoot down its potential. (See PBT: New Kid on the Metro Block.)

With most of the carrier community watching from the sidelines, equipment vendors have argued vociferously about the validity of PBT (the pre-standards connection-oriented flavor of Ethernet) as a technology worthy of commercial deployment, with the pro- and anti-PBT camps clashing again at the Carrier Ethernet World Congress in Geneva last week. (See PBT vs MPLS: Round VII.)

There, Nortel Networks Ltd. , Ciena Corp. (NYSE: CIEN), Extreme Networks Inc. (Nasdaq: EXTR), Meriton Networks Inc. , and Nokia Networks were PBT's most vocal supporters, while the leading MPLS vendors -- Alcatel-Lucent (NYSE: ALU), Cisco Systems Inc. (Nasdaq: CSCO), and Juniper Networks Inc. (NYSE: JNPR) –- were the technology's major detractors in presentations and panel sessions. (See Nortel Touts Ecosystem and Extreme Tests PBT.)

That division exists because PBT is regarded as an alternative to MPLS in metro networks, a tension highlighted in the latest Light Reading Insider, MPLS vs. PBT: The Empire Strikes Back.

In that report, author Simon Sherrington finds the MPLS vendors under pressure from advances in Carrier Ethernet technology, and having to fight hard to "justify the role of their technology in metro and access infrastructures." (See MPLS: Metro a No-Go?.)

The end result, he feels, is that the emergence of PBT as an option for carriers will drive MPLS innovation and new product development -- something that will ultimately have a positive impact on the router vendors.

Validating multivendor deployments
Pressure on the MPLS vendors intensified in Geneva, where German test facility European Advanced Networking Test Center AG (EANTC) replicated a metro and access network using technology from 24 different vendors. (See Hammerhead Demos PBT, WWP Combines MPLS, PBT, RAD Plays Ethernet Test Role, Gridpoint Plans PBT, Soapstone Goes to CEWC, and TPack Talks Ethernet.)

The demonstration network showed how Ethernet services could run end-to-end across network clouds that were using three different transport and aggregation technologies –- MPLS, PBT, and Transport MPLS (T-MPLS), a stripped down version of MPLS that is similar in nature to PBT. (See EANTC Preps MEF Demo.)

The resulting white paper is available at EANTC's Website..

The challenge set by constructing that test network, notes EANTC managing director Carsten Rossenhoevel, was "to interconnect the three metro clouds to an MPLS core" and run services across the clouds. "Interworking between MPLS and PBT was more or less seamless," says Rossenhoevel.

Having conducted numerous network tests involving many fixed and wireless technologies previously, the EANTC man was surprised by the success attained with a non-standard technology. "Successful interoperability with PBT at such an early stage is very reassuring," he says. "This has been a milestone" for the technology.

Independent evidence that PBT and MPLS can co-exist will be reassuring for carriers looking to deploy the new flavor of Ethernet, and none more so than BT Group plc (NYSE: BT; London: BTA), the one major carrier to have thrown its weight behind PBT.

BT has worked with Nortel on developing PBT, is involved in the standards development work at the Institute of Electrical and Electronics Engineers Inc. (IEEE) , has already deployed PBT in Italy, and is working towards deployment in the U.K. (See BT Goes Live With PBT.)

PBT survey reveals carrier indecision
But while the pro-PBT camp has gathered increasing support, and other major carriers are known to be checking out PBT's potential, the technology is still regarded as a risk by many carriers, while vendors with PBT solutions admit that the current interest shown by operators is largely based on curiosity. (See Deutsche Telekom Flirts With PBT, Nortel Lands More PBT Action, and Verizon Preps God Box RFP.)

A survey of carriers conducted by Synergy Research Group Inc. shows that a vast majority, around 70 percent, are "uncertain" about whether they might deploy PBT, while less than 25 percent stated they were definitely interested in deploying the technology. A small percentage, less than 10 percent, had no interest in PBT at all.

Synergy's research showed that the lack of a standard was PBT's major negative. The technology is currently going through the standards process at the Institute of Electrical and Electronics Engineers Inc. (IEEE) , where it is known as PBB-TE (Provider Backbone Bridging - Traffic Engineering), but is not expected to be ratified until some time in late 2008 or during 2009.

In the meantime, PBT continues to attract further vendor support. (See Ciena Falls in PBT Camp, Bay Adds PBT, and Lightstorm Charges Into Ethernet.)

— Ray Le Maistre, International News Editor, Light Reading

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franco_mv 12/5/2012 | 3:01:12 PM
re: Vendors Clash Over PBT I would like to put some light on the CAPEX discussions so far.

I've seen lot of claims about PBB/PBT being cheaper, just because it's simple technology.
When we look at existing MPLS solutions - ALU (ESS/SR), CSCO (7600) and JNPR (MX) - I understand that their hw cost is related to do wirespeed filter, classification and queueing (thousand's of queues per port) and this is not related to control plane. If this is the case PBB/PBT boxes
will sit at same cost level as the QoS requirements are still demanded, but nobody is talking about this.

Btw, there's people in our industry comparing PBB/PBT switches against core routers, putting power consumption and manuals in the table.
What a shame!
t.bogataj 12/5/2012 | 3:01:13 PM
re: Vendors Clash Over PBT M. Vissers,

Thank you for clarification of technical aspects. Indisputably, it cannot be questioned.

I was not saying that PBBNs required no configuration. They do. The point I was making was elsewhere: it was in the difference between configuration, and embedded control plane mechanisms -- like, for example, active MAC-learning and active topology protocols (xSTP).

Let's take it step by step. 802.1Q bridges require configuration (VIDs, port membership, tagging, etc.). But they actively learn MACs by flooding, and are able to resolve loops. No path provisioning through bridge network required.

802.1ad bridges require configuration as well. Unlike .1Q bridges, they also need multiple-tag configuration (C- and P-VIDs). But only on edge bridges: core bridges may be .1Q-compatible. No path provisioning through bridge network required.

802.1ah bridges require even more configuration (C-VIDs, S-VIDs, etc.). But again, only edge bridges (BEBs) need this configuration: core bridges (BCBs) may be .1Q-compatible. No path provisioning through bridge network required.

Therefore, in PBNs (.1ad) and PBBNs (.1ah), no path provisioning is required. Only edge bridges (edge meaning service edge) require a bit more complex configuration. Core bridges require only .1Q-like configuration. All forwarding through PBN or PBBN is learned actively using .1Q mechanisms. All loops within PBN or PBBN are resolved using, say, xSTP.

PBB-TE, on the other hand, requires manual path set-up. All learning mechanisms within transport equipment are disabled. Transport equipment becomes dumb. And path provisioning is moved to external control/management plane equipment. For which GMPLS is the most likely (if not the only) candidate.

In terms of cost, how does PBB compare to PBB-TE? PBB requires BCBs to support nothing more but 802.1Q. PBB-TE requires *all* BCBs to support PBB-TE. And PBB-TE enabled networks require costly GMPLS control plane.

And comparison to T-MPLS? Again: T-MPLS comes with control plane. PBB has it built-in. With PBT -- pay a bit more for PBB-TE enabled BCBs, and pay a lot more for GMPLS.


macster 12/5/2012 | 3:01:14 PM
re: Vendors Clash Over PBT PBB requires a lot of configuration to get any service up and running. PBB is the first ethernet network with two layers: backbone service and B-VLAN (i.e. a tunnel layer).

Provider layers - yes.
macster 12/5/2012 | 3:01:15 PM
re: Vendors Clash Over PBT Agreed. Re-visited your earlier post and read it whole.

At first pass, thought MSTP to mean smtg else - apologies...
CoreRouterBuilder 12/5/2012 | 3:01:15 PM
re: Vendors Clash Over PBT where is the traffic engineering here ?
mvissers 12/5/2012 | 3:01:15 PM
re: Vendors Clash Over PBT MSTP: Multiple Spanning Tree Protocol; see clause 13/802.1Q-2005.

802.1D networks include a single VLAN. 802.1Q networks include multiple VLANs, still within one layer.

802.1ad networks introduce a single layer network in the provider domain, able to carry customer VLAN signals.

802.1ah introduces two layers in the provider network. When applied UNI-to-UNI, there are only those two layers in the provider domain. When applied between PB networks, then you will have three layers in the provider domain; that is one more than necessary.
macster 12/5/2012 | 3:01:17 PM
re: Vendors Clash Over PBT t.bog,

I am not going to comment on cost savings - as mentioned in a previous article.

What I wanted to point out is that we cannot compare PBT with PBB. That's like comparing a motorcycle with a car. True, both gets us from point A to B, but such a comparison beggars disbelief!
macster 12/5/2012 | 3:01:17 PM
re: Vendors Clash Over PBT PBB requires a lot of configuration to get any service up and running. PBB is the first ethernet network with two layers: backbone service and B-VLAN (i.e. a tunnel layer).

Ethernet's flat hierarchy required improvement. VLANs (802.1q) brought about a 2-layer hierarchy.

Q-in-Q (802.1ad) and (MAC-in-MAC) made this a THREE layer hierarchy.


Each PBB network domain contains a few B-VLANs which you need to set up on top of a MSTP environment .....
You do not need an MSTP/MSPP in a PBB environment!!!

I earnestly ask request that you go and read up on this topic before posting... did not bother reading further...
t.bogataj 12/5/2012 | 3:01:18 PM
re: Vendors Clash Over PBT Welcome, M.V.! Thought you'd never join... :)
t.bogataj 12/5/2012 | 3:01:18 PM
re: Vendors Clash Over PBT macster: "Sum this up!"

I did, several times. Whichever way I did it, I got the same answer: 42. (Well, what else could it be?)

OK, seriously. T-MPLS comes with control plane. PBB has it built-in. With PBT -- pay extra for it.

Who can save with PBT? Perhaps... big incumbents, who can keep their SDH/SONET mindset, and the way they operate their networks? Only faking a transition to IP (or NGN or whatever you call it)? Yes, it can be appealing to them. But not for the cost of PBT itself, rather for the whole calculation.

tata, T.
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