x
Optical/IP

Extreme Tunes Up Metro Strategy

With recent standards work and some new proprietary technology, Extreme Networks Inc. (Nasdaq: EXTR) is fine-tuning its approach to metro Ethernet.

Extreme has been involved in metro networks for some time, of course, with its BlackDiamond line of switches. Lately, though, the company seems to be getting more aggressive, hoping to secure a foothold in the future of carrier Ethernet.

Extreme's ideas center around carriers using Layer 2 MPLS, rather than IP routing, to scale Ethernet in the metro. Extreme was pushing the concept particularly hard at last month's Supercomm, targeting the reignited obsession with the triple-play of voice, video, and data services running on one network.

"Carriers are really interested in how triple-play is going to work on the Ethernet network. They were going to do that on the ATM network, and that didn't work," says Craig Easley, director of service provider marketing for Extreme.

Juniper Networks Inc. (Nasdaq: JNPR), for one, agrees that Layer 2 is appropriate for metro networks. It's when networks extend to multiple cities -- say, joining Dallas to Los Angeles -- that IP routing needs to come into play, says Mike Capuano, senior product manager with Juniper.

The Layer 2 approach will work "especially if it's a multipoint-to-multipoint Ethernet offering to connect offices together, and especially if there are ITU or IEEE enhancements that come out for monitoring an Ethernet network," Capuano says.

Extreme's latest contribution is a proprietary traffic management scheme for the BlackDiamond line of switches. The idea is to help carriers cope with the broadening number of services coming to the edge.

The new features enable a switch to steal bandwidth from unused services, so that a voice call could use the bandwidth originally allocated for a video service that's dormant, for example. Previously, carriers had to reserve bandwidth for each service, and if the service went unused, so did the bandwidth.

The ability to split and share bandwidth could be important, because providers prefer selling to "mom-and-pop" businesses that need connections of 10 Mbit/s or less, which can be conjoined on Gigabit Ethernet pipes. By contrast, bigger businesses go for a full 1 Gbit/s and use up the entire pipe, creating less margin for the provider. "A lot of the big metro Ethernet providers discourage their guys from selling to [large] businesses," Easley says.

To help push its case in metro Ethernet, Extreme has been increasingly vocal at standards bodies and industry forums. Extreme is hoping this work will help it stand out next to competitors including Atrica Inc., Cisco Systems Inc. (Nasdaq: CSCO), Foundry Networks Inc. (Nasdaq: FDRY), Nortel Networks Ltd. (NYSE/Toronto: NT), and Riverstone Networks Inc. (OTC: RSTN.PK), among others.

Standards work is particularly important, given that most of these companies have introduced proprietary technologies for metro Ethernet, some of which are just beginning to settle in as standards. Proprietary technologies from Cisco and Nortel, for example, helped kick off discussions that led to the IEEE 802.17 standard for Resilient Packet Ring Technology. Companies other than Cisco can't afford to get left out of the process. "Extreme's not going to be able to sell something very effectively without standards," says Erik Suppiger, an analyst with Pacific Growth Equities Inc.

To that end, Extreme is backing tag stacking, also called Q-in-Q, through the IEEE, as part of the 802.1ad standard for provider bridging. Tag stacking creates a two-layer hierarchy of VLAN tags, making larger networks possible by grouping VLAN destinations in a hub-and-spoke fashion.

Extreme has also turned its proprietary Ethernet Active Protection System (EAPS) into IETF Request for Comment 3619, although this document is only "informational," Easley says. "We're not pushing to make it be a standard. We published it to make it open, so partners like Ericsson and Siemens can implement it."

Version 2 of EAPS came out this summer, and it shortens the restoration time to less than 50 milliseconds, the gold standard commanded by service providers. EAPS has been around for some time, as have some other proprietary Ethernet-ring schemes. Atrica had claimed to have accomplished 50ms restoration with its Atrica Resilient Ethernet Access (AREA) in 2002; separately, Riverstone developed Rapid Ring Spanning Tree Protocol (RRSTP), another fast protection scheme for Ethernet rings, in 2001 (see Metro Ethernet).

— Craig Matsumoto, Senior Editor, Light Reading
For more on this topic, check out:


For further education, visit the archives of related Light Reading Webinars:

Page 1 / 2   >   >>
sgan201 12/5/2012 | 1:28:07 AM
re: Extreme Tunes Up Metro Strategy Hi Mr. Zippy,
There is an assumption here which may or may not be true. Bandwidth is cheap and it can be sacrificed to provide simpler access like Ethernet. That assumption is probably true in some situation and wrong in others..

But, treating this as universal truth and that is where it failed..

Dreamer
mr zippy 12/5/2012 | 1:28:07 AM
re: Extreme Tunes Up Metro Strategy I'm all for ethernet being used more widely, in the metro and long distance areas. I think the fundamental benefit it delivers is lower costs, due to the already commodity and simplicity nature of ethernet technology.

However, one of the fundamental characteristics of ethernet, which are taken advantage of by all popular or soon to be popular protocols eg., IPv4, IPv6 etc., are broadcasts or multicasts ie., the ability to have a node send a single packet, and have the network replicate it to all or a subset of all devices attached to the network.

Reading through this article, it seems all the commentary is saying "get rid of routing, layer 2 forwarding is better and simpler". The problem with this argument is that routing provides two things - fine grained traffic direction based on specific destinations, and broadcast / multicast control.

Anybody who has dealt with a reasonably large, switched ethernet LAN knows that broadcast / multicast traffic can become an issue, as the switches flood this traffic to all nodes, whether they are interested or not.

For multicast, you can implement tricks such as IGMP snooping to minimise this effect, however, to implement that usefully, you need to implement inter-switch protocols to start keeping track of which devices are interested in which multicasts across the whole network. To be honest, I don't know if these "inter-switch" protocols exist - I know them as routing protocols, eg. PIM, MOPSF etc. Oops, looks like you might need to implement routers after all.

So, you can take care of multicasts using IGMP snooping, and multicast routing protocols . What about broadcasts ? Broadcasts still have to be forwarded to all devices, as that is the definition of a "broadcast". How do you limit the scope of a broadcast ? Implement routers, creating multiple broadcast domains.

Radia Perlman has a whole chapter on bridges verses routers ie. layer 2 verses layer 3 forwarding in her book "Interconnections, 2nd Edition".

So, have I somehow missed the point ? Or is it that the attraction of an extremely commodity protocol like ethernet caused people to forget the problems routing is trying to solve, such that they think layer 2 forwarding is the best solution ?
Tony Li 12/5/2012 | 1:28:06 AM
re: Extreme Tunes Up Metro Strategy
Zippy,

You are not dumb. However, I think that the motivations here are quite transparent. In my opinion, the vendor is accentuating their strengths and downplaying the shortcomings of their approach. The informed consumer is unlikely to be taken in by this little charade and will debit the vendor's reputation accordingly.

Tony
wilecoyote 12/5/2012 | 1:28:03 AM
re: Extreme Tunes Up Metro Strategy Nuff said.

Nah, I'm already here, and in a mood. What the heck.

When's the last time Extreme made a strategic move that was anything more than a press release? Where's their WiFi product? Ask the people at Cisco, Trapeze, Aruba or Airspace if they've ever even seen Extreme compete there.

Where are the carrier wins? They gave up.

Where's the 10Gig product? Still at least a year out and won't even compete against Mucho Grande much less Sup720/Constellation 3, Force10.

So what is Extreme actually doing? Squandering their war chest and floundering around. Time for someone to hook this fish and gut it.
vinay 12/5/2012 | 1:27:54 AM
re: Extreme Tunes Up Metro Strategy So, have I somehow missed the point ? Or is it that the attraction of an extremely commodity protocol like ethernet caused people to forget the problems routing is trying to solve, such that they think layer 2 forwarding is the best solution ?
----------

Metro ethernet does not necessarily involve pure L2 forwarding in lieu of L3 forwarding. Metro ethernet strategy with MPLS is clearly becoming the choice for deploying in the metro transport. This what the artcile is talking about.

If most of the L3 traffic is aggregated at the central office or the pop(s), I don't need to plop a router all over the metro network. I would be looking for alternatives that are cheaper and easier to manage and maintain. Metro ethernet and MPLS address this situation.

Vinay Bannai
rs50terra 12/5/2012 | 1:27:53 AM
re: Extreme Tunes Up Metro Strategy I am sure I miss something profound in this discussion. But being a novice, I will still ask the question.

I thought MPLS is a sort of Layer2.5. It still depends on OSPF to build the forwarding table and its big advantage is to simplify forwarding and, with the new additions, to provide resiliance and traffic engineering.

That being so, it seems MPLS is rather similar to a L3 protocol than to pure Ethernet.

Would somebody be kind enough to tell me if I got it all wrong and where?

Thanks.
coreghost 12/5/2012 | 1:27:52 AM
re: Extreme Tunes Up Metro Strategy I thought MPLS is a sort of Layer2.5. It still depends on OSPF to build the forwarding table and its big advantage is to simplify forwarding and, with the new additions, to provide resiliance and traffic engineering.



MPLS is a layer-2 technology for tunneling and
label-switching packets. The labels are set up
across the network using signaling protocols
that work at layer-3. Your creating a layer-2
path across a network (a tunnel) using layer-3
to discover the topology and signal the tunnel
setup end to end.

Its big advantage as I see it is that it provides
a way of creating tunnels over an IP network
in a clean way as compared to IP tunnels. It
also provides a way to create tunnels with
resource reservations that does not require ATM
hardware.

There isn't one overwhelming advantage though.
What MPLS does is provide a toolbox that enables
many different things to be done that are of
use in networks.
mr zippy 12/5/2012 | 1:27:51 AM
re: Extreme Tunes Up Metro Strategy If most of the L3 traffic is aggregated at the central office or the pop(s), I don't need to plop a router all over the metro network. I would be looking for alternatives that are cheaper and easier to manage and maintain. Metro ethernet and MPLS address this situation.

Is this the "VPLS" - Virtual Private LAN Service - that is being talked about ? I'll admit I haven't done any research into it, so I'm purely speculating. Part of my motivation for asking if "I was dumb" was to see if somebody might give me a quick heads up.

As I understand it, the motiviation for these solutions is to be able to provide the customer with a "routerless" environment ie. the carrier provides an ethernet jack at the customer sites, and all of the sites are made into a single LAN via layer 2 MPLS VPNs across the carrier networks. Any and all "complexity" is in the carrier network, the customer just plugs in the ethernet to a local ethernet switch, and away they go. No routers, no multiple subnets.

Even if bandwith is large and cheap, there are still a few issues that I'm curious about :

(a) what mechanism within the MPLS network is used to ensure broadcasts / multicast / unknown destinations are flooded to all sites that are part of the "LAN" ?

(b) at a certain scaling point, broadcasts / multicasts / unknown destination layer 2 traffic will become excessive, due to either endnodes receiving too much traffic, or the MPLS network struggling to replicate too many packets across too many sites. I think routers would have to be implemented to solve this problem. In that case the "Virtual (single) LAN" would now consist of multiple subnets ie. it wouldn't be a single LAN anymore, which I would think would be the major selling point of this solution to customers.

As I understand it, this solution is basically shifting some of the network complexity (ie. routing-like functionatlity) from the customer site to within the carrier network. I can understand the idea of shifting it, however, the way it is talked about, the complexity seems to have been "eliminated", which is why it is so "wonderful". Even though a lot of experts have worked on the layer 2 vs layer 3 forwarding problem for many years (and I think MPLS is one of the outcomes of that effort), it seems too good to be true if the complexity has just evaporated.


Tony Li 12/5/2012 | 1:27:50 AM
re: Extreme Tunes Up Metro Strategy One of the ways that this can be addressed is by playing some games with multiple VLANs arriving at the same customer switch. If the provider uses a VLAN to effectively model a point-to-point serial link and then lets the customer switches form those links into a mesh, then all of the multicast/broadcast replication issues remain in the customer switch.

Yes, this shifts some of the complexity back to the customer, but addresses the issues that you raise.

Tony
vinay 12/5/2012 | 1:27:49 AM
re: Extreme Tunes Up Metro Strategy Is this the "VPLS" - Virtual Private LAN Service - that is being talked about ? I'll admit I haven't done any research into it, so I'm purely speculating. Part of my motivation for asking if "I was dumb" was to see if somebody might give me a quick heads up.
---------------

VPLS is one such service. There are also quite a few applications which can be solved using ethernet private lines. As Tony mentioned earlier in the previous post you can push the task of multicasting/broadcasting/flooding to the customer edge device.

As far your concerns regarding (a) and (b)

(a) One of mechanisms for the MPLS device is to replicate packets on the different LSPs. This is easier said than done. Another mechanism is to use the native multicast mechanism of the underlying layer (if the support exists). For instance in RPR networks, the broadcast/multicast is done using source stripping. Another way to abstract replciating is to create a multicast MPLS LSP.

(b) Most organizations while creating a geographical L2 VPN would balk at creating such a flat network. What you are talking about involves customer sites directly connecting to the service provider's ethernet jack through a L2 switch.

I think the argument is backwards. The customer does connect to the service provider using a router/firewall/NAT and the service provider does not inherit the customers routing and handing off to the POP router. The solution appeals to pure transport service providers or the groups within a ISP which are responsible for transport.

Vinay Bannai
Page 1 / 2   >   >>
HOME
Sign In
SEARCH
CLOSE
MORE
CLOSE