[AusNOG] 10GBase-T SFP modules?

[James Andrewartha]

On Thu, 10 Jul 2014, Beeson, Ayden wrote:

> I'd disagree; we are looking at installing it not for single user performance, but for multi-user throughput, particularly in semi-dense or dense deployment areas.

Are you aware that client chipsets need to support MU-MIMO too? So you 
won't see any improvements for a few years yet.

> A single user has no use (right now) for that sort of bandwidth, but you start throwing a few users on w/ high bitrate applications and the beam forming allows you to realise a lot more of that theoretical bandwidth than before in large deployments.
> 
> Even with 80 MHz channels (which you can use those restricted ones if you have the radios that are certified for it with DFS and TPC, giving a total of 4 usable IIRC) you can easily make over 1gbps per user with the multiple streams.

Do you currently use DFS channels?

> They can also do some cool stuff with split 160 MHz channels, allowing them to join 80 MHz blocks in a staggered fashion to create alternate channels to reduce overlap, but you are still right, it's unlikely to see use in the enterprise space.

IIRC split channels require another radio chain, which means more power 
again and hence less likely to be supported in mobile chipsets.

> As for the 10gbps ports, watch this space, a lot will change in the next few years, we are on the cusp of a new network refresh and will definitely be looking to design for wave 2. Our current 11n wireless is saturated pretty much 99% of the time by student traffic already.
>
> I know a few manufacturers have a lot more 10Gbase-T stuff about to come out, some of them a lot more access focused....
> 
> Power wise, you would be hard pressed to find new POE gear these days that didn't do 802.3at. The equipment we are installing now in the interim is 3850 UPOE switches, which can do a full 60w per port. Older deployments will obviously have problems there, but I don't expect many people will be installing AC wave 2 wireless radios without some thought to upgrading the wired equipment behind it anyway....

Sure, you may have fancy new switches that do 802.3at, but then you'll 
have to refresh again when 10GBASE-T with PoE becomes available. I know my 
switch lifetime is about 8 years at the moment. Also, per the other half 
of this thread, the 10GBASE-T PHY has significant power draw too.

> I definitely agree, it's a niche market at the moment but I think we will all be shocked how quick the ac deployments ramp up once wave 2 drops and there is a compelling reason to upgrade...

Sure, if you're upgrading your wireless now there's no reason not to go 
ac, and shipments are showing that. But 10GBASE-T to the AP? YAGNI.

> Heaps of good info in this btw:
> http://www.cisco.com/c/en/us/products/collateral/wireless/aironet-3600-series/white_paper_c11-713103.html#_Toc331821649

I nearly linked to that page myself :) It also includes a graph that shows 
4SS 80MHz Wave 2 having a data rate of 1500Mbps at up to 20 feet (I assume 
the distance is in feet). Assuming a 70% efficiency rate (again from that 
document), that's 1050Mbps. Are you going to upgrade your entire switch 
infrastructure so people within 6m of the AP can share an extra 5% peak 
bandwidth?

And that assumes that all traffic is in one direction, since 802.11 is 
half duplex, but 802.3 is full duplex. I bet of enough of the increased 
wireless load is things like Instagram etc. uploading pictures that you're 
not going to hit 1Gbps unidirectional.

> Disclaimer - Obviously wave 2 could turn out to not meet any of these expectations, it's hard to say seeing as I don't have any of the gear yet but for now, it looks useful to me and something we are definitely planning for.

IMHO, given you're seeing capacity problems now, you'd be better served 
increasing density. An AP with a single 5GHz wave 2 802.11ac radio should 
come in inside 803.3af, then you can deploy lots of them with 40MHz 
channels. This will improve things for existing 802.11n clients rather 
than just those with 802.11ac as well.


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