We have a big roll out of new .11ac APs this summer and we have decided
to run one CAT6a cable to the APs for future capacity. I expect that 10G
switches and APs will be common place before the next refresh. I can
understand running a second wire only if you are doing a refresh and
dual 2.5G was common place. Even then I would be running a CAT6a as the
second cable.
Kevin McCormick
uTech Network Services
Western Illinois University
On 3/24/2015 11:58 AM, Deshong, Kenneth wrote:
With the advance in Cisco's new Multigigabit technology you can use existing
CAT5e\CAT6 cables and run speeds 5GB/10GB respectively over copper. No need to
run multiple cables to your Access Points. I saw a presentation by Cisco where
the new 3850's coming out this year will already support this technology. I'm
assuming their Wave 2 Access Points will also support this and you can
effectively run 5gbps over your older CAT5e cables. While I do agree, 20-40
users on an access points doesn't make it necessary to run 10GB to that access
point, I would rather have it and not need it. Any Cisco shops can attest, most
of the time when they roll out a new AP/Switch, the price point is usually
pretty close or the same as the older model so it only makes sense to roll out
the new technology.
http://www.cisco.com/c/dam/en/us/solutions/collateral/enterprise-networks/catalyst-multigigabit-switching/multigigabit-ethernet-technology.pdf
Ken DeShong
Network Engineer
USF Health Information Systems
Desk: 813-396-9472
Fax: 813-974-5198
Amazing Things Happen When You Connect the Unconnected
-----Original Message-----
From: The EDUCAUSE Wireless Issues Constituent Group Listserv
[mailto:[email protected]] On Behalf Of McClintic, Thomas
Sent: Tuesday, March 24, 2015 11:45 AM
To: [email protected]
Subject: Re: [WIRELESS-LAN] 1GBE as a bottleneck to APs?
For now mgig doesn't seem necessary from a wireless perspective. I think new
installations may justify multiple drops if you know funding for some areas
comes and goes. Like a slow refresh on switch gear, but the ability to upgrade
to full AC Aps. Mgig will most likely be driven from our research departments
as they upgrade machines with newer NICs and expect to take advantage of it. We
try to anticipate the needs and so far we see very little need for mgig on the
wireless front.
-----Original Message-----
From: The EDUCAUSE Wireless Issues Constituent Group Listserv
[mailto:[email protected]] On Behalf Of Chuck Enfield
Sent: Tuesday, March 24, 2015 10:24 AM
To: [email protected]
Subject: Re: [WIRELESS-LAN] 1GBE as a bottleneck to APs?
I'd add to Frank's list:
- Wave 2 won't increase spectral efficiency as much as initially projected.
Expect 2x once most of the client radios are wave-2 11ac rather than the 4x
that was being tossed around a year ago.
- Most, if not all, ac client devices will be 2-stream.
- There's insufficient spectrum available to leverage 80MHz channels.
Even if more spectrum becomes available in the next couple years, it will be
years after that before a large enough percentage of client devices support
those new channels for them to be useful.
Add all this up and it is likely to be at least 5 years before you achieve Gbit
on the wire to 802.11ac APs, and it may never happen. If you agree with this
assessment, then there's no reason to rush into proprietary multi-gig edge
switching. It seems wise to wait for an IEEE standard.
Chuck Enfield
Manager, Wireless Systems & Engineering
Telecommunications & Networking Services The Pennsylvania State University
110H, USB2, UP, PA 16802
ph: 814.863.8715
fx: 814.865.3988
-----Original Message-----
From: The EDUCAUSE Wireless Issues Constituent Group Listserv
[mailto:[email protected]] On Behalf Of Frank Sweetser
Sent: Tuesday, March 24, 2015 11:06 AM
To: [email protected]
Subject: Re: [WIRELESS-LAN] 1GBE as a bottleneck to APs?
Personally, I'm not too worried about it.
While naively adding up the wireless marketing sheets gets you to > 1Gb
numbers, especially when treated with Wave 2 pixie dust, I think there are a few
factors which make this a low concern.
- The wireless numbers are half duplex, while that 1Gb wired connection is
full duplex. This means that while your client bandwidth is probably going to
be biased download more than upload, the upload and download packets that are
bottlenecked through the common air time each have their own contention-free
1Gb channel once they hit the wired network.
- Wireless throughput is *very* picky at top speeds. I've seen estimates
that those magic wave 2 numbers won't be reachable more than a few meters away
from the AP.
- It only takes a few legacy clients hopping onto your nice new 11ac AP to
drag you back down to a fraction of your peak throughput. Given how many
budget laptops are being sold today with 2 stream, 2.4GHz only 11n adapters,
this problem will be with us for a long time.
Even if you do end up in a situation that legitimately needs over 1Gb, I'd be
careful before relying on the LACP based solutions. Unless you're terminating
your user sessions locally, all of the traffic will be going through an
encapsulated tunnel between the AP and controller, which can easily end up
hashing all of the traffic down one link. There are tricks to work around this
(I believe Aruba opens up multiple tunnels with different endpoint IP
addresses, for example), but this it's still an imperfect solution where 1 + 1
!= 2.
So my guess is that we have a few years before it's a major concern, and I'm
waiting on a decent answer for 2.5Gb switching before I do any real investment
in a solution.
Frank Sweetser fs at wpi.edu | For every problem, there is a solution
that
Manager of Network Operations | is simple, elegant, and wrong.
Worcester Polytechnic Institute | - HL Mencken
On 3/24/2015 10:37 AM, Hinson, Matthew P wrote:
I've seen a few articles here and there regarding possible solutions
for "the gigabit bottleneck" as it pertains to .11ac access points.
Said solutions include Cisco's forthcoming protocols for 2.5G and 5G
over CAT5 cabling as well as LACP'ing two gigabit ports per switch and
AP as some vendors suggest...
My question for the group is: Has anyone actually seen a throughput
issue using gigabit to the edge? Certainly your distribution layer
gear could be a limitation if it's not specced correctly, but I've
just never seen a situation where I've wished for more than 1000BASE-T
to an AP. Our fastest 802.11ac access points can "only" hit
600-700mbit/s real TCP throughput, and that's in ideal, almost
laboratory conditions.
Thoughts?
Thank you!
Matthew Hinson
Network Operations
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