RE: 1GBE as a bottleneck to APs?
Yes the math and real performance does not add up. I am comfortable relying on 1 gig uplinks for now. There may be special case areas the you could consider needing more uplink but I agree with many of the other responders to this. Legacy clients, consumer grade clients, designing toward capacity rather coverage really divide the load and reduce some of the chances of hitting the Gig bottleneck. I have also seen a decrease in client throughput capability now that clients are moving from N to ac. All of our N cards were 3 streams. All the new PC's with ac cards are 2 Streams. If I am designing my 5Ghz at 40 Meg channels the older 3 stream N can run faster than a new ac client minus the other ac features of course. I have recently seen some installs where 2 or 3 cables are pulled per AP and have been considering this but I think I will keep it to 1 cable at this point. Tracking and storing those extra cables will really multiply idle cabling in our closets. I am sure that by the time we need that much more uplink per AP we may be in the area doing other upgrades as well. John Cosgrove Network Staff Specialist Penn State Hershey College of Medicine From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU] On Behalf Of Hinson, Matthew P Sent: Tuesday, March 24, 2015 10:38 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: [WIRELESS-LAN] 1GBE as a bottleneck to APs? 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 ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
RE: 1GBE as a bottleneck to APs?
I think that is there is a need for it, it will be in highly specific locations and uses. It is definitely not an issue for the general population. I applaud Cisco for working on a way to up the bandwidth over existing cabling, as that is obviously an ideal solution for most of us. Particularly because I never saw the justification, price or otherwise, for running 2 cables to an AP on the off chance that one day we'll need to use both for it to operate properly. Having to double the needed patch panels, cabling, and switches in the closet is reason enough not to do it. Also, considering that we'll need to use 160Mhz channels to get to these speeds, I can't imagine too many of us having that configuration as the default configuration. Great for someone's home where there's no co-channel interference, not as much for the enterprise. -Patrick From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU] On Behalf Of Hinson, Matthew P Sent: Tuesday, March 24, 2015 10:38 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: [WIRELESS-LAN] 1GBE as a bottleneck to APs? 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 ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
RE: 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:WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU] On Behalf Of Chuck Enfield Sent: Tuesday, March 24, 2015 10:24 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU 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:WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU] On Behalf Of Frank Sweetser Sent: Tuesday, March 24, 2015 11:06 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU 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 ** Participation and subscription information for
RE: 1GBE as a bottleneck to APs?
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:WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU] On Behalf Of McClintic, Thomas Sent: Tuesday, March 24, 2015 11:45 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU 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:WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU] On Behalf Of Chuck Enfield Sent: Tuesday, March 24, 2015 10:24 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU 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:WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU] On Behalf Of Frank Sweetser Sent: Tuesday, March 24, 2015 11:06 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU 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
RE: 1GBE as a bottleneck to APs?
Lots of varying opinions out there on this. http://www.revolutionwifi.net/revolutionwifi/2015/1/multi-gigabit-ap-backhaul-do-you-need-it http://www.theruckusroom.net/2014/02/will-80211ac-stab-you-in-the-backhaul.html From: The EDUCAUSE Wireless Issues Constituent Group Listserv [mailto:WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU] On Behalf Of Hinson, Matthew P Sent: Tuesday, March 24, 2015 10:38 AM To: WIRELESS-LAN@LISTSERV.EDUCAUSE.EDU Subject: [WIRELESS-LAN] 1GBE as a bottleneck to APs? 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 ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/. ** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
