Aruba also has a reference design document for HMDs (highly mobile devices). It covers a lot of the same material, including a good focus on preserving/extending battery life for these devices. While Aruba tends to favor having fewer SSIDs, it doesn't seem possible to achieve all of the best practices for mobile VoIP phones without a dedicated SSID. Most of the phones require that the DTIM (delivery traffic indication message) be set higher than the typical defaults. As the DTIM is increased, it helps to prolong battery life (devices can sleep longer), but it comes at the expense of high throughput devices. This is one of those items where having a dedicated SSID is desirable - it allows the DTIM to be left at it's default (typically 1) for general devices, while being increased for only the dedicated VoIP SSID. Jeff
>>> On Wednesday, May 14, 2014 at 4:37 AM, in message <7f8cae21f9c1c94a90f11320ef3974cee02a6...@luemsmail01.university.liberty.edu>, "Osborne, Bruce W (Network Services)" <[email protected]> wrote: Jeffrey, We have not currently configured roaming between controllers, but roaming between APs on the same controller seems to work well for us currently. Thank you for the details you adjusted. We will need to keep these issues in mind as we move ahead. For now, moving from our legacy (hidden WEP) SSID to our 802.1x SSID makes the most sense. As we continue to grow and things change, we may need to revisit a dedicated phone SSID. Bruce Osborne Network Engineer – Wireless Team IT Network Services (434) 592-4229 LIBERTY UNIVERSITY Training Champions for Christ since 1971 From: Jeffrey Sessler [mailto:[email protected]] Sent: Tuesday, May 13, 2014 11:29 AM Subject: Re: Wifi Phone on Separate SSID` Bruce, One of the difficulties with supporting VoIP on a general SSID is that many of the standards that enhance roaming and call quality conflict and/or cause regular clients to behave oddly. For example, you wouldn't enable 802.11r on a general SSID as it is not compatible with a lot of legacy clients seen in EDU. In order to then support it, you now have the same SSID broadcasting with different supported features i.e. one with 802.11r and one without 802.11r. At this point one has to do this, it's just easier to dedicate a SSID to VoIP. Probably the biggest challenge is in roaming, and while it wasn't terrible when we had our phones associated to a general WPA2-Ent SSID, roaming was noticeable to the end-user. Most didn't complain since the experience was no worse then what you expect from a cell phone. Once we built a dedicated VoIP SSID, we enabled many of the fast roaming features - especially CCKM. This of course is proprietary to Cisco, but it does get roaming times well under 100 ms, and the client phone can now move across building/campus seamlessly. We also made changes such as extended the client re-auth time >24 hours, making WMN required, altering the DTIM period, load based CAC, etc. The call quality now is equal to that of our ethernet connected Cisco VoIP desktop phones and roaming is seamless. best, Jeff >>> On Tuesday, May 13, 2014 at 4:30 AM, in message <7f8cae21f9c1c94a90f11320ef3974cee02a5...@luemsmail01.university.liberty.edu>, "Osborne, Bruce W (Network Services)" <[email protected]> wrote: Jeffrey, Your advice is probably good for Cisco wireless, but not other vendors. On Aruba wireless, client-specific settings can be configured on the firewall user role. Aruba also intelligently detects voice traffic to prioritize and process it differently. We have not had any issues with our Cisco wireless phones on our normal WPA2-Enterprise SSID. Bruce Osborne Network Engineer – Wireless Team IT Network Services (434) 592-4229 LIBERTY UNIVERSITY Training Champions for Christ since 1971 From: Jeffrey Sessler [mailto:[email protected]] Sent: Monday, May 12, 2014 6:51 PM Subject: Re: Wifi Phone on Separate SSID` Stick to the dedicated SSID for wireless. There are a number of knobs that need to be adjusted to ensure a wireless phone works well and some of these same knobs can interfere with normal client operation. We started out with our wireless cisco phones on our general WPA2-Ent network but there were a lot of consistency issues, especially with roaming. We then setup a separate VoIP SSID (not broadcast), turned all the knobs to the correct settings, and now the phones are flawless in operation including roaming. Our VoIP SSID is WPA2-Ent (peap-mschapv2), and we create a dedicated user for each phone based on its extension. There is a Cicso document out there with step-by-step instructions for setting up a dedicated VoIP SSID. The document is a work of art - probably one of the best I've seen with screen grabs of the WLC/WCS/Prime configuration screens. If you can't find it, email me off-list and I'll send you the copy I have. Jeff >>> "Legge, Jeffry" <[email protected]> 5/8/2014 9:39 AM >>> I currently have a separate SSID for wireless cisco phones. I am thinking about using my wpa2 secure SSID for them. Anybody got any caveats or suggestions? Jeff Legge Network Services Radford University (540)-831-7727 ********** 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/. ********** 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/. ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.
