physical separation of VOIP vs data only stacks

[brazenhead]

Hi,

We are planning on deploying VOIP in the near future and I am curious about how others might have adjusted their network topology when implementing VOIP. Specifically, I hoping some of you might have a similar situation as ours: in a typical wiring closet at our institution, we have several network connections (that will be) voice and/or data (employee offices, etc) and others that will only ever be data, no voice (computer labs). Currently, ALL connections come back to a single stack of switches, logically seperated by VLANs. I'm thinking it might make sense to break up the stack in order to physically seperate all potential VOIP phone connections and non-VOIP connections each to their own stacks.

For clarity, here is an example: say I currently have a stack of 4 switches. 2 switches in the stack will connect VOIP phones and/or computers and 2 switches in the stack will connect computers only (ever). I'm considering breaking up the stack to physically seperate the potential VOIP phones into one stack and the computer lab into another stack. Have any of you bothered to go this far? Obviously the phones will have their own voice VLAN and QOS will be in place regardless, so I'm wondering if it is worth it. I don't think bandwidth will be a concern with either setup - the stack of 4 currently has dual gig uplinks to a separate 8600 IST pair.

It seems to make sense to me to physically seperate the VOIP connections onto their own stack but there is an obvious cost associated with this: it will essentially double the number of uplinks to our core 8600 requiring additional gbics/jumpers on both ends, additional ports used on the 8600 cards, and it will increase the number of stacks to manage - the last one is not a huge deal even though we have approx 65 wiring closets because there is no real $ amount involved associated with it. And if I separate the stacks, I have to decide if I give the computer lab stacks dual redundant links or just a single link (cost of gbics and additional 8600 ports is the limiting factor here). My main concern is for the quality of the VOIP experience to the users and to try to avoid any potetial issues, especially during early roll-out, because you know how people will react if there is a problem with their new VOIP phone.

I'm not asking anyone to design my network for me here, just curious what you might have done if you can relate to my situation (higher education setting). I haven't found any "best practices" related to physical separation of VOIP vs data only stacks.

Thanks in advance.

[brazenhead]

One more thing: does anybody bother to physically separate wireless access points on the edge from voice and/or data?

[Flintstone]

Hi brazenhead,

We also use Vlans to separate the VoIP and Data.  The port is setup for 'untagPvidOnly', so data is always presented untagged, so it doesn't matter whether you want VoIP and Data or just Data.

CheerZ and good luck

[Dominik]

Hi brazenhead,

I canīt see any proft in a physical separation of VoIP Phones and normal Data ports.
If you use the mini switch in the VoIP Phones and hang your clients in the Data VLAN behind your VoIP
Phones it will safe half of the needed ports in your network.

In fact with QoS and VLAN seperation you have logical devided voice and data network.
Havenīt see in the past a network where they had done a physical separtion.
If you want to have a nice structure in your switchports maybe to use always e.g. port 1-24 for VoIP Phones and 25-48 for Data Clients could be an option.

Cheers

[Telair]

Hey brazenhead.  I did one location where they wanted their VoIP system physically separated from their data infrastructure.  They wanted to keep their old Dell PowerConnect 3248 10/100 non-PoE data switches for their computers, but decided to use two or three 5650TD-PWR's on each floor just to run the phones.  I guess the VoIP system was the phone guys project, so they didn't want the data network guys to be involved or get any of their new equipment.  Ran a two cable copper MLT back from each floor's wiring closet to a "core" stack of 2x 5520's that linked to their VoIP servers, voicemail and the PBX in the main data center.  Then they added enough UPS power in the closets to run the VoIP switches for 3 hours.  Needless to say, it worked very well for them. 

As for wireless, I hang the AP's off a separate wireless VLAN that is piped to all the switches with AP's.  One place I worked with couldn't mix wireless "public" and wired "private" data on the same switches due to some regulations they were working under.  Since it was a small 3 story building, I just cabled the AP's directly back to a 4548GT-PWR switch connected to the controller and the customer was happy.

[Michael McNamara]

In my opinion there's no valid reason to build physically separate networks in this day and age for voice, data or video. The only place I still build completely separate networks is for physiological bedside monitoring. The networks that connect all those monitors at the bed side demand the highest level of redundancy and resiliency available. These networks aren't usually too big (largest hospital has 7 5520 stacks connected to 2 5530s in IST/SMLT configuration) so the cost isn't that big of an issue but it provides peace of mind for everyone (including risk management).

In my opinion your wasting money... you can do everything you want today on a single network and leverage that infrastructure to propel your core business needs.

Cheers!

[brazenhead]

Sold! Thanks for the responses. It was just an fleeting idea ... "If I have a thousand ideas and only one turns out to be good, I am satisfied" ... lol.

[TankII]

We mixed the PWR/non POE switches in the same stack, SLT'd back to out 8600's.
Our VOIP and WLAN devices are distributed between them so if one switch/stack goes down, we only lose half of the phones/Access Points.
Same goes with Code Upgrades.  It is mostly painless to do it as you don't affect the entire floor at the same time.
Two stacks in each IDF...

TankII