Equipment Choice

Unanswered Question
Feb 19th, 2008
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Hello, I work for a town, and one of the schools needs a hardware upgrade. Looking for advice. The school connects to Town Hall thru its' own VLAN. The fiber comes into the school into a room which needs 240 ethernet ports. In a wiring closet on the other side of the school, I need hardware which will accommodate 132 ethernet ports. On a different side of the school, I need hardware to accommodate 84 ethernet ports. Looking for options & advice on how to link the 3 rooms, while maintaining one VLAN. Thanks

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lamav Tue, 02/19/2008 - 09:58
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To span the vlan across the floor, you must deploy a switched user-access layer and then trunk the vlan between the different switches.


One way (there are more) to do it is to:


1. Terminate the fiber MAN connection on the primary switch that will require the 240 ports.


2. Set VTP mode to transparent on each switch


3. Create the layer 2 vlan on each switch and name it.


4. Designate one of the ethernet ports on each switch as a trunk port (or bundle a few of them to create an etherchannel with more bandwidth -- also, the primary switch that terminates the MAN connection will need two trunks) and configure it/them for either dot1q or ISL trunking.


We can get into more detail about how to do all this if you need/want it, but I am just giving you the general approach.


As for the hardware to use, I would look into using a 4500 series switch as the primary and then stackable 3750s for the rooms that require fewer connections.


I'm sure others will have different recommendations...


HTH


Victor


Joseph W. Doherty Tue, 02/19/2008 - 11:47
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My guess is cost is going to be a major issue. If true, you'll probably want to consider less expensive L2 switches that have VLAN support, i.e. the more expensive L3 switches and/or chassis solutions might be beyond your budget.


Is the expectation for one VLAN for the whole school building or multiple VLANs spanning the school building?


Also important to cost is what speed copper Ethernet you need to supply, and whether POE is also needed. (Speed options are also going to be dependent on the kind of Ethernet cabling installed)


You mention fiber to the school, but what's the media (copper/fiber) and distances between the rooms?


In general, the least expensive configuration would likely be one "head" switch in each wiring closet that connects to either school "head" switch or connects to the outside fiber connection. The wiring closet interconnections could be gig, copper if close enough, otherwise fiber.


"User" switches might just be 10/100 with a gig copper uplink. If the head switch only has a couple of gig ports, one is used for the closet uplink, the second is used to cascade the other switches. If the head switch has multiple gig ports, connect each user switch's uplink to it directly.


E.g.

head switch: WS-CE500G-12TC

8 10/100/1000Base-T ports and 4 10/100/1000Base-T or SFP ports


user switch: WS-CE500-24TT

24 10/100 ports and 2 10/100/1000Base-T uplinks


NB: Your requirement of 240 Ethernet ports in one closet would seem to exceed what the WS-CE500G-12TC can provide, but a SFP port should be able to also do copper. Or, just cascade two pairs of WS-CE500-24TT.


Other switches offer higher port densities and/or more gig ports, e.g. WS-CE520G-24TC-K9 or 2960-48TC-S. Fewer higher port density switches might be less costly.

craigwoody Thu, 02/21/2008 - 07:16
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Cost is not a huge factor, but it is a factor. I was thinking a 4500 series at the head room, a fiber link to each of the wiring closets into a Cisco switch, and run the existing switches in these wiring closets(3COM's with the Matrix Module)off of that Cisco. What I am least sure about is how to link the Cisco and 3Com's. I would prefer to trunk them, but am not sure how to go about it.

Joseph W. Doherty Thu, 02/21/2008 - 07:40
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Could you clarify how many closets we're dealing with, the Ethernet density for each closet, and the number of fiber runs to each closet. I had thought only 3 and assumed only one fiber per closet.


Could you also clarify how may 3Com units you intend to retain, their number of ports and bandwidths, and whether these are in addition to the number of ports indicated in the original post?


As to using a 4500, fine series. Performance wise, slot bandwidth a bit dated except for the latest E series. Often a hard choice between it and the 3750 stackable for user access edge. Important decision will be choice of 4500 supervisor, and whether just L2 or L3 supervisor.


With regard to you question of trunking (VLANs) between Cisco and 3Com, if both support IEEE 802.1q, should be possible.

craigwoody Thu, 02/21/2008 - 07:55
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We have the room where the Fiber comes into the building, which currently has a 48 port Cisco switch (Not sure of the model) and 8-24 port 3Com's. Room 212 (one of the wiring closets) has 6-24 port 3 Com's. The Music Wing (the last wiring closet) has 3-24 port and 1-12 port 3 Com's. As for the fiber runs, we are planning to add 1 or 2 to room 212, and add 1 to the music wing. We would like to keep as many 3Com's as possible, since they still work. Glad to hear that I can trunk to the 3Com, just not sure how.


Joseph W. Doherty Thu, 02/21/2008 - 17:11
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Depending on your actual VLAN needs, you might not have to trunk between Cisco and 3Com switches. If you trunk between the closet's (Cisco) head switches, and then attach other closet (3Com or Cisco) stand alone switches to its ports (star configuration), then if that head switch has port based VLANs, all ports of the attached switch would also be within that VLAN. Trunking would only be necessary if you needed to set the ports of the downstream 3Com switches (on the same 3Com switch) into different VLANs. I.e. different 3Com switches would host different VLANs.


If you have multiple fiber runs, using stand alone separate switches, you can have two head switches, and with spanning tree, avoid the single point of failure of one switch taking down the whole closet.


Or, you can channel multiple ports and increase bandwidth between closets.


Or, with something like a dual member 3750 stack, have a channel that crosses member switches, i.e. provides the benefit of both, no head single point of failure, and additional bandwidth.


Don't know what all the 4500 supports. Do know, without second sup, sup is potential single point of failure.

lamav Thu, 02/21/2008 - 07:57
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Joseph:


"Could you clarify how many closets we're dealing with, the Ethernet density for each closet"


He already has in his original post.


"Important decision will be choice of 4500 supervisor, and whether just L2 or L3 supervisor."


Not really. He has already stated that this vlan is in use and is being extended to this building, so the choice is L2 with a L2 uplink to the already existing routed core.


Craig:


Are these 3Com switches manageable or are they just plug and play? If they are not manageable, that is good reason to probably get rid of them, since you will have no capability to troubleshoot port latency issues or configure them for STP, trunking, etc. Do they even have Gbit uplink capability (copper or fiber) or are they just all 10/100 ports?


These are some of the things you want to think about...


Please Rate My Posts if they have been helpful. :-)


Thanks


Victor


Joseph W. Doherty Thu, 02/21/2008 - 17:40
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Victor,


vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv

"Could you clarify how many closets we're dealing with, the Ethernet density for each closet"


He already has in his original post.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


Yes he did in his original post, but especially with the mention of the 3Com switches in his second post, thought it best to confirm, along with clarification of additional information provided in his second post.


vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv

"Important decision will be choice of 4500 supervisor, and whether just L2 or L3 supervisor."


Not really. He has already stated that this vlan is in use and is being extended to this building, so the choice is L2 with a L2 uplink to the already existing routed core.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


Yes, but since we're already at 456 hosts, I could see the need for L3 within the building. (Also possible growth in hosts.) So with his mention of a 4500, also in his second post, I believe it wise to remember to carefully chose 4500 supervisor. Plus, we still don't know what bandwidth we're attempting to support, another point for careful consideration of 4500 supervisor.

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