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VTP and STP

mo shea
Level 1
Level 1

I have some general questions about practically implementing vlans in a network.

I will be using a 6509 core and 19 switches each connected via a single fiber (trunk) to the core (no redundant links).

After creating VTP domains and vlans on the core, I want to know the following:

1)On the core, shall I configure the Gigabit ports that connect to edge switch as trunklinks or they will be trunk links by default?

2)On the edge switch gigabit port, shall I configure it as trunklink or is it so by default?

3)Shall I change each edge switch manually to client mode and assign ports to vlans or does it switch to client mode automaticaly?

4)Do I need to enable STP on the core if I dont have any physical redundant links to any edge switch and if I have to, is it on the core alone or on the core and edge switch?

5)Is it a good Vlan design to have a vlan spread around many switches?

Help is greatly appreciated, i really need to clear these points.

Thanx

6 Replies 6

pflunkert
Level 4
Level 4

Okay,

hera are the answers:

1: They are trunking by default when you have several vlans an the switch

2: i would configure manually trunking, because so i can shure that i allways have a trunk connection. But it depends from your vlans on the edge switch. When you have only one vlan, a trunk is not necessary:

3: You must configure this on the core:

conf t

vtp mode server (default)

vtp domain name_xyz

The other switches working as server also. So must configure the client mode:

conf t

vtp mode client

vtp domain name_xyz

4:You should enable stp. When a third person plug in a second cable into the switch, you will have a loop. So i would recommend it

5: To this questions i don't have a exact answer. When the several departments are spread over your whole network, why not. All users of a department could connect the same vlan. When you have some more vlans that won't hurt.

Regards

Peter

Thanks a lot for your valuable response.

Regarding stp, is it on by default, and if not, whcih standard shall i use for stp (pvst, pvst+, cst)

I really do not need something fancy, just easy to configure (because plan to have 3 redundant links to the core only) and is it done on the core only?

Thanx

yes, it's on by default. When you have only 3 redundant links you can use pvst+. It should be default (depends n your software). When all switches are capable to use RSTP/MST you can also use this. With pvst you have nearly 50 seconds convergence time and with rstp you have up to 6 seconds. But how often your network links will flap??

So it would say, what you use, depends from what you want to configure.

Regards

Peter

lfulgenzi
Level 7
Level 7

Just to let you know, #5, is not supported or recommended when you go with redundant links (via HSRP). Pervasive VLANs was the 'in' thing a while back and we went with it whole hog - VLANs everywhere. We're now paying for it, having to migrate VLANs to localized VLANs before implementing redundancy. It's more effective to implement seperate VLANs on each switchstack if required.

If you are just planning out your network, don't plan for pervasive VLANs, stick to them on your stack.

Thanks for your help.

I think your are right for #5. Probably I will stick to vlans per physical location.

Since I work in a hospital, the only thing worrying me is an image transfer system between different departments which will be implemented two years from now.

I am thinking about the pros and cons of putting all the image capture devices (spread all over the hospital) on a vlan and give priority for the transfer using Qos although I know that in my LAN I wont have any bandwith issues. Still I have got almost a months time to decide on my vlan design.

Hi,

when you will have the possibility to seperate the vlans to the pysical locations it is good. But it's not really necessary. In our company i'am working in our tac team and i have many customers which spread the vlans over the whole campus. And i'am speaking from networks with 50 to 60 4500 catalysts.

What Lelio wrote is not wrong, but it's not the only way.

Perhaps you can post you design and we can discuss it.

Regards

Peter

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