in Sybex book p 310, they list five benefits of VTP.

the last one is, plug and play VLAN adding.

what does Lammle mean by this. i always think of plug and plag as some hardware you can plug in and the computer will do the rest for you. is this term used for configuring software too?

does he mean the VLAN adding in automatic once you set up VTP.

thanks,
rain.

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Hi Rain

If van managment is in place then you can move a user/machine from one port to another or even another switch and the port on the switch will configure the port to the correct vlan based on the user or MAC address of the machine.

I think this is what is meant

Golgi

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Yo Golgi

I am not so sure that the switch port would configure itself from the device's MAC address. The switch (certainly Caytalst 5509 & 6509) holds details of all the ports and the 'live' MAC addresses of the devices attached to them in the switch's CAM table. If a device is removed from a port, then I guess its CAM table entry times out, since there is no keep alive packets.

Reconnecting a device in a new port on the same switch or even a different switch would entail configuration of the port speed, duplex and VLAN memebership. VTP, VLAN Trunking Protocol, works across switches - provided they are interconnected and ISL configured - such that a device on switch A in VLAN 100, is logically on the same segment as another device on switch B also in VLAN 100.

I think this is what Todd Lammle means by 'Plug & Play', although from my experience, some port config is required.

More Beans Please.
Cheers
Hippo

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Hi Hippo

I bow to greater knowledge, i seem to remember a section in the Sybex book that stated essentially what i mentioned - I will check it out.

It is difficult see a definition of plug and play that does not involve the ablility to move ports without having to manually reconfigure?

Golgi

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Hi Hippo

Here is a paste from Syngress chapter on VLANS

Dynamic VLAN Configuration

"Dynamic VLANs are ports on a switch that can automatically determine their VLAN assignment. VLANs are determined using a centralized VLAN management application. The users’ MAC address is stored in a database. When the user’s workstation is moved to a different area, the database dynamically configures the switch port with the VLAN information. In most cases, all Ethernet ports, except trunk ports and secured ports, can be configured as dynamic ports. An advantage to using dynamic VLAN configuration is less administration in the wiring closet when users are added or moved. Also, centralized notification occurs when unrecognized users are added to the network."

This is what i was pertaining to, I hope this helps


Golgi

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Sure does Golgi.

I haven't dabbled with 'dynamic' VLAN configuration on Cat switches, only a manual method. Or maybe it's a new Cat operating system.

Thanks for the info.

Hippo

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thanks you both, i had my suspicion that it could be dynamic VLAN. now i am sure.

rain.

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VTP and dynamic VLANs are different beasts, but they work nicely together. However, all combinations are valid:

- no VTP, no dynamic VLANs;
- no VTP, yes dynamic VLANs;
- yes VTP, no dynamic VLANs;
- yes VTP, yes dynamic VLANs.

With VTP, a VLAN added to a switch in server mode is automagically added to all switches in server and client mode in the VTP domain. That's what Todd means bu "plug and play VLAN adding".

With dynamic VLANs one needs a VMPS (VLAN Membership Policy Server). The VMPS maintains a database of MAC address to VLAN id mappings for the network. When a switch sees a frame from a certain MAC address on a dynamic VLAN port, it queries the VMPS for the VLAN to which that MAC address belongs. The answer from the VMPS tells the switch to which VLAN to assign that port.

Of course, there's a lot of other details...

HTH


[This message has been edited by dmaftei (edited 01-26-2001).]

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as always,

thanks dmaftei,
rain.

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this may be fun reading.
http://www.cisco.com/univercd/cc/td...elp/vmpscfg.htm

ah hell, here:
http://www.cisco.com/univercd/cc/td...lhelp/index.htm

------------------
chunder -- Network+, MCSE, CNE


[This message has been edited by chunder (edited 01-26-2001).]

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