Domain names on VLANs

datchcha

I have been reviewing my VLAN and switch commands and technology, but I am still unsure of the Domain Name field.

Q1: Does a Domain Name need to be given to a VLAN in order to be currectly configured? Will the VLAN still perform normally with ou this information?

Thank you

LOkrasa

Not if you are using STP... Need to have the Domain name setup if you are using STP to prevent switching loops. Then it needs to be on the same domain in order for it to work...

I am not a CCNA so I may be wrong.

LOkrasa

Oh and if you are using just one switch then you dont need STP at all and no domain name is required...
Anyone wanna cosign on this... ? hehe

dtlokee

The domain name is for VTP, not the VLANs themselves.

You do not need a doman name to configure VLANs. When frames are sent on a trunk link they are tagged with a number (VLAN ID) not the name or any other information. The function of the VTP domain is so switches can share their VLAN databases, that is the information about the number of VLANs, the names of the VLANs and so on. The actual switchport assignments are not shared and are done locally.

If you are allowing your switches to trunk usng DTP then the switches need to be in the same VTP domain otherwise the interfaces will not become a trunk. If you use the "switchport mode trunk" command the switches will form a trunk regardless of the VTP domains.

As far as the one switch, you don't need really need STP but it is on by default and I would leave it that way, somone is bound to add another switch in the future and you'll only need to turn it back on. Last thing you want is a Layer 2 loop in your network.

itdaddy

dtlokee

dude you are like a 5 star general with all your certs. how in the Hel$ did you get so many.
Dont tell me you sit around playing video games and then read a boook on a cert you like and take the test with a blind fold on and pass!

serious you must be an instructor?? how have you gottten so many? and I bet your home lab
is awesome!

thanks

any good study tips for us dummies??

itdaddy

dtlokee


hey, I would like to ask a question on this Domain name.


Domain meaning Active Directory Forest Domain architecture? or Domain name
relating to the VLAN VTP type?

Thanks

dtlokee

VTP domain name is just a name used to identify a group of switches sharing VLAN database information. The VTP frames are sent between switches every 5 minutes by default or when there are changes to the domain. VTP frames are only sent on trunk interfaces and are not forwarded by L3 interfaces (routers for example). They have no relationship to Active Directory or a DNS domain name.

The VTP switch type just determines how it behaves in the VTP domain. Switches in server mode can have VLANs added and removed using the command line (either the VLAN database mode or from global config) and they store the config in flash as a file named "vlan.dat". Client switches do not store the vlan configuration in flash and must learn it from another switch when they boot up, they will not allow changes from the command prompt either. Transparent switches store their configuration in flash, but they do not share the config, they will however forward VTP frames from other switches out any active trunk port.

I am an instructor and the owner of a school that is a Cisco Sponsored Organization. I deliver training using Cisco Courseware (by far the best stuff out there for Cisco certification). As for a home lab, you'd be suprised what you can learn with 4 2500's and a 2924 switch (it's the $750k worth of equipment at my school that's impressive) I also work for an ISP part time on their global IPv6 deployment using mostly 7600, 12000, and about a dozen CRS platforms (they are so cool)

Study tips: take it one exam at a time and you can acheive your goals.

datchcha

dtlokee wrote:

VTP domain name is just a name used to identify a group of switches sharing VLAN database information.

Thank you for your help, so let me see if i get this right.

Switch 1: part of 'Floor 1 domain'
Switch 2: part of 'Floor 2 domain'
Switch 3: 'Floor 1 Domain'

So switch 1 and switch 3 will share vlan databases since both are in the same domain even if all three switches have trunk lines to each other?

Thank you

dtlokee

Yes provided they have a direct trunk link between them. If "Switch 2" is in the path between "Switch 1" and "Switch 3" it will not forward the VTP frames from a different VTP Domain (Floor 1 domain in this case).

datchcha

dtlokee wrote:

Yes provided they have a direct trunk link between them. If "Switch 2" is in the path between "Switch 1" and "Switch 3" it will not forward the VTP frames from a different VTP Domain (Floor 1 domain in this case).

Great...thank you for your help.

hectorjhrdz

WTF?