03-03-2007 08:50 AM - edited 03-05-2019 02:41 PM
If I was told that 3 network devices needed to be in the same subnet. Does this necessarily mean the same vlan?
03-03-2007 09:19 AM
Yes, same vlan.
03-03-2007 11:07 PM
Yes. A VLAN equates to a broadcast domain: You would typically have only one subnet per VLAN / broadcast domain.
Good Luck
Scott
04-18-2007 02:24 PM
Hi All
Say that you have a VLAN across several switches. And you want to use a 20 bit subnet mask. What are the cons? The broadcast domain is so big that your network is going to collapse? That will happen?
Thanks for any comments...
04-18-2007 02:57 PM
It's the same, regardless of the nature of the broadcast domain.
If the broadcast domain (VLAN, Subnet)has too many hosts, you end up eating a lot of bandwidth (too many broadcasts) ... and if the broadcast domain spans one or more WAN links, you've wastd a lot of expensive bandwidth.
The other downside to too many broadcasts is that the nature of the broadcast means that all hosts that hear it (everything in teh broadcast domain) must accept the traffic, and process it up the stack, at least to a point where it can decide that it doesn't apply to that host and it can throw the traffic away (like an ARP, DHCP request, multicasts ....)
So, if you decide you want to have a single flat network with a couple thousand hosts on it, and it's going to span several physical locations, plan on running at about 20% efficiency, and for Spanning-tree convergence to take a loooooooooong time.
FWIW
Good Luck
Scott
04-19-2007 05:52 AM
Thanks Scott
There is documentation about what are the limits on a broadcast domain? I meant, How many host will make a broadcast domain unusable...
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