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VLAN switches
- Thread starter ezguine
- Start date
jimbopalmer
Programmer
Is ebay an option? I have used Nortel's Accelar 1xxx level 3 switches a lot and while discontinued they are available kinda cheap on ebay
Nortel also sold them as Passport 1xxx, but that is harder to look up
I tried to remain child-like, all I acheived was childish.
Nortel also sold them as Passport 1xxx, but that is harder to look up
I tried to remain child-like, all I acheived was childish.
Before you complicate your network by adding VLANs you need to look at why you are adding VLANs.
My guess is you are using a 24 bit subnet mask (255.255.255.0). I have seen many companies go to routing and VLANs instead of changing the subnet mask to allow more devices on the same subnet. By simply changing your subnet mask to a 23 bit mask or 255.255.254.0 you can have 510 devices in the same broadcast domain.
But isn't that too many devices on the same broadcast domain? No, the key to how many devices should be on the same broadcast domain is the number of broadcasts per second observed on the network. A rate above 30 per second is cause for concern. You will not approach this number with just 510 stations. I have seen many networks using 2046 devices on the same broadcast domain with no problem.
If you are going to use VLANs for security reasons, good. If you are using them to connect devices that are using non-routable protocols, that are located in multiple buildings and you want to take advantage of your existing infrastructure, good. But, if you are going to VLANs just because you are running out of IP addresses in a 24 bit subnet range, bad.
Flipping that one bit will save you lots of money.
mpennac
My guess is you are using a 24 bit subnet mask (255.255.255.0). I have seen many companies go to routing and VLANs instead of changing the subnet mask to allow more devices on the same subnet. By simply changing your subnet mask to a 23 bit mask or 255.255.254.0 you can have 510 devices in the same broadcast domain.
But isn't that too many devices on the same broadcast domain? No, the key to how many devices should be on the same broadcast domain is the number of broadcasts per second observed on the network. A rate above 30 per second is cause for concern. You will not approach this number with just 510 stations. I have seen many networks using 2046 devices on the same broadcast domain with no problem.
If you are going to use VLANs for security reasons, good. If you are using them to connect devices that are using non-routable protocols, that are located in multiple buildings and you want to take advantage of your existing infrastructure, good. But, if you are going to VLANs just because you are running out of IP addresses in a 24 bit subnet range, bad.
Flipping that one bit will save you lots of money.
mpennac
- Thread starter
- #4
" By simply changing your subnet mask to a 23 bit mask or 255.255.254.0 you can have 510 devices in the same broadcast domain. "
That's very interesting. It is true for the most part I want to setup VLANs because I'm running out of IP Adresses. 510 devices would be more than sufficient. I must admit I'm a little stuck on some questions though. Would my IP addresses need to change, or just the mask, and would there be an issue with my 3Com 4400SE switches ? I beleive I can only stack 8 of these, but could I just start another stack and use gigabit uplink between them ?
Thanks
Kenny
That's very interesting. It is true for the most part I want to setup VLANs because I'm running out of IP Adresses. 510 devices would be more than sufficient. I must admit I'm a little stuck on some questions though. Would my IP addresses need to change, or just the mask, and would there be an issue with my 3Com 4400SE switches ? I beleive I can only stack 8 of these, but could I just start another stack and use gigabit uplink between them ?
Thanks
Kenny
jimbopalmer
Programmer
To a purist 192.168.1.x with a subnet mask of 255.255.254.0 is 'wrong' but it will work fine. if your current subnets third octet is Odd (192.168.201.x) then the new subnet is the even number just smaller (192.168.200.x) if you current subnet's third octet is Even (192.168.152.x) then the new subnet is the one just larger (192.168.153.x)
the gateway number does not change in either case
BEFORE
IP Address 192.168.101.37
Subnet Mask 255.255.255.0
Gateway 192.168.101.1
AFTER
IP Address 192.168.101.37
Subnet Mask 255.255.254.0
Gateway 192.168.101.1
and new boxes
IP Address 192.168.100.57
Subnet Mask 255.255.254.0
Gateway 192.168.101.1
Yes gig links between stacks should be fine, if there are obvious 'groups' you can try to put all users of server A in one stack and all users of server B in another stack, but it is not vital
I tried to remain child-like, all I acheived was childish.
the gateway number does not change in either case
BEFORE
IP Address 192.168.101.37
Subnet Mask 255.255.255.0
Gateway 192.168.101.1
AFTER
IP Address 192.168.101.37
Subnet Mask 255.255.254.0
Gateway 192.168.101.1
and new boxes
IP Address 192.168.100.57
Subnet Mask 255.255.254.0
Gateway 192.168.101.1
Yes gig links between stacks should be fine, if there are obvious 'groups' you can try to put all users of server A in one stack and all users of server B in another stack, but it is not vital
I tried to remain child-like, all I acheived was childish.
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