3

We have 2 (main) vlans:

Vlan1 - Management (iDrac, switches etc)
Vlan2 - Hosting, both servers and dedicated client IPs

We have over 900 IPs in the VLAN2 which is located in a data center, for shared web hosting. We use IPv4 addresses in different ranges in the VLAN2 for hosting. One Switch stack consisting of 2 Dell PowerConnect 6248 switches and another switch stack consisting of 2 Cisco Catalyst 3650 switches (WS-C3650-48TQ).

Adding further IPs in the same hosting VLAN will make any problems in our environment in future??

Will cause any conflicts in shared hosting environment, if we use separate VLANs rather than a single VLAN??

Please update your valuable suggestions or thoughts in this.

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  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can provide and accept your own answer.
    – Ron Maupin
    Feb 19 '18 at 5:43
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A VLAN is a broadcast domain, the larger the number of hosts in a VLAN, the more broadcast you have, the more performance are degraded.

Additionally, it's a single failure domain, in the sense that is still a shared medium and one host having trouble could potentially impact the connectivity of all other hosts within the same VLAN

Third it is also a security boundary. Even if you have a correctly configured firewall on all hosts (and I hope so in an hosting environment), Access Control Lists on the router (or better, a true firewall) will also increase security. (Depending on the switch used, there's some measure that can be taken to prevent hosts within a same VLAN to communicate together)

So it's not advisable to have too many hosts within a VLAN.

Some people will tell you "no more than 500 hosts in a VLAN" , referring to some Cisco best practice, other put the limit at 1000.

Personally I prefer to reduce the number, and avoid using larger than /23.

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  • "Additionally, it's a single failure domain, in the sense that is still a shared medium and one host having trouble could potentially impact the connectivity of all other hosts within the same VLAN" - very limited so; it's not a shared medium as everything will be switched; a malfunctioning host effectively impacting the others is very rare.
    – Zac67
    Jun 8 '17 at 17:36
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Vlan1 - Management (iDrac, switches etc) Vlan2 - Hosting, both servers and dedicated client IPs

We have over 900 IPs in the VLAN2 which is located in a data center, for shared web hosting. We use IPv4 addresses in different ranges in the VLAN1 for hosting. Another VLAN2 for Management (iDrac, switches etc).

VLAN2 in 1st paragraph contradicts that of last sentence.

Adding further IPs in the same hosting VLAN will make any problems in our environment in future??

As long as all MACs can be stored in the switches and there's enough space in your subnets, no. However, only your hoster can answer that for sure.

Will cause any conflicts in shared hosting environment, if we use separate VLANs rather than a single VLAN??

Usually, your hoster should be able to accomodate several VLANs.

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  • Thank you for your comments :) I have corrected the mistake in the question
    – AkhileshP
    Jun 9 '17 at 9:34

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