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At the moment, user devices have multiple IPs if they need to access multiple services.

All devices are physically connected into to the same switched network. I know it's bonkers and am pleased to say it had nothing to do with me.

I am introducing a pair of servers, to act as router/proxy/firewall/vpn, replacing a lot of existing archaic infrastructure.

I've reached a point where I can either do this:

# using physical ports
eth0 -     # The main network, dhcp'd user devices live here.
eth1 -   # a couple of out-of-scope routers in here. 
eth2 -   # in-scope and out-of-scope servers and stuff.
eth3 - 81.x.x.x/x      # internet facing


# using virtual ports
eth0   -
eth0:0 -
eth0:1 -
eth1   - 81.x.x.x/x

Considering the server pair, the first option requires 8 interfaces/8 switch ports while the second option only requires 4 interfaces/4 switch ports.

What should I be considering when making this decision?

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You realize that the is masking away public address space you don't own? Are you sure you got that mask right? – Zoredache Jun 14 '13 at 20:53
thanks, a brain fart I think – Mr Not A. Clue Jun 14 '13 at 21:02

This is dependent entirely on the capabilities of your switch and the bandwidth required. You should setup vLANs on a single bonded/aggregated interface. Since this is fairly critical, you should use at least two connections. Do no assign multiple subnets to the same broadcast domain, use vLANs if your switch supports them. Also, each interface will support whatever speed it connects at (100Mb, 1Gb, etc). If you require more bandwidth then you'll need multiple connections, plus one for redundancy.

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Thank you, that's very informative. Bandwidth is currently a non issue. Redundancy is an issue and I need to find a balance. I shall think very hard about vlans. I have a Layer 1 headache. Thanks again. – Mr Not A. Clue Jun 14 '13 at 21:58

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