Re: Multiple IP's (virtual interfaces) on ONE VLAN?
On Thu, 22 May 2008, Jogi [utf-8] Hofmüller wrote:
> You'll probably need to use vconfig [1]. That is if you have to
> terminate an 802.1q tagged vlan trunk. We use it on our router here and
> it works very well.
tomorrow i will have to deploy a similar arrangement.
I will use some Linksys SLM2024 and Allied Telesyn GS950 switches.
I have 4 subnets but for historical resaon for some months i will have to
carry all the traffic on a single cable.
Most WS are only on one subnet, so i would untag some ports for each
subnets and carry the traffic between switches on the single wire as
untagged. There are howewer some server that now are connected on two or
three of the subnets.
I was thinking of using only one tagged interface for all three subnets
(the single GB channel is not the bottleneck, that is the disk
performances).
The doubt however arise from the fact that two of then do the following
thing:
sudo ifconfig eth0:xx K.K.K.xx netmask 255.255.255.0
sudo iptables -t nat -A POSTROUTING -s 192.168.L.yy -j SNAT --to-source
K.K.K.175
whre K.K.K.xx are addresses on the K subnet, and 192.168.L.yy in the L
subnet.hereby allowing host on the private subnet L to use public subnet K
(note that on phisical subnet K there is also a logical subnet J with
addresses as 172.25.J.ww and server has either a K.K.K.n and a 172.25.J.n
address bound to eth0 and eth0:1 so it is even possible the natting is
active between the same subnet. (not to say that the same host does VPN
for remopte users wanting to present themselves as 192.168.L.rr
Given these costraints it is better to keep three interfaces on three
tagged port ? (the advantage of vlanning them would be just the saving of
6 cables around and 6 ports on a switch, with further semplification of
the net. what is the price however ?
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