Cisco Systems Implementing test network

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Subject Author Date
Implementing test network Andrew Hodgson 08-15-06
Posted by Andrew Hodgson on August 15, 2006, 5:52 pm
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Hi,

Just wondered what people thought about the idea of a test network
being used in a company.

We have such a beast, however, I am just wanting to clarify some
things which I am not 100% comfortable with, and just wanted to know
am I being very old fashioned, or is there some basis to it?

We currently have a core switch with several Vlans on it for internal
purposes. The people who configured this put an extra Vlan for the
test network, currently all traffic can pass through, but it will be
locked down using ACLs on the core switch. The reason for this
apparently is so we can use the Vlan capabilities on the internal
switch to assign ports to the test network.

Is this really a separate network from the "live" environment, could
there be any problems?

The other thing is, we have a small ADSL connection to simulate WAN
access, however, for some reason, we have had a few of our existing
public IP addresses (on the live system) set aside for the test
network, going through our existing Pix through to the test network.
The reason for this is that the ADSL connection will act as a loop
through so we can do external tests. I have tested this and it works,
but I was thinking we would be able to use a set of public IP
addresses (or even just one address on the DSL interface), and use
them/it as our external address if required?

I realise I have only scratched the surface, but I just wondered what
sort of problems we may come into with this type of setup (if of
course there are any)?

Thanks.
Andrew.
--
Andrew Hodgson in Bromyard, Herefordshire, UK.
My Email: use <andrew at hodgsonfamily dot org>.

Posted by amigan on August 15, 2006, 7:11 pm
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Good questions. You should not have a test network on your production
switches. Test networks are vulnerable to experimentation - and a bad
experiment with say multicast or broadcasting or turning off spanning
tree or...could bring down the production VLANs. Get the test network
off there!

I don't understand what you mean by using ADSL to simulate WAN access.
WAN generally refers to connecting multiple sites together. But you go
on to describe wanting to test your Internet facing services and how
the production pix leads you to the test network. While I don't
entirely follow - my gut reaction is - get the production Pix off the
test network and use another device to protect egress to the Internet.
Likely you are wanting to test your production apps from the
perspective of someone outside. IOS firewall should be fine for this
purpose or use another pix.

Michael


Andrew Hodgson wrote:
> Hi,
>
> Just wondered what people thought about the idea of a test network
> being used in a company.
>
> We have such a beast, however, I am just wanting to clarify some
> things which I am not 100% comfortable with, and just wanted to know
> am I being very old fashioned, or is there some basis to it?
>
> We currently have a core switch with several Vlans on it for internal
> purposes. The people who configured this put an extra Vlan for the
> test network, currently all traffic can pass through, but it will be
> locked down using ACLs on the core switch. The reason for this
> apparently is so we can use the Vlan capabilities on the internal
> switch to assign ports to the test network.
>
> Is this really a separate network from the "live" environment, could
> there be any problems?
>
> The other thing is, we have a small ADSL connection to simulate WAN
> access, however, for some reason, we have had a few of our existing
> public IP addresses (on the live system) set aside for the test
> network, going through our existing Pix through to the test network.
> The reason for this is that the ADSL connection will act as a loop
> through so we can do external tests. I have tested this and it works,
> but I was thinking we would be able to use a set of public IP
> addresses (or even just one address on the DSL interface), and use
> them/it as our external address if required?
>
> I realise I have only scratched the surface, but I just wondered what
> sort of problems we may come into with this type of setup (if of
> course there are any)?
>
> Thanks.
> Andrew.
> --
> Andrew Hodgson in Bromyard, Herefordshire, UK.
> My Email: use <andrew at hodgsonfamily dot org>.


Posted by Walter Roberson on August 16, 2006, 2:56 pm
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>I don't understand what you mean by using ADSL to simulate WAN access.
>WAN generally refers to connecting multiple sites together. But you go
>on to describe wanting to test your Internet facing services and how
>the production pix leads you to the test network.

Right. In the past we've done the same thing: used a seperate
link to test our connectivity and security. The seperate link was
from a different ISP in a different IP range, so while we were
at our desks we could be testing how our equipment interacted with
"outside" packets.

> While I don't
>entirely follow - my gut reaction is - get the production Pix off the
>test network and use another device to protect egress to the Internet.
>Likely you are wanting to test your production apps from the
>perspective of someone outside. IOS firewall should be fine for this
>purpose or use another pix.

When we did this, our seperate link had a different demarc. We plugged
it in to a layer 2 switch, on a different VLAN, and trunked
that VLAN around through more layer 2 switches to reach our testbed PIX.

This differs from what you are suggesting in that we did not have
a *complete* seperation of test and production network. Any packets
that weren't addressed to the distinct address range weren't going to
make it through the ISP to our secondary demarc, and the layer 2 switches
were not -themselves- going to act upon packets not addressed to them
and not in their management VLAN. We considered the risk of someone
managing to inject a successful VLAN hopping attack between the ISP
and our demarc to be negligable, particularily as the link was
encrypted.

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