[cisco-voip] offline network - using NAT/PAT to connect to the outside world

[Lelio Fulgenzi]

Thanks Charles!

The servers I’m talking about connecting to in the real network would include servers I have no control over and would be difficult to replicate. For example, our active directory servers. For the most part, I will be replicating any and all servers off-line, especially those that I need to make changes to, e.g. DNS servers. I won’t be using the NAT/PAT solution to build any sort of client connection like phone or jabber to cucm, that will all happen offline. Same for Unity connection. The routing will be very specific – likely even host based – to allow access to the outside world.


Besides – the collaboration servers are all on the same network – I wouldn’t even begin to know how to route individual IPs on the same network out the NAT/PAT link! Although there’s probably a way! ☺


Lelio


---
Lelio Fulgenzi, B.A.
Senior Analyst, Network Infrastructure
Computing and Communications Services (CCS)
University of Guelph

519-824-4120 Ext 56354
lelio at uoguelph.ca
www.uoguelph.ca/ccs
Room 037, Animal Science and Nutrition Building
Guelph, Ontario, N1G 2W1

From: Charles Goldsmith [mailto:wokka at justfamily.org]
Sent: Wednesday, July 19, 2017 3:20 PM
To: Lelio Fulgenzi
Cc: voyp list, cisco-voip (cisco-voip at puck.nether.net)
Subject: Re: [cisco-voip] offline network - using NAT/PAT to connect to the outside world

Be careful of SIP connections from your offline network getting to production devices.  You don't want your Unity Connection to start reporting MWI status back to your production network or if using Single Inbox, to sync with your Exchange.

My advice is to not let your offline network connect to anything on the public network, other than a couple of devices for you to go in and manage it from (ie, your workstation) and for specific tests.

On Wed, Jul 19, 2017 at 1:28 PM, Lelio Fulgenzi <lelio at uoguelph.ca<mailto:lelio at uoguelph.ca>> wrote:

A while back we had a good discussion about offline network upgrade preparation. A few people mentioned using NAT/PAT in order to connect to servers that would be too difficult to replicate in the off-line network.

I'm trying to get my head around this and thought I'd share this simplified plan that I want to start off with.

In the offline network we have:


*         a layer 3 switch that does the routing for the offline network

*         a router which does some other tasks like NTP, DHCP, etc.

*         layer 3 switch is connected to router

Here's what I envision:


*         connect the router to a public network, i.e. network 45

*         configure NAT/PAT on the router so that all the inside networks (on the switch) are patted using the public network address

*         configure static routes on the router for all inside networks (on the switch) pointing to the switch

*         configure static routes on the router for specific outside networks pointing network 45 gw

*         configure static routes on the switch for specific outside networks pointing to the router interface

The biggest issue here is that we have replicated many of our public networks in this offline network and there can't be any chance of that leaking.

But I'm pretty sure this would prevent that.

Thoughts? Gotchas?

Lelio

---
Lelio Fulgenzi, B.A.
Senior Analyst, Network Infrastructure
Computing and Communications Services (CCS)
University of Guelph

519-824-4120 Ext 56354<tel:519-824-4120%20Ext%2056354>
lelio at uoguelph.ca<mailto:lelio at uoguelph.ca>
www.uoguelph.ca/ccs<http://www.uoguelph.ca/ccs>
Room 037, Animal Science and Nutrition Building
Guelph, Ontario, N1G 2W1


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