Link to home
Start Free TrialLog in
Avatar of jetli87
jetli87

asked on

Redundant inbound and outbound internet connections via Cisco hardware

Hi Experts,

I'm currently in the works of deploying a redundant / load balancing internet setup of my new company.

Basically:

ISP A = Main incoming Connection:  for Citrix and Exchange email, i.e. RPC-HTTPS connections
ISP B = Backup Line or used primarily for outgoing connections.

I'm aware the the ASA Firewalls provide an effective solution for seamless outbound connections between 2 seperate ISP connections, but not inbound.  I know i could just reconfig public DNS entries, but i'm looking for an automated solution.  Preferrably Cisco based.

Please advise.

Avatar of purplepomegranite
purplepomegranite
Flag of United Kingdom of Great Britain and Northern Ireland image

For the inbound, the easiest solution is to publish both your external IP addresses (i.e. from each ISP) in your public DNS.  You could have two MX records, one for each IP.  Each router would forward SMTP traffic from it's external address to the same internal IP address.  If a connection goes down, your mail server is still available - while one of the MX records would fail, SMTP servers should then try the second record if there is one.

The same theory can be applied to other incoming connections (two DNS entries per service).
Avatar of jetli87
jetli87

ASKER

I see, so just map 2 public ips to the same DNS record and point to the same internal ip address, correct?

But how does that work when those DNS records are pulled for service?

is it random between the identical DNS records or what order?
Avatar of jetli87

ASKER

And I ask in terms of just regular DNS records, not MX
ASKER CERTIFIED SOLUTION
Avatar of purplepomegranite
purplepomegranite
Flag of United Kingdom of Great Britain and Northern Ireland image

Link to home
membership
This solution is only available to members.
To access this solution, you must be a member of Experts Exchange.
Start Free Trial