Just got new ISP and need help cutting over

[Georgethenewbie]

Hi Everyone

We have a Fortigate 80F currently configured with WAN1 only.

There are many MIPs configured with this current Class C under Policy Objects -> IPv4 Policy

We are migrating to a new ISP provider and have a new Class C.

I am hoping to be able to configure this new ISP on WAN2 and create new MIPs  using the new Class C.

Is this possible without bringing down the current WAN1?

This is a production FW so causing a routing issue will be a disaster.

The current WAN1 will be disconnected once the new WAN2 is tested successfully.

Any help or direction is GREATLY appreciated!

[dingjerry_FTNT]

Hi @Georgethenewbie ,

Do you mean "Mapped IP" with "MIP"?  If yes, I guess you are referring VIP (Virtual IP), right?

If yes, you may:

1) Create a new default route with WAN2 as the same Admin Distance as the current one with WAN1.

2) Create similar MIPs using the new WAN2 IP;  (You may copy the current MIPs configurations, just change the name, WAN1 IP/interface --> WAN2 IP/interface)

3) Apply the new MIPs in new firewall policies.

In this way, even if you retire the WAN1 IP later, it should not impact your production.

[Georgethenewbie]

Thank you for your reply. Yes I do mean Virtual IP.

Can you let me know what to set the Priority of the static route for WAN2? should it be higher than WAN1 (currently set to 0)?

If they are both set to the same priority will the current configuration get confused where to send the traffic?

[dingjerry_FTNT]

Hi @Georgethenewbie ,

First, if two same routes have the same AD (Admin Distance), they will be installed into the routing table together.

Then, if they have the same priorities, it's called ECMP.  The selection is based on the ECMP selection mechnism.

If they have different priorities, the one with higher Priority will be preferred first.

You may check the following articles for more information:

https://community.fortinet.com/t5/FortiGate/Technical-Tip-Setting-priority-on-static-default-routes-...

https://community.fortinet.com/t5/FortiGate/Technical-Tip-Routing-behavior-depending-on-distance-and...

[Georgethenewbie · Accepted solution]

thank you for your help, this is now working properly.