Tuesday, July 3, 2018

Best Practise to replace the default Gateway of a Client

So we want to replace a ASA 5540 with a FPR4120 (with ASA image). The ASA runs in Muli context mode and it is providing the default Gateway for a dozent of /24 subnets in multiple Contexts. The Plan is to migrate one Context after another. The Business side of things wants a silent migration for smaller customers that dont work in the time between 10PM and 4 AM.

Our Initial assasment was that migrating a context should be pretty straight forward with little downtime. We Preconfigure the New Context of the FPR acordingly, disable the Interfaces of the old Context on the ASA and enable the Interfaces in the new Context on the FPR. After my understanding, this will however not work out because the VM's and Servers don't actually loose network connectivity and will retain their ARP Table with the old Mac Address for the default Gateway.

In my opinion we have the following options:

-Restart all Clients where the DFG will change /Clear the arp Table of the Clients ( our Sys Admins don't want that)

-Change the Mac Adress for all Virtual Interfaces on the ASA that are the DFG (we from the Network Team don't want that)

So basicly i want to find out, if any of you know a way to handle this without Restarting devices or to "spoof" the mac address of the old device.



No comments:

Post a Comment