A method of preserving symmetrical routing in a communication system comprising a server farm connected to the Internet by an Internet access router IAR. The server farm includes at least two customer cabinets each having a WEB server, and at least two firewalls. The firewalls use Virtual Router Redundancy Protocol (VRRP) to set up a primary firewall that supports communication between a customer server and an Internet user. The IAR selects the firewall to be used as being the firewall corresponding to the interface having the lowest weight in a routing table. The cost assigned to each interface associated with a firewall is automatically generated, at the initial time, according to the priority assigned by the VRRP protocol to said interface associated with said firewall.