Dell SmartFabric OS10 User Guide Release 10.5.3

Anycast IP Gateway for VLANs

Anycast IP is a network addressing and routing method that allows for multiple devices to share the same IP address in a network.

Starting with Release 10.5.2.0 or later, you can configure anycast IP functionality for VLAN interfaces in a VLT domain. In earlier releases, this feature was applicable only for the virtual-network interfaces. For more information, see Enable overlay routing between virtual networks.

Anycast IP is a lightweight gateway router redundancy protocol that allows the hosts to use a virtual IP and a virtual MAC address to forward traffic out of a VLT domain. You can configure virtual IP addresses on VLAN interfaces in addition to a primary address, and the anycast gateway MAC address is configured to be the same on all the VLT switches. This configuration allows devices to use a common IP address as their network gateway. The VLT domain-specific information is used to determine the primary node, which responds to ARP requests for anycast IP. If the primary VLT node goes down, the secondary VLT node owns the gateway IP addresses and starts responding to ARP requests.

The following figure shows the anycast IP-based gateway configuration for a VLAN:

The ip virtual-router address and ipv6 virtual-router address commands assign the specified address as the virtual IPv4 or IPv6 address for the VLAN interface, respectively. Before assigning the anycast IP address to a VLAN interface, configure a virtual MAC address to the switch using the ip virtual-router mac-address command. All virtual addresses on all VLAN interfaces resolve to the configured virtual MAC address.

This feature supports only Active-Active mode of data plane forwarding. That means, the traffic is processed by any switch that is configured with a virtual gateway address. As the requests come into a single IP address associated with the anycast network, the network distributes the data among the switches based on best route in the routing table. Anycast IP gateway routing is able to route incoming connection requests across multiple data centers.