Overview of Virtual Routers

The ExtremeXOS software supports virtual routers (VRs). This capability allows a single physical switch to be split into multiple VRs. This feature separates the traffic forwarded by a VR from the traffic on a different VR.

Each VR maintains a separate logical forwarding table, which allows the VRs to have overlapping IP addressing. Because each VR maintains its own separate routing information, packets arriving on one VR are never switched to another.

Note

Note

VRs should not be connected together through a Layer 2 domain. Since there is a single MAC address per switch in the ExtremeXOS software, this same MAC address is used for all VRs. If two VRs on the same switch are connected through a Layer 2 domain, the intermediate Layer 2 switches learn the same MAC address of the switch on different ports, and may send traffic into the wrong VR.

Ports on the switch can either be used exclusively by one VR, or can be shared among two or more VRs. One reason to configure a port for the exclusive use of a single VR is to be sure that only packets from that VR egress from that port. One reason to configure a port to be shared by multiple VRs is to pass traffic from multiple VRs across a shared link.

Each VLAN can belong to only one VR.

Because a single physical switch supports multiple VRs, some commands in the ExtremeXOS software require you to specify to which VR the command applies. For example, when you use the ping command, you must specify from which VR the ping packets are generated. Many commands that deal with switch management use the management VR by default. See the ExtremeXOS 16.2 Command Reference Guide for the defaults for individual commands.

Note

Note

The term VR is also used with the Virtual Router Redundancy Protocol (VRRP). VRRP uses the term to refer to a single VR that spans more than one physical router, which allows multiple switches to provide redundant routing services to users. For more information about VRRP, see the VRRP Overview.