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virtual-gateway-v6-mac

 

Syntax

Hierarchy Level

Release Information

Statement introduced in Junos OS Release 14.2R5.

Statement introduced in Junos OS Release 15.1X53-D63 for QFX Series switches.

Description

Explicitly configure an IPv6 media access control (MAC) address for a default virtual gateway.

A default virtual gateway is created when you specify a virtual gateway address (VGA) while configuring an integrated routing and bridging (IRB) interface on a Juniper Networks device that functions as a Layer 3 Virtual Extensible LAN (VXLAN) gateway in an Ethernet VPN-Virtual Extensible LAN (EVPN-VXLAN) centrally-routed bridging overlay (EVPN-VXLAN topology with a two-layer IP fabric). Through the IRB interface with which it is configured, the default virtual gateway enables communication between non-virtualized hosts, virtual machines (VMs), and servers in different VXLANs or IP subnetworks.

When you configure a VGA for an IRB interface, the Layer 3 VXLAN gateway automatically generates IPv6 MAC address 00:00:5E:00:02:01 for that particular virtual gateway. (This topic refers to the virtual gateway MAC address as a virtual MAC.) The automatically generated virtual MAC is not included as the source MAC address in packets generated by the Layer 3 VXLAN gateway. Instead, data packets and the source MAC address field in the outer Ethernet header of Address Resolution Protocol (ARP) replies and neighbor advertisement packets include the MAC address for the IRB interface. (This topic refers to the MAC address for the IRB interface as the IRB MAC.)

When an ARP reply includes the IRB MAC as the source MAC address instead of the virtual MAC, an issue might arise in a centrally-routed bridging overlay. This issue might result in the flooding of unknown-unicast packets throughout the domain.

If you explicitly configure a MAC address for a default virtual gateway, the automatically generated virtual MAC is overridden by the configured virtual MAC. That is, when the Layer 3 VXLAN gateway sends data packets, ARP replies, and neighbor advertisement packets, the configured virtual MAC is in the outer Ethernet header of these packets. As a result, the possibility that the domain is flooded with unknown-unicast packets is eliminated.

For more information about the flooding issue and its resolution, see Understanding the MAC Addresses For a Default Virtual Gateway in an EVPN-VXLAN Overlay Network.

Options

ipv6-mac-addressIPv6 MAC address for the default virtual gateway.

Required Privilege Level

admin—To view this statement in the configuration.

admin-control—To add this statement to the configuration.

Related Documentation