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Home Documentation Junos OS Junos CLI Reference CLI Reference V

Junos CLI Reference

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Junos CLI Reference
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virtual-gateway-v4-mac

date_range 20-Nov-23
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Syntax

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virtual-gateway-v4-mac ipv4-mac-address

Hierarchy Level

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[edit dynamic-profiles name interfaces name unit logical-unit-number],
[edit dynamic-profiles name logical-systems name interfaces name unit logical-unit-number],
[edit interfaces name unit logical-unit-number]

Description

Explicitly configure an IPv4 media access control (MAC) address for a default virtual gateway.

A Juniper Networks device creates a default virtual gateway when you specify a virtual gateway address (VGA) for an integrated routing and bridging (IRB) interface on the device. You use this option on a device that functions as a Layer 3 gateway in an EVPN-VXLAN or an EVPN-MPLS centrally-routed bridging (CRB) overlay fabric.Through its IRB interface, the default virtual gateway enables communication between non-virtualized hosts, virtual machines (VMs), and servers in different VXLANs, MPLS networks, or IP subnetworks.

When you configure a VGA for an IRB interface, the Layer 3 gateway automatically generates IPv4 MAC address 00:00:5e:00:01:01 for that particular virtual gateway. In this topic, we refer 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 gateway. Instead, the device includes the MAC address for the IRB interface in:

  • Data packets

  • The source MAC address field in the outer Ethernet header of:

    • Address Resolution Protocol (ARP) replies

    • Neighbor advertisement packets

In this topic, we refer 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, in CRB overlays you might see unknown unicast packet flooding throughout the domain.

If you explicitly configure a MAC address for a default virtual gateway, the configured virtual MAC overrides the automatically generated virtual MAC. That is, when the Layer 3 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, explicitly configuring the virtual MAC eliminates the possibility of flooding the domain with unknown unicast packets.

00
Note:

The MAC address range 02:00:00:00:00:00 through 02:00:00:00:00:FF is used for internal communication. Don't use addresses in this range for a manual virtual MAC assignment.

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

ipv4-mac-address

IPv4 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.

Release Information

Statement introduced in Junos OS Release 14.2R5.

Related Documentation

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