no-arp-suppression
Syntax
no-arp-suppression;
Hierarchy Level
For routing instance type evpn:
[edit bridge-domains bridge-domain-name], [edit logical-systems logical-system-name routing-instances routing-instance-name protocols evpn], [edit routing-instances instance-name protocols evpn]
For routing instance type virtual-switch:
[edit routing-instances instance-name bridge-domains domain-name], [edit logical-systems logical-system-name routing-instances routing-instance-name vlans vlan-name], [edit routing-instances routing-instance-name vlans vlan-name], [edit vlans vlan-name]
Description
The no-arp-suppression statement disables Address Resolution
Protocol (ARP) and Neighbor Discovery Protocol (NDP) suppression on a VLAN. When
configured, the device stops answering ARP/NDP requests on behalf of hosts and
instead floods all ARP requests and IPv6 Neighbor Solicitation (NS) packets within
the VLAN or across the EVPN fabric. In other words, ARP/NDP resolution reverts to
traditional broadcast-based behavior, and the EVPN fabric no longer provides proxy
ARP/proxy NDP responses.
When you configure no-arp-suppression:
-
ARP requests are not suppressed or proxied locally.
-
All ARP requests and NDP NS packets are flooded to all members of the VLAN (and across the EVPN fabric as applicable).
-
The device does not respond on behalf of known MAC-IP bindings, even if they exist in the EVPN MAC/IP database.
-
MAC-IP learning still occurs (unless
no-mac-ip-learningis also configured), so the device continues to track MAC/IP mappings but does not use them for suppression/proxy.
Default Behavior (without no-arp-suppression)
By default, Junos OS and Junos OS Evolved enable proxy ARP/NDP and ARP/NDP suppression.
In EVPN environments, this means the device:
-
Learns MAC/IP bindings (for example, via EVPN).
-
Responds locally to ARP and NDP requests using its MAC/IP database.
-
Suppresses ARP requests and NDP NS packets when it can answer them, reducing broadcast traffic.
This default behavior is recommended for almost all deployments because it reduces unnecessary flooding and improves bandwidth efficiency and scalability.
Operational Impact
Disabling ARP/NDP suppression has several consequences:
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Increased ARP/NDP flooding—All ARP requests and NDP NS packets are propagated across the VLAN/EVPN instead of being answered locally.
-
Higher bandwidth consumption—More broadcast and multicast traffic consumes additional fabric bandwidth.
-
Reduced scalability—In large EVPN-VXLAN deployments with many endpoints, the increased ARP/NDP broadcast load can stress both the data plane and control plane.
-
Loss of EVPN efficiency benefits—You lose the primary advantages of EVPN proxy ARP and proxy NDP—namely, reduced broadcast traffic and more efficient address resolution.
Usage Guidance
-
no-arp-suppressionis intended for exceptional or specialized scenarios where ARP/NDP must not be proxied or suppressed. -
In modern EVPN deployments, disabling suppression is rarely beneficial and can negatively impact performance and scalability.
-
We recommend leaving ARP/NDP suppression enabled (default) in most environments, keeping proxy ARP, proxy NDP, and their suppression mechanisms active.
Required Privilege Level
routing—To view this statement in the configuration.
routing-control—To add this statement to the configuration.
Release Information
Statement introduced in Junos OS Release 17.2R1 .
Support for logical systems on MX Series routers added in Junos OS Release 17.4R1.
Statement hidden in Junos OS Release 19.1R1 and subsequent releases.
Statement unhidden in Junos OS Release 26.1R1 and subsequent releases.