layer2-map
Syntax
layer2-map;
Hierarchy Level
[edit logical-systems logical-system-name protocols isis], [edit logical-systems logical-system-name protocols isis interface interface-name], [edit logical-systems logical-system-name routing-instances routing-instance-name protocols isis], [edit protocols isis], [edit protocols isis interface interface-name], [edit routing-instances routing-instance-name protocols isis]
Description
Enable Layer 2 mapping of ARP or neighbor discovery next hops in the kernel for the specified instance or interface. IS-IS Layer 2 mapping ensures that forwarding next-hop resolution is topology-driven rather than traffic-driven, which results in minimal traffic loss while activating an Ethernet link.
IS-IS LAN and point-to-point Hellos supply all relevant Layer 2 and Layer 3 binding address information for address resolution. The device at the receiving end can extract the information and populate the ARP or neighbor discovery cache of the kernel even before the route installation time. When Layer 2 mapping is enabled, IS-IS installs ARP or neighbor discovery next-hop entries into the forwarding table. Because this provides Layer 2 next-hop bindings ahead of time, IS-IS networks do not experience traffic loss while bringing up a link.
Default
The default setting is no-layer2-map for
both instances and interfaces.
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 16.1.