Alcatel-Lucent 7750 SR OS Service Manual page 546

VPLS Service Configuration Commands
Static hosts can be defined on the SAP using the host command. Dynamic hosts are enabled on the
system by enabling the lease-populate command in the SAP's dhcp context. In the event that both a
static host and a dynamic host share the same IP and MAC address, the VPLS ARP reply agent will
retain the host information until both the static and dynamic information are removed. In the event
that both a static and dynamic host share the same IP address, but different MAC addresses, the VPLS
ARP reply agent is populated with the static host information.
The arp-reply-agent command will fail if an existing static host on the SAP does not have both MAC
and IP addresses specified. Once the ARP reply agent is enabled, creating a static host on the SAP
without both an IP address and MAC address will fail.
The ARP-reply-agent may only be enabled on SAPs supporting Ethernet encapsulation.
The no form of the command disables ARP-reply-agent functions for static and dynamic hosts on the
SAP.
Default
not enabled
Parameters
sub-ident — Configures the arp-reply-agent to discard ARP requests received on the SAP that are
targeted for a known host on the same SAP with the same subscriber identification.
Hosts are identified by their subscriber information. For DHCP subscriber hosts, the subscriber hosts,
the subscriber information is configured using the optional subscriber parameter string.
When arp-reply-agent is enabled with sub-ident:
host
Syntax host {[ip ip-address] [mac ieee-address]}[subscriber sub-ident-string] [sub-profile sub-
profile-name] [sla-profile sla-profile-name] [ancp-string ancp-string]
no host {[ip ip-address] [mac ieee-address]}
no host all
Context config>service>vpls>sap
Description
This command creates a static subscriber host for the SAP. Static subscriber hosts may be used by the
system for various purposes. Applications within the system that make use of static host entries
include anti-spoof, ARP reply agent and source MAC population into the VPLS forwarding database.
Multiple static hosts may be defined on the SAP. Each host is identified by either a source IP address,
a source MAC address or both a source IP and source MAC address. Every static host definition must
have at least one address defined, IP or MAC.
Static hosts can exist on the SAP even with anti-spoof and ARP reply agent features disabled. When
enabled, each feature has different requirements for static hosts.
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• If the subscriber information for the destination host exactly matches the subscriber information
for the originating host and the destination host is known on the same SAP as the source, the
ARP request is silently discarded.
• If the subscriber information for the destination host or originating host is unknown or undefined,
the source and destination hosts are not considered to be the same subscriber. The ARP request is
forwarded outside the SAPs Split Horizon Group.
• When sub-ident is not configured, the arp-reply-agent does not attempt to identify the subscriber
information for the destination or originating host and will not discard an ARP request based on
subscriber information.
7750 SR OS Services Guide