Juniper BGP, Configuration Manual

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requirements and procedures for subscriber policies are the same whether you
employ BGP or LDP signaling for VPLS.
Network Interface Types
VPLS instances, like bridge groups, support two types of network interfaces:
■
Subscriber (client)—A subscriber (client) interface is downstream from the traffic
flow; that is, the traffic flow direction is from the server (trunk) to the client
(subscriber). This is the default network interface type for both VPLS instances
and bridge groups.
■
Trunk (server)—A trunk (server) interface is upstream from the traffic flow; that
is, the traffic flow direction is from the client (subscriber) to the server (trunk).
To configure a trunk interface, you must specify the
subscriber-trunk keyword
as part of the bridge-group command. The VPLS virtual core interface always
acts as a trunk interface, and cannot be configured as a subscriber interface.
Default Subscriber Policies
Each network interface is associated with a default subscriber policy for that interface
type. The subscriber policy is a set of forwarding and filtering rules that defines how
the specified interface handles various packet or attribute types, as follows:
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For each packet type listed in Table 79 on page 596, the subscriber policy specifies
whether the network interface permits (forwards) or denies (filters or drops)
packets of that type.
■
For the relearn attribute, the subscriber policy specifies whether the network
interface can relearn a MAC address entry on a different interface from the one
initially associated with this entry in the forwarding table. Permit indicates that
relearning is allowed; deny indicates that relearning is prohibited.
Table 79 on page 596 lists the default values for each packet or attribute type defined
in the policies for subscriber interfaces and trunk interfaces. The default subscriber
policy differs in one way from the default trunk policy: broadcast packets and packets
with unknown unicast destination addresses (DAs) are denied in the subscriber policy
and permitted in the trunk policy.
Table 79: Default Subscriber Policies for VPLS Network Interfaces
Default Trunk Policy Default Subscriber Policy Packet/Attribute Type
Permit Permit ARP
Permit Deny Broadcast
Permit Permit IP
Permit Permit MPLS
Permit Permit Multicast
Permit Permit PPPoE
596 ■
Configuring Subscriber Policies for VPLS Network Interfaces
JUNOSe 11.1.x BGP and MPLS Configuration Guide