Mac Address-Related Parameters; Mac Address Flooding; Mac Address-Based Forwarding; Mac Address Source-Based Learning - Cisco CRS Configuration Manual

MAC Address-related Parameters

addition, the packets that are received on one pseudowire are not replicated on other pseudowires in the same
VFI.
MAC Address-related Parameters
The MAC address table contains a list of the known MAC addresses and their forwarding information. In the
current VPLS design, the MAC address table and its management are maintained on the route processor (RP)
card.
These topics provide information about the MAC address-related parameters:

MAC Address Flooding

Ethernet services require that frames that are sent to broadcast addresses and to unknown destination addresses
be flooded to all ports. To obtain flooding within VPLS broadcast models, all unknown unicast, broadcast,
and multicast frames are flooded over the corresponding pseudowires and to all attachment circuits. Therefore,
a PE must replicate packets across both attachment circuits and pseudowires.

MAC Address-based Forwarding

To forward a frame, a PE must associate a destination MAC address with a pseudowire or attachment circuit.
This type of association is provided through a static configuration on each PE or through dynamic learning,
which is flooded to all bridge ports.
In this case, split horizon forwarding applies; for example, frames that are coming in on an attachment
Note
circuit or pseudowire are not sent out of the same attachment circuit or pseudowire. The pseudowire
frames, which are received on one pseudowire, are replicated on to other attachment circuits, VFI
pseudowires and access pseudowires.

MAC Address Source-based Learning

When a frame arrives on a bridge port (for example, pseudowire or attachment circuit) and the source MAC
address is unknown to the receiving PE router, the source MAC address is associated with the pseudowire or
attachment circuit. Outbound frames to the MAC address are forwarded to the appropriate pseudowire or
attachment circuit.
MAC address source-based learning uses the MAC address information that is learned in the hardware
forwarding path. The updated MAC tables are propagated and programs the hardware for the router.
The number of learned MAC addresses is limited through configurable per-port and per-bridge domain MAC
address limits.

MAC Address Aging

A MAC address in the MAC table is considered valid only for the duration of the MAC address aging time.
When the time expires, the relevant MAC entries are repopulated. When the MAC aging time is configured
Cisco IOS XR Virtual Private Network Configuration Guide for the Cisco CRS Router, Release 6.1.x
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Implementing Multipoint Layer 2 Services