Mac Address-Related Parameters; Mac Address Flooding; Mac Address-Based Forwarding; Mac Address Source-Based Learning - Cisco ASR 9000 Series Configuration Manuallines

Implementing Multipoint Layer 2 Services
router bgp 1
address-family l2vpn vpls
neighbor 5.5.5.2 activate
neighbor 5.5.5.2 prefix-length-size 2 --------> NLRI length = 2 bytes
exit-address-family

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:
Note
After you modify the MAC limit or action at the bridge domain level, ensure that you shut and unshut the
bridge domain for the action to take effect. If you modify the MAC limit or action on an attachment circuit
(through which traffic is passing), the attachment circuit must be shut and unshut for the action to take effect.

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.
Note
Split horizon forwarding applies in this case, for example, frames that are coming in on an attachment circuit
or pseudowire are sent out of the same pseudowire. The pseudowire frames, which are received on one
pseudowire, are not replicated on other pseudowires in the same virtual forwarding instance (VFI).

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.
L2VPN and Ethernet Services Configuration Guide for Cisco ASR 9000 Series Routers, IOS XR Release 6.3.x
MAC Address-related Parameters
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