This chapter describes how to configure unknown unicast flooding suppression on the Cisco ASR 1000 Series Routers. This chapter contains these topics:
- About Unknown Unicast Flooding on Bridge Domain
- Limitations for Unknown Unicast Suppression
- Enabling Unknown Unicast Flooding on Bridge Domain
- Feature Information for Unknown Unicast Flooding Suppression
About Unknown Unicast Flooding on Bridge Domain
Occasionally, unknown unicast traffic is flooded to all the provider edge devices because the device does not know the destination MAC address of a received packet. By default, the unknown unicast traffic will be flooded to all devices. To prevent forwarding such traffic, you can configure the unknown-unicast-suppress command.
Limitations for Unknown Unicast Suppression
If Unknown Unicast Flooding Suppression is enabled, unicast traffic towards an unknown host will be dropped. A host becomes unknown or silent when its MAC address ages out from the MAC address table on the PE. The PE might rely on Unknown Unicast Flooding to re-learn the MAC address.
Enabling Unknown Unicast Flooding on Bridge Domain
To enable unknown unicast flooding suppression, perform the following steps.
Summary Steps
? By default, the unknown unicast flooding is disabled.
configure terminalbridge-domain {interface number}
Detailed Steps
| Command or Action | Purpose |
|---|---|
Step 1configure terminalExample: Router# configure terminal | Enters global configuration mode. |
Step 2bridge-domain {interface number}Example: Router(config)# bridge-domain 10 | Configures the bridge domain on the interface. |
Step 3flooding-suppression unknown-unicastExample: Router(config-bdomain)# flooding-suppression unknown-unicast | Enables unknown unicast flooding suppression on the bridge domain. |
Step 4endExample: Router(config-bdomain)# end | (Optional) Returns to privileged EXEC mode. |
Verifying the Unknown Unicast Flooding Suppression
Verify that you have enabled the unknown unicast flooding suppression by entering the following command:
Device(config-bdomain)# do show run | sec bridge
bridge-domain 10
flooding-suppression unknown-unicast
This example shows the packets that are suppressed and dropped.
QFP L2BD Bridge Domain Information
| BD id | 1 |
| State enabled | Yes |
| Aging timeout (sec) | 300 |
| Aging active entry | Yes |
| Max mac limit | 65536 |
| Unkwn mac limit flood | Yes |
| mac_learn_enabled | Yes |
| mac_learn_controled | Yes |
| Unknown unicast olist | Yes |
| otv_aed_enabled | No |
| otv_enabled | No |
| mcast_snooping_enabled | No |
| Feature | evpn, uuf-suppression |
Feature Information for Unknown Unicast Flooding Suppression
Table 1: Feature Information for Unknown Unicast Flooding Suppression
| Feature Name | Releases | Feature Information |
|---|---|---|
| Unknown Unicast Flooding Suppression | Cisco IOS XE Bengaluru 17.4 | This feature was introduced. |
Bridge Domain Statistics
| Statistic | Value |
|---|---|
| Total bridged | pkts: 0, bytes: 0 |
| Total unknown unicast | pkts: 0, bytes: 0 |
| Total broadcasted | pkts: 0, bytes: 0 |
| Total to BDI | pkts: 0, bytes: 0 |
| Total injected | pkts: 0, bytes: 0 |
| Total mac-sec violation drop | pkts: 0, bytes: 0 |
| Total mac-sec move drop | pkts: 0, bytes: 0 |
| Total mac-sec unknown drop | pkts: 0, bytes: 0 |
| Total source filter drop | pkts: 0, bytes: 0 |
| Total bfib policy drop | pkts: 0, bytes: 0 |
| Total replication start drop | pkts: 0, bytes: 0 |
| Total recycle tail drop | pkts: 0, bytes: 0 |
| Total static MAC move drop | pkts: 0, bytes: 0 |
| Total BD disabled drop | pkts: 0, bytes: 0 |
| Total STP state drop | pkts: 0, bytes: 0 |
| Total UUF suppression drop | pkts: 0, bytes: 0 |
