- play_arrow Introduction
- play_arrow Common Features (All Deployment Modes)
- play_arrow L3 Features
- play_arrow Cloud-Native Router CNI Configuration Examples
- play_arrow Monitoring and Logging
- play_arrow Troubleshooting
- play_arrow Appendix
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MAC Learning and Aging
Juniper Cloud-Native Router provides automated learning and aging of MAC addresses. Read this topic for an overview of the MAC learning and aging functionality in the cloud-native router.
MAC Learning
MAC learning enables the cloud-native router to efficiently send the received packets to their respective destinations. The cloud-native router maintains a table of MAC addresses grouped by interface. The table includes MAC addresses, VLANs, and the interface on which the vRouter learns each MAC address and VLAN. The MAC table informs the vRouter about the MAC addresses that each interface can reach.
The cloud-native router caches the source MAC address for a new packet flow to record the incoming interface into the MAC table. The router learns the MAC addresses for each VLAN or bridge domain. The cloud-native router creates a key in the MAC table from the MAC address and VLAN of the packet. Queries sent to the MAC table return the interface associated with the key. To enable MAC learning, the cloud-native router performs these steps:
Records the incoming interface into the MAC table by caching the source MAC address for a new packet flow.
Learns the MAC addresses for each VLAN or bridge domain.
Creates a key in the MAC table from the MAC address and VLAN of the packet.
If the destination MAC address and VLAN are missing (lookup failure), the cloud-native router floods the packet out all the interfaces (except the incoming interface) in the bridge domain.
By default:
MAC table entries time out after 60 seconds.
The MAC table size is limited to 10,240 entries.
We recommend that you do not change the default values. Please contact Juniper Support if you need to change the default values.
You can see the MAC table entries by using:
Introspect agent at http://host server IP:8085/mac_learning.xml#Snh_FetchL2MacEntry
The command show bridge mac-table on the Cloud-Native Router controller CLI:
content_copy zoom_out_mapshow bridge mac-table Routing Instance : default-domain:default-project:ip-fabric:__default__ Bridging domain VLAN id : 3002 MAC MAC Logical address flags interface 00:00:5E:00:53:01 D bond0
The command purel2cli --mac show on the CLI of the vRouter pod:
content_copy zoom_out_mappurel2cli --mac show ================================================== || MAC vlan port hit_count|| ================================================== 00:01:01:01:01:03 1221 2 1101892 00:01:01:01:01:02 1221 2 1101819 00:01:01:01:01:04 1221 2 1101863 00:01:01:01:01:01 1221 2 1101879 5a:4c:4c:75:90:fe 1250 5 12 Total Mac entries 5
If you exceed the MAC address limit, the counter pkt_drop_due_to_mactable_limit increments. You can see this counter by using the introspect agent at http://host server IP:8085/Snh_AgentStatsReq.
If you delete or disable an interface, the cloud-native router deletes all the MAC entries associated with that interface from the MAC table.
MAC Entry Aging
The aging timeout for cached MAC entries is 60 seconds. You can configure the aging timeout at deployment time by editing the values.yaml file. The minimum timeout is 60 seconds and the maximum timeout is 10,240 seconds. You can see the time that is left for each MAC entry through introspect at http://host server IP:8085/mac_learning.xml#Snh_FetchL2MacEntry. We show an example of the output below:
l2_mac_entry_list vrf_id vlan_id mac index packets time_since_add last_stats_change 0 1001 00:10:94:00:00:01 5644 615123154 12:55:14.248785 00:00:00.155450 0 1001 00:10:94:00:00:65 6480 615108294 12:55:14.247765 00:00:00.155461 0 1002 01:10:94:00:00:02 5628 615123173 12:55:14.248295 00:00:00.155470
