Hi UeharaAyano,
Welcome to Meraki Community 🙂
Problem Statement: Despite being enabled under "Network-wide --> Alerts' page", UDLD alert "Unidirectional link detection (UDLD) errors exist on a port" is not being sent via email.
Point 1 - It seems you are experiencing a known issue. Please, create a case with Meraki Support Team, so we can keep you up-to-date as soon as the issue is resolved by our Development Team.
Go To "?" on the top right corner on Meraki dashboard --> "Get Help & Cases" --> "MS switching --> "Submit a case".
Point 2 - Troubleshooting steps to verify the UDLD alert
A port should receive its own device and port ID information from its neighbor if the link is bi-directional. If a port does not receive information about its own device and port ID from its neighbor, the link is considered to be unidirectional. This can occur when the link is up on both sides but one side is not receiving packets, or when wiring mistakes occur, causing the transmit and receive wires to not be connected to the same ports on both ends of a link.
UDLD frames can be confirmed by taking a packet capture on each end of the link to ensure that they’re being sent/received:
Point 3 - Loop Guard feature
https://documentation.meraki.com/MS/Port_and_VLAN_Configuration/Configuring_Spanning_Tree_on_Meraki_...
Loop guard | Loop guard is used to protect a network from unidirectional loops. A unidirectional link failure may stop a port in the blocking state from receiving BPDUs causing it to erroneously transition the forwarding state, creating a loop in the network. If a non-designated port with Loop Guard enabled stops receiving BPDUs, it will transition into a loop-inconsistent blocking state. In this state, the port will still process BPDUs but will not learn MAC addresses or forward traffic, thereby preventing a loop from forming. It is recommended that Loop Guard be enabled on non-designated fiber ports in physically redundant topologies. It is also recommended that Loop Guard be paired with Unidirectional Link Detection (UDLD). For more information on UDLD, check out our Unidirectional Link |
If you have any further questions, please don't hesitate to contact us.
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