In Express Route Circuit when metric type Arp and BGP Availability reaches 100% what it indicates. How can we identify and process the threshold or alert for this metrics.

Question

In my Express route circuit while I am capturing the metrics I found the following type of metrics: Arp Availability and BGP Availability has showing 100%(Arp Availability (Avg)). So what is this impact on Express Route Circuit. If it reaches maximum threshold in which way we can identify this and how I can notified this through alerts.

Answer 1

Hello @Murarisetty Yamuna ,

Welcome to Microsoft Q&A Platform. Thank you for reaching out & hope you are doing well.

I understand that in your Express route circuit metrics, you found the following type of metrics: Arp Availability and BGP Availability showing 100% (Arp Availability (Avg)). And you would like to know what its impact on your Express Route Circuit is and how to identify when it reaches maximum threshold and get notified about this through alerts.

You can find all the ExpressRoute metrics listed in the below doc:

https://learn.microsoft.com/en-us/azure/expressroute/expressroute-monitoring-metrics-alerts

ARP Availability - Split by Peering:

You can view near to real-time availability of ARP (Layer-2 connectivity) across peerings and peers (Primary and Secondary ExpressRoute routers). This dashboard shows the Peering (for both Private and Microsoft) ARP session status across both peers.

• If it shows 100% for Private/Microsoft peering, it means the Private/Microsoft Peering ARP session status is up across both peers.
• If it shows 0% for Private/Microsoft peering, it means the Private/Microsoft Peering ARP session status is down for both peers.

This metric is split by peering meaning, you will see the metric for each peering type (Private/Microsoft).

Refer: https://learn.microsoft.com/en-us/azure/expressroute/expressroute-monitoring-metrics-alerts#arp-availability---split-by-peering

BGP Availability - Split by Peer:

You can view near to real-time availability of BGP (Layer-3 connectivity) across peerings and peers (Primary and Secondary ExpressRoute routers). This dashboard shows the status for both Primary & Secondary BGP session status for each peering type.

• If it shows 100% for a session for a selected peering type, it means that particular BGP session status is up for the selected peering.
• If it shows 0% for a session for a selected peering type, it means that particular BGP session status is down for the selected peering.

This metric is split by peer meaning, you will see the metric for each BGP peer (Primary/Secondary router) in a selected peering type (Private/Microsoft).

Refer: https://learn.microsoft.com/en-us/azure/expressroute/expressroute-monitoring-metrics-alerts#bgp-availability---split-by-peer

To understand more about ARP and BGP, you can refer the below doc:

https://learn.microsoft.com/en-us/azure/expressroute/expressroute-troubleshooting-expressroute-overview#validate-arp

Azure Monitor alerts proactively notify you when important conditions are found in your monitoring data. They allow you to identify and address issues in your system before your customers notice them. You can set alerts on metrics, logs, and the activity log. Different types of alerts have benefits and drawbacks.

You can configure alerts for ARP availability down and BGP availability down referencing the below docs:

https://learn.microsoft.com/en-us/azure/expressroute/monitor-expressroute#alerts

https://learn.microsoft.com/en-us/azure/azure-monitor/alerts/alerts-types#metric-alerts

https://learn.microsoft.com/en-us/azure/azure-monitor/reference/supported-metrics/microsoft-network-expressroutecircuits-metrics

https://learn.microsoft.com/en-us/azure/azure-monitor/alerts/alerts-create-new-alert-rule?tabs=metric

In addition to above, you can also configure alerts for Azure ExpressRoute circuit maintenance:

https://learn.microsoft.com/en-us/azure/expressroute/maintenance-alerts

Kindly let us know if the above helps or you need further assistance on this issue.

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