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Configure Upstream Resource Monitoring

Upstream Resource Monitoring

Upstream resource monitoring (URM) lets you monitor Mist Edge clusters so that if a service disruptions is detected, the system can automatically fail-over to the backup. URM supports ARP, PING, and TCP for monitoring, and you can engage any one, two, or all three (although we recommend that you only set up what you need to prevent duplication).

Monitor the upstream connections in the Monitor > Insights > Mist Edge | service dashboard, or by looking at the Mist Edge cluster configuration page under Upstream Resource Monitoring. A green icon indicates a healthy connection, and a red icon means the connection is down.

Figure 1: Configure Upstream Resource Monitoring Configure Upstream Resource Monitoring

Note that when creating a Mist Edge cluster from individual Mist Edge members, the cluster will inherit the URM configuration from the member. If you move a Mist Edge or claim it elsewhere, the previous URM settings will stay with the Mist Edge.

Source and Destination IP Addresses

When setting up URM to monitor a given service or device, you need to provide an IP address to act as the source address for the monitoring service (TCP, ARP, or PING). The IP address you use must be unique, and it must be valid (available) on VLAN from which it will be sent. The destination IP address is that of the device or service you are monitoring. For tunnel interfaces, the source VLAN is automatically assumed to be VLAN1.

By default, Mist Edge assumes that these source and destination IP addresses are on the same subnet. If they are not, you need to set up a next hop to resolve it. See below for instructions on configuring a next hop to bridge different source and destination subnets.

Using an Out-of-Band Management Interface

If you have configured out-of-band management (OOBM) for DHCP or Static IP addresses, Mist Edge can get the IP source address directly from the VLAN. On the other hand, if OOBM IP Address is Disabled or Unmanaged, you need to create a new VLAN and then specify a valid IP address that is available in that VLAN and use that as the source IP address.

Figure 2: Out-of-Band Management Out-of-Band Management

Enabling URM

To configure URM on a Mist Edge,

  1. In the main Mist menu, select Mist Edges in the main menu, and then either choose an existing Mist Edge from the Inventory page or click the Create Mist Edge button for a greenfield device.
  2. In the configuration page that appears, scroll down to find the Upstream Resource Monitoring section.
  3. Select Enable to expose the configuration options and the Add Resources.
    • Protocols—Choose how you want to monitor the device:
      • ARP (Layer 2, for devices on the subnet)
      • Ping (ICMP, both IPv4 and IPv6 are supported)
      • TCP (both IPv4 and IPv6 are supported, and both port 80 and port 443 are supported)

    • Destination Hostname—Specify hostname or IP address of the service you want to monitor.

    • Timeout—Specify the time, in seconds, after which the fail-over will be triggered for the unresponsive device.

    • Select Source VLAN—This is the client VLAN that the IP address you specify belongs to. Site variables are not supported here. Specify a VLAN interface if the upstream resources are not directly reachable via the tunnel interface and the route specified. Otherwise, URM uses the default VLAN which is the tunnel interface.

      • Click the drop-down and select an existing source VLAN (as configured for the VLAN Interfaces section).
      • Alternatively, click Add VLAN to configure a VLAN that is not on the list. You will need to provide a VLAN ID, netmask, and IP address.
  4. To accept your changes, click the check mark in the configuration section.
  5. To commit the changes, scroll to the top of the Inventory page and click Save.
After a few minutes, you can check your settings by refreshing the configuration page. A green icon next to the settings indicates the connection is good. If the icon is red, wait a few minutes and try again, or check your settings and be sure you are using the right IP addresses and/or VLAN ids. If the source and destination are in different subnets, you will need to set up a next hop to provide a route, as explained below.

Setting Up A Next Hop for Different Subnets

If the source and destination are in different subnets, you'll need to set up a next hop to bridge them.

Figure 3: Connecting Different Subnets Connecting Different Subnets

  1. Under the DHCP relay section of the Mist Edge configuration page, select Configure DHCP Relay .

  2. Click the Extra Routes tab and then Add Route.

  3. In the Host/Subnet field that appears, specify the IP address and subnet for the network you are using as the source VLAN (that is, the client) in your URM configuration.

  4. In the Next Hop field, specify the IP address of a gateway that can reach the destination service that you are monitoring (this is the service or device specified in the destination field of the URM configuration).

  5. Click the check mark icon to keep your changes, and then click Save at the top of the page to save the new configuration.