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TR7Enterprise Application Delivery & Security Platform
What is Gateway Monitoring; how does it affect VIP failover?
Short answer
Gateway monitoring is the monitoring of whether the default gateway of a route table is reachable by pinging it regularly. In TR7, it is selected from the Gateway Monitoring field that appears in the Add Route or Edit Route form while Default Gateway is checked: No check (default), Default monitor profile (probes every 3 seconds; OK after 2 consecutive successes, Error after 5 consecutive failures) or a health check profile of the Ping type. In a cluster, each device probes the gateway itself, and the result is shown per device: in the Gateway Health column on the Route Tables screen (for the IPv4 gateway) and next to the default gateway row in the interface list. Its effect on VIP failover depends on the VIP Transition Method field of the interface: if TR7 GW check or TR7 link and GW check is selected, the VIP moves to the peer device when the gateway cannot be reached from the Master device only; in Only VRRP and TR7 link check, the gateway result is for information only. Gateway monitoring does not take the route out of service.
Where It Is Used in TR7
| Where | Field / label | What for |
|---|---|---|
| Network → Interfaces → Add Route (or Edit Route on the default gateway route) → Default Gateway checked | Gateway Monitoring: No check, Default monitor profile, Ping-type profiles | Selecting the profile that will probe the gateway |
| Network → Route Tables | Gateway Health column: OK (green), Error (red), Evaluating (yellow/amber), NO GW/check (gray); a half circle per device in a cluster | Seeing the monitoring result of the IPv4 default gateway |
| Network → Interfaces list | A ✓ / ✕ indicator per device next to the default gateway row; "…" is successful at <device name> in the tooltip (Interface and IP statuses) | Seeing from which device the gateway cannot be reached |
| Network → Interfaces → Edit Interface (in a cluster) | VIP Transition Method | Whether the gateway result takes part in VIP failover |
| Settings → General Settings → Notification Management | Notification Type = GW health status | Receiving a notification on the Gateway monitor failed for <interface> event |
| Load Balancer → Profiles → Health Checks | Check Type = Ping | Creating a custom profile to be selected in gateway monitoring (only the Ping type is listed) |
VIP Transition Method and Gateway
| Method | Effect of the gateway monitoring result |
|---|---|
| Only VRRP (default) | None; only the VRRP advertisements are examined |
| TR7 Link Check | None; the interface link is examined |
| TR7 GW Check | Yes; if the gateway check succeeds on only one device, the VIP runs on that device |
| TR7 Link and GW Check | Yes; the link and gateway checks are evaluated together |
If the checks of both devices succeed or both fail, the VIP runs according to the configured Master/Slave role (How does a cluster work?). The methods that include GW check require a Gateway monitoring profile to be selected on the default gateway of the route table; while No Check is set, the gateway check is not considered successful. In these methods, the VRRP advertisement interval drops to 0.2 seconds.
Common Misconceptions
- "If Gateway health is red, the VIP always moves." It moves only in the methods that include GW check and when the gateway cannot be reached from the Master device only; if neither device can reach the gateway, the VIP stays in the configured role.
- "When the gateway is unreachable, the route is taken out of service." Gateway monitoring only monitors; the route stays in place.
- "The profile selected in the default gateway form on the Route Tables screen is saved." The Gateway Monitoring selection in that form is not written to the route record; the profile is assigned from the Add Route or Edit Route form (Route Tables · The Default Gateway Form (Edit Default Gateway)).
How it is done in the documentation
