Specifications

Reference Guide
190 VMware, Inc.
Subnet or Routing Issues
In a LAN or WAN deployment, the following connection problems can occur.
LAN Deployment
Incorrectly configured subnets or routing can cause channel problems resulting in poor performance or failure
to connect.
Symptom
The Channel disconnects or fails to connect in a LAN deployment.
Causes
The Channel disconnects or fails to connect due to the Principal (Public) NIC and/or one or more channels
sharing the same subnet.
Resolution
If vCenter Server Heartbeat is deployed in a LAN environment, the Principal (Public) IP address and the
Channel IP address on a server must be in separate subnets. When multiple redundant channels are present,
each must have its own subnet. Check the network configuration for each NIC on both servers in the pair and
correct any issues.
WAN Deployment
Incorrect routing can prevent the active and passive servers from connecting in a WAN environment.
Symptom
The VMware Channel disconnects or fails to connect in a WAN deployment.
Cause
When the VMware Channel disconnects or fails to connect in a WAN deployment, the static route might not
be configured or might be configured incorrectly.
When vCenter Server Heartbeat is deployed in a WAN, the Principal (Public) IP address and the VMware
Channel IP addresses cannot be in different subnets, because there usually is a single network path between
the two servers. Configure a static route between the endpoints to route traffic in the VMware Channel.
Resolution
Refer to knowledge base article 1008451 (vCSHB-Ref-466) - Creating a static route for the VMware Channel
Connection Where the Channel and Principal (Public) IP Addresses are on the Same Subnet in a WAN Environment for
a detailed discussion about WAN channel routing issues, and for instructions on configuring a static route for
the VMware Channel.
MaxDiskUsage Errors
vCenter Server Heartbeat uses queues to buffer the flow of replication data from the active server to the
passive server. This configuration provides resilience in the event of user activity spikes, VMware Channel
bandwidth restrictions, or VMware Channel drops across a WAN deployment. Some types of file write activity
also require buffering as they can cause a sharp increase in the amount of channel traffic. The queues are called
the active server (unsafe) queue or the passive server (safe) queue.