What is the ideal latency between cluster nodes for Red Hat Cluster Suite?

Issue

What is the ideal latency (ie. ping time) between cluster nodes for Red Hat Enterprise Linux Clusters?
How can I configure Multicast TTL of >2 to work in normal GFS setup
- I can't get a multicast communication Time To Live anything less than 2 to work.

Red Hat Enterprise Linux (RHEL) including:
- Red Hat Enterprise Linux 3 (RHEL3) with Cluster Suite Add-on
- Red Hat Enterprise Linux 4 (RHEL4) with Cluster Suite Add-on
- Red Hat Enterprise Linux 5 (RHEL5) Advanced Platform
- Red Hat Enterprise Linux 6 (RHEL6) with High Availability or Resilient Storage Add-on
Red Hat Cluster Suite Cluster with 2 or more nodes
- Greater than 2ms round-trip latency between any pair of cluster nodes
  - There may or may not be a firewall between networks that causes high latency for multicast traffic between hosts.
  - It may be a large physical distance between nodes

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