THE INFORMATION IN THIS ARTICLE APPLIES TO:
- EFT v6 and later
DISCUSSION
EFT active-active, High Availability (HA) configuration uses Reliable Multicast and MSMQ to communicate between nodes to achieve HA.
More details of each protocol can be found at the links below:
- PGM: http://en.wikipedia.org/wiki/Pragmatic_General_Multicast
- MSMQ: http://en.wikipedia.org/wiki/Microsoft_Message_Queuing
Issue:
- Cisco has removed support for PGM on their Nexus 6K/7K device and possibly others not listed. The commands are no longer in the CLI and the onboard processor does not have the programming to acknowledge the RA bit inside the packet. There is no expected plan to reintroduce this feature in any future releases per Cisco Network Consultants.
- In Junos OS release 14.2 PGM functionality is still available, but the commands are hidden, that is, they no longer appear in the CLI.
Troubleshooting:
To determine if you are experiencing this issue, refer to the High Availability tab inside the EFT administration interface. The nodes will show “unknown” respectively when on each server between the two nodes.
Wireshark can be used to help verify the root cause of the issue, as shown in the screen shots below.
As you can see there is no traffic coming inbound to the nodes from the multicast address. This can also be directly related to the VLAN not supporting multicast. Contact your network admin team to verify feature status.
If a Cisco UCS or Nexus 1K/5K is being used, refer to this KB article to help resolve the issue on that hardware: http://www.cisco.com/c/en/us/support/docs/servers-unified-computing/unified-computing-system/117360-configure-product-00.pdf
Options:
Cisco recommends using an iOS-based device to manage traffic for the VLAN that the PGM traffic will be passed on or manage that traffic with another PGM-supported device.
In a virtual environment, moving the devices to the same host and verifying after a 5-minute wait time can resolve the issue if the switching/routing infrastructure does not support PGM. If your infrastructure hardware does not support PGM, a DRS Affinity rule can be created to keep the Virtual Machines on the same host.
Contact Globalscape support to assist in the verification and testing of the environment.