TRAFFIC BETWEEN EPHEMERAL PORTS HOW TO
TRAFFIC BETWEEN EPHEMERAL PORTS WINDOWS

The increased number of concurrent connections will reduce the amount of memory available for other processing and may slow the performance of applications. Further, each TCP end-point also consumes non-swapable kernel memory for the TCP Send and Receive queues.

TRAFFIC BETWEEN EPHEMERAL PORTS WINDOWS

Sites that have many or all backup windows configured to open simultaneously may find that their platforms and NetBackup now have the capacity to saturate the ephemeral port window, which can lead to connection and job failures. Sites that spread their backup and duplication windows throughout the night/weekend/day are unlikely to see any effect, other than jobs going from Queued to Active more quickly (until the concurrent per policy/client/storage limits are reached). This will allow jobs to go active more quickly, and will increase the concurrent connection and port usage in the seconds and minutes immediately following when a backup window opens. Note: NetBackup 8.2+ also no longer limits the startup of backup jobs to 1 job per second.

NetBackup 8.2 removed the need for some connections and shortened the lifespan of others. NetBackup 8.2 roughly halved the ephemeral port use added by secure communication connections. NetBackup 8.1 significantly increased ephemeral port use when introducing secure communication connections. NetBackup 7.1 minimized service port use by allowing many legacy services to accept connections via PBX. NetBackup 4.5 minimized ephemeral port use by deprecating legacy call-back. However, certain new features and functionality have also expanded the number of ports potentially in concurrent use. NetBackup has made design and implementation changes over the years to minimize the number of ports needed for concurrent operation. Computing hosts have become bigger, faster, and more interconnected (memory, CPU, network interfaces, I/O devices, etc.), but the limitations of TCP port availability have remained largely unchanged for decades. The goal is to allow NetBackup to perform as many operations as possible, as quickly as possible, without conflict. Otherwise applications may receive the wrong data, that was intended for a previous process, and either fail or behave in an unexpected fashion.

TRAFFIC BETWEEN EPHEMERAL PORTS HOW TO

Second, how to ensure that recently used TCP ports can be safely reused by other processes.

When the range is exhausted applications must fail, although many - NetBackup included - will retry briefly in hopes one does become available quickly. First, how to ensure that as many TCP ports as possible are available for application use.

Traffic between ephemeral ports