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![]() HP OpenVMS Systemsask the wizard |
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The Question is: What is the command to see the value of the TCP/IP parameter TIME_TO_LIVE ? The Answer is : The default Time To Live (TTL) value is a hard-coded value under TCP/IP Services for OpenVMS (UCX) V4, though you can change it -- via a call to setsockopt -- for specific connections. As there is no way to change the system-wide default setting, no mechanism to view the current (hardcoded) setting was implemented. All recent versions of UCX use a TTL of 128, for both TCP and UDP outgoing packets -- the value was increased from 30 to 128 back around 1993. The Wizard suspects that most networks will operate quite nicely with a TTL circa 60 -- few exceed 30 and only very seldom is 50 reached -- and that the current value of 128 is too large. Inordinately large values for TTL will simply leave the packets churning around the network (unnecessarily) in the event of a routing loop. The upcoming V5 release includes the ability to change the TTL value on a system-wide basis, see the output from "sysconfig -q inet". In the V5 release, the new TTL default is 60.
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