3Com 5500-EI PWR Reference Manual page 960

Description
Use the udp-helper ttl-keep enable command to enable the UDP Helper TTL-keep function. With this
function enabled, the UDP Helper can forward broadcasts with the TTL field being 1 without
decrementing the TTL value by one.
Use the undo udp-helper ttl-keep enable command to restore the default.
By default, the UDP Helper TTL-keep function is disabled.
Note that you need to enable UDP Helper before enabling the TTL-keep function; otherwise, the
TTL-keep function does not take effect.
Examples
# Enable the UDP Helper TTL-keep function on the switch.
<Sysname> system-view
System View: return to User View with Ctrl+Z.
[Sysname] udp-helper ttl-keep enable
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