[LU-14945] LNet: don't use hops to determine whether the route is up or down

• Type: Bug
• Resolution: Fixed
• Priority: Minor
• Fix Version/s: Lustre 2.15.0
• Severity: 3
• Assignee: Serguei Smirnov
• Reporter: Serguei Smirnov

Description

 NodeA <-tcp1-> GW1 <-tcp2-> GW2 <-tcp3-> NodeB

Assuming GW1 knows how to reach tcp3 network and GW2 knows how to reach tcp1 network, it should be possible to add routes without specifying hop count = 2 on nodes A and B to reach tcp3 and tcp1 respectively and then be able to lnetctl ping between them. Changes introduced by LU-13785 interpret default hops to be equivalent to hops = 1 set explicitly for the purpose of determining route aliveness, which results in the routes created as described above to be considered "down". Fix it so that default hop setting doesn't prevent the multi-hop scenario from working.