[HECnet] "Dropped by adjacent node" ....

[Paul_Koning at Dell.com]

On May 25, 2014, at 10:20 PM, Johnny Billquist <bqt at softjar.se> wrote:

On 2014-05-26 04:17, Johnny Billquist wrote:
On 2014-05-26 03:47, Bob Armstrong wrote:
Increased it to 32, ...

  That's probably a good idea, but I don't actually think that's the
problem.   Like I said, I see this happening with several nodes, all on
the
bridge QNA - MIM, PONDUS, A5RTR, SGC, etc.

Yeah. I checked some more, and I actually only have 18 adjacent nodes at
MIM:: so this is definitely not the problem. From my point of view, it
only seems to be LEGATO:: that is currently acting like a yo-yo...

I would guess that either some packets are lost, or else the packet trip times varies a *lot*. We should investigate more, but it's really getting late for me   

Varying round trip time itself doesn   t matter.   Routing layer hellos are sent out periodically; the round trip time is not considered.   What is necessary is that they must be delivered reliably enough.   For Ethernet, two lost packets are allowed; for point to point links, only one.   (Beware of braindead tunnel protocols that look like point to point links but run over UDP.)   In other words, the listen timeout for Ethernet is 3 * hello time, for point to point it is 2 * hello time.

	paul