[Simh] Packet Loss

[David Coolbear]

I have simh running on a Linux host. When I installed simh (compiled from
source) the host was running OpenSUSE 13.1. It subsequently was upgraded to
13.2. The Linux host has two NICs - one of them is dedicated to simh. The
host os loads the kernel module for the NIC and admins it up, but does not
configure an IP address. Both NICs are cabled into a gig-e switch and the
switch is cabled into a cable modem.

When the host was running OpenSUSE 13.1, networking on simh worked
perfectly. I'm not certain, but I suspect that it also worked perfectly
under 13.2. I recently ran both the PDP11 simulator and the VAX simulator.
Both of these had about 50% packet loss when pinging between simulators or
between the Linux host and either simulator.

The pertinent portion of the simh initialization file looks like this:
  set xq mac=08-00-2B-AA-BB-CC
  at xq enp4s1

Where the host's Etherent device is /dev/enp4s1.

Versions look like this:
  Host OS = OpenSUSE 13.2
  simh version = V3.9-0
  libpcap1-32bit-1.6.2-1.2.x86_64
  libpcap1-1.6.2-1.2.x86_64
  libpcap-devel-32bit-1.6.2-1.2.x86_64
  libpcap-devel-1.6.2-1.2.x86_64

The pdp11 simulator starts up normally...
  PDP-11 simulator V3.9-0
  libpcap version 1.6.2
  Eth: opened OS device enp4s1
  Disabling CR

  73Boot from ra(0,0,0) at 0172150
  :

...and networking does work a bit, but shows heavy packet loss...

  # /etc/netstart
  Assuming NETWORKING system ...
  add host spdp11: gateway localhost
  add net default: gateway 192.168.1.1
  # ping 192.168.1.1
  PING 192.168.1.1 (192.168.1.1): 56 data bytes
  64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=933.352 ms
  64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=266.672 ms
  64 bytes from 192.168.1.1: icmp_seq=3 ttl=64 time=250.005 ms
  ^C
  --- 192.168.1.1 ping statistics ---
  5 packets transmitted, 3 packets received, 40% packet loss
  round-trip min/avg/max = 250.005/0/933.352 ms
  #

Any ideas why this would be?
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