[Simh] Packet Loss

[Mark Pizzolato]

Hi David,

First I would suggest that you run the latest code which has significantly improved networking.
The latest is available from https://github.com/simh/simh/archive/master.zip

It is not clear from the below description, but from what Johnny read ‘in between
the lines’  you have both the VAX and PDP11 simulators configured with the same
MAC address.  This would indeed be an error on your part (and the latest code
would tell you that).

Meanwhile, once unique MAC addresses are configured for each simulator (which
would happen automatically if you didn’t explicitly have a “SET XQ MAC=…”
command using the latest code), then your dedicated to simh NIC model should
work well.

If it doesn’t, please create an issue at https://github.com/simh/simh/issues and
we can explore the details further.

Good Luck.


-          Mark

From: Simh [mailto:simh-bounces at trailing-edge.com] On Behalf Of David Coolbear
Sent: Tuesday, August 23, 2016 10:12 AM
To: simh at trailing-edge.com
Subject: [Simh] Packet Loss

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<http://192.168.1.1>: icmp_seq=1 ttl=64 time=933.352 ms
  64 bytes from 192.168.1.1<http://192.168.1.1>: icmp_seq=2 ttl=64 time=266.672 ms
  64 bytes from 192.168.1.1<http://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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