UCX Communication Error

[C Ravi]

I am working on a VAXStation 4000-60. Open VMS Version 7.1 and DIGITAL TCP/IP services for OpenVMS Version V4.2

I am having problem with communication with an external device.

The IP of my machine is 192.168.1.1 with subnet mask 255.255.255.0.

The IP of the external device is 192.168.1.3 with subet mask 255.255.255.0

when i try to ping to this device it gives an error.

ucx>ping 192.168.1.3
%UCX-I-LOOPINACT, 192.168.1.3 does not respond.

the arp details show

ethernet internet host name ARP status
192.168.1.3 HDL01 INUSE

Ping to the localhost and the machine IP works.

What could be the problem?

[Karl Rohwedder · Accepted solution]

Does the other way round functions? Is there some network hardware inbetween blocking ping?
Are other TCPIP services functioning?
What is 'external device'?

regards Kalle

[C Ravi]

No there is no network device in between. The device i am talkin about is an Highway Data link, which is used in plant network. But the device itself is working, as it gets configured using COM port communication.

[Volker Halle]

$ UCX SHOW ARP should also give you the ethernet MAC address in column 1, you did not post that information, so we must believe, that the information is NOT available ! That means, that there was NO ARP response from the external device !

Can you be sure, that sending and receiving ethernet packets via the LAN interface does work at all ? Is there anything else connected to that network, with which your system can communicate ? Pinging localhost and the local node IP address does NOT tell you, whether the LAN interface can actually send/receive patckets at all.

Check the LAN interface counters:

$ ANAL/SYS
SDA> SHOW LAN/COUNTER
...
SDA> EXIT

Does the external device have any counter information (like received/sent packets) ? Do these counters increase ?

Volker.

[C Ravi]

No there is no other device connected to this machine, except the one i mentioned before.

I checked the Lan counters, where the received counter value is zero in all cases, but the sent counter shows some value.

Also I can see 8 ESA devices.

[Volker Halle]

If the SENT counters are non-zero, this indicates, that the LAN interface is a least able to send data. If the RECEIVE ounters are 0, it indicates, that no ethernet packets are being received at all.

The fact that you 'see 8 ESA devices' only indicates, that multiple protocols have been started on physical interface ESA0. SDA> SHOW LAN will show you the various protocols.

You now need to look at the counters of the external device. Does it receive any packets ? Does it send any packets ?

Can you connect any other TCPIP-capable device on that 'LAN' ? Maybe your laptop with the correct IP address instead of the 'external device' ?

Volker.

[C Ravi]

The problem is the external device, is a highway data link, used in plants, this acts as a switch, and hence i cannot check, whether this recives any data or not.

Also i cannot connect my laptop as the Vaxstation uses BNC cable for ethernet communication.

Is there any other way?

[C Ravi]

Also while configuring the Highway Data link, it asks for the IP address of the Vaxstation and also for the ethernet_address. I provided the ethernet address of the interface(SE0).

But this address is different from the ethernet address of ESA0 which is the ethernet device?

[Volker Halle]

So this is a NEW installation, right ?

There may be 2 MAC adresses involved with a network interface, the HW MAC address (ROM on interface) and the current MAC address, which may have been changed, if DECnet has been started on the interface !

$ ANAL/SYS
SDA> SHOW LAN/FULL

will show you both the hardware MAC address and the current MAC (physical) address as:

Physical address AA-00-04-00-9F-C5 Hardware address 00-12-3F-7D-96-A2

Volker.

[C Ravi]

Yes, i can see two address,

Physical address AA-00-04-00-14-28

Hardware address 08-00-2B-34-55-4E

Through which address should the communication take place?

[Volker Halle]

As you are running DCnet on this LAN interface, you MUST specifiy the DECnet MAC address AA-00-04-00-14-28

When DECnet Phase IV software starts on a LAN interface, it re-programs the MAC address of the LAN interface to use the DECnet MAC address. It is calculated as AA-00-04-00 (fixed prefix) and then the DECnet-address (in your case 10.20) by calculating area*1024 + node-in-area (e.g. 10*1024+20) and swapping the 2 hex bytes.

The interface will then ONLY recognize the newly programmed MAC address.

Volker.

[C Ravi]

I have used the physical DECNet address, but the device still does not ping?

[Volker Halle]

From the VAXstation side, you can only look at the LAN counters. If no packets are being received, either the 'other side' doesn't send them or there is a HW problem in the receiver part of the LAN interface.

If you are programming the 'Highway Data link', is there no way to ping from the 'external device' ?

If UCX SHOW ARP does not show the MAC address of the 'external device' HDL01, the VAXstation has never received an ARP response from that device, so it cannot send an ICMP message to that device.

If you doubt that the LAN interface on the VAXstation does work correctly, it may be possible to test with a loopback connector and some console-level test.

Volker.

[C Ravi]

No there is no way of pinging to the Vaxstation from the Highway Data Link.

Also can you please tell, what type of tests can be performed on the LAN interface on the Vaxstation.

Also can this be a problem with the connection of the BNC Cable.

[Volker Halle]

Yes, it could also be a problem with the transceiver cable and wherever you plug in the other end of the cable.

Here is a pointer to the 'VAXstation 4000 Model 60 Ownerâ s and System Installation
Guide'

http://vt100.net/mirror/mds-199909/cd1/vax/pmarioma.pdf

Chapter 4 describes 'Testing your Ethernet Subsystem'. Note that you may need a AUI loopback connector and a T-Connector with 2 terminators for the ThinWire port.

Volker.

[C Ravi]

Hi volker

Thanks for the document, it was helpful.
It is no pinging to the highway data link device, there was a problem in the position of the network switch and also a terminator had to be attached at the thin wire ethernet end.

Thanks again, i had been stuck with this problem for the past two weeks