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SDLC VMAC?

Hi all.

I need to configure a simple SDLC/DLSw scenario:

3174 --(SDLC)--Router1 == (DLSw/IP) == Router2 -- (E/FE)HOST

As far as the serial interface of Router1 is concerned, I understand that the parameter of the "sldc partner" command should be the non-canonical MAC address of the Host.

But what about the parameter of the "sdlc vmac" command? Is it arbitrarily chosen? Should it match any parameter in the 3174?

Your hints are very appreciated

Thank you very much!

1 ACCEPTED SOLUTION

Accepted Solutions
Silver

Re: SDLC VMAC?

What is the SDLC role setting on the PU2.0?

Most PU2.0 is SDLC secondary. Thus, you should set the router as SDLC primary. I think that you are hitting CSCdi73339. Well, CSCdi73339 is not a bug. It is an incompatibility issue between RS-232C and RS-232D devices.

Cisco routers support RS-232D. RS-232D newly defines pin 18 as loopback. Some old devices which support RS232C MAY raise pin 18. It causes the SNRM frames to loopback to the router.

There are 3 workarounds documented in the bug as follows:

1.Remove pin 18 from the cable.

2.Use a Cisco adapter cable, product number CAB-2500-LLADAPT. This cable attaches between the seria port of the router and the Cisco serial cable.

3.On the low-speed serial ports of certain platforms, you can use a version of IOS that has the fix described in CSCdi73339. With this fix, you can configure the serial port to ignore the local loopback signal with the "ignore-hw local-loopback" command.

Another way to test it is to use a breakout box and ground pin 18.

4 REPLIES
Silver

Re: SDLC VMAC?

The restrictions on sdlc vmac is as follows:

The rules for the vmac are as follows:

1. the same vmac cannot assign to two SDLC interfaces on the same router

2. The MAC address for the SDLC controller (i.e. VMAC and the most right byte substitutes by the SDLC address of the controller) has to be unique on your network. The easiest way to do so is to assign different vmac on different SDLC interface. Also, make sure that no other devices (i.e. any tokenring, ethernet, and FDDI device) has the same vmac as the controller.

3. IEEE allows users to locally administrate MAC address. The range is 4000.0000.0000 to 7fff.ffff.ffff (in non-canonical format). IOS does not put any restriction on the value of vmac. If you assign the vmac in the above defined by IEEE, that's good. Otherwise, the VMAC you defined may be clash with some other NIC. Any mac address above 8000.0000.0000 will not work; even though IOS allows you to do so.

There is no parameter on the 3174 to match.

New Member

Re: SDLC VMAC?

Thank you for your prompt and useful answer.

I'll try your advices and let you know.

Best regards

New Member

Re: SDLC VMAC?

Kasing,

thanks to your advice I have chosen my sdlc vmac and I get a successful sdlc test.

But I can't get traffic through.

My scenario has changed to the following:

PU2.0 --(SDLC)--Router -- (E/FE)HOST

and this is what happens:

- if I set "sdlc role primary", SDLC is stuck in SNRMSENT state and complaints that there could be a station role issue as the router receives SNRM frames

- if I set "sdlc role secondary", SDLC is stuck in DISCONNECT state and doesn't receive SDLC frames

Can I please forward you some configuration details and debug outputs to your business address?

Thank you

Silver

Re: SDLC VMAC?

What is the SDLC role setting on the PU2.0?

Most PU2.0 is SDLC secondary. Thus, you should set the router as SDLC primary. I think that you are hitting CSCdi73339. Well, CSCdi73339 is not a bug. It is an incompatibility issue between RS-232C and RS-232D devices.

Cisco routers support RS-232D. RS-232D newly defines pin 18 as loopback. Some old devices which support RS232C MAY raise pin 18. It causes the SNRM frames to loopback to the router.

There are 3 workarounds documented in the bug as follows:

1.Remove pin 18 from the cable.

2.Use a Cisco adapter cable, product number CAB-2500-LLADAPT. This cable attaches between the seria port of the router and the Cisco serial cable.

3.On the low-speed serial ports of certain platforms, you can use a version of IOS that has the fix described in CSCdi73339. With this fix, you can configure the serial port to ignore the local loopback signal with the "ignore-hw local-loopback" command.

Another way to test it is to use a breakout box and ground pin 18.

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