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wiring between serial links

Hello,

Does anyone know if it's possible to connect a v.35 serial interface to a 56 kbps rj45. I believe I would use (tx+, tx- and rx+, rx-) on the rj45 56kbps to (sd+, sd- and rd+, rd-) on the v.35 side. Is this correct? Thanks.

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New Member

Re: wiring between serial links

test

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New Member

Re: wiring between serial links

Those two interface types aren't even close to one another. First of all, V.35 requires clock signals. But more importantly, you are likely to smell some smoke if you hook this up. They are not electrically comaptible.

New Member

Re: wiring between serial links

Is there anything to simulate a 56k line to my 1602 router?

New Member

Re: wiring between serial links

I don't have a 56k DSU laying around anywhere so unfortunately I can't give you a config that I know will work. Physically, you just need to cross tx+ to rx+ and tx- to rx-. Logically, you need a clock source on one side and recovered timing on the other. This link is for 2500 series routers, but I suspect the CSU is the same. I would start here:

http://www.cisco.com/warp/public/471/75.html

New Member

Re: wiring between serial links

Hi, I'm trying to simulate a lease line on (2) 2500 routers using the V.35 interfaces cabled directly back-to-back (DCE & DTE V.35 cables). For the DCE end , I set the clockrate for 56000, then try to do "dce-terminal-timing-enable". When attempting this, I get a error message that reads "Not allowed on DTE interface". How can I properly configure this DTE interface into a DCE interface? Thanks

New Member

Re: wiring between serial links

I don't have any V.35 interfaces in any of our 2500 series routers so I can't offer any configuration advice that I know will work. I do question whether or not dce-terminal-timing-enable is necessary. Your routers are back to back. Terminal timing is usually only necessary (at least in the case of Cisco routers) if there is a significant propagation delay on the physical cable. Surely that will not be the case in your situation.

New Member

Re: wiring between serial links

Hi, Sorry about the confusion. The router doesn't come with V.35 serial interfaces from the back. What I basically have is a one router with a V.35 DTE cable connected to S0, and another router with a V.35 DCE cable (also connected to S0). I want to create a back-to-back serial connection, but the router with the DCE cable will not go into DCE mode. I have the right cable for the DCE side (CAB-V35FC), and I have a DTE cable for the DTE side. Thanks!

New Member

Re: wiring between serial links

This link demonstrates two back-to-back routers using V.35 DCE and DTE cables as appropriate:

http://www.cisco.com/warp/public/116/ppp_back.html

This link shows the pinouts for the cables:

http://www.cisco.com/univercd/cc/td/doc/product/access/acs_fix/cis2500/2509/acsvrug/cables.htm

By all accounts, you should be able to plug the two cables together and issue the clockrate commmand on the DCE router. No other commands should be required. Notice in the first link the output of the show controller commands. The cable is proplerly detected as V.35 DCE or DTE as appropriate.

Is your protocol not up? Or the interface? Not sure what makes you think your interface is not behaving properly.

Regards,

Scott

New Member

Re: wiring between serial links

Hi Scott, After my last entry, I got hold of a pair of DSUs, so I set up a phony T1 connection back-to-back to complete my troubleshooting. I do have another set of routers to play with, so I will try this tomorrow. With what I have to deal with, this method is easier to deal with.

In my configuration, I did not have PPP encapsulation, but I had the clockrate set at 56000 on the DCE side of the scenario. My interface at both ends showed Interface Up, Protocol Down. I was using the default standard HDLC protocol. It's a given that I missed something along the way. :)

Thanks for your help Scott. I will test it tomorrow and let you know how I made out.

-Frankie

New Member

Re: wiring between serial links

test

New Member

Re: wiring between serial links

I'm not sure if I understand what you're trying to accomplish, but if you just want to get the router up for testing/lab purpose, you can always make a "loopback RJ-45" and plug it into your built-in 56k csu/dsu. The pin-out for the 56k circuit is 1,2,7,8. 1 and 2 are Tx and 7,8 are Rx. Connect 1 to 7 and 2 to 8.

Hope this helps!

New Member

Re: wiring between serial links

Yes, this is a lab router, and I just want the interface up for testing purposes. I have made the loopback plug, and its' up and up, but have a question in regards to routing protocols on this interface now. When doing appletalk routing, the routes are not advertised from this interface, but when doing rip routing, ip routes are advertised , any idea why that is? Thanks.

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