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FrameRelay connection with a DB25 to RJ45 black cable.. It's possible!??


Tengo  esta escenario..
Un DTU MainStreet 2701 con puerto DB25 conectado a un router Vanguard 340  Motorola atraves de otro puerto DB25.

Yo quiero sustituir ese  Vanguard por un router cisco 800, pero no tengo donde conectar el puerto  DB25. Mi pregunta es, puedo usar el cable negro DB25 to RJ45(el mismo  que viene en las cajas, junto con el de azulito de consola y el amarillo  patch cord) para conectar el DTU con el router y establecer el enlace?  esta comprobado que fisicamente si pueden ser conectados.. pero en que  puerto etherhet colocaria el otro extremo del cable? en el Console?(en  el AUX no puede xq no tiene) o en un Ethernet normal?

Que  configuraciones son necesarias?? estas son mis dudas... les estaria  eternamente agradecido



Today I need your support

I Have this scenario.. A DTU MainStreet 2701 with port DB25 connected to a router Vanguard 340 Motorola through another port DB25, with a establish Frame Relay Connection.

I wish to replace that Vanguard for a router cisco 800, but i do not have where connecting the port DB25. My question is, I can use the black cable DB25 to RJ45(the same that comes in the boxes, along with the blue console and the yellow patch cord) to connect the DTU with the router and establish the link? I know its possible phisicaly… but what port etherhet i put the other end of the cable? In the Console?(in the AUX cannot because the Cisco 800 dont have one) or in a normal Ethernet? what Configurations are necessary? These are my doubts... Im eternally grateful if  you answer my question... its possible?

Richard Burts
Hall of Fame Guru


Thank you for posting in both Spanish and English. I have not seen many posts that do this and I believe that your doing it is a positive sign of the multinational nature of our forum.

The Frame Relay connection is over a serial interface. The quick search that I have done on the Cisco site does not show any Cisco 800 routers with a serial interface. If the Cisco 800 does not have a serial interface then it would not be possible to replace the Vanguard router by the Cisco 800.

If anyone can show a Cisco 800 that does have a serial interface I would be glad to know what slipped by my search.





Hi collagues

I appreciate your interest to solve my problem.. or its not really a problem.. I think It's a way to hit the job with the weapons that I have in my hand(like Jackie Chan). I'm from Venezuela and my native lenguage is spanish but I can handle the english... thats the reason that I post in both lenguage.

Well.. In the proposition I offer to use a Cisco 871 (with 1 Console Port, 1 WAN ethernet Port and 4 Ethernet SwitchPort)... But if I need a Serial Port.. I can use a Cisco 803 (and if my memories dont fails me..It have a 1 SmartSerial, 1 Console port and 1 ethernet).. is it possible to configure the smartserial with framerelay's parameters and make a kind of "jump" to the WAN ethernet Port??

Or If I dont other choise I think .. I can dig in the depot if I can found a Cisco 1700 with a free slot to add a WIC.. It can be possible Cisco 803 o Cisco 1700? what do you think??

Hi Jose,

Since you have 1700 router, I would put a WIC in there and terminate the T1 using a copper interface.

See below link:



Reza Sharifi
Hall of Fame Expert

Hi Jose,

If I understand your question correctly, you need a T1/WIC card with build in CSU/DSU.  You can not connect it to console, aux or Ethernet  You need to connect it to your WAN interface.

I do not think that 800 come with T1 interfaces.  What is the model number of your router? Is it 860, 850, 805, etc?