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New Member

Configure for T1 Pass Through

I have a Cisco 1700 and was wondering it is was possible to configure as a T1 Pass Through?  The customer is getting a T1 as a backup to our fiber- required by German corporate.  They however, don't want to buy a different Router and want to still use the silly Sonic Wall the IT Person put in.  I was trying to up sell to a Cisco. 


Anyway, they would like to put a 1700 off the T1 but want NO routing done within the 1700 -- just a pass through to convert to Ethernet to hand to the Sonic Wall - which will do all the routing.  ANY IDEAS? 

This is what I am looking to do 

Verizon T1---- To Cisco 1700 Serial 0/0 CSU/DSU no routing - ETH 1/0 -  Hand off to Sonic Wall.

Cheers!

14 REPLIES
Hall of Fame Super Gold

Re: Configure for T1 Pass Through

You cannot go from T1 to ethernet without routing - it's as simple as that.

New Member

Re: Configure for T1 Pass Through

Thank you.  This what I thought however one of the cabling guys who doesn't deal with Routers was 100% positive that I could get it to work.  He brought 3 routers and wanted me to work on it until I got it working.  I told him it was possible.  So I thought I would post because if I was missing something than someone on here always has an answer!  Thanks for proving me RIGHT! 

Cheers

New Member

Re: Configure for T1 Pass Through

Sorry I told him it WASN'T possible. 

Hall of Fame Super Gold

Re: Configure for T1 Pass Through

But that is not a problem really. To your customer eyes the router will just convert T1 to ethernet.

When the technical details are above someone understanding, better not even discussing them.

Please remember to rate useful posts clicking on the stars below and help CSC raise money for Haiti disaster relief.

Cisco Employee

Re: Configure for T1 Pass Through

This can be done without routing on a router. This is called transparent bridging where we only do bridging between serial T1 to Ethernet.

Configuring Transparent Bridging

http://www.cisco.com/en/US/tech/tk331/tk660/technologies_tech_note09186a0080094471.shtml

Look for Simple Transparent Bridging section in the above document. Instead of the second ethenet interface, add the bridge-group command under the serial interface.

Hall of Fame Super Gold

Re: Configure for T1 Pass Through

This can be done without routing on a router. This is called transparent  bridging where we only do bridging between serial T1 to Ethernet.

Incorrect, layer 2 encapsulation used by ISP used on T1 circuits (HDLC or PPP) is NOT bridgeable because there are no MAC addresses.

New Member

Re: Configure for T1 Pass Through

I know this was posted long time ago but i am trying to do similar thing with T1. I thought it is posible becasue you can do it on  ADSL? I have done transparent bridging on WIC-ADSL module and Ethernet Port. According to my knowledge it also uses ppp. Can you explain it in more details or send some refernce documents?

Take care

Hall of Fame Super Gold

Re: Configure for T1 Pass Through

Pertinent to your problem, what are you trying to do, and why ?

Incidentally, I note that only a very ignorant person may have low-rated my post above, because what I wrote is the simple, uncontestable truth.

New Member

Re: Configure for T1 Pass Through

I am attaching Visio Diagram of what i am trying to do. I think it explain better than words. Let me know what you think and if anything like this is possible. The reason why i would do something like this is when ISP gives you only one IP address and you do not want to do double NAT.

Regards

Pawel Bargiel

Hall of Fame Super Gold

Re: Configure for T1 Pass Through

Please use only standard image formats for attachments, do not use proprietary formats.

What is the physical media used by ISP ? ADSL, T1, Ethernet ?

In case of ADSL, What is the protocol, PPPoE, Bridged RFC ?

New Member

Re: Configure for T1 Pass Through

Sorry about that. Is JPEG ok? This drawing really explains evrything i am trying to do.

Hall of Fame Super Gold

Re: Configure for T1 Pass Through

Sorry, I do not understand the purpose of it.

It is a study lab or a real scenario ?

New Member

Re: Configure for T1 Pass Through

It is a lab scenario to test if this is possible or if there is any walk around it. Example: (Based on the Lab scenario) R2 is an ISP router conntected to my (R1) router via T1 (in this lab both routers use WIC-T1-CSU/DSU to simulate T1 link). I am provided only one IP address that i can use "172.1.1.2" and i want to bridge that address from R1 (S0/0) to sonicwall firewall WAN interface. Is there any way i can do it?

Hall of Fame Super Gold

Re: Configure for T1 Pass Through

In the real world, ISPs using T1 do not provide only one address.

When you will produce a real scenario, things can be looked at.

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