Point to Point LAN Connetion

[jazzman20014]

Not sure if this is possible but here is the requirement.....

The local LAN needs to be extended from one building to another, it has to use telephone copper that is already installed into each building and goes back to a central exchange on site (this is a quick fix hopefully) and it would need to use the same IP subnet as the existing one on site (as in both on a layer two if possiible). 

What I am thinking about is a pair of 2600s with T1 Data Service Unit/Channel Service Unit (DSU/CSU) WAN interface cards, and configure them to look at each other to create a T1 line, then using a GRE tunnel to create the layer 2 connection between the two buildings.

Having never had to create a network from a straight bit of copper without any other protocols over the top it may well be that this is not a sensible solution.

Also I should mention that budget is virtually nil and I am up against it on time - not of my doing it must be said. 

Thanks in advance

Jazzman

[Peter Paluch]

Jazzman,

The biggest problem with your currently available equipment may be that the CSU/DSU cards may not be able to work in a back-to-back connection. I can try to find out if such a setting is possible but I am not very optimistic. Usually, these cards are only capable of working in a client mode, and emulation of a CO functionality can be beyond their capabilities. In any case, I would need to know the exact type of these two cards.

Best regards,

Peter

[jazzman20014]

Hi Peter,

Thanks for your reply, I have a feeling that you may be right but cannot think of another way to overcome the issue of a phone pair that is in effect point to point over at least half a mile.

Eventually we will get fible laid in but that is not going to be for a few months at best. 

The cards are WIC 1DSU T1 V2 cards. 

Matt

[John Blakley]

I'm not sure if it fits your requirements, and Peter may have well answered your question, but you can create a T1 crossover cable to get the CSU to come up between the WICs. I've done it in a lab and it works fine. Your pinouts would be:

*** Edit *** (Try this site instead):

http://sh-run.com/2009/06/04/how-to-make-a-t1-crossover-cable/

*Note: This would be just for the vwics to turn to up/up state and run standard l2 protocols over (hdlc,ppp). As far as your other requirement, you may look into bridging the internal interfaces but I'm not sure the 2600 supports IRB.

HTH,
John

*** Please rate all useful posts ***

[Peter Paluch]

Hi Matt,

Please follow John's link to make a T1 crossover cable. It appears that these CSU/DSU cards should actually be able to work in a back-to-back fashion.

One of the routers shall be configured as follows:

interface Serial0/0
 encapsulation ppp
 ip address 10.0.0.1 255.255.255.252
 service-module t1 clock source internal
 service-module t1 timeslots 1-24 speed 64
 service-module t1 framing esf
 service-module t1 linecode b8zs
 no shutdown 

The other router shall be configured as

interface Serial0/0
 encapsulation ppp
 ip address 10.0.0.2 255.255.255.252
 service-module t1 clock source line
 service-module t1 timeslots 1-24 speed 64
 service-module t1 framing esf
 service-module t1 linecode b8zs
 no shutdown

These commands are shamelessly stolen from Edison Ortiz from the following thread:

https://supportforums.cisco.com/thread/2028581

If the line comes up we can start looking for ways of extending your VLAN to the other building. An L2TPv3 pseudowire would normally be used for this.

Best regards,

Peter