Noob question about T1s

mthomas22

A while ago, I came across a scenario in class involving a business with a main office and a branch office. The main office had an internet T1 connection and there was also a point-to-point T1 connection between the offices. The scenario then went on to say that the point-to-point T1 between the offices was being replaced by something cheaper like cable or DSL, and would require a VPN for security.

A few things about this confused me - first of all, are a "T1 internet connection" and a "point-to-point T1" two different things? Second, why would a VPN be required with DSL or cable but not with a T1?

itdaddy

hey bud

I can answer your questions easily....

I work for a credit union. We have T1 (bandwidth of 1.544Mbps) that is 23 channels x 64 kbps
T1 line has 24 lines each 64K (USA specs) 23 data channels and 1 signal channel.

23 x 64 is approx 1.544 MBPS


a T1 p2p is a dedicated line 24 channels (23 data and 24th signalling)
you can divide a T1 say 5 channels for voice and 18 for data etc... ifyou want..
we have 9 channels for voice data and 14 for normal data.
We have T1 ptp to each branch all from one mother ship branch. we have 3 CSU/DSU Adtrans and what you call smart jacks to connecto a dedicated T1 line to each branch office.

T1 is bandwidth 1.544 MBPS for internet speed
then T1 same speed to each branch office that has 24 channels (23 for data/voice and 1 for signalling) get it!



just focus on bandwidth and 24 channels with the internet T1 connection just look at it as one big pipe running 1.544 and the p2p T1 lines as 24 channels to each branch with 64k per channel.
easy





(vpn question)

your T1 are generally dedicated closed loop circuits dedicated to your IT infrastructure.
whereaas DSL or cable home type setup is open to public....you can do VPN/SSL or VPN/ipsec
from ptp. you need to because your will be encrypted for safety and security from others.
cable and dSL run public circuits any one can grab the data so you need the vpn...
they run cheaper cause your devices on each end are doing the work of security whereas
when you have T1 it is expensive. but it is more secure....based off of regualtions and policies that your company needs to follow...

mthomas22

Thanks for the quick reply. I'm familiar with the information about channels/bandwidth/etc but I'm still not really clear on if there is a difference between a point-to-point T1 and an internet connection T1. For example, at the credit union you work for do the point-to-point T1s between branches also provide internet connectivity, or is a seperate 'internet T1' or other form of WAN connection needed?

liven

point to point t1 should go from a branch office to main office, not routing through the public internet. If the branch offices want inet connectivity they will have to get it through the main office or some other form of connectivity.

Where your typical dsl/cable connection would go to an ISP and then get routed back to the main office. Giving you inet and connetivity from the branch office to the main office.

The main office has a T1 that sounds like it is routed back to an ISP for inet connectivity. Think of it as the central hub of communications for all the branch offices.

itdaddy

Liven

is correct. we have all PTP T1 lines comming back to our branch office all hooked from smart jack to CSU/DSU they are dedicated lines (think of them as hard wired) wires that go from each branch to main branch (orwhat I call the Mother Ship) then traffice from all branchs goes through our Firewalll then out to internet through one T1 lineto ISP. this is a closed system whereall internet traffic goes from each branch office back to mother ship and then through firewall and then out too ISP and INET. this is for secure reaasons..our VOIP system is riding on our T1 as well that is why you can subdivide a T1 up to have your VOIP work from branch to branch saving you long distance call money!