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View Full Version : Am I getting my T-1's full capabilities?


ITstudent2006
Dec 2, 2010, 06:52 AM
We currently have a T-1 running to our DR site and the only thing utilizing this is our replication from our backup ARCA to our ARCA vault.

The servers are set to use 100% of the T-1. The image below is a look at the replication process and I was wondering if I was getting the full 1.5MB?

Shouldn't this say 1.5MB or equivalent Mbps?

cajalat
Dec 2, 2010, 08:06 PM
Rick,

When troubleshooting bandwidth issues it is best to start from the ground up. Looking at the application (looks like Breakthrough) you're not getting the full picture. There is overhead involved and the problem could be with the application as well.

So you might want to start with something that checks line performance of the T-1. There are many apps out there but my preferred apps for checking line characteristics (bandwidth, latency, jitter, etc) are ttcp and iperf. Both require that you have a sender and a receiver on either end of the connection.

Do you have access to the routers on both ends of the connection that you can perhaps run some basic diagnostics on for things like errors or retransmits?

ITstudent2006
Dec 3, 2010, 08:33 AM
Yes I have access to routers on both ends!

cajalat
Dec 3, 2010, 09:29 AM
What kind of routers are they? Cisco?

ITstudent2006
Dec 3, 2010, 01:44 PM
Is there a reason you assumed Cisco??

:) No they are Netgear!

cajalat
Dec 3, 2010, 02:38 PM
I know Cisco very well and was going to suggest some specific things to look for. But it doesn't matter so long as you can look for things that would indicate a potential problem. For instance, look for these:

Errors (Input & Output):
- CRC
- Frame
- Overruns
- Underruns
- Ignored
- Giants
- throttles
- Excessive lost carrier signal
- interface resets
- buffer failures

There may be other counters on the netgear as well to look for. If you don't see any errors then that's good. If you do see errors it doesn't necessarily mean you have problems. These errors could have been recorded a while back. You may want to reset the counters and watch them again.

Also look for interface input and output rate (either bits per second or packets per second). During your transfer of data see if you're actually maxing out the line on the router by monitoring it concurrently.

Since you have access to both ends then during an off time you might want to setup a system with ttcp and/or iperf and run them while no other traffic is present. These should be able to tell you if your line is capable of running 1.5Mbps. Test with UDP traffic in each direction independently and then concurrently.

What is the model of your router (I can do some digging on specifics to look for).