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anoop
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Lease Lines Over heads

Thu Jan 12, 2006 10:11 am

Can any body tell me wat all are the over heads in the lease lines procurement..as of now i know that one cause of overhead is IP header which add extra bits to the data...wat all other factors adds to the same..??????? :?:
anoops

TravisT
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Fri Jan 13, 2006 6:39 pm

It all depends on what protocols you use. Different protocols use different overheads

anoop
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lease line issue ????

Sat Jan 14, 2006 8:48 am

The Querry is regarding the Over heads in the lease lines caused due to the extra bits that are added to the Data field.
I mean if there is 100Mbps of data to be send from the data centre to the DR site over say on a 4 Mbps link then the ideal time taken should be say X min for the DR site to come up once the Data Centre goes down.
But if we take all the other fields like fragement offset,flags,Ver and all the entries in IP header than some more Bits are added to the Data Field,which makes the total data size greater than 100 Mbps ie (100+YZ)Mbps.
another thing is Throughput ie effeciency of the lease line,as it is not 100% it also leads to some over heads.
So the total time for the DR site to come up increases to (X+A)mins.

1)So the querry is there any way to calculate the correct effeciency of the Lease line ..???

2)Apart from the above mebntioned overheads what all overheads are there.And is there any way to Calculate the overheads so that we can get the exact time for the DR site to come up once the Data Centre goes Down..??

3) Is there any Formula to Calculate the above mentioned (YZ)Mbps and (A) Mins..????

Thanks...
anoops

geko29
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Fri Feb 10, 2006 9:43 pm

Not to be an ass, but why do you care? You're not getting 100Mbps over a leased line unless you're talking OC3 or better, and at that point, is 5mbps really going to make or break the usability of your connection? But since you asked, here's a couple for you:

OC1: 51.84 Mbit/s (payload: 50.112 Mbit/s; overhead: 1.728 Mbit/s)
OC3: 155.52 Mbit/s (payload: 150.336 Mbit/s; overhead: 5.184 Mbit/s)
OC12: 621.84 Mbit/s (payload: 601.344 Mbit/s; overhead: 20.736 Mbit/s)
OC48: 2488.32 Mbit/s (payload: 2405.376 Mbit/s; overhead: 82.944 Mbit/s)
OC192: 9953.28 Mbit/s (payload: 9621.504 Mbit/s; overhead: 331.776 Mbit/s)

So that's about 3% for SONET, I don't have any hard numbers for T-carrier lines, but it should be right around 8% once you add HDLC encapsulation. Your theoretical 4Mbps line can actually push around 3.7Mbps in each direction. Which shouldn't make a marked difference unless you're pushing so much data that it'd be faster to drive there with a data tape and run a restore. In which case, do that. :)

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Steve
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Fri Feb 10, 2006 11:43 pm

geko29 wrote:Not to be an ass, but why do you care? You're not getting 100Mbps over a leased line unless you're talking OC3 or better, and at that point, is 5mbps really going to make or break the usability of your connection? But since you asked, here's a couple for you:

OC1: 51.84 Mbit/s (payload: 50.112 Mbit/s; overhead: 1.728 Mbit/s)
OC3: 155.52 Mbit/s (payload: 150.336 Mbit/s; overhead: 5.184 Mbit/s)
OC12: 621.84 Mbit/s (payload: 601.344 Mbit/s; overhead: 20.736 Mbit/s)
OC48: 2488.32 Mbit/s (payload: 2405.376 Mbit/s; overhead: 82.944 Mbit/s)
OC192: 9953.28 Mbit/s (payload: 9621.504 Mbit/s; overhead: 331.776 Mbit/s)

So that's about 3% for SONET, I don't have any hard numbers for T-carrier lines, but it should be right around 8% once you add HDLC encapsulation. Your theoretical 4Mbps line can actually push around 3.7Mbps in each direction. Which shouldn't make a marked difference unless you're pushing so much data that it'd be faster to drive there with a data tape and run a restore. In which case, do that. :)


Good info, thanks.

anoop
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lease

Sat Feb 11, 2006 2:14 pm

Thanks 4 the Info geko29
anoops


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