Hi,
First of all this is my view that did not come from here nor is it necessarily the
opinon of the company that I work for. (or probably anyone else)
OK the technology.
Point to point leased line.
You have control over what it is in terms of end to end conectivity remains constant.
ie 1Meg remains 1Meg or 2Meg remains 2Meg depending on what you buy and your
connection method. (modems or whatever)
Frame relay.
This is not so cut and dried.
You may have a service setup for 1Meg and to cut costs a CIR of 0. You can get upto
1Meg at times but if you get 0 that is what you have and usually no sympathy but
advice to suggest uping the CIR.
If you are connecting to a supplier. There is a chance the supplier will have a
number of people connected to the same physical port and may load the ports to match
the CIR of all the circuits. Say the supplier does not for some reason support
traffic shaping. (and there are valid reasons for not supporting it) OK for an
example of what can happen. You are connected by a 1Meglink with a 256K CIR to the
supplier (WRONG you are connected by a 1Meg link to the frame switch). The supplier
has 10 people people connected to the interface with vaying CIR's some at 64K, you at
256K and Fred the rich guy at 1Meg. All totalling less than 2Meg the speed at which
the supplier connects to the frame switch. At this point it is not a problem. It is
likely however you will not see the 1Meg very often when you really need it as that is
when the other guys do to.
Ok now you do what you really wanted to do. Leave your service at 1Meg stick in
another PVC to your remote site this way you only need one service back to the Frame
switch saves heaps. Remember the supplier has a 2meg link back to the frame. You have
1Meg back with 2 PVCs one to the supplier CIR 256K the other to your remote office CIR
64K way less than your 1meg. No traffic shaping at the suppliers end. He is good to
you you have requested an FTP file be sent via the supplier. The supplier send it at
you at 2Meg you say stop/slow send the supplier says "eh what's a BECN" 2Meg keeps
pouring at you bits fall no problem upper layers take care of this. You 1Meg service
however is getting 1Meg down it. What happens to the remote office? (he is gone)
Nasty isn't it.
Long winded but not often realised. Frame relay is briliant and does a good job but
in some circumstances it has problems. Usually only when most needed. Direct
physical type services do not have these problems but that costs. Horses for courses.
Hope this helps
Teunis
Hobart, Tasmania
Australia
You the decide
On Monday, January 08, 2001 at 10:31:05 PM, Kevin Welch wrote:
> Can someone please help me with any negative issues or downsides to =
> frame relay? =20
>
> I am trying to make a comparison between frame relay, dedicated leased =
> lines like T1's, and VPN's using existing internet connectivity. =20
> Complexity doesnt even really compare to most VPN solutions. In all but =
> the extreme cases frame relay is cheaper than a leased T1. Frame relay =
> is described as a more shared medium like cable or DSL than a leased =
> line, but isnt the point of the CIR to make sure that you get what you =
> are paying for? Also the normal NBMA and split horizon problems with =
> point-to-multipoint configurations.=20
>
> Are there any other negative reasons not to choose frame relay in the =
> WAN? =20
>
> -- Kevin
>
> _________________________________
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