Mike
First of all, thanks for your reply.
I didnt know there was such a thing as physical
access circuit going to providers access switch. All
I was thinking as a connection mechanism was PVC.
I understood that central routers sending rate could
be different from branch offices receiving rate
because of, as you explained, different physical
access circuits to FR cloud.
However, I got new question derived from your example.
How could each pvc transfer rate be calculated? When
central router has T1 connection (1.544 Mbps), and
there are 4 pvcs, then each pvcs transfer rate would
be 1.544M/4=386K?
If it is, the companies that have 30 to 50 branch
offices around the country would have not very fast
speed rate? Or am I understanding something wrong?
As far as I the traffic shaping was concerned based on
what I understood from the Cisco book, I thought that
traffic shaping would be configured on central router
which sends more traffic than a branch office router
can handle. But you mentioned that traffic shaping
comes handy by throttling the traffic coming from
branch office router. It sounds to me that traffic
shaping is configured on branch office router. Isnt
that supposed to be configured on central router?
I will appreciate you reply.
--- "Coker, Michael" <[EMAIL PROTECTED]> wrote:
> jw,
>
> When using Frame Relay the router will have:
>
> - a physical access circuit (this is the circuit
> between the router and the
> Frame Relay provider, i.e. T1)
>
> - a PVC or SVC (this is the "virtual" circuit
> through the Frame Relay cloud
> to the other router)
>
> The physical access circuits can be different for
> each router. However, a
> PVC connected between Router A and Router B will be
> the same speed. I think
> you may be confusing the two types of circuits.
>
> Example:
>
> Router A (main branch router) can have a single T1
> to the Frame Relay
> provider (CO). This would be the Physical Access
> Circuit. Router A could
> then have multiple PVC mappings, let's say 256k
> each, to multiple branch
> office routers (i.e. Rtr B, Rtr C, Rtr D, Rtr E, Rtr
> F, etc.). All of these
> branch offices may have 512k physical access
> circuits to the Frame Relay
> cloud, but it's the PVC's that will have the same
> transmission rate (256k
> each) back to Router A.
>
> Traffic shaping comes in handy when you have
> multiple PVC's that basically
> oversubscribe your T1 (meaning the cumulative amount
> of PVC's, in bps, is
> more than the bps of the physical access circuit of
> Router A). Traffic
> shaping allows you to keep from oversubscribing your
> central router by
> throttling the amount of traffic transmitted by all
> of the other branch
> offices.
>
> Hope this helps.
>
> Best Regards,
>
> --Mike
>
> -Original Message-
> From: jeongwoo park
> To: Groupstudy
> Sent: 12/1/00 1:12 PM
> Subject: newbie question on Frame Relay!!
>
> Hi all
> I have a quick question.
> On the traffic between central router and branch
> office router on frame relay, how could central
> router's connection rate to FR cloud be different
> from
> branch office router's connection rate to FR cloud?
> I could understand if cloud had traffic congestion.
> But when there are no traffic congestions, how could
> they be different?
> These two routers are using same mechanism, Frame
> Relay, which gives relatively high-speed transfer
> rate.
> I happened to ask myself this question while I was
> reading about FR traffic shaping. Traffic shaping
> could be useful under this situation. ( according to
> the book)
> Could anyone give clear answer?
>
> I appreciate your reply.
>
> jw
>
>
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