Frame-Relay "hub"... Why?

ptlinva

I'm trying to grasp a concept that you guys/ladies might be able to help me clear up in my head...

I'm studying Chris's example of a frame-relay network in a hub/spoke configuration, found at...

YouTube - CCNA CCNP Frame Relay Switching 1 / 2
or
http://www.thebryantadvantage.com/Frame Relay Switch.htm

It seems to me that all traffic goes through the FR switch and that all traffic also goes through R1 (acting as the hub). Also, it seems to me, that if either one of these routers (or the R1/FR connection) goes down, everything is down.

Is it me or does this not make sense as far as redundancy and performance...

--= I guess I'm not grasping the purpose of the "hub". =--

Mike was kind enough to send me a TechExams.com's FR network tutorial, found at...

TechExams.Net CCNA TechLab: Configuring Frame Relay

...and it didn't seem to have a "hub" at all and it seems to me that all of the routers were, in effect, spokes.

This seem to make a bit more sense to me for numerous reasons.

What are the advantages to having a "hub" on a frame-relay network?

Does frame-relay always require one of the routers to the "hub"?

Thanks again for putting up with my long-winded questions... <grin>

Your friend,
Paul L.

EdTheLad

I didn't bother to look at your examples, but i'll continue anyway.
The example you mention above has a single FR switch, hanging off this switch are some routers, if each of these routers has a dedicated FR dlci to every other router this is a full mesh and you dont have a hub and spoke topology.
But lets say the FR switch is replaced by a FR cloud which consists of 50 FR switches, RA has a dlci to RB and RC, RB has a dlci only to RA and likewise RC has a dlci only to RA.This arrangement is known as a hub and spoke with RA being the hub, unfortunately due to the geographic locations of the 50 FR switches its not economical to create a dlci between RB and RC.
Any traffic from RB must flow via RA to get to RC and vice versa.

Netwurk

ptlinva wrote: »

It seems to me that all traffic goes through the FR switch and that all traffic also goes through R1 (acting as the hub). Also, it seems to me, that if either one of these routers (or the R1/FR connection) goes down, everything is down.

Is it me or does this not make sense as far as redundancy and performance...

The "FR switch" router is only acting as a frame relay simulator, so redundancy and performance isn't what you're after. Once you set up FR1, save the config and forget about it.

Understanding the configs on the R1, R2, and R3 routers are what you need to know for the CCNA.

blackninja

I know the topology you are using as I have the same

Yes - if the Hub router goes down the FR network goes down, there will be a way to build redundancy into this but this network is just a study model.

The advantage of having a hub and spoke is the Hub sits at Head Office and all the branch offices are the spokes - less VCs


"Does frame-relay always require one of the routers to the "hub"? "

No - you could use the example in the TechExams.com's FR network tutorial - more VCs