Frame-relay interface-dlci contradictions?

altjx

Sorry for all these threads, I'm just really trying to master this material before I take this exam.

According to the book's configuration and the DLCI labels on top of the routers, each router is mapping the DLCI on the opposite side...

According to the test, the interface-dlci number is using the labels on top of the routers.

This just brought up more confusion because now if I see it on the exam, I don't know which DLCI number to map to which router.

SharkDiver

I think what is confusing you is that the two drawings are using different ways of describing the DLCI. This is actually pretty confusing when you first learn it, so don't feel bad.

In the jpg on the left, they are using global addressing. All of the routers are going to refer to the link between them by the number over the opposite router.

In the jpg on the right, you are supposed to notice that the DLCI is over the link rather than the router.

As far as I can tell, it really isn't clear on the right jpg which method you are to use. I could certainly see someone messing this one up.

The one on the left, however, is very clear. What you need to notice is that the Atlanta router has one DLCI labeled (DLCI 51) and has three links. Obviously, being that the links are programmed as point-to-point links, Atlanta is going to have three separate DLCIs. That should let you know that global addressing in in effect and Atlanta is going to refer to its DLCIs by the numbers labeled at the other routers. All three of the other routers will use DLCI 51 to refer to their link to the Atlanta router.

The DLCI is still locally significant either way, but the global addressing method is just a way of organizing things and making them more standard rather than using random numbers.

altjx

SharkDiver wrote: »

I think what is confusing you is that the two drawings are using different ways of describing the DLCI. This is actually pretty confusing when you first learn it, so don't feel bad.

In the jpg on the left, they are using global addressing. All of the routers are going to refer to the link between them by the number over the opposite router.

In the jpg on the right, you are supposed to notice that the DLCI is over the link rather than the router.

As far as I can tell, it really isn't clear on the right jpg which method you are to use. I could certainly see someone messing this one up.

The one on the left, however, is very clear. What you need to notice is that the Atlanta router has one DLCI labeled (DLCI 51) and has three links. Obviously, being that the links are programmed as point-to-point links, Atlanta is going to have three separate DLCIs. That should let you know that global addressing in in effect and Atlanta is going to refer to its DLCIs by the numbers labeled at the other routers. All three of the other routers will use DLCI 51 to refer to their link to the Atlanta router.

The DLCI is still locally significant either way, but the global addressing method is just a way of organizing things and making them more standard rather than using random numbers.

Gotcha. I have a headache from this Boson Exam. I feel very confident in talking about CCNA material with other test takers at work, and the Boson just seems to be tougher than expected, but then again it was the same way for ICND1.

Thanks for that explanation