Local vs Global Frame Relay Addressing

"Local addressing, which is a common term for the fact that DLCIs are locally significant, is a fact. It is how Frame Relay works. Simply put, a single access link cannot use the same DLCI to represent multiple VCs on the same access link."

- Odom, CCNA ICND2 Official Exam Certification Guide, PG #470.

"Because local addressing is a fact, global addressing does not change these rules."

- Odom, CCNA ICND2 Official Exam Certification Guide, PG #470.

"If two VCs terminate at the same DTE, and a single DLCI is shown, it probably represents the global DLCI convention. If one DLCI is shown per VC, local DLCI addressing is depicted."

- Odom, CCNA ICND2 Official Exam Certification Guide, PG #473.

The first two comments seem to be contradicting the third in my mind. If local addressing is a fact, then how can a single DLCI exist for two different VCs?

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Comments

marlon23

Third one is explaining DLCI system used in book's figures. Has nothing to do with technology explanation.

At least this is what I remember from book.

flurrball

Yea, I just looked at it, and it looks like they came up with global addressing because people were getting confused about DLCI's and their local significance. All it does is display the DLCI's so that it makes logical sense, since DLCI source and dest. are actually backwards from the source and dest. addresses we are used to with ethernet (i.e. with DLCIs the source DLCI is the one closer to the receiver and the dest. DLCI is the one closer to the sender, backwards from sending an ethernet frame) Just a diff way to draw the diagrams.

Dunno if that makes sense, but I watched CBTNuggets, and the way he explained DLCIs made sense.

sir_creamy_

flurrball wrote:

Yea, I just looked at it, and it looks like they came up with global addressing because people were getting confused about DLCI's and their local significance. All it does is display the DLCI's so that it makes logical sense, since DLCI source and dest. are actually backwards from the source and dest. addresses we are used to with ethernet (i.e. with DLCIs the source DLCI is the one closer to the receiver and the dest. DLCI is the one closer to the sender, backwards from sending an ethernet frame) Just a diff way to draw the diagrams.

Dunno if that makes sense, but I watched CBTNuggets, and the way he explained DLCIs made sense.

Yeah, I know what you're saying now. I didn't particularly like the CBTNuggets explanation (what's up with his analogies?) but after watching it a few times it soaked in. Thanks.

flurrball

Yea he has some weird analogies (flowers and football players wth?), but he makes me laugh with his nerdiness.