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Home > Archive > CCNP > November 2003 > DLCI question...I dont understand...
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DLCI question...I dont understand...
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| Guys, I need some help with the DLCI thing. I understand WHAT a DLCI is. I can understand how a ROUTER would use a DLCI number, but I DONT understand how a SWITCH would, or even could for that matter, use a DLCI number.
Maybe I dont know the difference between a switch that a provider uses and a switch that I have been studying about during my cisco pursuit.
Here are my questions, and if someone could tell me the difference in a provider switch and a switch on my local network, that would be great.
1. How does a switch know what my DLCI number is for my PVC on my router?
2. How are these IP-to-DLCI maps entered (dynamically somehow or statically by a tech)?
3. Even if the switch knows the DLCI of my PVC on router A, how does it know the DLCI on my router B for that PVC?
Ill stop at that and maybe I can piece it together with what you give me. I have read numerous articles, but none really seem clear on how the SWITCH KNOWS these DLCI numbers. I wonder if I implimented another router (brand new), ordered a frame relay circuit for my office site and a remote, how would the switch (or number of switches) KNOW those DLCI numbers if I am the one configuring them? | |
| OHCCNP2003 2003-11-20, 1:13 am |
| Sounds like you are referring to the EDGE switches that reside within your providers frame relay cloud. You can search on the Cisco site for EDGE switch or EDGE concentrator and get a list of the different products that are offered, along with the configuration guides. | |
| Yankee 2003-11-20, 5:04 am |
| let's see if I can help a little. The switch you are referring to is a frame-relay switch owned and configured by the carrier. It is the "master" and could care less what is programed on your router. You have to match the carrier's config for DLCIs or get them to change to match you.
Every 10 seconds by default your router sends out an LMI request and the switch replies. On every 6th request your router asks the frame switch for a full report and it replies with DLCIs, CIRs and state of the PVCs.
DLCIs are of local significance to the switch but the PVC is programed by the carrier as end to end (your site to your site thru their network).
Frame relay is layer two, so the carrier could care less about IP mapping, that is up to you and your router at either end.
You can configure a router to act as a frame-relay switch for your lab. Cisco provides examples how to do this and it may help you understand.
Yankee | |
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| Thanks Yankee. I didnt realize at this point that the frame relay switch and my router were sending LMI every 10 seconds or so. This helps, and I appreciate it. | |
| Yankee 2003-11-20, 6:31 pm |
| Glad to help when I can.
Yankee | |
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| Yankee, just a small note. I finally read the Cisco Press material on DLCI. It made alot more sense that Suckbex. Plus, it seemed like all of the Internet material that I found on it was very generic as well. But, the CP book did seem to have a better explanation on it. Anyhow, thanks bro. | |
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