ppp and frame relay

Answered Question
Feb 26th, 2009
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Hi every body!

suppose we have router"R1" with integrated T1 card.


R1--------------frame relay switch at CO

ppp protocol is used to connect R1 to frame relay switch. My questions are:

1)Does " data field" in ppp header contain " frame relay frame" ? if yes then what " type" field in ppp header contains ?


Thanks a lot!

Correct Answer by Richard Burts about 8 years 1 month ago

Sarah


Yes. That is the common way of doing it.


HTH


Rick

Correct Answer by Richard Burts about 8 years 1 month ago

Sarah


There are many protocols which support point to point serial connections. It is certainly not limited to ppp. The common solution when a router is connected to a frame relay switch by T1 is to use encapsulation frame relay on the serial link. The data link protocol is Frame Relay.


HTH


Rick

Correct Answer by Richard Burts about 8 years 1 month ago

Sarah


I am a bit confused about your question. If R1 is connected to a frame relay switch at CO then why would the router not have encapsulation frame-relay? why would it try ppp encapsulation?


HTH


Rick

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Correct Answer
Richard Burts Thu, 02/26/2009 - 19:08
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Sarah


I am a bit confused about your question. If R1 is connected to a frame relay switch at CO then why would the router not have encapsulation frame-relay? why would it try ppp encapsulation?


HTH


Rick

sarahr202 Thu, 02/26/2009 - 19:14
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Thanks a lot for your reply!

i was reading my book , it says r1 is connected by T1 to frame relay switch. Since this is the point to point connection between frame relay switch and r1, i assume ppp must be used to carry frame relay as pay load. Could you please explain how the router is connected to frame relay switch? what data link protocol is used between the router and frame relay switch?

thanks a lot!

Correct Answer
Richard Burts Thu, 02/26/2009 - 19:22
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Sarah


There are many protocols which support point to point serial connections. It is certainly not limited to ppp. The common solution when a router is connected to a frame relay switch by T1 is to use encapsulation frame relay on the serial link. The data link protocol is Frame Relay.


HTH


Rick

sarahr202 Thu, 02/26/2009 - 19:38
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Thanks Rick! So R1 simply encapsulates ip packet in frame relay frame and forwards it to frame relay switch?

Correct Answer
Richard Burts Thu, 02/26/2009 - 19:41
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Sarah


Yes. That is the common way of doing it.


HTH


Rick

Richard Burts Thu, 02/26/2009 - 19:50
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Sarah


You are quite welcome. When you do not have the experience of having done it, some of these concepts are a bit hard to understand.


I am pleased to see the increase in your understanding in your continuing posts to the forum.


Thanks for the ratings.


HTH


Rick

Marwan ALshawi Thu, 02/26/2009 - 23:41
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by the way

some times frame relay over PPP is useful wen:

u want have some authentication as frame relay lack to this feature with FR over PPP u can hav authentication through chap or pap


also if you want to hav multiline topology


with FR over PPPmultilinke you can do it as well


Hope this helps as well :)

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