- A virtual community of network engineers
 Home  BookStore  StudyNotes  Links  Archives  StudyRooms  HelpWanted  Discounts  Login
Re: FECN/BECN configuration [7:112365] posted 08/07/2006
[Chronological Index] [Thread Index] [Top] [Date Prev][Date Next] [Thread Prev][Thread Next]

An entity claiming to be Keegan Holley (nobody@xxxxxxxxxxxxxx) wrote:
: They might consider the CPE devices as part of the "network" as they put
: not sure.

There are clauses that address NNI behavior, but in this context the router
is consideried DTE.

: IF they are generated at the same point, why do you have to configure one
: them on the CPE?

You have to configure the router to adjust its transmission rate upon the
receipt of BECN from the network.  However, the older "frame-relay
becn-response-enable" was turned on by default.

: excerpt from the BCRAN self study guide pg. 302
: If a Frame Relay switch senses congestion in the network it sets the FECN
: bit to 1 in the Frame Relay header for traffic moving toward the
: device.  This number indicates a congestice situation.  Once recieved, the
: destination device flips the BECN bit in return traffix to the source.
: informs the source device of the congestion in the network and that it
: should reduce the transmission rate.

I think the author may have been confusing the behavior of DCE that split
the logical ECN function between ingress and egress.  However, it is still
the network setting BECN, even though the mechanism may a closed control
loop on two separate circuit packs.  From the user perspective, however,
the behavior still complies with the ITU spec.

: Furthermore, if ECN's were set at a single point in the network there would
: be no need for two types.  The frame switches could send FECN's to both
: since they are always "forward" of the CPE.

That would cause one of the CPE devices to respond when it shouldn't.


[]                         |
[] Mark Rogaski            |       Growth for the sake of growth is the
[] wendigo@xxxxxxxxx       |       ideology of the cancer cell.
[] mrogaski@xxxxxxxx       |       -- Edward Abbey
[]                         |

[GroupStudy removed an attachment of type application/pgp-signature which
had a name of signature.asc]

Message Posted at:
FAQ, list archives, and subscription info: