>b. HDLC --> The job of HDLC is to ensure that data passed up to the next
>layer has been received exactly as transmitted (i.e error free, without loss
>and in the correct order).
Except Cisco's HDLC doesn't do all that, and for the CCIE test you should
know the Cisco way. Cisco's HDLC does error detection only. It does not
retransmit.
Great answer otherwise!
Priscilla
>c. SDLC --> Less error control than HDLC in that it only provides link
>integrity. Frames received correctly are acknowledged by the receiver while
>erroneous frames are ignored.
>
>d. Frame-relay --> There is no guarantee of data integrity at all. Error
>control is sacrificed in the interest of speed. Its assumed that higher
>layer protocols will handle all necessary error control. The network
>delivers frames, whether the CRC check matches or not. It does not even
>necessarily deliver all frames, discarding frames whenever there is network
>congestion.
>
>e. DLSw+ --> Error control is provided by SNA, not DLSw. DLSw only handles
>link control. Most bridging protocols (as far as I know anyway) deal
>strictly with getting the data from point A to point B and let the layer 3/4
>protocols handle error control/correction.
>
>f. ATM --> ATM does not have error control functionality (think about what
>goes into an ATM cell - and what doesn't). Any error control has to be
>performed by the protocols that are encapsulated in the ATM cells.
>
>g. T1, E1 --> These are layer 1 protocols. T1 and E1 deals with signaling
>and encoding. At this level, its just bits, not frames or packets. Error
>control is generally handled at layers 2 through 4 (when its done at all).
>
>Hope this helps,
> Karen
>
>*********** REPLY SEPARATOR ***********
>
>On 4/30/2001 at 12:28 AM Kuldip Singh wrote:
>
> >Hi,
> >
> >Can someone help me find out who (router or host) will
> >retransmit the packets if they were lost in the cloud
> >while using:
> >a. X.25 --> guarantees data integrity by using HDLC to handle error
control.
> >b. HDLC --> the purpose of this protocol is to provide an error free link
>between two connected devices.
> >c. SDLC --> provides link integrity. Frames received correctly are
>acknowledged by the receiver while erroneous frames are ignored.
> >d. Frame-relay --> Think about what makes Frame-Relay different from X-25.
>There is no guarantee of data integrity at all.
> >e. DLSw+ --> Error control is provided by SNA, not DLSw.
> >f. ATM --> ATM does not have error control functionality (think about what
>goes into an ATM cell - and what doesn't).
> >g. T1, E1 --> These are layer 1 protocols. Error control is generally
>handled at layers 2 through 4.
> >to connect from one router to another.
> >
> >HostRoutercloudRouterHost
> >
> >Thanks
> >
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________________________
Priscilla Oppenheimer
http://www.priscilla.com
Message Posted at:
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