Frame Relay show command

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Hello-I have been studying FR for a while now .cant find anywhere to
answer what  these numbers mean,from the show frame-relay map
command-----
Serial1/2 (up): ip 172.16.1.4 dlci 401(0x191,0x6410),

I am understanding that the IP is the next hop address? and the DLCI
is local to the I/F you are on?
but what do 0X191 and 0x6410 mean? many thanks.

I


Re: Frame Relay show command
daytime wrote:
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0x191 = 401 = DLCI
0x6410 = 25616 = It's a mapping to the serial interface, someone may be
able to confirm how this works a little bit better.

Re: Frame Relay show command
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Many thanks-the DLCI is in Hex, that makes alot of sense-much
appreciated.


Re: Frame Relay show command

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Hi,

Actually 0x6410 is the how the number is written by the protocol:
    DLCI         DLCI
    110010|xx-0001|xxxx

The Xs represent the other header fields ( DE, EA, etc. ). If you exchange
Xs with 0, you got 0x6410.

Regards,
Gabriele



Re: Frame Relay show command
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So 0x6410 is the same as 401?
Thanks for clearing that up-does any1 know of a good simulator for FR
please?
I have tried netsimk but it doesnt support it at the moment


Re: Frame Relay show command

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Hi,

Yes, is 401 decimal; You you look carefully I've done a little mistake...
should be 011001-0001 ( 401 ) and not as above 110010-0001 (801)

This is the format of the FR frame
flag (8bits) | Address (16bits) | Data ... | FCS (16bits) | flag (8bits)

Address is:
    DLCI (6bits) | C/R (1bit) | EA (1bit)
    DLCI (4bits) | FECN (1bit) | BECN (1bit) | DE (1bit) | EA (1bit)

So, if you have DLCI 102 ( 0x66 hex, [000]1100110 bin ) you'll end up with
something like this in the address field
        000110[00]
        0110[0011]        ( DE bit and the last octet EA bit are set )

    that is    0x1863. IOS will return 0x1860 'cause it apply a mask leaving
only the 10bit DLCI address ( 0x1863 and 0xfcf0 )

Note that I do not think you'll go to this kind of "details" on the exam (
it is pretty meaningless )... so when you know that 102 is the DLCI and it
is a 10bit address I think it suffice


I've not used any simulator personally, but sometimes I've read about Bosom
Sim used by people pursuing cisco certs.

Regards,
Gabriele



Re: Frame Relay show command
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Many thanks-I hope to be as knowledgeable as you -through much study
and hard work.


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