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Subject
- Posted on
Frame Relay show command
- 05-13-2007
May 13, 2007, 3:39 pm

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
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

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
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