From: Lee, Vaughan (vaughan.lee@xxxxxxxxxxx)
Date: Thu Jan 27 2000 - 07:22:02 GMT-3
Not having seen the solution, it is either wrong or you may have interpreted
it wrongly by taking the mask in a 200 range access list to be the SAP.
The SAP for Netbios is 0xF0F0. The SAP for SNA though INCLUDES 0x0404 but
goes further, leading to a neat way of coding a 200 range access list.
SNA SAPs are actually 0x04, 0x08 and 0x0C. The last bit of the SSAP is used
to distinguish command or response functionality in XID or TEST LLC frames,
and the last bit of the DSAP is used for flow control. Including the test /
XID frames using a SAP of 0x00, this means that for SNA the 0x04, 0x08 and
0x01 bits of the SAP can all be either 1 or 0, and so can be ignored in an
access list. All other bits, however, MUST be 0. This leads to a single
catch all line for SNA in an access list where the DSAP/SSAP are specified
as 0x0000 and the mask is specified as 0x0D0D (which is one of the answers
you seem to have).
I may be that Netbios has also been matched in the access-list as 0xF0F0
with a mask of 0x0F0F (another of your answers), though that answer could
also pick up IPX raw which uses 0xFFFF in the DSAP / SSAP fields.
Hope thats of some help!
Regards,
Vaughan
Vaughan Lee, Network Specialist.
CCIE #5250
debis IT Services (UK) Ltd.
E-mail: vaughan.lee@debis.co.uk
Direct Phone: 01908 279561
Direct Fax: 01908 279061
http://www.debis.co.uk/
-----Original Message-----
From: Manjeet Chawla [mailto:mchawla@asanet.com]
Sent: 26 January 2000 20:19
To: CCIE Group Study
Subject: SNA and Netbios SAPS
While going through one of the DLSW lab scenarios, I found that the
solution to the scenario mentioned that the sap type for SNA traffic is
if 0x0F0F and for Netbios it is 0x0D0D. I thought that was 0404 for SNA
and F0F0 for Netbios.
Can some one please explain.
Thanks
Manjeet Chawla
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