km@mathcs.emory.edu (Ken Mandelberg) (03/13/91)
Here are several 802.2 issues I could use some help with. Any info
would be appreciated:
1) The 1985 IEEE 802.2 standard book says that "A number of LSAP code
points have been identified for particular uses. A list of these code
points can be obtained from the IEEE standards office". Does anyone
have a list of these handy?
2) I know informally about the SAP "AA", which goes with a SNAP
discriminator. Is "AA" one of these code points? Where can I find a
formal description of the "AA" SAP and SNAP?
3) What SNAPs have been defined to date?
4) Is there any public domain Unix software for 802.2 monitoring on a mixed
ethernet/tcp-ip and 802.2/802.3 lan. I regularly use tcpdump, nnstat,
nfswatch, and etherfind on a Sun to monitor the ethernet traffic, but
don't have a good way to sort out the 802.2 traffic at the same time.
--
Ken Mandelberg | km@mathcs.emory.edu PREFERRED
Emory University | {rutgers,gatech}!emory!km UUCP
Dept of Math and CS | km@emory.bitnet NON-DOMAIN BITNET
Atlanta, GA 30322 | Phone: Voice (404) 727-7963, FAX 727-5611rpw3@rigden.wpd.sgi.com (Rob Warnock) (03/14/91)
In article <7160@emory.mathcs.emory.edu> km@mathcs.emory.edu writes: +--------------- | 1) The 1985 IEEE 802.2 standard book says that "A number of LSAP code | points have been identified for particular uses. A list of these code | points can be obtained from the IEEE standards office". Does anyone | have a list of these handy? +--------------- See RFC 1060 "Assigned Numbers" for a few of them: IEEE Internet binary binary decimal 00000000 00000000 0 Null LSAP [IEEE] 01000000 00000010 2 Indiv LLC Sublayer Mgt [IEEE] 11000000 00000011 3 Group LLC Sublayer Mgt [IEEE] 00100000 00000100 4 SNA Path Control [IEEE] 01100000 00000110 6 Reserved (DOD IP) [104,JBP] 01110000 00001110 14 PROWAY-LAN [IEEE] 01110010 01001110 78 EIA-RS 511 [IEEE] 01111010 01011110 94 ISI IP [JBP] 01110001 10001110 142 PROWAY-LAN [IEEE] 01010101 10101010 170 SNAP [IEEE] 01111111 11111110 254 ISO DIS 8473 [64,JXJ] 11111111 11111111 255 Global DSAP [IEEE] +--------------- | 2) I know informally about the SAP "AA", which goes with a SNAP | discriminator. Is "AA" one of these code points? Where can I find a | formal description of the "AA" SAP and SNAP? +--------------- Here's an informal one... When 802.2 was being defined, there were some various interests who lobbied succesfully for an "escape hatch" to LLC, which became SNAP. [I've heard various explanations for the acronym, but all of them seem to agree that it's some variation of {Sub-,Sudden,Special} Network Access Protocol.] If the SSAP/DSAP are each 0xAA, then the next three bytes after the LLC header are an OUI (Organization-Unique Identifier) -- I could be wrong, but I think the upper 24 bits of your registered 48-bit MAC address group will do nicely here -- and the two bytes after that are "reserved for organization definition". That is, each "organization" (OUI number) is allowed to define those two bytes (and the rest of the packet!) any way they like. Rumor had it that Xerox had registered OUI==0 and had pronounced that their definition for those two bytes would be identical to Ethernet type codes ("SNAPpy Xerox"). Whether or not that rumor was correct, the present de-facto industry and Internet standard is that "OUI==0" means the next two bytes are an Ethernet "type" which describes the rest of the packet, thus allowing good old Ethernet packets to be encapsulated in 802.2 LLC frames. See RFC 1042 and RFC 1103 for a more formal description of the LLC/SNAP/OUI==0 encapsulation. Note that the use of "Ethernet types" for those two bytes applies *ONLY* to OUI==0. Other organizations may (and have?) used SNAP (with OUI != 0) for their own proprietary purposes... +--------------- | 3) What SNAPs have been defined to date? +--------------- Besides OUI==0 (RFC 1042/1103), who knows...? Try the IEEE. -Rob ----- Rob Warnock, MS-1L/515 rpw3@sgi.com rpw3@pei.com Silicon Graphics, Inc. (415)335-1673 Protocol Engines, Inc. 2011 N. Shoreline Blvd. Mountain View, CA 94039-7311
koning@koning.enet.dec.com (Paul Koning) (03/15/91)
|>... |>| 2) I know informally about the SAP "AA", which goes with a SNAP |>| discriminator. Is "AA" one of these code points? Where can I find a |>| formal description of the "AA" SAP and SNAP? |>+--------------- |> |>Here's an informal one... |> |>When 802.2 was being defined, there were some various interests who lobbied |>succesfully for an "escape hatch" to LLC, which became SNAP. [I've heard |>various explanations for the acronym, but all of them seem to agree that |>it's some variation of {Sub-,Sudden,Special} Network Access Protocol.] |> |>If the SSAP/DSAP are each 0xAA, then the next three bytes after the LLC |>header are an OUI (Organization-Unique Identifier) -- I could be wrong, but |>I think the upper 24 bits of your registered 48-bit MAC address group will |>do nicely here -- and the two bytes after that are "reserved for organization |>definition". That is, each "organization" (OUI number) is allowed to define |>those two bytes (and the rest of the packet!) any way they like. Yes, the OUI is what's used in the first 24 bits of the Ethernet address, and also the first 24 bits of the SNAP Protocol Identifier (that's what the 40-bit field after the LLC header is called). For an official definition of SNAP, as well as assorted other useful things, refer to IEEE 802.1a, "Architecture and Overview". |>... |>See RFC 1042 and RFC 1103 for a more formal description of the LLC/SNAP/OUI==0 |>encapsulation. 1103 has been superseded (by 1188, I think). Also, if you do what 1042 talks about on Ethernet, please be sure to follow the rules for that case which are mentioned in RFC 1122. |>... |>+--------------- |>| 3) What SNAPs have been defined to date? |>+--------------- |> |>Besides OUI==0 (RFC 1042/1103), who knows...? Try the IEEE. IEEE doesn't assign Protocol Identifiers. It does assign OUIs, of course, but as far as I know those assignments are not made public by IEEE. paul