From: Scott Morris (swm@emanon.com)
Date: Fri Jul 08 2005 - 01:48:48 GMT-3
If it's something passed BETWEEN the DLSW peers, then I would use an LSAP
output list which would be looking for the 04 values (SNA on Ethernet SAP
code). The ethertype values would not get filtered by applying it in that
manner. Since it's an "LSAP" output list, it is looking for SAP values not
the ethertypes.
If the ACL was applied inbound to the ethernet interface, then you could use
it that way.
For using LSAPs, it is a little tricky and there will be some memorization.
There are examples on the DocCD using the 0xF0F0 with a mask of 0x0101 which
is for Netbios. (F0 and F1 entries in both DSAP and SSAP fields)
For many DLSW filters, you'll see 0x0000 with a mask of 0x0D0D on the DocCD.
This is way overkill for an ethernet-only lab, but it's a defendable
position since it's the prime example on the DocCD. 04 and 05 are really
the values that you'll see in Ethernet. 08, 09, 0C and 0D you MAY see with
specific PDU controllers, but not with pure routers. 00 is for explorer
packets which aren't likely without SRB run. And 01 doesn't exist. So,
while it's overkill (best IMHO is 0x0404 with a mask of 0x0001), as stated
it's able to be found on the DocCD and therefore a defendable position.
I wouldn't spend a lot of my brain cycles memorizing those things. I would
just be comfortable in looking it up and finding an example to refresh my
memory.
HTH,
Scott
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Amit
Jain
Sent: Friday, July 08, 2005 12:28 AM
To: swm@emanon.com; 'Schulz, Dave'; 'Group Study'
Subject: Re: protocol type-code information on DocCD
Scott
This question is in referance to a lab requirement where you only want a
certain type of traffic like SNA or Netbios to be passed between DLSW peers.
The link sent by Sila Moni http://www.cisco.com/warp/public/698/acl200.html
is useful but I dont think it would be accessible from lab as the article is
not specifically under DocCD domain. So I guess I have to memorize the most
common codes. :-)
Amit Jain
----- Original Message -----
From: "Scott Morris" <swm@emanon.com>
To: "'Amit Jain'" <netsteps@rediffmail.com>; "'Schulz, Dave'"
<DSchulz@dpsciences.com>; "'Group Study'" <ccielab@groupstudy.com>
Sent: Friday, July 08, 2005 8:08 AM
Subject: RE: protocol type-code information on DocCD
> It's a stretch...
>
> First, per the DocCD:
> "Usage Guidelines
>
> Type-code access lists can have negatively affect system performance;
> therefore, keep the lists as short as possible and use wildcard bit masks
> whenever possible.
>
> Access lists are evaluated according to the following algorithm:
>
> .If the packet is Ethernet Type II or SNAP, the type-code field is used.
>
> .If the packet is another type, then the LSAP is used."
>
> So with a valuer of 80D5, I can tell you right away that's not a SAP code.
> It's an ethertype code. I haven't got a clue of the context of the lab,
but
> ethertype code 0x80D5 is used to indicate IBM/SNA traffic (NOTE: NOT
> specifically DLSW, but native SNA) within a SNAP type ethernet header. I
> haven't found a great reference of ethertypes on the DocCD other than
random
> ones in different places.
>
> If you want more esoteric things to look up like that, check out:
>
> http://www.netwho.com/frame/ethertype.htm
>
> HTH,
>
> Scott
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Amit
> Jain
> Sent: Thursday, July 07, 2005 1:39 PM
> To: Schulz, Dave; Group Study
> Subject: Re: protocol type-code information on DocCD
>
> Hey Dave
>
> The list no doubt looks useful, but I am still nowhere. In an IE example
we
> needed to permit SNA traffic. Answer says:
> access-list 200 permit 0x0000 0x0D0D
> but the list you mentioned says SNA type code as 80D5. What is the part of
> puzzle I am missing?
> Also I could not look for Netbios type code in list.
>
> Amit
> ----- Original Message -----
> From: "Schulz, Dave" <DSchulz@dpsciences.com>
> To: "Amit Jain" <netsteps@rediffmail.com>; "Group Study"
> <ccielab@groupstudy.com>
> Sent: Thursday, July 07, 2005 8:29 PM
> Subject: RE: protocol type-code information on DocCD
>
>
> Amit -
>
> The type codes can be found under volume 1 of 2 (Cisco IOS Bridging and
> IBM Networking Command Reference, Volume 1 of 2: Bridging, Release 12.3)
> of the configuration document CD.....
>
>
http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123cgcr/ibm_
> r1/index.htm
>
> Does this help?
>
>
> Dave Schulz
>
> Email: dschulz@dpsciences.com
>
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Amit Jain
> Sent: Thursday, July 07, 2005 7:42 AM
> To: Group Study
> Subject: protocol type-code information on DocCD
>
> Hi
>
> In the DLSW examples where we have to permit/deny traffic based on
> protocol
> type-code, I am have difficulty figuring out the correct type-code. Can
> somebody help me locate the same on DocCd ?
>
> Amit
>
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