[c-nsp] IS-IS Ethertype

[Ivan Pepelnjak]

This might help:

http://wiki.nil.com/IS-IS_in_OSI_protocol_stack

The drafts you've found deal with the fact that LLC1 packets (those that don't use Ethertypes) cannot use the "length" field higher than 1500 (otherwise the differentiation between LLC1 and Ethernet-II breaks down).

Ivan

> -----Original Message-----
> From: Justin Shore [mailto:justin at justinshore.com]
> Sent: Tuesday, January 05, 2010 5:50 PM
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] IS-IS Ethertype
> 
> Hey guys.  I hope you all had a good holiday break.
> 
> Does anyone know for sure what the Ethertype is for the CLNS packets?
> I've found a couple IEFT drafts that talk about it it to a degree:
> 
> http://tools.ietf.org/html/draft-ietf-isis-ext-eth-01
> http://tools.ietf.org/html/draft-ietf-isis-ext-eth-01
> 
> They imply that for packet sizes under 1500 that CLNS uses the standard
> IEEE 802.3 ethertypes.  The drafts specifically address packets over
> 1500 bytes though.  One suggests 0x8872 and the other suggests 0x8870.
> I can't find anything definitive though.
> 
> I'm trying to think what all could affect the Ethertype for IS-IS.  MPLS
> won't.  LAGs might (I can't find anything about Ethertype for PAgP or
> LACP either).  Nothing else comes to mind though.
> 
> Can anyone tell me for sure what the Ethertype is on IS-IS packets?
> 
> Thanks
>   Justin