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Conference 7.286::fddi

Title:FDDI - The Next Generation
Moderator:NETCAD::STEFANI
Created:Thu Apr 27 1989
Last Modified:Thu Jun 05 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:2259
Total number of notes:8590

489.0. "IP Packet Fragmentation and ELMS ??" by TOOHOT::RWILSON (Once around isn't always enough) Tue Mar 03 1992 16:35

    I was just told by a C/S representative that they were advised by their
    support organization that ELMS was required to activate IP packet
    fragmentation in the DECbridge 500. It's been my understanding that the
    DECbridge's implementation RFC 791 performed fragmentation of large
    FDDI IP packets being forwarded to Ethernet LANs transparently and
    without any user intervention. 
    Bottom line question, is fragmentation a settable parameter which
    requires ELMS or equivalent software to manipulate? This just doesn't
    sound exactly right to me or did I actually miss something somewhere at 	
    sometime.  
    
    Later, 
    
    Ray
T.RTitleUserPersonal
Name		DateLines
489.1KYOA::KOCHIt never hurts to ask...Tue Mar 03 1992 20:423
    I expect that may be only on old DECbridges which don't have
    Out-of-Band Management support. The new DECbridges have OBM and it
    should be settable from that.
489.2Not yet !BONNET::LISSDANIELSWed Mar 04 1992 06:069
As I understand it, it was only the DECconcentrator that got Out of Band
management in February...

So the initial question is currently valid:

Do we need to enable DECbridge IP fragmenting with a management tool ?
If that is the case - wich tool ?

Torbjorn
489.3IP Packet Fragmentation?TOOHOT::RWILSONOnce around isn't always enoughWed Mar 04 1992 09:5415
    
    Thanks for the responses, however, the question still remains as per
    .2: Is it necessary to enable packet fragmentation in the DECbridges?
    The problem I'm having with this is, the 802.3/Ethernet Specifications 
    define the maximum frame size as 1518 octets, therefore why would it
    be necessary to enable fragmentation when the DECbridge is supposed to
    be design to meet the 802.3/Ethernet Specs. and implements RFC 791 for   
    fragmenting IP packets.
    
    Thank you in advance.
    
    Later,
    
    Ray
489.4KONING::KONINGPaul Koning, NI1DWed Mar 04 1992 11:039
The bridge allows turning fragmentation (per RFC 791) off.  There wasn't any
really good reason for that; it was put in as a somewhat paranoid precaution.

This switch is supposed to be set to "enable fragmentation" by default, and
according to the implementers is indeed set that way.  So you should NOT need
ELMS to have fragmentation.  (You would need ELMS to disable it, but as I said
there is no known reason to do that and various good reasons to leave it alone!)

	paul
489.5Suspicions confirmedTOOHOT::RWILSONOnce around isn't always enoughWed Mar 04 1992 18:139
    Paul,
    
    That's just what I suspected and was hoping to hear from those in the
    know. 
    
    Thanks...
    
    		Ray