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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

170.0. "IP Fragmentation again !!" by WOTVAX::HATTOS (I think, Therefore I'm paid less) Fri Nov 09 1990 12:10

    Can someone please clear something up that has been bugging me lately.
    
    If an IP packet is circumnavigating the ring and destined for a node
    off of a DECbridge 500, what happens to the packet if it has the 'dont
    fragment' bit set in the header. Does the bridge ignore the bit and
    fragment anyway or does the packet get stripped and junked or what??
    
    Thanx in advance for any replies.
    
    Stuart
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170.1KONING::KONINGNI1D @FN42eqFri Nov 09 1990 16:046
Fragmenting anyway would be a protocol violation and should be considered
data corruption.

The bridge does the right thing: it looks at the bit and does as it's told.

	paul
170.2IP Trailer ProtocolBERN01::DEYWalter Dey, EIS, Berne SwitzerlandMon Nov 19 1990 03:231
What about IP trailer protocols ? How will the bridge act on them ?
170.3KONING::KONINGNI1D @FN42eqMon Nov 19 1990 13:1010
It will pass them right through without processing.  Note that RFC 1103
specifically says that trailer protocol shall not be used by FDDI nodes.
(Support for trailers has always been optional and is negotiated at
connection setup; if either side doesn't like it, it isn't used.)

Because of that rule, the only possible trailer frames on the FDDI are those
that originated on an Ethernet.  Clearly those will fit on an Ethernet, so
the segmentation function doesn't need to worry about them.

	paul