Conference 7.286::fddi

2013.0. "FDDI and TIMERS and STANDARDS" by PRSSOS::HOFFMANN (HOFFMANN Lionel/loc=evt/DTN number=858 5647) Tue Apr 16 1996 06:11

    Hello evrybody,
    
    I had some very specific questions from a customer about the way 
    a FDDI ring works, more precisely how it is initialised and the goal
    of the different timers as T_REQ ,T_NEG (TTRT)....
    Looking at the ANSI standards and also at the DIGITAL FDDI DATALINK
    SPECIFICATIONS ,I could find many informations but some I need are
    missing
    SO my questions are:
    
    1)The negotiated TRT called the TTRT during the claiming process
    must be in the range of T_MIN =4ms and T_MAX =167.77216 ms
    BUt on a digital interface ,when we are looking at the characteristics
    or counters ,it seems that T_MAX=173 ms .Generally, the ANSI standard 
    uses that higher value in the case of DUPLICATE ADDRESS during the
    claiming process.IT is the parameter T_REQ_DUP into the ANSI standard
    So do you know why?
    
    2)During the claiming process,at the time of initialisation,each
    station requests for a particular value for TTRT,which is called T_REQ
    as mentionned above.The minimum of such requested values is used as the
    operational value of TTRT for the ring.
    If the parameters T_min and T_MAX are hard coded because of the
    standards ,can somedy explain to me how a station chooses the value of
    its requested value?is it at random?is it depending of the application?
    Or is it settable by the network management? 
    
    3)The FDDI standard specifies a number of rules that must be followed
    for setting TTRT.One of these rules is that the TOKEN ROTATION TIME can
    be as long as two times the TTRT
    Do you know why?how has it been choosed?does it come from simulation
    models?
    
    4)When we look at the RFC1512 (FDDI MIB) the different parameters are 
    described with a specific syntax like :
    	FDDIMIBMACTMAX for exemple
    
    The corresponding name into DIGITAL FDDI DATALINK SPECIFICATIONS 
    is still different
    
    ANd if,from a Network management station,we look at the corresponding 
    SNMP parameters ,it isstill a little bit different.My customer likes to
    get a map giving the correspondance 
    Does it exist a table giving the correspondance between ANSI syntax
    and SNMP syntax ???any pointer?
    
    
    
    	Any pointer about any useful document is interesting for me
    Do you know where to find on line the last versions of the FDDI
    DATALINK specifications and the ANSI standards??I am used to look at
    FILES::NET$ARCH but nothing there ........
    
    Any help appreciated
    Thank you very much
    
    Best regards
    
    Lionel

	Your questions are answered in the following book:
	
	FDDI HANDBOOK
	
	Raj Jain

	Addison Wesley
	ISBN 0 201 56376 2


	Regards.
	Naeem