[Search for users] [Overall Top Noters] [List of all Conferences] [Download this site]

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

239.0. "Why 2 Mac,s ???" by GOONS::HAFFENDEN () Fri Apr 19 1991 04:53

Can somebody plaese tell me why anyonr would wish to have 2 mac,s in a
concentrator??  One I can understand, but two??
    
    Terry H
    
T.RTitleUserPersonal
Name
DateLines
239.1KONING::KONINGLietuva laisva!Fri Apr 19 1991 13:2818
Two possible answers:

1. In a dual-attached concentrator, to put one on the primary and one on
   the secondary ring, so you can hear management etc. requests on either.

   This assumes that there are management nodes which are connected only
   to the secondary ring and not to the primary.  We don't think this makes
   much sense: the primary ring is primary -- so you're either connected
   to that ring, or perhaps to both rings -- but not to the secondary only.

2. "Roving MAC" case: to run some proprietary protocol or algorithm at
   station insertion.  A commonly mentioned example is "graceful insertion"
   which claims to allow station insertion without loss of the token.
   Apart from being non-standard, such a procedure has questionable merit
   in practice.  It also adds greatly to the complexity (and therefore
   the cost and failure rate) of the concentrator.

	paul
239.2FSWS01::WKLEUNGMon Apr 22 1991 07:4436
    
    Re. -1
    
    Would you please describe in more detail how the 'grateful insertion'
    works ?  I know this word from the 'system level description' but
    I never know how it operate.  Are we the only vendor providing this
    feature ?  If so, do you think we need to emphasis this feature
    to the customer, just from 'selling' point of view ?
    
    I have another question, but not related to the above question.
    According to the manual, our bridge adapts RFC1042 (RFC1103 ?) for
    packet translation.  Then for the following configuration,
    
    
    
               VAX or any
               other host
               on Ethernet
                |
             ___|_________DECbridge 500 ---VAX on FDDI Ring
                          
    Suppose systems on both Ethernet and FDDI ring talk via IP and
    DECbridge just get a packet from the VAX on the FDDI ring.  What
    I want to ask is that: How can the DECbridge 500 knows that the
    VAX (or other system) on the Ethernet side is speaking 802.3+802.2
    or Ethernet format so that it can translate it into correct format
    ?  Does it convert the packet to Ethernet format by default or it 
    just sends two packets (one for Ethernet and one for 802.3+802.2)
    onto the Ethernet network (IBM-8209 works like this ?) ?
    
    Thanks in advance.
    
                     
    Kin
    
    
239.3KONING::KONINGLietuva laisva!Mon Apr 29 1991 17:315
"Graceful insertion" is undefined.  We do NOT have anything called that.
Some other vendors do.  See elsewhere for a discussion why this is of
dubious value.

	paul