Channels, Interfaces and Loose ends

Channels, Interfaces and Loose ends

Channels, Interfaces and Loose ends

Bill Wagner bwagner at digprod.com
Mon Oct 21 01:54:18 EDT 1996


     The teleconference brought up some interesting points. Of course,  Jay 
     is correct in that the MIB II system and the printer need not be the 
     same. One can think up special cases from multi-printer server boxes 
     to workstation-attached printers where the node is not unique to the 
     printer. However, these seem to me to be unlikely candidates to be 
     supporting the printer MIB, and as the request implied, the main 
     target of the identification within the printer MIB is to circumvent 
     sloppy NIC implementations that don't reflect printer identification 
     in MIB 2.
     
     Now, since we are in the mood to support purity and goodness, let me 
     again bring up the question of interfaces and MIB 2.
     
      Interfaces are a major  group in the printer model. According to 
     paragraph 2.2.9, the interface subunits of a`printer are represented 
     by the interfaces group if MIB -II. (RFC 1213.)
     
     Now:
        1. it would seem that, if we agree that the MIB-II node does not 
     necessarily represent the printer for purposes of identification, how 
     can it for purposes of interface?
     
        2. further, if we take the case of the printserver box with four 
     printers attached (the reason why we need a separate Object ID in the 
     printer MIB) the MIB-II will undoubted refer to the network interface 
     of the printserver. What about the ...say IEEE 1284 ports ... by which 
     the printers are connected to the printserver box? 
     
     Well... even if we list them in, how do we determine which one belongs 
     to which printer? AH..we can associate channel with printer, and we 
     can associate channel with interface. Therefore, the  printserver with 
     one ethernet port which services four printers over IEEE 1284 ports 
     should identify the four 1284 ports... of should identify 8, since it 
     has a four 1284 ports and the for printers each has a 1284 port?
     
        3. Now, lets say that each of the printers also has a serial port 
     and a local talk port. These may each be connected, and the printer 
     has hot ports. So should we now also list 4 RS 232 interfaces and 4  
     localtalk interfaces?
     
        4. But look, RFC1213 only applies to network interfaces. So lets 
     drop all those non-network interfaces.
     
        5. Indeed, even for simple one printer configurations, I have not 
     yet seen a printer MIB implementation that reflects the non-network 
     interfaces on the printer. 
     
        6. But these interfaces are keyed to the channels...or should we 
     simply not key non-network interfaces to their channels. Or perhaps we 
     should drop non network channels... that would simplify channels 
     nicely.
     
     One could maintain that, for network administration, we need not care 
     about non-network connections. But if that is the decision, I think it 
     should be more clearly identified in the rfc.  On the other hand, if 
     all possible interfaces to the printer are to be identified, that also 
     should be made clear; and if that is the case, then the problem with 
     rfc1213 dealing only with network interface should be addressed.
     
     If this is confusing, I think you have the picture.
     
     Bill Wagner, DPI
     



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