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Conference irocz::common_brouters

Title:Digital Brouters Conference
Notice:New common-code brouter family: RouteAbout, DECswitch 900
Moderator:MARVIN::HARTLL
Created:Mon Jul 17 1995
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:929
Total number of notes:3736

845.0. "FrameRelay CIR=0 setup" by TKOVOA::NAKANO_K (Koichi Nakano/NPB/Japan) Wed Apr 09 1997 22:59

Hello,

NTT, the Japanese largest communication service provider, provides low 
cost frame relay service. Restriction of this frame relay service is 'CIR=0'. 
However the lowest value of CIR on RouteAbout is 300. We could not set CIR 
to 0.

Would anyone please comment for how should we setup the RouteAbout for this 
service. 

Thanks in advance.

K.Nakano

T.RTitleUserPersonal
Name
DateLines
845.1MARVIN::TURNERNeil Turner IPEG REO, 830-4140Thu Apr 10 1997 04:3024
The RouteAbout will not actually let you configure a CIR value  of  zero 
since this would mean that it could never actually transmit a packet...

CIR=0  services  are  difficult  to  understand  because they provide no 
committed bandwidth at all. So in theory at least on any given  day  you 
may  get  no packets through the network at all! In practice however you 
must be able to get some data over the connection for it to  be  useful. 
But I suspect the effective CIR over the connection may fluctuate widely 
from day to day based on the general load in the  FR  network.  (Do  NTT 
quote  any  figures  for the likely achievable transmission speed over a 
typical CIR=0 PVC...I suspect not?)

Anyway I would recommend that you configure the CIR in the router to  be 
the  minimum  possible  (300)  and  also  make  sure  you  configure the 
LINE-SPEED on the frame relay interface to the actual line speed of  the 
access  connection.  Configuring  it  this way means that the RouteAbout 
will steadily increase its transmission speed from 300 up  to  the  line 
speed provided it does not receive BECN's from the network. The speed is 
then reduced when BECNs  are  received.  Hence,  over  time  the  actual 
transmission  speed  of the router should 'settle' to approximately what 
is available at any given time.

Neil
845.2MARVIN::CLEVELANDThu Apr 10 1997 07:305
    BTW, MCI offerred us this service in the US as well, so it is a fairly
    common configuration, I think.  With zero CIR they gave a much cheaper
    per-packet price.
    
    Tim