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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

1175.0. "Would this work (DECbridge600/Cluster)???" by EEMELI::SOHLMAN (Jouko Sohlman CS/PTG Helsinki Finland) Wed Dec 08 1993 10:30

	Hello !

	I have a question from customer about the DECbridge600.

	Is the following configuration legal and would it work?
	Performance?

				FDDI ring
			      ^ ^   ^ ^
			______I_I___I_I______
			I		     I
			I   DECbridge600     I
			I                    I
			I____________________I
			    I     I     I
			    I     I   --T----------------T----- Eth,
			    I	  I 			 I
			    I	--T-------T--- Eth.     VAXA
			    I             I
  Eth.	----------T----------T--         VAXB
 		  I
		 VAXC

		*VAXA, VAXB and VAXC are members of same CI-cluster!!!

		Thanks in advance

				Jouko

		PS. Asked also in DECNETVAX-notes

T.R	Title	User	Personal Name	Date	Lines
1175.1		SSDEVO::PARRIS	The SLED is dead, long live RAID	`Wed Dec 08 1993 14:58`	4
	This is legal and will work. VAX systems which have an XMI bus, Q-bus, or TURBOchannel can also be connected directly to FDDI, of course.
1175.2		KONING::KONING	Paul Koning, B-16504	`Wed Dec 08 1993 16:52`	3
	... or EISA (oh yes, that's Alpha only)... paul
1175.3	Thanks to .1 and .2	EEMELI::SOHLMAN	Jouko Sohlman CS/PTG Helsinki Finland	`Thu Dec 09 1993 01:40`	0
1175.4	More about DECbridge600	EEMELI::SOHLMAN	Jouko Sohlman CS/PTG Helsinki Finland	`Mon Dec 27 1993 07:44`	18
	Hello ! Could somebody explain what does the figures about forwarding and filtering rates mean when you talk about DECbridge620 with three ethernets. (Forwarding rate/ethernet???) In the materials I have the figures are: Filtering rate = 480.000 pps Forwarding rete = 22.000 p (Not so good if you calculate it per ethernet == 7.400 pps/eth. !!!!) Also posted to decnet and FDDI-notes Jouko
1175.5	22k forwarding is enough for real-world apps	NOTAPC::LEVY		`Thu Dec 30 1993 11:45`	12
	Filtering rate of ~480k packets is worst-case (all min size packets) on all four ports. Forwarding rate of ~22k packets is obviously less than the worst-case rate of ~45k packets. The DECbridge was originally designed to support one Ethernet, not three. However, 22k is completely adequate for almost all real-world applications. Only back-to-back packets shorter than ~120 bytes (simultaneously on all three ports) would exceed the 22k figure. There is a white paper available which explains in much more detail why 22k forwarding isn't a relevant performance limitation.