Conference 7.286::fddi

1693.0. "Errors on Ethernet after FDDI installation" by DECPRG::KUPKA () Mon May 22 1995 12:39

One of our major customers start to build backup centre with BRS plans in the
future. The current status is on the scheme bellow. 
Nodes PRC014 and PRC018 form a VAX cluster using DSSI as the only cluster 
interconnect. Nodes PRC002,PRC003,PRC004 form the second cluster with a satelite
PRC025 ( which is serving the jukebox ). In this case both CI and NI are used
for cluster communication.
In the past both the old and backup centres were connected via DECnises (PRCN01
and PREN01) and no problems were observed.
Now both centres are connected via SMF FDDI. Randomly circuit goes down on
ethernet connected routers (PRC014,PRC018,PRE016) with DECnet event 4.7,
circuit down, circuit fault - Line synchronization lost. The time circuit is
down is from 0.02s to 0.8s .Same time DECnet event 4.18 , adjacency down ,
Circuit MFA-0, Dropped by adjacent node, is logged on other L1 routers 
sitting on FDDI.

Any idea?

Thanks,
Tomas  


	 Thickwire backbone
        
        |
        |     |--------|
        O-----| PRC012 | L1, L2
        |     |--------| DECNIS500
	|
	|     |--------|
	O-----| PRC014 | routing IV
	|     |--------| VAX4000
	|                 
        |     |--------|
	O-----| PRC018 | routing IV
	|     |--------| VAX4000
	|
	|     |--------|   |--------|
	0-----| DELNI  |---| PRC025 | satelite
	|     |--------|   |--------| MV3100
	|
	|     |--------|---  SEVERAL MVAXes (end nodes)
	0-----| DELNI  |---  DECservers
	|     |--------|---  HUB90 
	|
	|     |--------|
	0-----| HUB 90 |
        |     |--------|
        |         H U B 9 0 0              H U B 9 0 0
        |   |---|   |---|   |---|         |---|   |---|   
        |   | S |   | C |   | C |        /| C |   | S |     |-----------|
	|   | W |===| O |===| O |       / | O |===| W |     |  DELNI    |
	|   | I |   | N |   | N |   SMF/  | N |   | I |     |-----------|
	0---| T |   | C |   | C |     /   | C |   | T |-------| |     |
        |   | C |   | E |   | E |    /    | E |   | C |         |     |
        |   | H |   | N |   | N |   /     | N |   | H |         |     |
        |   | 9 |   | 9 |   | 9 |  /      | 9 |   | 9 |         |     |
        |   | 0 |   | 0 |   | 0 | /       | 0 |   | 0 |         |     |
        |   | 0 |   | 0 |   | 0 |/        | 0 |   | 0 |         |     |
	|   |---|   |---|   |---|         |---|   |---|   |-------| |--------|
	|             |                     |             | HUB90 | | PRE016 |
		      |                     |             |-------| |--------|
                     //// 4x MMF           // 2x MMF
                      |                     |
                      |  |--------|         |  |--------|
                      |--| PRC002 | rou IV  |--| PRE005 | rou IV
                      |  |--------| VAX6000 |  |--------| VAX7000
                      |                     |
                      |  |--------|         |  |--------|
                      |--| PRC003 | rou IV  |--| PREN01 | L2
                      |  |--------| VAX6000    |--------| NIS600
                      |
                      |  |--------|
                      |--| PRC004 | rou IV
                      |  |--------| VAX7000
                      |
                      |  |--------|
                      |--| PRCN01 | L2
                         |--------| NIS600