Conference netcad::hub_mgnt

Sorry I made some mistakes to the 900ET on the Token ring 1 side.

Note that all hub modules are on the two DEChub900s
This is the correction.

Simplified diagram:

 
                        ( 10.18.0.0 ) -  HP Unix
                            |
                      ( Cisco network , OSPF)
                        /            \
    10.91.0.0     (Token ring 1)      (Token ring 2)   10.92.0.0
                      |                   |          \      
                      |                   |            \      
                      |                   |10.92.92.45   \
   (switch-only mode) 900ET                900ET              \       
                      |                  |10.170.170.48      \
                      |                  |                    \
                      |                  |Ethernet                     \
                      |                 900EF                   \
                      |                  /                       \
                      |       ======= FDDI ==== 10.170.0.0        |
              Ethernet|                |                          |Token ring
                      |                |                          |
                      |              10.170.170.56                |
                       ---------[Digital Unix]---------------------
                  10.91.91.40                              10.92.92.40
                       


[Posted by WWW Notes gateway]

I doubt IP fragmentation is the problem, but anyways
turning it off at the switch would cause more problems.

My guess would be that you have a problem with the
adapter/driver/ IP config setup. You might want to look in the 
digital_unix conference.

-Mike

I haved the ftp problem at the 10.170 (FDDI) side by
adjusting the MTU size of the 900ET routers to 4399
which is the one comparable with custoemr's token ring
network.


By at the 900ET with switch-only mode side, the problem
is even worse. We fail to ping the Ethernet interface
of Digital Unix connecting to the 900ET switch, when
we do this from an subnet across a  router, no matter
Cisco or our 900ET routers. We can succeed to do so only 
after I ping the router interface from the Digital Unix
side. But after a while, the problem re-apperar again.
The ftp problem still persist, despite the MTU of the
switch has been adjusted. 

This occurs even when we do it on a PC  connected to
a 900EF switch on the 10.170 side. In this case , the
path only involve : 

  PC-Ethernect -> switch by 900EF to -> router-mode 900ET  Ethernet
  -> route to router-mode 900ET Token ring 
  -> switch-only mode 900ET Token ring
  -> switch to switch-only mode 900ET Ethernet
  -> Digital Unix Ethernet 


It sounds like that the 900ETs in switch-only mode fails
when connected to the token-ring routers. 

-feynman

[Posted by WWW Notes gateway]

    I am not sure of my product names, but if the 900ET is the
    one of the token ring to ethernet switches based upon the Comet
    software code base, then it is very likely that IP fragmentation
    does not exist for bridged packets.
    
    Originally, this code base only provided IP fragmentation for
    IP packets that were routed.  We extended the functionality for
    the VNswitches so that bridged packets are also fragmented.
    Check with product management on when this functionality will
    be merged to other products.
    
    Hugh

Thanks for indication.

If the 900Et switch-only mode does not support IP fragmentation
(like the 900EF does), can I conclude that we can only make
it works switching between Token ring and Ethernet  by either:

1) The hosts support Path MTU discovery. (Is it true for Digital Unix?)

or 

2) Making the Token ring network to have the same MTU as
   Ethernet ?? (I think it is impossible in the customer's case)

If both cases cannot be done, does it make sense to use
switch-only mode in 900ET any more?

-feynman

[Posted by WWW Notes gateway]