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From: rene@geveke.nl (Rene van der Hauw)
Newsgroups: comp.dcom.sys.cisco
Subject: (none)
Message-ID: <34244@boulder.Colorado.EDU>
Date: 17 Apr 91 08:21:38 GMT
Sender: news@boulder.Colorado.EDU
Lines: 101

Dear people
 
At this moment, I am investigating the options of redundancy in
a network by using routers. In this case not between the routers
(because that is documented properly), but between a host and a
router. To be more precise: Having two or more routers on one
segment(figure 1), or only having one router per segment? (figure
2)
 
        Host                                     Host
         |                                        |
 --+-----+-----+--                        ---+----+---
   |           |                             |
 +-+-+       +-+-+                        +--+--+ 
 | R |       | R |                        |  R  |
 +-+-+       +-+-+                        +-+-+-+
   |           |                           /   \
 --+-----+-----+--                       /       \
         |                            +-+-+     +-+-+
        Server/Host                   | R |-----| R |
                                      +-+-+     +-+-+
                                         \       /
                                           \   /             
                                          +-+-+-+
    figure 1                              |  R  |  
                                          +--+--+
                                             |
                                     ---+----+---
                                        |
                                       Server/Host           
 
                                           figure 2
 
 
TCP/IP.
 
When talking about TCP/IP it is necessary that the host station
is listening to RIP, using the well known routed process (or
gated). THe problem is that as far as I know it is only
implemented for unix systems. For the DOS environment (as well
as for cisco's terminal server) it is needed to configure a
default router. In this way you are going to have a problem when
this default router is shutdown (figure 1). There is a backup,
but the host will never try to go to the other router. Up till
now the best solution I have seen is fooling the host by telling
him that there are no subnets in the network. In this way the
router will respond to a local ARP of the host. As long as the
ethernet address of the remote host (in this case cisco ethernet
address) will stay in the ARP cache of the host, it will take to
switch to the other router (because of a new ARP). 
(thanks Jerry Aquirre of Olivetti, it works!)
 
When using a router layout as mentioned in figure 2 you have
never the problem of configuring one default router, because
there is only one. But the only redundacy is between the routers,
and not between the host and the router. In this way you have got
a singly point of failure!
 
+-----------------------------------------+
| So here is my question....              |
| What is the best network design?        |
+-----------------------------------------+
 
Novell(/XNS).
 
I have collected as much as possible information about novell and
routing, but up till now I couldn't find out the following issue:
 
1. Using a novellhost in figure 1, this host can make a
connection to the server using one router. What is going to
happen when this router is shutdown? 
 
+----------------------------------------------------+
| Will the protocol decide to take the other router  |
| and what is the time to do this?                   |
+----------------------------------------------------+
 
Figure 1 isn't the same as having two cisco routers with two
serial links in between, because the host then knows just one
ethernet address instead of two. 
 
 
2. When routing novell localy the file transfers are much slower,
about two times, this is because of the protocol. So this is my
last question:
 
+---------------------------------------------+
| Is it better to bridge or to route novell,  |
| using a local router?                       |
+---------------------------------------------+

(When it isn't possible of switching of router as mentioned above
from my point of view it is better to bridge! Please respond on this) 
 
Looking forward to your reply
With kind regards
 
 
Rene van der Hauw
Geveke electronics
The Netherlands.