tkevans@oss670.UUCP (Tim Evans) (02/22/91)
I have a VAX 11/750, with 4.2BSD (NOTE: 4.2, not 4.3), which I'm
trying to place onto my network and am having curious results. (Before
describing them, I have to say that I cannot upgrade to 4.BSD, so
must deal with the situation as is.)
Our network formerly consisted of 6 separate networks, which have only
recently been bridged with hardware bridges into a single spanning
tree network. Prior to the bridging, I'd implemented subnetting in
our class B address space, with a netmask of 255.255.255.0. Each
of the 6 networks was a subnet. Now, I still maintain the fiction of
having 6 subnets, even though they're all the same cable. (I'd really
rather not have to go back to all machines and rip out the subnetting
stuff.)
I set up /etc/networks showing the 6 "subnets." Here's what it looks
like:
loopback 127
oss-lan 137.200
lan1 137.200.1 localnet # VAX is on this subnet
lan2 137.200.2
lan3 137.200.3
lan4 137.200.4
lan5 137.200.5
lan6 137.200.6
In addition, the VAX's rc.local installs routes to each of the 5 "subnets"
outside its own, as shown below:
route add lan2 `hostname` 0
route add lan3 `hostname` 0
route add lan4 `hostname` 0
route add lan5 `hostname` 0
route add lan6 `hostname` 0
The VAX, which is on "subnet" 1 can see and access all machines on
"subnets" 1, 2, and 3, but not on 4, 5, and 6. Similarly, machines
on "subnets" 1-3 can telnet/ftp to the VAX, but those on 4-6 cannot.
The next curious thing is that even after installing the routes to
the "subnets," 'netstat -r' doesn't report them. All that's reported
is the route to "osslan" (see networks file above).
More interestingly, if I reassign the VAX's IP address to one in
another "subnet" (say, "subnet" 5, one that's *not* reachable) and
modify the /etc/networks and installed routes accordingly, I have the
same results as before! That is, even with an IP address in "subnet" 5,
the VAX can see *only* "subnets" 1-3, and not 4-6.
Now, I could understand it if the VAX couldn't see *anything* outside its
own "subnet" (4.2BSD doesn't know about subnets, right?), but the fact
that it can see some but not others is really confusing. And, that it
can see/not see the same subnets, regardless of its own "subnet,"
makes it even more curious.
Comments? Suggestions? (That is, other than upgrading the BSD.)
Thanks.
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