(conclusion): Routing problem
2007-12-25 8:17:00
> QUESTION:
>
> >I say 'netstat -r', and I see this:
> >
> > ---------------------
> > zinc# netstat -r
> > Routing tables
> > Destination Gateway Flags Refcnt Use Interface
> > localhost localhost UH 9 23390 lo0
> > blazer zinc UH 0 0 du0
> > default blazer UG 1 963 du0
> > 192.159.15.96 zinc U 34 268792 le0
> > 192.159.15.64 zinc U 1 389 le0
> > ---------------------
> >
> >The last line, where network .64 points to zinc, is wrong, and should
> >be removed. (It shows up automatically, I don't know why.)
>
> EXTRA CREDIT (unresolved):
> --------------------------
> It's still not clear why the .64 route showed up in the first place.
> Many respondents asked to see the 'ifconfig' readout: here it is.
>
> le0: flags=63<UP,BROADCAST,NOTRAILERS,RUNNING>
> inet 192.159.15.102 netmask ffffffe0 broadcast 192.159.15.127
>
> Also, here is the /etc/netmasks file:
>
> 192.159.15.0 255.255.255.192
> 192.159.15.64 255.255.255.224 < wrong route to this net
> 192.159.15.96 255.255.255.224
> 192.159.15.128 255.255.255.224 < zinc lives here
> 192.159.15.160 255.255.255.252
> 192.159.15.164 255.255.255.252
> 192.159.15.168 255.255.255.252
> 192.159.15.172 255.255.255.252
> 192.159.15.176 255.255.255.252
> 192.159.15.180 255.255.255.252
> 192.159.15.240 255.255.255.248
> 192.159.15.248 255.255.255.248
>
> Someone at Sun recently told me that this is an 'illegal'
> netmasks file, because there was more than one line.
DISCLAIMER:
In hindsight I should have mentioned that the router involved
here is a Telebit NetBlazer, not a 'typical' router used on
Sun networks. In particular, the NetBlazer has different rules
about netmasks, as I will detail below.
SOLUTION:
It turns out that the extra route, to network .64 is *not* incorrect.
It's probably a route RIP'ed to zinc by the Blazer. Normally, I would
expect that route to .64 should have a gateway of 'blazer' (the router),
but I have been told that, with a Blazer, a route through gateway 'zinc'
is OK. In other words, it appears that nothing is wrong.
NETMASKS:
Some respondents have told me that the above /etc/netmasks file
is indeed illegal, and that it should have only one line, which
gives the one-and-only netmask for our Class C subnet.
Yes, Suns-when-used-as-routers and 'typical' Sun routers (e.g. Cisco)
only know how to deal with one netmask per subnet. Such a router
simply scans the entry to see if it's Class A/B/C, and then assigns
the netmask to that network.
But, we are using a Telebit NetBlazer as a router, which can handle
much more general netmasks. In particular, it is possible for the
Blazer to handle several different netmasks for the same subnet,
which is what we are doing. Now, the Blazer evidently does not
consult /etc/netmasks, so our /etc/netmasks has no real function
except for reference.
THANKS:
to the following good souls for their help:
Tobias Weingartner
Geordie F. Klueber
Barry Margolin
Casper Dik
Tom Crummey
David Comay
Christian Lawrence
Russ Poffenberger
Dan Jiracek
Rod Livingood
Mike Raffety
Jerry Springer
Matt Mauss
Paul Lord
Geert Jan de Groot
-------------------------------------------------------------------
David Mostardi Email: david@capmkt.com
Senior Support & Systems Manager Phone: (510) 540-6400
Capital Market Technology, Inc. FAX: (510) 540-5505
1995 University Ave. #390, Berkeley CA 94704
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