[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: routing problem?



Cedar,
You could simplify the table if you use only class C (255.255.255.0) masks
for 192.168 networks. . now, if you follow the ADSL howto, your B and C
hosts get the default routes pointing to the internet. to ensure
connectivity to the other side of the VPN you had better use 192.168 net
for the cipcb0 , and rearange the nets:
192.168.0 and 192.168.1 on B (eth0 and eth1)
192.168.2 on C

take 192.168.4 to be for the vpn (cipcb0)
(b is 192.168.4.1 and c 192.168.4.2)
now for c you add the route 192.168.0.0 255.255.254.0 192.168.4.1
and for b you add the route 192.168.2.0 255.255.255.0 192.168.4.2

avoid using net 10 for anything but the ADSL connection.

and I still think you have another kind of problem.

Dani

On Tue, 4 Sep 2001, Cedar Cox wrote:

>
> About the routing table, that's what I thought, although I'm not sure how
> they could be simplified.  If I understand correctly, 10.0.1.2 should have
> nothing to do with 10.0.0.0, but not the other way around.  Someone
> correct me if I'm wrong, but route's Genmask doesn't really have anything
> to do with the interface's netmask, does it?  For example, B has is
> connected to two ethernets (192.168.1.0 and 192.168.10.0) and C to only
> one (192.168.2.0).  Is it correct to put a route on C like :
>
> Destination     Gateway         Genmask         Flags Metric Ref    Iface
> 192.168.0.0     10.0.1.1        255.255.240.0   UG    0      0        cipcb0
>
> or should it be
>
> 192.168.1.0     10.0.1.1        255.255.255.0   UG    0      0        cipcb0
> 192.168.10.0    10.0.1.1        255.255.255.0   UG    0      0        cipcb0
>
> I hoped to avoid the second case so I don't have to touch C when I add
> another network to B.
>
> I failed to mention that eth2 (and eth1 on C) have nothing to do with the
> cipcb0 interfaces.  These are actually used for the ADSL "modems".
> Perhaps a little art will explain:
>
>      /---\
>      | A |
>      \___/
>        |
>        |
>      eth0=/---\
>           | B |=eth2-----[ADSL modem]
>      eth1=\___/  ||
>        |        ppp0------------ Internet
>        |         ||
>      /---\      cipcb0-----\
>      | Z |                 |
>      \___/                 |
>                            |
>                            |
>                            |
> /---\                      |
> | E |           cipcb0-----/
> \___/            ||
>   |             ppp0------------ Internet
>   |       /---\  ||
>   *--eth0=| C |=eth1-----[ADSL modem]
>   |       \___/
>   |
> /---\
> | D |
> \___/
>
> B eth0 is  192.168. 1.1 / 255.255.255.0
> B eth1 is  192.168.10.1 / 255.255.240.0
>
> C eth0 is  192.168. 2.1 / 255.255.255.0
>
> B eth2 is  10.200.1.1 / 255.0.0.0
> C eth1 is  10.200.1.1 / 255.0.0.0
>  (ADSL eth interfaces are set up from the adsl howto)
>
> B cipcb0 is 10.0.1.1 / 255.255.255.255  P-t-P 10.0.1.2
> C cipcb0 is 10.0.1.2 / 255.255.255.255  P-t-P 10.0.1.1
>
> I think B-eth1 should be /255.255.255.0 instead of /20, as well as a route
> to 192.168.0.0/20 by eth1.  I did this, but no change.. no surprise.
>
> At Henry's suggestion, I did a traceroute from E to A (D has a simi-broken
> network setup, but still works.. I don't want to reinstall window right
> now..).  I get basically the reverse (from D or E)
>
> traceroute to A
>  1  C (192.168.2.3)  <10 ms  <10 ms  <10 ms
>  2  * * *
>  3  A (192.168.2.2)  62 ms  64 ms  58 ms
>
> Again, ping works fine.  I really don't know where to start with tcpdump
> and how to look for path mtu discovery problems, but I supposed TIYFT
> (tcpdump is your friend too).  Tell me what to do/look for and I'll give
> it a shot (I do have tcpdump).
>
> -Cedar
>
>
> On Tue, 4 Sep 2001, Dani Arbel wrote:
>
> > Cedar,
> > maybe you might have some path mtu discovery problem?
> > try to tcpdump/ethereal on B and C and see what hapens.
> >
> > About the routing table:
> > more specific routes has precedence when being looked on for routing, so
> > the routing tables look ok (though may be simplified).
> > Dani
> >
> > On Mon, 3 Sep 2001, Cedar Cox wrote:
> >
> > >
> > > I'm not exactly sure what's going on here.  This is the setup:
> > >
> > >   A ==== B -------- C ==== D
> > >
> > > A, B, and C are running linux, D happens to be a running windows, if it
> > > matters.  The A-B link is ethernet, as is C-D.  B-C is a CIPE link over
> > > the internet (a VPN).
> > >
> > >  A is 192.168.1.4
> > >  B is 192.168.1.1 and 10.0.1.1
> > >  C is 192.168.2.1 and 10.0.1.2
> > >  D is 192.168.2.2
> > >
> > > I have the default route on A pointing to B, on D pointing to C.  On B I
> > > have:
> > >
> > > Destination     Gateway         Genmask         Flags Metric Ref    Iface
> > > 10.0.1.2        *               255.255.255.255 UH    0      0        cipcb0
> > > 192.168.2.0     10.0.1.2        255.255.255.0   UG    0      0        cipcb0
> > > 192.168.1.0     *               255.255.255.0   U     0      0        eth0
> > > 192.168.0.0     *               255.255.240.0   U     0      0        eth1
> > > 10.0.0.0        *               255.0.0.0       U     0      0        eth2
> > > loopback        *               255.0.0.0       U     0      0        lo
> > >
> > > On C I have:
> > >
> > > Destination     Gateway         Genmask         Flags Metric Ref    Iface
> > > 10.0.1.1        *               255.255.255.255 UH    0      0        cipcb0
> > > 192.168.2.0     *               255.255.255.0   U     0      0        eth0
> > > 192.168.0.0     10.0.1.1        255.255.240.0   UG    0      0        cipcb0
> > > 10.0.0.0        *               255.0.0.0       U     0      0        eth1
> > > loopback        *               255.0.0.0       U     0      0        lo
> > >
> > >
> > > What I can't do is telnet from B to D (port 5800.. VNC), but I can telnet
> > > from A to D.  I'm not sure how I might have messed up my routing or
> > > something else.  Maybe it's my Genmask's.  The "strange" thing is that I
> > > can ping D from A or B without problem.  A traceroute from A to D looks
> > > like:
> > >
> > > traceroute to D
> > >  1  B (192.168.1.4)  2.514 ms  1.572 ms  1.229 ms
> > >  2  * * *
> > >  3  D (192.168.2.2)  62.168 ms  64.307 ms  58.755 ms
> > >
> > > If this is not enough information, just say so and I'll give more.  Maybe
> > > I'll get creative and draw some ascii art of the big picture.. :)
> > >
> > > Thanks
> > > -Cedar
> > >
>
>


=================================================================
To unsubscribe, send mail to linux-il-request@linux.org.il with
the word "unsubscribe" in the message body, e.g., run the command
echo unsubscribe | mail linux-il-request@linux.org.il