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Gateway BUG on Alpha/Linux? Or just misconfigured?

daemon@ATHENA.MIT.EDU (Janice McCarthy)
Tue Oct 1 21:57:38 1996

Date: 	Tue, 1 Oct 1996 14:23:11 -0400 (EDT)
From: Janice McCarthy <janice@acpub.duke.edu>
To: linux-net@vger.rutgers.edu



First, thanks to those who have tried to help!

Here is the situation:  I have 24 UDB's all running Linux 2.0.20 with the 
axp-diffs applied.  I have 8 machines on a 'fast' backbone (they have 
100Mb ethernet adapters(pci) installed).  The UDB's also have an on-board 
10Mb ethernet.  This device is disabled on a few of the machines.  It is 
enabled on machines 1,3, and 4.  machine 1 is a firewall between my 
private network and internet.  machines 3 and 4 are gateways to two 
subnets of 8 computers each (all running 10Mb ethernet).  There are 
therefore 3 Hubs (2 10Mb, one 1000Mb).


Here is a diagram:


       OutsideNet

          |
          |              gw1     gw2               
FastNet  (1) --- (2) --- (3) --- (4) --- (5) --- (6) --- (7) --- (8)
         fw               |       |
                          |       |
                          |       |        HubB
            HubA          |       +---(18) --- (19) --- (20)... --- (24)
     (9) --- (10)...(17)--+    


Now, I *want* these routes defined *explicitly* (not defaults) and I want 
them to be *static*.  This system is to run PVM to act as a parallel 
processor for some monte carlo simulations.  I do not want to run gated 
or routed.

I am able to add the routes as I have defined.  For testing purposes I 
have configured only one gateway (from FastNet to HubA).

A machine on FastNet(100Mb subnet):

  Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
172.16.1.0      0.0.0.0         255.255.255.0   U     0      0        3 eth1
172.16.2.0      172.16.1.3      255.255.255.0   UG    1      0        0 eth1
127.0.0.0       0.0.0.0         255.0.0.0       U     0      0        1 lo


lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Bcast:127.255.255.255  Mask:255.0.0.0
          UP BROADCAST LOOPBACK RUNNING  MTU:7168  Metric:1
          RX packets:12 errors:0 dropped:0 overruns:0
          TX packets:12 errors:0 dropped:0 overruns:0

eth1      Link encap:10Mbps Ethernet  HWaddr 00:00:C0:34:39:DC
          inet addr:172.16.1.5  Bcast:172.16.1.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:3925 errors:0 dropped:0 overruns:0
          TX packets:675 errors:1 dropped:0 overruns:0
          Interrupt:15 Base address:0xb000




A machine on HubA (10Mb subnet):

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
172.16.2.0      0.0.0.0         255.255.255.0   U     0      0        0 eth0
172.16.1.0      172.16.2.3      255.255.255.0   UG    1      0        0 eth0
127.0.0.0       0.0.0.0         255.0.0.0       U     0      0        1 lo


lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Bcast:127.255.255.255  Mask:255.0.0.0
          UP BROADCAST LOOPBACK RUNNING  MTU:7168  Metric:1
          RX packets:12 errors:0 dropped:0 overruns:0
          TX packets:12 errors:0 dropped:0 overruns:0

eth0      Link encap:10Mbps Ethernet  HWaddr 08:00:2B:E2:C9:96
          inet addr:172.16.2.11  Bcast:172.16.2.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:31 errors:0 dropped:0 overruns:0
          TX packets:0 errors:0 dropped:0 overruns:0
          Interrupt:10 Base address:0xb000 



The Gateway:

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
172.16.2.0      0.0.0.0         255.255.255.0   U     0      0        0 eth0
172.16.1.0      0.0.0.0         255.255.255.0   U     0      0        3 eth1
127.0.0.0       0.0.0.0         255.0.0.0       U     0      0        0 lo


lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Bcast:127.255.255.255  Mask:255.0.0.0
          UP BROADCAST LOOPBACK RUNNING  MTU:7168  Metric:1
          RX packets:30 errors:0 dropped:0 overruns:0
          TX packets:30 errors:0 dropped:0 overruns:0

eth0      Link encap:10Mbps Ethernet  HWaddr 08:00:2B:E4:03:B3
          inet addr:172.16.2.3  Bcast:172.16.2.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:13 errors:0 dropped:0 overruns:0
          TX packets:13 errors:0 dropped:0 overruns:0
          Interrupt:10 Base address:0xb400 

eth1      Link encap:10Mbps Ethernet  HWaddr 00:00:C0:37:39:DC
          inet addr:172.16.1.3  Bcast:172.16.1.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:2236 errors:0 dropped:0 overruns:0
          TX packets:2189 errors:1 dropped:0 overruns:0
          Interrupt:15 Base address:0xb000 





Now, I can ping through the gateway (i.e. from a machine on HubA, to a 
machine on FastNet) with no problem.  But if I ping between any two 
machines on the same physical network, I get DUP! messages... in fact, 
each packet is duplicated 3 times.


PING drylab2.FastNet (172.16.1.2): 56 data bytes
64 bytes from 172.16.1.2: icmp_seq=0 ttl=64 time=9.7 ms
64 bytes from 172.16.1.2: icmp_seq=0 ttl=63 time=9.7 ms (DUP!)
64 bytes from 172.16.1.2: icmp_seq=0 ttl=64 time=19.5 ms (DUP!)
64 bytes from 172.16.1.2: icmp_seq=0 ttl=63 time=19.5 ms (DUP!)
64 bytes from 172.16.1.2: icmp_seq=1 ttl=64 time=0.0 ms
64 bytes from 172.16.1.2: icmp_seq=1 ttl=63 time=0.0 ms (DUP!)
64 bytes from 172.16.1.2: icmp_seq=1 ttl=64 time=0.0 ms (DUP!)
64 bytes from 172.16.1.2: icmp_seq=1 ttl=63 time=9.7 ms (DUP!)
64 bytes from 172.16.1.2: icmp_seq=2 ttl=64 time=0.0 ms
64 bytes from 172.16.1.2: icmp_seq=2 ttl=63 time=0.0 ms (DUP!)
64 bytes from 172.16.1.2: icmp_seq=2 ttl=64 time=0.0 ms (DUP!)
64 bytes from 172.16.1.2: icmp_seq=2 ttl=63 time=9.7 ms (DUP!)

--- drylab2.FastNet ping statistics ---
3 packets transmitted, 3 packets received, +9 duplicates, 0% packet loss
round-trip min/avg/max = 0.0/6.4/19.5 ms



Here is what 'traceroute' tells me:

traceroute drylab2
 1  drylab3.FastNet (172.16.1.3)  0 ms (ttl=64!)  0 ms (ttl=64!)  10 ms (ttl=64!)
 2  drylab2.FastNet (172.16.1.2)  10 ms (ttl=64!)  0 ms (ttl=64!)  0 ms (ttl=64!)



Any clues would be greatly appreciated!!!





Janice McCarthy 

janice@acpub.duke.edu




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