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Ernie Fontes

2005-Jul-22 20:22 UTC

[Xen-users] virtual routing issue

A most puzzling network conundrum has arisen while I was attempting to
create a virtual network behind a virtual router which in turn connects the
virtual network to my real network.

My machine (192.168.103.23) is on the network with my router
(192.168.103.1).  The virtual router, tiara, has to connect my

192.168.103.* network with the virtual 10.0.0.* network which comprises two
other virtual domains, tophat and bowler.

The three virtual machines are all running Fedora (hence the names).

I can ping between tiara, tophat, and bowler.  I can also ping from tiara
out to 192.168.103.1, 192.168.103.23, and the Internet. 

However, I cannot ping 192.168.103.23, 192.168.103.1, or the Internet from
tophat or bowler (which are routed through tiara).

I am reasonable certain that the problem has nothing to do with Domain-0.
In fact, I am almost positive that the guilt here rests on tiara.  Tiara is
apparently not passing packets from one of its ethernet cards to the other.

To further puzzle things, bowler and tophat are able to ping exactly two IP
addresses on the 192.168.103.* network:

 

[root@localhost ~]# ping 192.168.103.0

PING 192.168.103.0 (192.168.103.0) 56(84) bytes of data.

64 bytes from 192.168.103.30: icmp_seq=0 ttl=64 time=1.00 ms

64 bytes from 192.168.103.30: icmp_seq=1 ttl=64 time=0.218 ms

64 bytes from 192.168.103.30: icmp_seq=2 ttl=64 time=0.158 ms

64 bytes from 192.168.103.30: icmp_seq=3 ttl=64 time=0.170 ms

64 bytes from 192.168.103.30: icmp_seq=4 ttl=64 time=0.156 ms

--- 192.168.103.0 ping statistics ---

5 packets transmitted, 5 received, 0% packet loss, time 4007ms rtt
min/avg/max/mdev = 0.156/0.341/1.007/0.334 ms, pipe 2

 

[root@localhost ~]# ping 192.168.103.30

PING 192.168.103.30 (192.168.103.30) 56(84) bytes of data.

64 bytes from 192.168.103.30: icmp_seq=0 ttl=64 time=1.18 ms

64 bytes from 192.168.103.30: icmp_seq=1 ttl=64 time=0.173 ms

64 bytes from 192.168.103.30: icmp_seq=2 ttl=64 time=0.160 ms

64 bytes from 192.168.103.30: icmp_seq=3 ttl=64 time=0.177 ms

64 bytes from 192.168.103.30: icmp_seq=4 ttl=64 time=0.194 ms

--- 192.168.103.30 ping statistics ---

5 packets transmitted, 5 received, 0% packet loss, time 4007ms rtt
min/avg/max/mdev = 0.160/0.376/1.180/0.402 ms, pipe 2

 

Upon examination, it becomes apparent that tiara is, in fact, replying to
pings at both 192.168.103.30 and 192.168.103.0 (and 10.0.0.1, of course).

 

Any suggestions on how to fix tiara would be greatly appreciated.  I have
tried everything I could think to try.

 

The ifconfig and route results for all three virtual machines are attached
below.

 

Ernie E Fontes

 

-----------tiara:-----------

 

[root@localhost ~]# ifconfig

eth0      Link encap:Ethernet  HWaddr AA:00:00:27:00:F5

          inet addr:192.168.103.30  Bcast:192.168.103.255
Mask:255.255.255.0

          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

          RX packets:926 errors:0 dropped:0 overruns:0 frame:0

          TX packets:24 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000

          RX bytes:121636 (118.7 KiB)  TX bytes:1560 (1.5 KiB)

 

eth1      Link encap:Ethernet  HWaddr AA:00:00:4C:48:35

          inet addr:10.0.0.1  Bcast:10.255.255.255  Mask:255.0.0.0

          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

          RX packets:755 errors:0 dropped:0 overruns:0 frame:0

          TX packets:9 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000

          RX bytes:105949 (103.4 KiB)  TX bytes:414 (414.0 b)

 

lo        Link encap:Local Loopback

          inet addr:127.0.0.1  Mask:255.0.0.0

          UP LOOPBACK RUNNING  MTU:16436  Metric:1

          RX packets:0 errors:0 dropped:0 [root@localhost ~]# ping
192.168.103.0 PING 192.168.103.0 (192.168.103.0) 56(84) bytes of data.

64 bytes from 192.168.103.30: icmp_seq=0 ttl=64 time=1.00 ms

64 bytes from 192.168.103.30: icmp_seq=1 ttl=64 time=0.218 ms

64 bytes from 192.168.103.30: icmp_seq=2 ttl=64 time=0.158 ms

64 bytes from 192.168.103.30: icmp_seq=3 ttl=64 time=0.170 ms

64 bytes from 192.168.103.30: icmp_seq=4 ttl=64 time=0.156 ms

 

--- 192.168.103.0 ping statistics ---

5 packets transmitted, 5 received, 0% packet loss, time 4007ms rtt
min/avg/max/mdev = 0.156/0.341/1.007/0.334 ms, pipe 2 [root@localhost ~]#
ping 192.168.103.30 PING 192.168.103.30 (192.168.103.30) 56(84) bytes of
data.

64 bytes from 192.168.103.30: icmp_seq=0 ttl=64 time=1.18 ms

64 bytes from 192.168.103.30: icmp_seq=1 ttl=64 time=0.173 ms

64 bytes from 192.168.103.30: icmp_seq=2 ttl=64 time=0.160 ms

64 bytes from 192.168.103.30: icmp_seq=3 ttl=64 time=0.177 ms

64 bytes from 192.168.103.30: icmp_seq=4 ttl=64 time=0.194 ms

 

--- 192.168.103.30 ping statistics ---

5 packets transmitted, 5 received, 0% packet loss, time 4007ms rtt
min/avg/max/mdev = 0.160/0.376/1.180/0.402 ms, pipe 2 overruns:0 frame:0

          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0

          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

 

[root@localhost ~]# route

Kernel IP routing table

Destination     Gateway         Genmask         Flags Metric Ref    Use
Iface

192.168.103.0   *               255.255.255.0   U     0      0        0 eth0

10.0.0.0        *               255.0.0.0       U     0      0        0 eth1

default         192.168.103.1   0.0.0.0         UG    0      0        0 eth0

 

-----------bowler:-----------

 

[root@localhost ~]# ifconfig

eth0      Link encap:Ethernet  HWaddr AA:00:00:0C:15:FC

          inet addr:10.0.0.3  Bcast:10.255.255.255  Mask:255.0.0.0

          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

          RX packets:1108 errors:0 dropped:0 overruns:0 frame:0

          TX packets:145 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000

          RX bytes:147230 (143.7 KiB)  TX bytes:13562 (13.2 KiB)

 

lo        Link encap:Local Loopback

          inet addr:127.0.0.1  Mask:255.0.0.0

          UP LOOPBACK RUNNING  MTU:16436  Metric:1

          RX packets:8 errors:0 dropped:0 overruns:0 frame:0

          TX packets:8 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0

          RX bytes:660 (660.0 b)  TX bytes:660 (660.0 b)

 

[root@localhost ~]# route

Kernel IP routing table

Destination     Gateway         Genmask         Flags Metric Ref    Use
Iface

192.168.103.0   10.0.0.1        255.255.255.0   UG    0      0        0 eth0

10.0.0.0        *               255.0.0.0       U     0      0        0 eth0

 

 

-----------tophat:-----------

 

[root@localhost ~]# ifconfig

eth0      Link encap:Ethernet  HWaddr AA:00:00:28:71:5E

          inet addr:10.0.0.2  Bcast:10.255.255.255  Mask:255.0.0.0

          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

          RX packets:1273 errors:0 dropped:0 overruns:0 frame:0

          TX packets:24 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000

          RX bytes:163399 (159.5 KiB)  TX bytes:1984 (1.9 KiB)

 

lo        Link encap:Local Loopback

          inet addr:127.0.0.1  Mask:255.0.0.0

          UP LOOPBACK RUNNING  MTU:16436  Metric:1

          RX packets:20 errors:0 dropped:0 overruns:0 frame:0

          TX packets:20 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0

          RX bytes:1644 (1.6 KiB)  TX bytes:1644 (1.6 KiB)

 

 

[root@localhost ~]# route

Kernel IP routing table

Destination     Gateway         Genmask         Flags Metric Ref    Use
Iface

192.168.103.0   10.0.0.1        255.255.255.0   UG    0      0        0 eth0

10.0.0.0        *               255.0.0.0       U     0      0        0 eth0



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Michal Ludvig

2005-Jul-23 00:26 UTC

head link

Re: [Xen-users] virtual routing issue

Ernie Fontes wrote:
> My machine (192.168.103.23) is on the network with my router
> (192.168.103.1).  The virtual router, tiara, has to connect my
> 192.168.103.* network with the virtual 10.0.0.* network which comprises
> two other virtual domains, tophat and bowler.
> 
> The three virtual machines are all running Fedora (hence the names).
> 
> I can ping between tiara, tophat, and bowler.  I can also ping from
> tiara out to 192.168.103.1, 192.168.103.23, and the Internet.
> 
> However, I cannot ping 192.168.103.23, 192.168.103.1, or the Internet
> from tophat or bowler (which are routed through tiara).
1) Have you got IPforwarding enabled on Tiara? Do:
~# sysctl -w net.ipv4.ip_forward=1

2) Have you got correct routing tables on other hosts of your network
(most importantly on the router .103.1)? There must be an explicit route
to 10.0.0.0/24, e.g. do this on the router:
~# ip route add 10.0.0.0/24 via 192.168.103.30

Then you should be able to ping the router from Bowler/Tophat.

3) For accessing the internet from domains you need to makesure that the
router is SNATing (or masquerading) 10.0.0.0/24 to your public IP
address. Check your iptables rules for that (assuming your router is
Linux of course).

4) As an excercise read something about "proxy arp" and try to deploy
bowler/tophat directly on 192.168.103.0/24 network. With that approach
there would be no other changes necessary to your network ;-)

HTH,

Michal Ludvig
-- 
* Personal homepage: http://www.logix.cz/michal

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