Thanks for your reply Daniel. Suppose I want to create on more VM with static ip address 144.68.100.0 on host having ip address 10.2.0.25 then do i need to add one more routing table entry by specifying 10.2.0.25 as gateway or 10.2.0.20 as previous entry is enough to access that VM? Is there any provision to specify the gateway machine for (virbr1) while creating the routed networking with libvirt? Here the thing is I want to reach VMs running on different host machines having same subnet and same default gateway from another machine which is running on the LAN. ie VM1 running at Host1 and VM2 running at Host2 should be accessed from Host3 which is in LAN. Is there any other steps I have to do to reach the VMs residing on different host machines?? Thanks in Advance On Tue, Sep 14, 2010 at 3:45 PM, Daniel P. Berrange <berrange@xxxxxxxxxx> wrote: > On Tue, Sep 14, 2010 at 03:28:56PM +0530, Rajiv Rajaian wrote: >> Hi all >> I have installed KVM with fedora13 operating system and I have >> successfully created guest operating system with virt-install. >> Also I have configured routed networking in host machine. Here's my >> routed networking configuration >> >> [root@kvmcluster ~]# virsh net-dumpxml routed >> <network> >> <name>routed</name> >> <uuid>78b64a7e-48ed-4296-8794-a8450798d283</uuid> >> <forward dev='eth0' mode='route'/> >> <bridge name='virbr1' stp='on' delay='0' /> >> <ip address='144.68.100.100' netmask='255.255.255.0'> >> <dhcp> >> <range start='144.68.100.1' end='144.68.100.254' /> >> </dhcp> >> </ip> >> </network> >> >> Now I can reach the guest VM which is having static ip address >> 144.68.100.1 from the host machine(kvmcluster) >> >> [root@kvmcluster ~]# ping 144.68.100.1 >> PING 144.68.100.1 (144.68.100.1) 56(84) bytes of data. >> 64 bytes from 144.68.100.1: icmp_seq=1 ttl=64 time=0.910 ms >> >> >> The routing table entry of the host machine looks like this >> >> [root@kvmcluster ~]# route -n >> Kernel IP routing table >> Destination Gateway Genmask Flags Metric Ref Use Iface >> 10.2.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 >> 192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr0 >> 144.68.100.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr1 >> 169.254.0.0 0.0.0.0 255.255.0.0 U 1002 0 0 eth0 >> 0.0.0.0 10.2.0.100 0.0.0.0 UG 0 0 0 eth0 >> >> From the Default gateway machine (10.2.0.100) which is in the same >> subnet as that of host machine I have added a routing table entry as >> [root@careserver ~]# route add -net 144.68.100.0 netmask 255.255.255.0 >> gw 10.2.0.100 >> >> Now I can't reach the guest VM with this routing entry. > > This is because '10.2.0.100' is not the gateway for the subnet > you created. When you create a routed network in libvirt like > this, the gateway for that network is the host on which it is > running. This routing entry you added on the gateway machine > is just pointing the gateway back to itself - it still has > no clue which host has the 144.68.100.0 subnet. Your gateway > needs to know 'where do I send packets for 144.68.100.0?'. > The answer is the host 10.2.0.20... > > > Hence this second routing entry you show is the correct one: > >> But when I have added the routing table entry with 10.2.0.20(host >> machine's ip) as gateway I can reach the guest VM >> [root@careserver ~]# route add -net 144.68.100.0 netmask 255.255.255.0 >> gw 10.2.0.20 > >> >> [root@careserver ~]# route -n >> Kernel IP routing table >> Destination Gateway Genmask Flags Metric Ref Use Iface >> 10.2.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0 >> 192.168.122.0 0.0.0.0 255.255.255.0 U 0 0 0 virbr0 >> 144.68.100.0 10.2.0.20 255.255.255.0 UG 0 0 0 eth0 >> 169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0 >> 0.0.0.0 10.2.0.1 0.0.0.0 UG 0 0 0 eth0 >> >> Why the default gateway machine can't reach the guest VM with >> 10.2.0.100 as gateway. For each VM whether have to add separate >> routing table entry? > > You aren't adding a routing table entry per VM here. You added > an entry for the entire subnet 144.68.100.0/255.255.255.0, which > you said has one VM on 144.68.100.1. This subnet can have many > more VMs running on it without adding more routing table entries. > > > Daniel > -- > |: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/ :| > |: http://libvirt.org -o- http://virt-manager.org -o- http://deltacloud.org :| > |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| > |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :| > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
