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How openstack will get ip of all vm instances

asked 2014-09-22 23:54:43 -0500

sumit gravatar image

updated 2014-09-23 00:02:46 -0500

I am new to openstack, Please tell me if we create more then 1 vms then how each of them will communicate with each other.

what i know is that hypervisor (we are using zen) creates the vms and allocate dynamic ips to them, cloud middle-ware (openstack) sit above hypervisor. so how openstack will get the ips of all vm instances. Correct me if i am wrong anywhere.

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answered 2014-09-23 09:10:37 -0500

larsks gravatar image

what i know is that hypervisor (we are using zen) creates the vms and allocate dynamic ips to them, cloud middle-ware (openstack) sit above hypervisor. so how openstack will get the ips of all vm instances. Correct me if i am wrong anywhere.

OpenStack (either the nova-network service or the Neutron networking service) is responsible for allocating ip addresses. So OpenStack does not need to query Xen for this information.

IP addresses are allocated to your instances from the "fixed" networks that you create.

Addresses are provided to your instances through the use of DHCP servers that OpenStack manages.

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Thnaks for clearing my doubt, I have one more question that how one vm will get the ip of other vms.I know that it can communicate with other vms through nuetron but it should know the ip first.

sumit gravatar imagesumit ( 2014-09-23 23:55:10 -0500 )edit

Typically, you provide your instance with the address of other instances. You can do this automatically through something like a Heat template, or using the appropriate API; you could also use some sort of service discovery mechanism or even something like DNS.

larsks gravatar imagelarsks ( 2014-09-24 09:44:42 -0500 )edit

Thanks for reply but still i didn't get, i wanna know some mechanism like contextualization in nimbus

sumit gravatar imagesumit ( 2014-09-24 23:15:51 -0500 )edit

Then you are probably going to need to open a new question with a much more explicit description of the information you are looking for, because I no longer have any idea what you are asking.

larsks gravatar imagelarsks ( 2014-11-13 08:17:49 -0500 )edit
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answered 2014-09-23 00:01:36 -0500

dbaxps gravatar image

updated 2014-09-23 01:29:57 -0500

View https://www.hastexo.com/system/files/... page 19
VXLAN tunnel will work same way
One DNSMASQ process for each private network

[root@icehouse1 ~(keystone_admin)]# ps -ef | grep dnsmasq
nobody    3143     1  0 08:49 ?        00:00:00 /sbin/dnsmasq --conf-file=/var/lib/libvirt/dnsmasq/default.conf
nobody    5713     1  0 09:05 ?        00:00:00 dnsmasq --no-hosts --no-resolv --strict-order --bind-interfaces --interface=tapc094ce87-74 --except-interface=lo --pid-file=/var/lib/neutron/dhcp/3fea1108-c707-49f9-b317-f7bb531ad48a/pid --dhcp-hostsfile=/var/lib/neutron/dhcp/3fea1108-c707-49f9-b317-f7bb531ad48a/host --addn-hosts=/var/lib/neutron/dhcp/3fea1108-c707-49f9-b317-f7bb531ad48a/addn_hosts --dhcp-optsfile=/var/lib/neutron/dhcp/3fea1108-c707-49f9-b317-f7bb531ad48a/opts --leasefile-ro --dhcp-range=set:tag0,20.0.0.0,static,86400s --dhcp-lease-max=256 --conf-file=/etc/neutron/dnsmasq.conf --domain=openstacklocal

nobody    5717     1  0 09:05 ?        00:00:00 dnsmasq --no-hosts --no-resolv --strict-order --bind-interfaces --interface=tap707ec6ff-71 --except-interface=lo --pid-file=/var/lib/neutron/dhcp/8b22b262-c9c1-4138-8092-0581195f0889/pid --dhcp-hostsfile=/var/lib/neutron/dhcp/8b22b262-c9c1-4138-8092-0581195f0889/host --addn-hosts=/var/lib/neutron/dhcp/8b22b262-c9c1-4138-8092-0581195f0889/addn_hosts --dhcp-optsfile=/var/lib/neutron/dhcp/8b22b262-c9c1-4138-8092-0581195f0889/opts --leasefile-ro --dhcp-range=set:tag0,40.0.0.0,static,86400s --dhcp-lease-max=256 --conf-file=/etc/neutron/dnsmasq.conf --domain=openstacklocal

nobody    5721     1  0 09:05 ?        00:00:00 dnsmasq --no-hosts --no-resolv --strict-order --bind-interfaces --interface=tap6b3d1487-a3 --except-interface=lo --pid-file=/var/lib/neutron/dhcp/140d25a4-0d98-4424-a35a-2a985b2f0a17/pid --dhcp-hostsfile=/var/lib/neutron/dhcp/140d25a4-0d98-4424-a35a-2a985b2f0a17/host --addn-hosts=/var/lib/neutron/dhcp/140d25a4-0d98-4424-a35a-2a985b2f0a17/addn_hosts --dhcp-optsfile=/var/lib/neutron/dhcp/140d25a4-0d98-4424-a35a-2a985b2f0a17/opts --leasefile-ro --dhcp-range=set:tag0,10.0.0.0,static,86400s --dhcp-lease-max=256 --conf-file=/etc/neutron/dnsmasq.conf --domain=openstacklocal
root      7491  4489  0 09:12 pts/0    00:00:00 grep --color=auto dnsmasq

[root@icehouse1 ~(keystone_admin)]# cat /var/lib/neutron/dhcp/140d25a4-0d98-4424-a35a-2a985b2f0a17/addn_hosts
10.0.0.25   host-10-0-0-25.openstacklocal host-10-0-0-25
10.0.0.48   host-10-0-0-48.openstacklocal host-10-0-0-48
10.0.0.1    host-10-0-0-1.openstacklocal host-10-0-0-1
10.0.0.11   host-10-0-0-11.openstacklocal host-10-0-0-11
10.0.0.45   host-10-0-0-45.openstacklocal host-10-0-0-45
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Asked: 2014-09-22 23:54:43 -0500

Seen: 438 times

Last updated: Sep 23 '14