Difference between revisions of "Networks"

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=== Floating IP ===
 
=== Floating IP ===
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If you want to assign a floating IP to an existing instance, '''it is highly advised to create a new (cloned) instance''' by creating a snapshot of the existing instance. Otherwise, the instance will have two IPs on the same network which could result in a bad network configuration. The new instance will then select the private network at creation, instead of the public network.
  
 
Steps for getting a floating (stable) IP:
 
Steps for getting a floating (stable) IP:

Revision as of 11:07, 9 February 2019


Use the 'public' net if you want some form of public (but possibly restricted) access from the internet and don't care about having an extremely stable IP. Somewhat counter-intuitively, you want a 'private' network if you want to get a stable "floating" IP address (called an elastic IP address in Eucalyptus and AWS); this is also highly reccomended if you plan to have a registered domain name pointing to the instance. You can also use a private network if you want some or all of the instances on the private network to not be directly accessible from the internet. The list of networks for the currently selected project can be viewed in OpenStack Horizon.

Note that you can actually have an instance that is both part of the 'public' network and a 'private' network.

Public Net

  • No action is needed to use this, other than selecting it.
  • This should be acceptable for many uses, e.g. compute instances.
  • IP address will be stable through reboots, but not necessarily through hard shutdowns (e.g. shelving).
  • You can not assign a floating IP to an instance via its membership in a public network. Please do not allocate floating IP addresses on a public network.

Private Network

Setting up your own private network

  • ssh into linuxlogin.cac.cornell.edu; this can be done using your CU netid and CAC password: ssh netid@linuxlogin.cac.cornell.edu.
  • Set the required environment variables for accessing Red Cloud by sourcing the /opt/openstack/login-redcloud.sh file like this:
 -bash-4.2$ source /opt/openstack/login-redcloud.sh 
 Please enter your CAC project: Enter CAC project name
 Please enter your user name for your CAC project <Your CAC project name>: Enter CAC user name
 Please enter your password for project <Your CAC project name> as user <Your CAC user name>: Enter CAC password
  • Run the network creation script with a single argument (network name), e.g.: /opt/openstack/create-private-net.sh my-net-name.

You can switch an instance from public to private by doing attach interface / detach interface from the instance dropdown menu.

Note that network names are not unique, but IDs are. You can rename a network without renaming the subnet (but you can rename it too, separately), all possible via the Horizon web UI. The subnets are private, and exposed externally by a Router. Networks and routers won't be deleted if there are any active connections on them. There is also a delete network script that should be used instead of the Horizon web UI for a cleaner deletion: /opt/openstack/delete-private-net.sh.

Floating IP

If you want to assign a floating IP to an existing instance, it is highly advised to create a new (cloned) instance by creating a snapshot of the existing instance. Otherwise, the instance will have two IPs on the same network which could result in a bad network configuration. The new instance will then select the private network at creation, instead of the public network.

Steps for getting a floating (stable) IP:

  • See the prerequisite steps above for "Setting up your own private network"
  • In Horizon, under the Networks tab, select "Floating IPs", which should send you here.
  • Click "Allocate IP to Project"
  • The only pool will be "public"; click "allocate".
  • From the list of floating IPs, click "Associate"; make sure you pick a "port" that is an instance's interface on a previously created private network, NOT a public network.
  • Note that if you not longer need the floating IP, please release it back to the pool by selecting the "Release Floating IP" from the Actions dropdown menu.
  • When changing the associated floating IPs of an instance, security groups may be dropped, so you may need to edit the security groups after the fact from the instance dropdown menu.