[Engine-devel] network features review

[Moti Asayag]

On 05/22/2012 11:45 AM, Livnat Peer wrote:
> Hi All,
> 
> This is a summary of comments we(*) gathered while reviewing the current
> network related functionality in oVirt, we'll open the relevant RFE/Bugs
> but wanted to share first to get comments:
> 
> 
> Default Gateway:
> ----------------
> current status -
>   In the UI/API we expose to the user the possibility to configure the
>   default gateway for the host. We expose this option only when editing
>   the management network.
> 
> comments -
> Apparently we do not configure the host default gateway but the
> network gateway.
> 
> 1. We need to fix the phrasing to gateway (not default gateway)
> 2. Why do we block it for networks which are not the management network
> 3. We need to support configuring the host default gateway.
> 
> 
> Non VM (Bridge-less) Network:
> -----------------------------
> current status -
> During bootstrap we configure the management network on the host. We did
> not implement configuring bridge-less management network during bootstrap.
> 
> comments -
> 1. Supporting bridge-less network is a new feature,the design of this
> feature did not include changing the bootstrap process which make this
> feature non-useful when it comes to management network.
> 
> Today one can edit a network only when it is not attached to clusters,
> at this point you can change the management network to be non-VM
> network, the problem is that we configure the management network on the
> host during bootstrap and we do not get a parameter if to create a
> bridge or not (we always create a bridge).
> 
> What we end up with is - we can't change the management network once we
> added clusters/hosts but if changing it before attaching a cluster we
> ignore it in the bootstrap process.
> 
> 
> Check connectivity:
> --------------------
> current status -
> The 'check connectivity' functionality is available only when editing
> the management network, it validates that we did not loose connectivity
> to the host, if we did the changes are rolled backed automatically.
> 
> comments -
> 1. Sometimes when changing configuration of another network we can
> 'damage' the connectivity to the host. We want to expose the check
> connectivity functionality on any network configuration change.
> 
> VLAN tagging of management Network
> -----------------------------------
> 
> current status -
> The user can set a VLAN tag on the management network.
> 
> comments -
> 1. Any configuration of the management network needs support in the
> bootstrap process (see explanation above for bridge-less network)
> 2. In case of VLAN tagging it is even more complicated, when adding a
> host to oVirt we add it's address and it can not be changed after the
> host was added to the system. in the bootstrap process we set the
> management network on the nic oVirt engine used to ssh through, unless
> the VLAN device is already configured and the IP used for the ssh is
> already on this VLAN (for which it will work) we can't set the network
> to be on another IP address.
> 

The host IP can be change, however it requires re-installing the host,
that runs the bootstrap script.

> Rollback network configuration:
> --------------------------------
> current status -
>  We have the option to make changes to the host network configuration
> and not persist the changes (they won't survive machine reboot)
> 
> comments -
> 1. We are missing the functionality of rolling back the changes (without
> rebooting the machine), this functionality is the complementary behavior
> of 'save network configuration'.
> 
> 
> Predefined bonds:
> -----------------
> current status -
> In the bootstrap process we create bonds0-5 on the hosts and then
> we use them when creating a bond on the host

minor correction: There are 5 bonds, named bond0-4.

> 
> comments -
> 1. Creating the bonds in the host during the bootstrap process is not
> needed and we can let the user choose the bond name (limited to bondX)
> and create bonds only upon request.
> 
> 
> Editing Network properties while Network is attached to cluster/s
> ------------------------------------------------------------------
> current status -
> Changing the network properties is blocked if the network is attached to
> a cluster.
> 
> comments -
> 1. We should relax this approach. to start with we can enable editing
> when there are no active hosts in the cluster/s.

Modifying a cluster network with hosts in it seems problematic, since
we'd have to propagate the network changes to the hosts. E.g. updating a
network to be bridge-less, or tagging a network.

Perhaps we should allow updating a network only if the clusters have no
hosts at all.

> 
> doing more than the above requires substantially more work both in VDSM
> and engine.
> 

Another missing behavior is the capability to refresh Host nics by
demand. At the moment it is enabled by activating a host, which requires
moving the host to maintenance first or when facing network issues.
Else, changes on host nics will not reflect to the ovirt-engine.

> 
> 
> Thank you, Livnat
> 
> 
> (*) we == {Dan Kenigsberg, Igor Lvovsky, Mike Kolesnik, Moti Asayag,
> Muli Salem, Alona Kaplan, Livnat Peer}
> 
> (**) We have even longer list for the UI changes needed, for them we'll
> open bugs directly to avoid another long email.
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