Re: OSPF to the host

[Luis Periquito <periquito@xxxxxxxxx>]

Nick,

TL;DR: works brilliantly :)

Where I work we have all of the ceph nodes (and a lot of other stuff) using OSPF and BGP server attachment. With that we're able to implement solutions like Anycast addresses, removing the need to add load balancers, for the radosgw solution.

The biggest issues we've had were around the per-flow vs per-packets traffic load balancing, but as long as you keep it simple you shouldn't have any issues.

Currently we have a P2P network between the servers and the ToR switches on a /31 subnet, and then create a virtual loopback address, which is the interface we use for all communications. Running tests like iperf we're able to reach 19Gbps (on a 2x10Gbps network). OTOH we no longer have the ability to separate traffic between public and osd network, but never really felt the need for it.

Also spend a bit of time planning how the network will look like and it's topology. If done properly (think details like route summarization) then it's really worth the extra effort.

On Mon, Jun 6, 2016 at 11:57 AM, Nick Fisk <nick@xxxxxxxxxx> wrote:

Hi All,

 

Has anybody had any experience with running the network routed down all the way to the host?

 

I know the standard way most people configured their OSD nodes is to bond the two nics which will then talk via a VRRP gateway and then probably from then on the networking is all Layer3. The main disadvantage I see here is that you need a beefy inter switch link to cope with the amount of traffic flowing between switches to the VRRP address. I’ve been trying to design around this by splitting hosts into groups with different VRRP gateways on either switch, but this relies on using active/passive bonding on the OSD hosts to make sure traffic goes from the correct Nic to the directly connected switch.

 

What I was thinking, instead of terminating the Layer3 part of the network at the access switches, terminate it at the hosts. If each Nic of the OSD host had a different subnet and the actual “OSD Server” address bound to a loopback adapter, OSPF should advertise this loopback adapter address as reachable via the two L3 links on the physically attached Nic’s. This should give you a redundant topology which also will respect your physically layout and potentially give you higher performance due to ECMP.

 

Any thoughts, any pitfalls?

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