There has been enough confusion regarding arp responders in ovn to warrant some additional comments; hence add a general description regarding why they exist and document the special cases.
Signed-off-by: Darrell Ball <[email protected]> --- ovn/northd/ovn-northd.8.xml | 25 ++++++++++++++++++++----- 1 file changed, 20 insertions(+), 5 deletions(-) diff --git a/ovn/northd/ovn-northd.8.xml b/ovn/northd/ovn-northd.8.xml index 77eb3d1..74ac5b3 100644 --- a/ovn/northd/ovn-northd.8.xml +++ b/ovn/northd/ovn-northd.8.xml @@ -415,14 +415,29 @@ <h3>Ingress Table 9: ARP/ND responder</h3> <p> - This table implements ARP/ND responder for known IPs. It contains these - logical flows: + This table implements ARP/ND responder for known IPs. The advantage + of the arp responder flow is to limit arp broadcasts by locally + responding to arp requests without the need to send to other + hypervisors. One common case is when the inport is a logical + port associated with a VIF and the broadcast is responded to on the + local hypervisor rather than broadcast across the whole network and + responded to by the destination VM. It contains these logical flows: </p> <ul> <li> Priority-100 flows to skip ARP responder if inport is of type - <code>localnet</code>, and advances directly to the next table. + <code>localnet</code> or <code>vtep</code> or <code>router</code>, + and advances directly to the next table. <code>localnet</code> + and <code>vtep</code> port types are skipped, otherwise the arp + request is received by multiple hypervisors, which all have the + same mac binding downloaded from northd, which will cause redundant + arp replies, confusing the originator of the arp request. If the + inport is of type <code>router</code>, we skip install since + there is no known valid use case. There is a special case: + north->south traffic using the l2gateway port will use an arp + responder on the l2 gateway chassis in the context of a logical + switch datapath. </li> <li> @@ -446,8 +461,8 @@ output; </pre> <p> - These flows are omitted for logical ports (other than router ports) - that are down. + These flows are omitted for router type ports and other + logical ports that are down. </p> </li> -- 1.9.1 _______________________________________________ dev mailing list [email protected] http://openvswitch.org/mailman/listinfo/dev
