Sned udp packets using netmap code#

This code is very close to a Netmap example program. Ring->head = ring->cur = nm_ring_next(ring, i) The minimal program receiving packets from eth3 RX queue #4 would look like: d = nm_open('netmap:eth3~4', NULL, 0, 0) īuf = NETMAP_BUF(ring, ring->slot.buf_idx)

Sned udp packets using netmap Patch#

The patch to Netmap is awaiting code review and is available here:

Eventually remove the interface from the Netmap mode and reattach the RX queues to the host stack.

On demand add or remove RX queues from the 'single RX queue mode'.

While leaving all the other queues attached to the host network stack.

This would allow netmap applications to receive packets from that specific RX queue.

Open a network interface in 'a single RX queue mode'.

The intention was to expose a minimal API which could: We call this functionality: 'single RX queue mode'. We want to keep most of the RX queues back in the kernel mode, and enable Netmap mode only on selected RX queues. Usually, when a network card goes into the Netmap mode, all the RX queues get disconnected from the kernel and are available to the Netmap applications. It’s easy to add support for new hardware.

The driver-specific modifications are trivial: most of the magic happens in the shared Netmap module.

The project is well maintained and reasonably mature.

It’s very fast: can reach line rate easily.

It’s fully open source and released under a BSD license.

Eventually we decided that the best way would be to patch Netmap with the functionality we need. We’ve considered PF_RING, DPDK and other custom solutions, but sadly all of them take over the whole network card.

Sned udp packets using netmap how to#

Over the last few months we’ve been thinking hard about how to achieve bypass for selected flows (aka: bifurcated driver) on non-Solarflare network cards. Unfortunately, we don’t have this functionality on our servers with Intel IXGBE NIC’s. This setup works perfectly on our servers with Solarflare network cards - we can use the ef_vi API to achieve the kernel bypass. It’s important to emphasize that the kernel bypass is enabled only for selected flows, which means that all other packets go to the kernel as usual. The small number of 'valid' packets are injected back to the kernel and handled in the same way as usual traffic. Most of the packets are dropped, as they belong to a flood. This application filters the packets at very high speed. During packet floods we offload selected network flows (belonging to a flood) to a user space application. Since the Linux Kernel can't really handle a large volume of packets, we need to work around it. In fact, it is entirely possible that the server which just served you this blog post is dealing with a many-million packets per second flood right now.

Our network constantly receives a large volume of packets, often coming from many, simultaneous attacks. In this blog post we'll describe our proposed changes.ĬC BY-SA 2.0 image by Binary Koala Our needsĪt CloudFlare we are constantly dealing with large packet floods. To improve the situation we decided to contribute to the Netmap project. Unfortunately, none of the discussed open source solutions supported our needs.

We detailed the available kernel bypass techniques allowing user space programs to receive packets with high throughput. In a previous post we discussed the performance limitations of the Linux kernel network stack.