Revision as of 10:53, 6 January 2017

A flowtable plugin

Provide a stateful node with flow-level API, available for consecutive nodes or external applications.

Objective

Provides a flowtable node to do flow classification, and associate a flow context that can be enriched as needed by another node or an external application.

The objective is to be adaptable so as to be used for any stateful use such as load-balancing, firewall ...

Compared to the classifier, it stores a flow context, which changes the following:

• a flow context (which can be updated with external information)
• it can offload
• flows have a lifetime

Sources

• vppsb : within flowtable directory
• github : https://github.com/GabrielGanne/vpp-flowtable

CLI

flowtable [max-flows <n>] [intf <name>] [next-node <name>] [disable]

The traffic from the given intf is redirected to the flowtable using vnet_hw_interface_rx_redirect_to_node()

API

I used ~0 (or 0xff for u8) to leave configuration parameter unchanged.

• flowtable configuration

flowtable_conf(flows_max, sw_if_index, next_node_index, enable_disable)

• send additional informations to the flowtable

flowtable_update(is_ip4, ip_src, ip_dst, port_src, port_dst # used to compute flow key
                 lifetime, offloaded, infos) # additional flow informations

Test

In itself, the flowtable only provides a context and an API.

I added a simple port-mirroring node to test with an external application receiving the mirrored traffic and updating the flowtable using the binary API.

Perfs

Tested with handoff node, with two working nodes :

• Total BW: 12Gbps
• Max flows 2.4 M # Breaking Point flows (2.4M) != vpp flows (4M)
• avg pps : 750~800 k
• avg flow rate : 18k/s
• ~4.5% recycled flows

The flow count difference between Breaking Point and vpp flowtable's is caused by the timer management.

Current status

• Is built as part of vpp (within src/plugins)
• Default behavior is to connect transparently to given interface.
• Can reroute packets to given node
• Can receive additional information
• Can offload sessions
• Only support IP packets
• if the maximum number of flows is reached, the flowtable will recycle a flow by expiring a flow which was about to expire (typically the first flow found in the timer-wheel's next-slot)

Planned

• externalize plugins
• split into two ip4/ip6 nodes

Main contributors

• Gabriel Ganne - gabriel.ganne@qosmos.com
• Christophe Fontaine - christophe.fontaine@qosmos.com (2016-07 ietf's hackathon : https://github.com/christophefontaine/flowtable-plugin)