Michael Bridgen
a1badfccc7
git read-tree -u --prefix=site/ gh-pages This is so we can work on code and docs at the same time.
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title, layout
| title | layout |
|---|---|
| How Weave works | default |
How does it work?
Weave creates a network bridge on the host. Each container is connected to that bridge via a veth pair, the container side of which is given the IP address & netmask supplied in 'weave run'. Also connected to the bridge is the weave router container.
A weave router captures Ethernet packets from its bridge-connected interface in promiscuous mode, using 'pcap'. This typically excludes traffic between local containers, and between the host and local containers, all of which is routed straight over the bridge by the kernel. Captured packets are forwarded over UDP to weave router peers running on other hosts. On receipt of such a packet, a router injects the packet on its bridge interface using 'pcap' and/or forwards the packet to peers.
Weave routers learn which peer host a particular MAC address resides on. They combine this knowledge with topology information in order to make routing decisions and thus avoid forwarding every packet to every peer. The topology information captures which peers are connected to which other peers; weave can route packets in partially connected networks with changing topology.
Weave routers establish TCP connections to each other, over which they perform a protocol handshake and subsequently exchange topology information. These connections are encrypted if so configured. Peers also establish UDP "connections", possibly encrypted, for the aforementioned packet forwarding. These "connections" are duplex and can traverse firewalls.
More details on the inner workings of weave can be found in the architecture documentation.