Bare UDP Tunnelling Module Documentation¶
There are various L3 encapsulation standards using UDP being discussed to leverage the UDP based load balancing capability of different networks. MPLSoUDP (__ https://tools.ietf.org/html/rfc7510) is one among them.
The Bareudp tunnel module provides a generic L3 encapsulation tunnelling support for tunnelling different L3 protocols like MPLS, IP, NSH etc. inside a UDP tunnel.
The bareudp device supports special handling for MPLS & IP as they can have multiple ethertypes. MPLS procotcol can have ethertypes ETH_P_MPLS_UC (unicast) & ETH_P_MPLS_MC (multicast). IP protocol can have ethertypes ETH_P_IP (v4) & ETH_P_IPV6 (v6). This special handling can be enabled only for ethertypes ETH_P_IP & ETH_P_MPLS_UC with a flag called multiproto mode.
Device creation & deletion
ip link add dev bareudp0 type bareudp dstport 6635 ethertype 0x8847.
This creates a bareudp tunnel device which tunnels L3 traffic with ethertype 0x8847 (MPLS traffic). The destination port of the UDP header will be set to 6635.The device will listen on UDP port 6635 to receive traffic.
ip link delete bareudp0
Device creation with multiple proto mode enabled
There are two ways to create a bareudp device for MPLS & IP with multiproto mode enabled.
ip link add dev bareudp0 type bareudp dstport 6635 ethertype 0x8847 multiproto
ip link add dev bareudp0 type bareudp dstport 6635 ethertype mpls
The bareudp device could be used along with OVS or flower filter in TC. The OVS or TC flower layer must set the tunnel information in SKB dst field before sending packet buffer to the bareudp device for transmission. On reception the bareudp device extracts and stores the tunnel information in SKB dst field before passing the packet buffer to the network stack.