1.. SPDX-License-Identifier: GPL-2.0 2 3======================================== 4Bare UDP Tunnelling Module Documentation 5======================================== 6 7There are various L3 encapsulation standards using UDP being discussed to 8leverage the UDP based load balancing capability of different networks. 9MPLSoUDP (__ https://tools.ietf.org/html/rfc7510) is one among them. 10 11The Bareudp tunnel module provides a generic L3 encapsulation support for 12tunnelling different L3 protocols like MPLS, IP, NSH etc. inside a UDP tunnel. 13 14Special Handling 15---------------- 16The bareudp device supports special handling for MPLS & IP as they can have 17multiple ethertypes. 18MPLS procotcol can have ethertypes ETH_P_MPLS_UC (unicast) & ETH_P_MPLS_MC (multicast). 19IP protocol can have ethertypes ETH_P_IP (v4) & ETH_P_IPV6 (v6). 20This special handling can be enabled only for ethertypes ETH_P_IP & ETH_P_MPLS_UC 21with a flag called multiproto mode. 22 23Usage 24------ 25 261) Device creation & deletion 27 28 a) ip link add dev bareudp0 type bareudp dstport 6635 ethertype mpls_uc 29 30 This creates a bareudp tunnel device which tunnels L3 traffic with ethertype 31 0x8847 (MPLS traffic). The destination port of the UDP header will be set to 32 6635.The device will listen on UDP port 6635 to receive traffic. 33 34 b) ip link delete bareudp0 35 362) Device creation with multiproto mode enabled 37 38The multiproto mode allows bareudp tunnels to handle several protocols of the 39same family. It is currently only available for IP and MPLS. This mode has to 40be enabled explicitly with the "multiproto" flag. 41 42 a) ip link add dev bareudp0 type bareudp dstport 6635 ethertype ipv4 multiproto 43 44 For an IPv4 tunnel the multiproto mode allows the tunnel to also handle 45 IPv6. 46 47 b) ip link add dev bareudp0 type bareudp dstport 6635 ethertype mpls_uc multiproto 48 49 For MPLS, the multiproto mode allows the tunnel to handle both unicast 50 and multicast MPLS packets. 51 523) Device Usage 53 54The bareudp device could be used along with OVS or flower filter in TC. 55The OVS or TC flower layer must set the tunnel information in SKB dst field before 56sending packet buffer to the bareudp device for transmission. On reception the 57bareudp device extracts and stores the tunnel information in SKB dst field before 58passing the packet buffer to the network stack. 59