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