2020-02-24 13:27:50 +08:00
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.. SPDX-License-Identifier: GPL-2.0
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========================================
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Bare UDP Tunnelling Module Documentation
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========================================
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There are various L3 encapsulation standards using UDP being discussed to
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leverage the UDP based load balancing capability of different networks.
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MPLSoUDP (__ https://tools.ietf.org/html/rfc7510) is one among them.
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The Bareudp tunnel module provides a generic L3 encapsulation tunnelling
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support for tunnelling different L3 protocols like MPLS, IP, NSH etc. inside
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a UDP tunnel.
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2020-02-24 13:28:35 +08:00
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Special Handling
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----------------
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The bareudp device supports special handling for MPLS & IP as they can have
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multiple ethertypes.
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MPLS procotcol can have ethertypes ETH_P_MPLS_UC (unicast) & ETH_P_MPLS_MC (multicast).
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IP protocol can have ethertypes ETH_P_IP (v4) & ETH_P_IPV6 (v6).
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This special handling can be enabled only for ethertypes ETH_P_IP & ETH_P_MPLS_UC
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with a flag called multiproto mode.
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2020-02-24 13:27:50 +08:00
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Usage
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------
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1) Device creation & deletion
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2020-07-20 23:46:58 +08:00
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a) ip link add dev bareudp0 type bareudp dstport 6635 ethertype mpls_uc
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2020-02-24 13:27:50 +08:00
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This creates a bareudp tunnel device which tunnels L3 traffic with ethertype
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0x8847 (MPLS traffic). The destination port of the UDP header will be set to
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6635.The device will listen on UDP port 6635 to receive traffic.
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b) ip link delete bareudp0
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2020-07-20 23:46:58 +08:00
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2) Device creation with multiproto mode enabled
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2020-02-24 13:28:35 +08:00
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2020-07-20 23:46:58 +08:00
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The multiproto mode allows bareudp tunnels to handle several protocols of the
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same family. It is currently only available for IP and MPLS. This mode has to
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be enabled explicitly with the "multiproto" flag.
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2020-02-24 13:28:35 +08:00
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2020-07-20 23:46:58 +08:00
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a) ip link add dev bareudp0 type bareudp dstport 6635 ethertype ipv4 multiproto
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2020-02-24 13:28:35 +08:00
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2020-07-20 23:46:58 +08:00
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For an IPv4 tunnel the multiproto mode allows the tunnel to also handle
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IPv6.
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b) ip link add dev bareudp0 type bareudp dstport 6635 ethertype mpls_uc multiproto
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For MPLS, the multiproto mode allows the tunnel to handle both unicast
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and multicast MPLS packets.
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2020-02-24 13:28:35 +08:00
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3) Device Usage
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2020-02-24 13:27:50 +08:00
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The bareudp device could be used along with OVS or flower filter in TC.
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The OVS or TC flower layer must set the tunnel information in SKB dst field before
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sending packet buffer to the bareudp device for transmission. On reception the
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bareudp device extracts and stores the tunnel information in SKB dst field before
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passing the packet buffer to the network stack.
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