docs: networking: convert ila.txt to ReST

- add SPDX header;
- adjust title markup;
- mark code blocks and literals as such;
- adjust identation, whitespaces and blank lines;
- add to networking/index.rst.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 0 insertions, 285 deletions

diff --git a/Documentation/networking/ila.txt b/Documentation/networking/ila.txt
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-Identifier Locator Addressing (ILA)
-
-
-Introduction
-============
-
-Identifier-locator addressing (ILA) is a technique used with IPv6 that
-differentiates between location and identity of a network node. Part of an
-address expresses the immutable identity of the node, and another part
-indicates the location of the node which can be dynamic. Identifier-locator
-addressing can be used to efficiently implement overlay networks for
-network virtualization as well as solutions for use cases in mobility.
-
-ILA can be thought of as means to implement an overlay network without
-encapsulation. This is accomplished by performing network address
-translation on destination addresses as a packet traverses a network. To
-the network, an ILA translated packet appears to be no different than any
-other IPv6 packet. For instance, if the transport protocol is TCP then an
-ILA translated packet looks like just another TCP/IPv6 packet. The
-advantage of this is that ILA is transparent to the network so that
-optimizations in the network, such as ECMP, RSS, GRO, GSO, etc., just work.
-
-The ILA protocol is described in Internet-Draft draft-herbert-intarea-ila.
-
-
-ILA terminology
-===============
-
-  - Identifier	A number that identifies an addressable node in the network
-		independent of its location. ILA identifiers are sixty-four
-		bit values.
-
-  - Locator	A network prefix that routes to a physical host. Locators
-		provide the topological location of an addressed node. ILA
-		locators are sixty-four bit prefixes.
-
-  - ILA mapping
-		A mapping of an ILA identifier to a locator (or to a
-		locator and meta data). An ILA domain maintains a database
-		that contains mappings for all destinations in the domain.
-
-  - SIR address
-		An IPv6 address composed of a SIR prefix (upper sixty-
-		four bits) and an identifier (lower sixty-four bits).
-		SIR addresses are visible to applications and provide a
-		means for them to address nodes independent of their
-		location.
-
-  - ILA address
-		An IPv6 address composed of a locator (upper sixty-four
-		bits) and an identifier (low order sixty-four bits). ILA
-		addresses are never visible to an application.
-
-  - ILA host	An end host that is capable of performing ILA translations
-		on transmit or receive.
-
-  - ILA router	A network node that performs ILA translation and forwarding
-		of translated packets.
-
-  - ILA forwarding cache
-		A type of ILA router that only maintains a working set
-		cache of mappings.
-
-  - ILA node	A network node capable of performing ILA translations. This
-		can be an ILA router, ILA forwarding cache, or ILA host.
-
-
-Operation
-=========
-
-There are two fundamental operations with ILA:
-
-  - Translate a SIR address to an ILA address. This is performed on ingress
-    to an ILA overlay.
-
-  - Translate an ILA address to a SIR address. This is performed on egress
-    from the ILA overlay.
-
-ILA can be deployed either on end hosts or intermediate devices in the
-network; these are provided by "ILA hosts" and "ILA routers" respectively.
-Configuration and datapath for these two points of deployment is somewhat
-different.
-
-The diagram below illustrates the flow of packets through ILA as well
-as showing ILA hosts and routers.
-
-    +--------+                                                +--------+
-    | Host A +-+                                         +--->| Host B |
-    |        | |              (2) ILA                   (')   |        |
-    +--------+ |            ...addressed....           (   )  +--------+
-               V  +---+--+  .  packet      .  +---+--+  (_)
-   (1) SIR     |  | ILA  |----->-------->---->| ILA  |   |   (3) SIR
-    addressed  +->|router|  .              .  |router|->-+    addressed
-    packet        +---+--+  .     IPv6     .  +---+--+        packet
-                   /        .    Network   .
-                  /         .              .   +--+-++--------+
-    +--------+   /          .              .   |ILA ||  Host  |
-    |  Host  +--+           .              .- -|host||        |
-    |        |              .              .   +--+-++--------+
-    +--------+              ................
-
-
-Transport checksum handling
-===========================
-
-When an address is translated by ILA, an encapsulated transport checksum
-that includes the translated address in a pseudo header may be rendered
-incorrect on the wire. This is a problem for intermediate devices,
-including checksum offload in NICs, that process the checksum. There are
-three options to deal with this:
-
-- no action	Allow the checksum to be incorrect on the wire. Before
-		a receiver verifies a checksum the ILA to SIR address
-		translation must be done.
-
-- adjust transport checksum
-		When ILA translation is performed the packet is parsed
-		and if a transport layer checksum is found then it is
-		adjusted to reflect the correct checksum per the
-		translated address.
-
-- checksum neutral mapping
-		When an address is translated the difference can be offset
-		elsewhere in a part of the packet that is covered by
-		the checksum. The low order sixteen bits of the identifier
-		are used. This method is preferred since it doesn't require
-		parsing a packet beyond the IP header and in most cases the
-		adjustment can be precomputed and saved with the mapping.
-
-Note that the checksum neutral adjustment affects the low order sixteen
-bits of the identifier. When ILA to SIR address translation is done on
-egress the low order bits are restored to the original value which
-restores the identifier as it was originally sent.
-
-
-Identifier types
-================
-
-ILA defines different types of identifiers for different use cases.
-
-The defined types are:
-
-      0: interface identifier
-
-      1: locally unique identifier
-
-      2: virtual networking identifier for IPv4 address
-
-      3: virtual networking identifier for IPv6 unicast address
-
-      4: virtual networking identifier for IPv6 multicast address
-
-      5: non-local address identifier
-
-In the current implementation of kernel ILA only locally unique identifiers
-(LUID) are supported. LUID allows for a generic, unformatted 64 bit
-identifier.
-
-
-Identifier formats
-==================
-
-Kernel ILA supports two optional fields in an identifier for formatting:
-"C-bit" and "identifier type". The presence of these fields is determined
-by configuration as demonstrated below.
-
-If the identifier type is present it occupies the three highest order
-bits of an identifier. The possible values are given in the above list.
-
-If the C-bit is present,  this is used as an indication that checksum
-neutral mapping has been done. The C-bit can only be set in an
-ILA address, never a SIR address.
-
-In the simplest format the identifier types, C-bit, and checksum
-adjustment value are not present so an identifier is considered an
-unstructured sixty-four bit value.
-
-     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-     |                            Identifier                         |
-     +                                                               +
-     |                                                               |
-     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
-The checksum neutral adjustment may be configured to always be
-present using neutral-map-auto. In this case there is no C-bit, but the
-checksum adjustment is in the low order 16 bits. The identifier is
-still sixty-four bits.
-
-     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-     |                            Identifier                         |
-     |                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-     |                               |  Checksum-neutral adjustment  |
-     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
-The C-bit may used to explicitly indicate that checksum neutral
-mapping has been applied to an ILA address. The format is:
-
-     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-     |     |C|                    Identifier                         |
-     |     +-+                       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-     |                               |  Checksum-neutral adjustment  |
-     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
-The identifier type field may be present to indicate the identifier
-type. If it is not present then the type is inferred based on mapping
-configuration. The checksum neutral adjustment may automatically
-used with the identifier type as illustrated below.
-
-     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-     | Type|                      Identifier                         |
-     +-+-+-+                         +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-     |                               |  Checksum-neutral adjustment  |
-     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
-If the identifier type and the C-bit can be present simultaneously so
-the identifier format would be:
-
-     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-     | Type|C|                    Identifier                         |
-     +-+-+-+-+                       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-     |                               |  Checksum-neutral adjustment  |
-     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-
-
-Configuration
-=============
-
-There are two methods to configure ILA mappings. One is by using LWT routes
-and the other is ila_xlat (called from NFHOOK PREROUTING hook). ila_xlat
-is intended to be used in the receive path for ILA hosts .
-
-An ILA router has also been implemented in XDP. Description of that is
-outside the scope of this document.
-
-The usage of for ILA LWT routes is:
-
-ip route add DEST/128 encap ila LOC csum-mode MODE ident-type TYPE via ADDR
-
-Destination (DEST) can either be a SIR address (for an ILA host or ingress
-ILA router) or an ILA address (egress ILA router). LOC is the sixty-four
-bit locator (with format W:X:Y:Z) that overwrites the upper sixty-four
-bits of the destination address.  Checksum MODE is one of "no-action",
-"adj-transport", "neutral-map", and "neutral-map-auto". If neutral-map is
-set then the C-bit will be present. Identifier TYPE one of "luid" or
-"use-format." In the case of use-format, the identifier type field is
-present and the effective type is taken from that.
-
-The usage of ila_xlat is:
-
-ip ila add loc_match MATCH loc LOC csum-mode MODE ident-type TYPE
-
-MATCH indicates the incoming locator that must be matched to apply
-a the translaiton. LOC is the locator that overwrites the upper
-sixty-four bits of the destination address. MODE and TYPE have the
-same meanings as described above.
-
-
-Some examples
-=============
-
-# Configure an ILA route that uses checksum neutral mapping as well
-# as type field. Note that the type field is set in the SIR address
-# (the 2000 implies type is 1 which is LUID).
-ip route add 3333:0:0:1:2000:0:1:87/128 encap ila 2001:0:87:0 \
-     csum-mode neutral-map ident-type use-format
-
-# Configure an ILA LWT route that uses auto checksum neutral mapping
-# (no C-bit) and configure identifier type to be LUID so that the
-# identifier type field will not be present.
-ip route add 3333:0:0:1:2000:0:2:87/128 encap ila 2001:0:87:1 \
-     csum-mode neutral-map-auto ident-type luid
-
-ila_xlat configuration
-
-# Configure an ILA to SIR mapping that matches a locator and overwrites
-# it with a SIR address (3333:0:0:1 in this example). The C-bit and
-# identifier field are used.
-ip ila add loc_match 2001:0:119:0 loc 3333:0:0:1 \
-    csum-mode neutral-map-auto ident-type use-format
-
-# Configure an ILA to SIR mapping where checksum neutral is automatically
-# set without the C-bit and the identifier type is configured to be LUID
-# so that the identifier type field is not present.
-ip ila add loc_match 2001:0:119:0 loc 3333:0:0:1 \
-    csum-mode neutral-map-auto ident-type use-format