nsh_packet.h revision 1a8e2a69
1/*
2 * Copyright (c) 2015 Cisco and/or its affiliates.
3 * Licensed under the Apache License, Version 2.0 (the "License");
4 * you may not use this file except in compliance with the License.
5 * You may obtain a copy of the License at:
6 *
7 *     http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software
10 * distributed under the License is distributed on an "AS IS" BASIS,
11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 * See the License for the specific language governing permissions and
13 * limitations under the License.
14 */
15#ifndef included_nsh_packet_h
16#define included_nsh_packet_h
17
18/*
19 * NSH packet format from draft-quinn-sfc-nsh-03.txt
20 *
21 * NSH Base Header
22 *  0                   1                   2                   3
23 *  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
24 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
25 *  |Ver|O|C|R|R|R|R|R|R|   Length  |    MD Type    | Next Protocol |
26 *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
27 *
28 *
29 * Base Header Field Descriptions:
30 *
31 * Version: The version field is used to ensure backward compatibility
32 * going forward with future NSH updates.
33 *
34 * O bit: Indicates that this packet is an operations and management
35 * (OAM) packet.  SFF and SFs nodes MUST examine the payload and take
36 * appropriate action (e.g. return status information).
37 *
38 * OAM message specifics and handling details are outside the scope of
39 * this document.
40 *
41 * C bit: Indicates that a critical metadata TLV is present (see section
42 * 7).  This bit acts as an indication for hardware implementers to
43 * decide how to handle the presence of a critical TLV without
44 * necessarily needing to parse all TLVs present.  The C bit MUST be set
45 * to 1 if one or more critical TLVs are present.
46 *
47 * All other flag fields are reserved.
48 *
49 * Length: total length, in 4 byte words, of the NSH header, including
50 * optional variable TLVs.  Length must be equal or greater than 6.
51 *
52 * MD Type: indicates the format of NSH beyond the base header and the
53 * type of metadata being carried.  This typing is used to describe the
54 * use for the metadata.  A new registry will be requested from IANA for
55 * the MD Type.  NSH defines one type, type = 0x1 which indicates that
56 * the format of the header is as per this draft.
57 *
58 * The format of the base header is invariant, and not described by MD
59 * Type.
60 *
61 * Next Protocol: indicates the protocol type of the original packet.  A
62 * new IANA registry will be created for protocol type.
63 *
64 * This draft defines the following Next Protocol values:
65 *
66 * 0x1 : IPv4
67 * 0x2 : IPv6
68 * 0x3 : Ethernet
69 */
70
71typedef CLIB_PACKED(struct {
72  u8 ver_o_c;
73  u8 length;
74  u8 md_type;
75  u8 next_protocol;
76  u32 nsp_nsi; // nsp 24 bits, nsi 8 bits
77  /* Context headers, always present */
78  u32 c1; u32 c2; u32 c3; u32 c4;
79
80  /* Optional variable length metadata */
81  u32 tlvs[0];
82}) nsh_header_t;
83
84#define NSH_VERSION (0<<6)
85#define NSH_O_BIT (1<<5)
86#define NSH_C_BIT (1<<4)
87
88/* Network byte order shift / mask */
89#define NSH_NSI_MASK 0xFF
90#define NSH_NSP_MASK (0x00FFFFFF)
91#define NSH_NSP_SHIFT 8
92
93#endif /* included_nsh_packet_h */
94