diff options
| author |   Ahmed Abdelsalam <ahabdels@cisco.com> | 2019-06-20 11:18:57 +0000 |
|---|---|---|
| committer |   Neale Ranns <nranns@cisco.com> | 2019-07-28 14:17:52 +0000 |
| commit | be83704c5b1482dfd2ba38423662a9da5a8d8f81 (patch) | |
| tree | 3f057ac50b73f3fa90f501d46ec9f6196eb44f8e /src | |
| parent | 0ae1d80f9a42158b8904e87179966713dfe9b650 (diff) | |
sr: ipv6 segment routing header (srh) update
SRH has passed WG review in IETF and currently an IESG document.
This patch updates the SRH definition to be compliant with IETF.
- Change "first_segment" to "last_entry"
- Change "reserved" to "tag"
Change-Id: I1765c968671655c5646f6de478d1f7196abbc040
Type: fix
Signed-off-by: Ahmed Abdelsalam <ahabdels@cisco.com>
Diffstat (limited to 'src')
| -rw-r--r-- | src/plugins/srv6-as/as.c | 6 | ||||
| -rwxr-xr-x | src/vnet/srv6/ietf_draft_05.txt | 1564 | ||||
| -rwxr-xr-x | src/vnet/srv6/sr.h | 4 | ||||
| -rwxr-xr-x | src/vnet/srv6/sr_packet.h | 19 | ||||
| -rwxr-xr-x | src/vnet/srv6/sr_policy_rewrite.c | 12 |
5 files changed, 21 insertions, 1584 deletions
diff --git a/src/plugins/srv6-as/as.c b/src/plugins/srv6-as/as.c index 8cd964b60f2..3a476044d60 100644 --- a/src/plugins/srv6-as/as.c +++ b/src/plugins/srv6-as/as.c @@ -77,13 +77,13 @@ prepare_rewrite (ip6_address_t src_addr, ip6_address_t * sid_list, srh->length = sr_hdr_len / 8 - 1; srh->type = ROUTING_HEADER_TYPE_SR; srh->segments_left = num_sids - 1; - srh->first_segment = num_sids - 1; + srh->last_entry = num_sids - 1; srh->flags = 0x00; - srh->reserved = 0x00; + srh->tag = 0x0000; /* Fill segment list */ ip6_address_t *this_address; - ip6_address_t *addrp = srh->segments + srh->first_segment; + ip6_address_t *addrp = srh->segments + srh->last_entry; vec_foreach (this_address, sid_list) { *addrp = *this_address; diff --git a/src/vnet/srv6/ietf_draft_05.txt b/src/vnet/srv6/ietf_draft_05.txt deleted file mode 100755 index e9bff04fa0a..00000000000 --- a/src/vnet/srv6/ietf_draft_05.txt +++ /dev/null @@ -1,1564 +0,0 @@ -Network Working Group S. Previdi, Ed. -Internet-Draft C. Filsfils -Intended status: Standards Track Cisco Systems, Inc. -Expires: August 5, 2017 B. Field - Comcast - I. Leung - Rogers Communications - J. Linkova - Google - E. Aries - Facebook - T. Kosugi - NTT - E. Vyncke - Cisco Systems, Inc. - D. Lebrun - Universite Catholique de Louvain - February 1, 2017 - - - IPv6 Segment Routing Header (SRH) - draft-ietf-6man-segment-routing-header-05 - -Abstract - - Segment Routing (SR) allows a node to steer a packet through a - controlled set of instructions, called segments, by prepending an SR - header to the packet. A segment can represent any instruction, - topological or service-based. SR allows to enforce a flow through - any path (topological, or application/service based) while - maintaining per-flow state only at the ingress node to the SR domain. - - Segment Routing can be applied to the IPv6 data plane with the - addition of a new type of Routing Extension Header. This draft - describes the Segment Routing Extension Header Type and how it is - used by SR capable nodes. - -Requirements Language - - The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", - "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this - document are to be interpreted as described in RFC 2119 [RFC2119]. - -Status of This Memo - - This Internet-Draft is submitted in full conformance with the - provisions of BCP 78 and BCP 79. - - - - -Previdi, et al. Expires August 5, 2017 [Page 1] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - - Internet-Drafts are working documents of the Internet Engineering - Task Force (IETF). Note that other groups may also distribute - working documents as Internet-Drafts. The list of current Internet- - Drafts is at http://datatracker.ietf.org/drafts/current/. - - Internet-Drafts are draft documents valid for a maximum of six months - and may be updated, replaced, or obsoleted by other documents at any - time. It is inappropriate to use Internet-Drafts as reference - material or to cite them other than as "work in progress." - - This Internet-Draft will expire on August 5, 2017. - -Copyright Notice - - Copyright (c) 2017 IETF Trust and the persons identified as the - document authors. All rights reserved. - - This document is subject to BCP 78 and the IETF Trust's Legal - Provisions Relating to IETF Documents - (http://trustee.ietf.org/license-info) in effect on the date of - publication of this document. Please review these documents - carefully, as they describe your rights and restrictions with respect - to this document. Code Components extracted from this document must - include Simplified BSD License text as described in Section 4.e of - the Trust Legal Provisions and are provided without warranty as - described in the Simplified BSD License. - -Table of Contents - - 1. Segment Routing Documents . . . . . . . . . . . . . . . . . . 3 - 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 - 2.1. Data Planes supporting Segment Routing . . . . . . . . . 4 - 2.2. Segment Routing (SR) Domain . . . . . . . . . . . . . . . 4 - 2.2.1. SR Domain in a Service Provider Network . . . . . . . 5 - 2.2.2. SR Domain in a Overlay Network . . . . . . . . . . . 6 - 3. Segment Routing Extension Header (SRH) . . . . . . . . . . . 7 - 3.1. SRH TLVs . . . . . . . . . . . . . . . . . . . . . . . . 9 - 3.1.1. Ingress Node TLV . . . . . . . . . . . . . . . . . . 10 - 3.1.2. Egress Node TLV . . . . . . . . . . . . . . . . . . . 11 - 3.1.3. Opaque Container TLV . . . . . . . . . . . . . . . . 11 - 3.1.4. Padding TLV . . . . . . . . . . . . . . . . . . . . . 12 - 3.1.5. HMAC TLV . . . . . . . . . . . . . . . . . . . . . . 13 - 3.2. SRH and RFC2460 behavior . . . . . . . . . . . . . . . . 14 - 4. SRH Procedures . . . . . . . . . . . . . . . . . . . . . . . 14 - 4.1. Source SR Node . . . . . . . . . . . . . . . . . . . . . 14 - 4.2. Transit Node . . . . . . . . . . . . . . . . . . . . . . 15 - 4.3. SR Segment Endpoint Node . . . . . . . . . . . . . . . . 16 - 5. Security Considerations . . . . . . . . . . . . . . . . . . . 16 - - - -Previdi, et al. Expires August 5, 2017 [Page 2] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - - 5.1. Threat model . . . . . . . . . . . . . . . . . . . . . . 17 - 5.1.1. Source routing threats . . . . . . . . . . . . . . . 17 - 5.1.2. Applicability of RFC 5095 to SRH . . . . . . . . . . 17 - 5.1.3. Service stealing threat . . . . . . . . . . . . . . . 18 - 5.1.4. Topology disclosure . . . . . . . . . . . . . . . . . 18 - 5.1.5. ICMP Generation . . . . . . . . . . . . . . . . . . . 18 - 5.2. Security fields in SRH . . . . . . . . . . . . . . . . . 19 - 5.2.1. Selecting a hash algorithm . . . . . . . . . . . . . 20 - 5.2.2. Performance impact of HMAC . . . . . . . . . . . . . 21 - 5.2.3. Pre-shared key management . . . . . . . . . . . . . . 21 - 5.3. Deployment Models . . . . . . . . . . . . . . . . . . . . 22 - 5.3.1. Nodes within the SR domain . . . . . . . . . . . . . 22 - 5.3.2. Nodes outside of the SR domain . . . . . . . . . . . 22 - 5.3.3. SR path exposure . . . . . . . . . . . . . . . . . . 23 - 5.3.4. Impact of BCP-38 . . . . . . . . . . . . . . . . . . 23 - 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24 - 7. Manageability Considerations . . . . . . . . . . . . . . . . 24 - 8. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 24 - 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 24 - 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 25 - 10.1. Normative References . . . . . . . . . . . . . . . . . . 25 - 10.2. Informative References . . . . . . . . . . . . . . . . . 25 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27 - -1. Segment Routing Documents - - Segment Routing terminology is defined in - [I-D.ietf-spring-segment-routing]. - - Segment Routing use cases are described in [RFC7855] and - [I-D.ietf-spring-ipv6-use-cases]. - - Segment Routing protocol extensions are defined in - [I-D.ietf-isis-segment-routing-extensions], and - [I-D.ietf-ospf-ospfv3-segment-routing-extensions]. - -2. Introduction - - Segment Routing (SR), defined in [I-D.ietf-spring-segment-routing], - allows a node to steer a packet through a controlled set of - instructions, called segments, by prepending an SR header to the - packet. A segment can represent any instruction, topological or - service-based. SR allows to enforce a flow through any path - (topological or service/application based) while maintaining per-flow - state only at the ingress node to the SR domain. Segments can be - derived from different components: IGP, BGP, Services, Contexts, - Locators, etc. The list of segment forming the path is called the - Segment List and is encoded in the packet header. - - - -Previdi, et al. Expires August 5, 2017 [Page 3] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - - SR allows the use of strict and loose source based routing paradigms - without requiring any additional signaling protocols in the - infrastructure hence delivering an excellent scalability property. - - The source based routing model described in - [I-D.ietf-spring-segment-routing] is inherited from the ones proposed - by [RFC1940] and [RFC2460]. The source based routing model offers - the support for explicit routing capability. - -2.1. Data Planes supporting Segment Routing - - Segment Routing (SR), can be instantiated over MPLS - ([I-D.ietf-spring-segment-routing-mpls]) and IPv6. This document - defines its instantiation over the IPv6 data-plane based on the use- - cases defined in [I-D.ietf-spring-ipv6-use-cases]. - - This document defines a new type of Routing Header (originally - defined in [RFC2460]) called the Segment Routing Header (SRH) in - order to convey the Segment List in the packet header as defined in - [I-D.ietf-spring-segment-routing]. Mechanisms through which segment - are known and advertised are outside the scope of this document. - - A segment is materialized by an IPv6 address. A segment identifies a - topological instruction or a service instruction. A segment can be - either: - - o global: a global segment represents an instruction supported by - all nodes in the SR domain and it is instantiated through an IPv6 - address globally known in the SR domain. - - o local: a local segment represents an instruction supported only by - the node who originates it and it is instantiated through an IPv6 - address that is known only by the local node. - -2.2. Segment Routing (SR) Domain - - We define the concept of the Segment Routing Domain (SR Domain) as - the set of nodes participating into the source based routing model. - These nodes may be connected to the same physical infrastructure - (e.g.: a Service Provider's network) as well as nodes remotely - connected to each other (e.g.: an enterprise VPN or an overlay). - - A non-exhaustive list of examples of SR Domains is: - - o The network of an operator, service provider, content provider, - enterprise including nodes, links and Autonomous Systems. - - - - - -Previdi, et al. Expires August 5, 2017 [Page 4] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - - o A set of nodes connected as an overlay over one or more transit - providers. The overlay nodes exchange SR-enabled traffic with - segments belonging solely to the overlay routers (the SR domain). - None of the segments in the SR-enabled packets exchanged by the - overlay belong to the transit networks - - The source based routing model through its instantiation of the - Segment Routing Header (SRH) defined in this document equally applies - to all the above examples. - - It is assumed in this document that the SRH is added to the packet by - its source, consistently with the source routing model defined in - [RFC2460]. For example: - - o At the node originating the packet (host, server). - - o At the ingress node of an SR domain where the ingress node - receives an IPv6 packet and encapsulates it into an outer IPv6 - header followed by a Segment Routing header. - -2.2.1. SR Domain in a Service Provider Network - - The following figure illustrates an SR domain consisting of an - operator's network infrastructure. - - (-------------------------- Operator 1 -----------------------) - ( ) - ( (-----AS 1-----) (-------AS 2-------) (----AS 3-------) ) - ( ( ) ( ) ( ) ) - A1--(--(--11---13--14-)--(-21---22---23--24-)--(-31---32---34--)--)--Z1 - ( ( /|\ /|\ /| ) ( |\ /|\ /|\ /| ) ( |\ /|\ /| \ ) ) - A2--(--(/ | \/ | \/ | ) ( | \/ | \/ | \/ | ) ( | \/ | \/ | \)--)--Z2 - ( ( | /\ | /\ | ) ( | /\ | /\ | /\ | ) ( | /\ | /\ | ) ) - ( ( |/ \|/ \| ) ( |/ \|/ \|/ \| ) ( |/ \|/ \| ) ) - A3--(--(--15---17--18-)--(-25---26---27--28-)--(-35---36---38--)--)--Z3 - ( ( ) ( ) ( ) ) - ( (--------------) (------------------) (---------------) ) - ( ) - (-------------------------------------------------------------) - - Figure 1: Service Provider SR Domain - - Figure 1 describes an operator network including several ASes and - delivering connectivity between endpoints. In this scenario, Segment - Routing is used within the operator networks and across the ASes - boundaries (all being under the control of the same operator). In - this case segment routing can be used in order to address use cases - such as end-to-end traffic engineering, fast re-route, egress peer - - - -Previdi, et al. Expires August 5, 2017 [Page 5] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - - engineering, data-center traffic engineering as described in - [RFC7855], [I-D.ietf-spring-ipv6-use-cases] and - [I-D.ietf-spring-resiliency-use-cases]. - - Typically, an IPv6 packet received at ingress (i.e.: from outside the - SR domain), is classified according to network operator policies and - such classification results into an outer header with an SRH applied - to the incoming packet. The SRH contains the list of segment - representing the path the packet must take inside the SR domain. - Thus, the SA of the packet is the ingress node, the DA (due to SRH - procedures described in Section 4) is set as the first segment of the - path and the last segment of the path is the egress node of the SR - domain. - - The path may include intra-AS as well as inter-AS segments. It has - to be noted that all nodes within the SR domain are under control of - the same administration. When the packet reaches the egress point of - the SR domain, the outer header and its SRH are removed so that the - destination of the packet is unaware of the SR domain the packet has - traversed. - - The outer header with the SRH is no different from any other - tunneling encapsulation mechanism and allows a network operator to - implement traffic engineering mechanisms so to efficiently steer - traffic across his infrastructure. - -2.2.2. SR Domain in a Overlay Network - - The following figure illustrates an SR domain consisting of an - overlay network over multiple operator's networks. - - (--Operator 1---) (-----Operator 2-----) (--Operator 3---) - ( ) ( ) ( ) - A1--(--11---13--14--)--(--21---22---23--24--)--(-31---32---34--)--C1 - ( /|\ /|\ /| ) ( |\ /|\ /|\ /| ) ( |\ /|\ /| \ ) - A2--(/ | \/ | \/ | ) ( | \/ | \/ | \/ | ) ( | \/ | \/ | \)--C2 - ( | /\ | /\ | ) ( | /\ | /\ | /\ | ) ( | /\ | /\ | ) - ( |/ \|/ \| ) ( |/ \|/ \|/ \| ) ( |/ \|/ \| ) - A3--(--15---17--18--)--(--25---26---27--28--)--(-35---36---38--)--C3 - ( ) ( | | | ) ( ) - (---------------) (--|----|---------|--) (---------------) - | | | - B1 B2 B3 - - Figure 2: Overlay SR Domain - - - - - - -Previdi, et al. Expires August 5, 2017 [Page 6] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - - Figure 2 describes an overlay consisting of nodes connected to three - different network operators and forming a single overlay network - where Segment routing packets are exchanged. - - The overlay consists of nodes A1, A2, A3, B1, B2, B3, C1, C2 and C3. - These nodes are connected to their respective network operator and - form an overlay network. - - Each node may originate packets with an SRH which contains, in the - segment list of the SRH or in the DA, segments identifying other - overlay nodes. This implies that packets with an SRH may traverse - operator's networks but, obviously, these SRHs cannot contain an - address/segment of the transit operators 1, 2 and 3. The SRH - originated by the overlay can only contain address/segment under the - administration of the overlay (e.g. address/segments supported by A1, - A2, A3, B1, B2, B3, C1,C2 or C3). - - In this model, the operator network nodes are transit nodes and, - according to [RFC2460], MUST NOT inspect the routing extension header - since they are not the DA of the packet. - - It is a common practice in operators networks to filter out, at - ingress, any packet whose DA is the address of an internal node and - it is also possible that an operator would filter out any packet - destined to an internal address and having an extension header in it. - - This common practice does not impact the SR-enabled traffic between - the overlay nodes as the intermediate transit networks never see a - destination address belonging to their infrastructure. These SR- - enabled overlay packets will thus never be filtered by the transit - operators. - - In all cases, transit packets (i.e.: packets whose DA is outside the - domain of the operator's network) will be forwarded accordingly - without introducing any security concern in the operator's network. - This is similar to tunneled packets. - -3. Segment Routing Extension Header (SRH) - - A new type of the Routing Header (originally defined in [RFC2460]) is - defined: the Segment Routing Header (SRH) which has a new Routing - Type, (suggested value 4) to be assigned by IANA. - - The Segment Routing Header (SRH) is defined as follows: - - - - - - - -Previdi, et al. Expires August 5, 2017 [Page 7] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - - 0 1 2 3 - 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 - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Next Header | Hdr Ext Len | Routing Type | Segments Left | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | First Segment | Flags | RESERVED | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | | - | Segment List[0] (128 bits IPv6 address) | - | | - | | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | | - | | - ... - | | - | | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | | - | Segment List[n] (128 bits IPv6 address) | - | | - | | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - // // - // Optional Type Length Value objects (variable) // - // // - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - - where: - - o Next Header: 8-bit selector. Identifies the type of header - immediately following the SRH. - - o Hdr Ext Len: 8-bit unsigned integer, is the length of the SRH - header in 8-octet units, not including the first 8 octets. - - o Routing Type: TBD, to be assigned by IANA (suggested value: 4). - - o Segments Left. Defined in [RFC2460], it contains the index, in - the Segment List, of the next segment to inspect. Segments Left - is decremented at each segment. - - o First Segment: contains the index, in the Segment List, of the - first segment of the path which is in fact the last element of the - Segment List. - - o Flags: 8 bits of flags. Following flags are defined: - - - - -Previdi, et al. Expires August 5, 2017 [Page 8] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - - 0 1 2 3 4 5 6 7 - +-+-+-+-+-+-+-+-+ - |U|P|O|A|H| U | - +-+-+-+-+-+-+-+-+ - - U: Unused and for future use. SHOULD be unset on transmission - and MUST be ignored on receipt. - - P-flag: Protected flag. Set when the packet has been rerouted - through FRR mechanism by an SR endpoint node. - - O-flag: OAM flag. When set, it indicates that this packet is - an operations and management (OAM) packet. - - A-flag: Alert flag. If present, it means important Type Length - Value (TLV) objects are present. See Section 3.1 for details - on TLVs objects. - - H-flag: HMAC flag. If set, the HMAC TLV is present and is - encoded as the last TLV of the SRH. In other words, the last - 36 octets of the SRH represent the HMAC information. See - Section 3.1.5 for details on the HMAC TLV. - - o RESERVED: SHOULD be unset on transmission and MUST be ignored on - receipt. - - o Segment List[n]: 128 bit IPv6 addresses representing the nth - segment in the Segment List. The Segment List is encoded starting - from the last segment of the path. I.e., the first element of the - segment list (Segment List [0]) contains the last segment of the - path while the last segment of the Segment List (Segment List[n]) - contains the first segment of the path. The index contained in - "Segments Left" identifies the current active segment. - - o Type Length Value (TLV) are described in Section 3.1. - -3.1. SRH TLVs - - This section defines TLVs of the Segment Routing Header. - - Type Length Value (TLV) contain optional information that may be used - by the node identified in the DA of the packet. It has to be noted - that the information carried in the TLVs is not intended to be used - by the routing layer. Typically, TLVs carry information that is - consumed by other components (e.g.: OAM) than the routing function. - - Each TLV has its own length, format and semantic. The code-point - allocated (by IANA) to each TLV defines both the format and the - - - -Previdi, et al. Expires August 5, 2017 [Page 9] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - - semantic of the information carried in the TLV. Multiple TLVs may be - encoded in the same SRH. - - The "Length" field of the TLV is primarily used to skip the TLV while - inspecting the SRH in case the node doesn't support or recognize the - TLV codepoint. The "Length" defines the TLV length in octets and not - including the "Type" and "Length" fields. - - The primary scope of TLVs is to give the receiver of the packet - information related to the source routed path (e.g.: where the packet - entered in the SR domain and where it is expected to exit). - - Additional TLVs may be defined in the future. - -3.1.1. Ingress Node TLV - - The Ingress Node TLV is optional and identifies the node this packet - traversed when entered the SR domain. The Ingress Node TLV has - following format: - - 0 1 2 3 - 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 - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Type | Length | RESERVED | Flags | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | | - | Ingress Node (16 octets) | - | | - | | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - - where: - - o Type: to be assigned by IANA (suggested value 1). - - o Length: 18. - - o RESERVED: 8 bits. SHOULD be unset on transmission and MUST be - ignored on receipt. - - o Flags: 8 bits. No flags are defined in this document. - - o Ingress Node: 128 bits. Defines the node where the packet is - expected to enter the SR domain. In the encapsulation case - described in Section 2.2.1, this information corresponds to the SA - of the encapsulating header. - - - - - -Previdi, et al. Expires August 5, 2017 [Page 10] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - -3.1.2. Egress Node TLV - - The Egress Node TLV is optional and identifies the node this packet - is expected to traverse when exiting the SR domain. The Egress Node - TLV has following format: - - 0 1 2 3 - 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 - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Type | Length | RESERVED | Flags | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | | - | Egress Node (16 octets) | - | | - | | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - - where: - - o Type: to be assigned by IANA (suggested value 2). - - o Length: 18. - - o RESERVED: 8 bits. SHOULD be unset on transmission and MUST be - ignored on receipt. - - o Flags: 8 bits. No flags are defined in this document. - - o Egress Node: 128 bits. Defines the node where the packet is - expected to exit the SR domain. In the encapsulation case - described in Section 2.2.1, this information corresponds to the - last segment of the SRH in the encapsulating header. - -3.1.3. Opaque Container TLV - - The Opaque Container TLV is optional and has the following format: - - - - - - - - - - - - - - - -Previdi, et al. Expires August 5, 2017 [Page 11] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - - 0 1 2 3 - 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 - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Type | Length | RESERVED | Flags | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | | - | Opaque Container (16 octets) | - | | - | | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - - where: - - o Type: to be assigned by IANA (suggested value 3). - - o Length: 18. - - o RESERVED: 8 bits. SHOULD be unset on transmission and MUST be - ignored on receipt. - - o Flags: 8 bits. No flags are defined in this document. - - o Opaque Container: 128 bits of opaque data not relevant for the - routing layer. Typically, this information is consumed by a non- - routing component of the node receiving the packet (i.e.: the node - in the DA). - -3.1.4. Padding TLV - - The Padding TLV is optional and with the purpose of aligning the SRH - on a 8 octet boundary. The Padding TLV has the following format: - - 0 1 2 3 - 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 - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Type | Length | Padding (variable) | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - // Padding (variable) // - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - - where: - - o Type: to be assigned by IANA (suggested value 4). - - o Length: 1 to 7 - - - - - - -Previdi, et al. Expires August 5, 2017 [Page 12] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - - o Padding: from 1 to 7 octets of padding. Padding bits have no - semantic. They SHOULD be set to 0 on transmission and MUST be - ignored on receipt. - - The following applies to the Padding TLV: - - o Padding TLV is optional and MAY only appear once in the SRH. If - present, it MUST have a length between 1 and 7 octets. - - o The Padding TLV is used in order to align the SRH total length on - the 8 octet boundary. - - o When present, the Padding TLV MUST appear as the last TLV before - the HMAC TLV (if HMAC TLV is present). - - o When present, the Padding TLV MUST have a length from 1 to 7 in - order to align the SRH total lenght on a 8-octet boundary. - - o When a router inspecting the SRH encounters the Padding TLV, it - MUST assume that no other TLV (other than the HMAC) follow the - Padding TLV. - -3.1.5. HMAC TLV - - HMAC TLV is optional and contains the HMAC information. The HMAC TLV - has the following format: - - 0 1 2 3 - 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 - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | Type | Length | RESERVED | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | HMAC Key ID (4 octets) | - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - | // - | HMAC (32 octets) // - | // - +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - - where: - - o Type: to be assigned by IANA (suggested value 5). - - o Length: 38. - - o RESERVED: 2 octets. SHOULD be unset on transmission and MUST be - ignored on receipt. - - - - -Previdi, et al. Expires August 5, 2017 [Page 13] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - - o HMAC Key ID: 4 octets. - - o HMAC: 32 octets. - - o HMAC and HMAC Key ID usage is described in Section 5 - - The Following applies to the HMAC TLV: - - o When present, the HMAC TLV MUST be encoded as the last TLV of the - SRH. - - o If the HMAC TLV is present, the SRH H-Flag (Figure 4) MUST be set. - - o When the H-flag is set in the SRH, the router inspecting the SRH - MUST find the HMAC TLV in the last 38 octets of the SRH. - -3.2. SRH and RFC2460 behavior - - The SRH being a new type of the Routing Header, it also has the same - properties: - - SHOULD only appear once in the packet. - - Only the router whose address is in the DA field of the packet - header MUST inspect the SRH. - - Therefore, Segment Routing in IPv6 networks implies that the segment - identifier (i.e.: the IPv6 address of the segment) is moved into the - DA of the packet. - - The DA of the packet changes at each segment termination/completion - and therefore the final DA of the packet MUST be encoded as the last - segment of the path. - -4. SRH Procedures - - In this section we describe the different procedures on the SRH. - -4.1. Source SR Node - - A Source SR Node can be any node originating an IPv6 packet with its - IPv6 and Segment Routing Headers. This include either: - - A host originating an IPv6 packet. - - An SR domain ingress router encapsulating a received IPv6 packet - into an outer IPv6 header followed by an SRH. - - - - -Previdi, et al. Expires August 5, 2017 [Page 14] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - - The mechanism through which a Segment List is derived is outside of - the scope of this document. As an example, the Segment List may be - obtained through: - - Local path computation. - - Local configuration. - - Interaction with a centralized controller delivering the path. - - Any other mechanism. - - The following are the steps of the creation of the SRH: - - Next Header and Hdr Ext Len fields are set according to [RFC2460]. - - Routing Type field is set as TBD (to be allocated by IANA, - suggested value 4). - - The Segment List is built with the FIRST segment of the path - encoded in the LAST element of the Segment List. Subsequent - segments are encoded on top of the first segment. Finally, the - LAST segment of the path is encoded in the FIRST element of the - Segment List. In other words, the Segment List is encoded in the - reverse order of the path. - - The final DA of the packet is encoded as the last segment of the - path (encoded in the first element of the Segment List). - - The DA of the packet is set with the value of the first segment - (found in the last element of the segment list). - - The Segments Left field is set to n-1 where n is the number of - elements in the Segment List. - - The First Segment field is set to n-1 where n is the number of - elements in the Segment List. - - The packet is sent out towards the first segment (i.e.: - represented in the packet DA). - - HMAC TLV may be set according to Section 5. - -4.2. Transit Node - - According to [RFC2460], the only node who is allowed to inspect the - Routing Extension Header (and therefore the SRH), is the node - corresponding to the DA of the packet. Any other transit node MUST - - - -Previdi, et al. Expires August 5, 2017 [Page 15] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - - NOT inspect the underneath routing header and MUST forward the packet - towards the DA and according to the IPv6 routing table. - - In the example case described in Section 2.2.2, when SR capable nodes - are connected through an overlay spanning multiple third-party - infrastructure, it is safe to send SRH packets (i.e.: packet having a - Segment Routing Header) between each other overlay/SR-capable nodes - as long as the segment list does not include any of the transit - provider nodes. In addition, as a generic security measure, any - service provider will block any packet destined to one of its - internal routers, especially if these packets have an extended header - in it. - -4.3. SR Segment Endpoint Node - - The SR segment endpoint node is the node whose address is in the DA. - The segment endpoint node inspects the SRH and does: - - 1. IF DA = myself (segment endpoint) - 2. IF Segments Left > 0 THEN - decrement Segments Left - update DA with Segment List[Segments Left] - 3. ELSE continue IPv6 processing of the packet - End of processing. - 4. Forward the packet out - -5. Security Considerations - - This section analyzes the security threat model, the security issues - and proposed solutions related to the new Segment Routing Header. - - The Segment Routing Header (SRH) is simply another type of the - routing header as described in RFC 2460 [RFC2460] and is: - - o Added by an SR edge router when entering the segment routing - domain or by the originating host itself. The source host can - even be outside the SR domain; - - o inspected and acted upon when reaching the destination address of - the IP header per RFC 2460 [RFC2460]. - - Per RFC2460 [RFC2460], routers on the path that simply forward an - IPv6 packet (i.e. the IPv6 destination address is none of theirs) - will never inspect and process the content of the SRH. Routers whose - one interface IPv6 address equals the destination address field of - the IPv6 packet MUST parse the SRH and, if supported and if the local - configuration allows it, MUST act accordingly to the SRH content. - - - - -Previdi, et al. Expires August 5, 2017 [Page 16] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - - According to RFC2460 [RFC2460], the default behavior of a non SR- - capable router upon receipt of an IPv6 packet with SRH destined to an - address of its, is to: - - o ignore the SRH completely if the Segment Left field is 0 and - proceed to process the next header in the IPv6 packet; - - o discard the IPv6 packet if Segment Left field is greater than 0, - it MAY send a Parameter Problem ICMP message back to the Source - Address. - -5.1. Threat model - -5.1.1. Source routing threats - - Using an SRH is similar to source routing, therefore it has some - well-known security issues as described in RFC4942 [RFC4942] section - 2.1.1 and RFC5095 [RFC5095]: - - o amplification attacks: where a packet could be forged in such a - way to cause looping among a set of SR-enabled routers causing - unnecessary traffic, hence a Denial of Service (DoS) against - bandwidth; - - o reflection attack: where a hacker could force an intermediate node - to appear as the immediate attacker, hence hiding the real - attacker from naive forensic; - - o bypass attack: where an intermediate node could be used as a - stepping stone (for example in a De-Militarized Zone) to attack - another host (for example in the datacenter or any back-end - server). - -5.1.2. Applicability of RFC 5095 to SRH - - First of all, the reader must remember this specific part of section - 1 of RFC5095 [RFC5095], "A side effect is that this also eliminates - benign RH0 use-cases; however, such applications may be facilitated - by future Routing Header specifications.". In short, it is not - forbidden to create new secure type of Routing Header; for example, - RFC 6554 (RPL) [RFC6554] also creates a new Routing Header type for a - specific application confined in a single network. - - In the segment routing architecture described in - [I-D.ietf-spring-segment-routing] there are basically two kinds of - nodes (routers and hosts): - - - - - -Previdi, et al. Expires August 5, 2017 [Page 17] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - - o nodes within the SR domain, which is within one single - administrative domain, i.e., where all nodes are trusted anyway - else the damage caused by those nodes could be worse than - amplification attacks: traffic interception, man-in-the-middle - attacks, more server DoS by dropping packets, and so on. - - o nodes outside of the SR domain, which is outside of the - administrative segment routing domain hence they cannot be trusted - because there is no physical security for those nodes, i.e., they - can be replaced by hostile nodes or can be coerced in wrong - behaviors. - - The main use case for SR consists of the single administrative domain - where only trusted nodes with SR enabled and configured participate - in SR: this is the same model as in RFC6554 [RFC6554]. All non- - trusted nodes do not participate as either SR processing is not - enabled by default or because they only process SRH from nodes within - their domain. - - Moreover, all SR nodes ignore SRH created by outsiders based on - topology information (received on a peering or internal interface) or - on presence and validity of the HMAC field. Therefore, if - intermediate nodes ONLY act on valid and authorized SRH (such as - within a single administrative domain), then there is no security - threat similar to RH-0. Hence, the RFC 5095 [RFC5095] attacks are - not applicable. - -5.1.3. Service stealing threat - - Segment routing is used for added value services, there is also a - need to prevent non-participating nodes to use those services; this - is called 'service stealing prevention'. - -5.1.4. Topology disclosure - - The SRH may also contains IPv6 addresses of some intermediate SR- - nodes in the path towards the destination, this obviously reveals - those addresses to the potentially hostile attackers if those - attackers are able to intercept packets containing SRH. On the other - hand, if the attacker can do a traceroute whose probes will be - forwarded along the SR path, then there is little learned by - intercepting the SRH itself. - -5.1.5. ICMP Generation - - Per section 4.4 of RFC2460 [RFC2460], when destination nodes (i.e. - where the destination address is one of theirs) receive a Routing - Header with unsupported Routing Type, the required behavior is: - - - -Previdi, et al. Expires August 5, 2017 [Page 18] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - - o If Segments Left is zero, the node must ignore the Routing header - and proceed to process the next header in the packet. - - o If Segments Left is non-zero, the node must discard the packet and - send an ICMP Parameter Problem, Code 0, message to the packet's - Source Address, pointing to the unrecognized Routing Type. - - This required behavior could be used by an attacker to force the - generation of ICMP message by any node. The attacker could send - packets with SRH (with Segment Left set to 0) destined to a node not - supporting SRH. Per RFC2460 [RFC2460], the destination node could - generate an ICMP message, causing a local CPU utilization and if the - source of the offending packet with SRH was spoofed could lead to a - reflection attack without any amplification. - - It must be noted that this is a required behavior for any unsupported - Routing Type and not limited to SRH packets. So, it is not specific - to SRH and the usual rate limiting for ICMP generation is required - anyway for any IPv6 implementation and has been implemented and - deployed for many years. - -5.2. Security fields in SRH - - This section summarizes the use of specific fields in the SRH. They - are based on a key-hashed message authentication code (HMAC). - - The security-related fields in the SRH are instantiated by the HMAC - TLV, containing: - - o HMAC Key-id, 32 bits wide; - - o HMAC, 256 bits wide (optional, exists only if HMAC Key-id is not - 0). - - The HMAC field is the output of the HMAC computation (per RFC 2104 - [RFC2104]) using a pre-shared key identified by HMAC Key-id and of - the text which consists of the concatenation of: - - o the source IPv6 address; - - o First Segment field; - - o an octet of bit flags; - - o HMAC Key-id; - - o all addresses in the Segment List. - - - - -Previdi, et al. Expires August 5, 2017 [Page 19] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - - The purpose of the HMAC TLV is to verify the validity, the integrity - and the authorization of the SRH itself. If an outsider of the SR - domain does not have access to a current pre-shared secret, then it - cannot compute the right HMAC field and the first SR router on the - path processing the SRH and configured to check the validity of the - HMAC will simply reject the packet. - - The HMAC TLV is located at the end of the SRH simply because only the - router on the ingress of the SR domain needs to process it, then all - other SR nodes can ignore it (based on local policy) because they - trust the upstream router. This is to speed up forwarding operations - because SR routers which do not validate the SRH do not need to parse - the SRH until the end. - - The HMAC Key-id field allows for the simultaneous existence of - several hash algorithms (SHA-256, SHA3-256 ... or future ones) as - well as pre-shared keys. The HMAC Key-id field is opaque, i.e., it - has neither syntax nor semantic except as an index to the right - combination of pre-shared key and hash algorithm and except that a - value of 0 means that there is no HMAC field. Having an HMAC Key-id - field allows for pre-shared key roll-over when two pre-shared keys - are supported for a while when all SR nodes converged to a fresher - pre-shared key. It could also allow for interoperation among - different SR domains if allowed by local policy and assuming a - collision-free HMAC Key Id allocation. - - When a specific SRH is linked to a time-related service (such as - turbo-QoS for a 1-hour period) where the DA, Segment ID (SID) are - identical, then it is important to refresh the shared-secret - frequently as the HMAC validity period expires only when the HMAC - Key-id and its associated shared-secret expires. - -5.2.1. Selecting a hash algorithm - - The HMAC field in the HMAC TLV is 256 bit wide. Therefore, the HMAC - MUST be based on a hash function whose output is at least 256 bits. - If the output of the hash function is 256, then this output is simply - inserted in the HMAC field. If the output of the hash function is - larger than 256 bits, then the output value is truncated to 256 by - taking the least-significant 256 bits and inserting them in the HMAC - field. - - SRH implementations can support multiple hash functions but MUST - implement SHA-2 [FIPS180-4] in its SHA-256 variant. - - NOTE: SHA-1 is currently used by some early implementations used for - quick interoperations testing, the 160-bit hash value must then be - - - - -Previdi, et al. Expires August 5, 2017 [Page 20] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - - right-hand padded with 96 bits set to 0. The authors understand that - this is not secure but is ok for limited tests. - -5.2.2. Performance impact of HMAC - - While adding an HMAC to each and every SR packet increases the - security, it has a performance impact. Nevertheless, it must be - noted that: - - o the HMAC field is used only when SRH is added by a device (such as - a home set-up box) which is outside of the segment routing domain. - If the SRH is added by a router in the trusted segment routing - domain, then, there is no need for an HMAC field, hence no - performance impact. - - o when present, the HMAC field MUST only be checked and validated by - the first router of the segment routing domain, this router is - named 'validating SR router'. Downstream routers may not inspect - the HMAC field. - - o this validating router can also have a cache of <IPv6 header + - SRH, HMAC field value> to improve the performance. It is not the - same use case as in IPsec where HMAC value was unique per packet, - in SRH, the HMAC value is unique per flow. - - o Last point, hash functions such as SHA-2 have been optimized for - security and performance and there are multiple implementations - with good performance. - - With the above points in mind, the performance impact of using HMAC - is minimized. - -5.2.3. Pre-shared key management - - The field HMAC Key-id allows for: - - o key roll-over: when there is a need to change the key (the hash - pre-shared secret), then multiple pre-shared keys can be used - simultaneously. The validating routing can have a table of <HMAC - Key-id, pre-shared secret> for the currently active and future - keys. - - o different algorithms: by extending the previous table to <HMAC - Key-id, hash function, pre-shared secret>, the validating router - can also support simultaneously several hash algorithms (see - section Section 5.2.1) - - The pre-shared secret distribution can be done: - - - -Previdi, et al. Expires August 5, 2017 [Page 21] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - - o in the configuration of the validating routers, either by static - configuration or any SDN oriented approach; - - o dynamically using a trusted key distribution such as [RFC6407] - - The intent of this document is NOT to define yet-another-key- - distribution-protocol. - -5.3. Deployment Models - -5.3.1. Nodes within the SR domain - - An SR domain is defined as a set of interconnected routers where all - routers at the perimeter are configured to add and act on SRH. Some - routers inside the SR domain can also act on SRH or simply forward - IPv6 packets. - - The routers inside an SR domain can be trusted to generate SRH and to - process SRH received on interfaces that are part of the SR domain. - These nodes MUST drop all SRH packets received on an interface that - is not part of the SR domain and containing an SRH whose HMAC field - cannot be validated by local policies. This includes obviously - packet with an SRH generated by a non-cooperative SR domain. - - If the validation fails, then these packets MUST be dropped, ICMP - error messages (parameter problem) SHOULD be generated (but rate - limited) and SHOULD be logged. - -5.3.2. Nodes outside of the SR domain - - Nodes outside of the SR domain cannot be trusted for physical - security; hence, they need to request by some trusted means (outside - of the scope of this document) a complete SRH for each new connection - (i.e. new destination address). The received SRH MUST include an - HMAC TLV which is computed correctly (see Section 5.2). - - When an outside node sends a packet with an SRH and towards an SR - domain ingress node, the packet MUST contain the HMAC TLV (with a - Key-id and HMAC fields) and the the destination address MUST be an - address of an SR domain ingress node . - - The ingress SR router, i.e., the router with an interface address - equals to the destination address, MUST verify the HMAC TLV. - - If the validation is successful, then the packet is simply forwarded - as usual for an SR packet. As long as the packet travels within the - SR domain, no further HMAC check needs to be done. Subsequent - - - - -Previdi, et al. Expires August 5, 2017 [Page 22] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - - routers in the SR domain MAY verify the HMAC TLV when they process - the SRH (i.e. when they are the destination). - - If the validation fails, then this packet MUST be dropped, an ICMP - error message (parameter problem) SHOULD be generated (but rate - limited) and SHOULD be logged. - -5.3.3. SR path exposure - - As the intermediate SR nodes addresses appears in the SRH, if this - SRH is visible to an outsider then he/she could reuse this knowledge - to launch an attack on the intermediate SR nodes or get some insider - knowledge on the topology. This is especially applicable when the - path between the source node and the first SR domain ingress router - is on the public Internet. - - The first remark is to state that 'security by obscurity' is never - enough; in other words, the security policy of the SR domain MUST - assume that the internal topology and addressing is known by the - attacker. A simple traceroute will also give the same information - (with even more information as all intermediate nodes between SID - will also be exposed). IPsec Encapsulating Security Payload - [RFC4303] cannot be use to protect the SRH as per RFC4303 the ESP - header must appear after any routing header (including SRH). - - To prevent a user to leverage the gained knowledge by intercepting - SRH, it it recommended to apply an infrastructure Access Control List - (iACL) at the edge of the SR domain. This iACL will drop all packets - from outside the SR-domain whose destination is any address of any - router inside the domain. This security policy should be tuned for - local operations. - -5.3.4. Impact of BCP-38 - - BCP-38 [RFC2827], also known as "Network Ingress Filtering", checks - whether the source address of packets received on an interface is - valid for this interface. The use of loose source routing such as - SRH forces packets to follow a path which differs from the expected - routing. Therefore, if BCP-38 was implemented in all routers inside - the SR domain, then SR packets could be received by an interface - which is not expected one and the packets could be dropped. - - As an SR domain is usually a subset of one administrative domain, and - as BCP-38 is only deployed at the ingress routers of this - administrative domain and as packets arriving at those ingress - routers have been normally forwarded using the normal routing - information, then there is no reason why this ingress router should - - - - -Previdi, et al. Expires August 5, 2017 [Page 23] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - - drop the SRH packet based on BCP-38. Routers inside the domain - commonly do not apply BCP-38; so, this is not a problem. - -6. IANA Considerations - - This document makes the following registrations in the Internet - Protocol Version 6 (IPv6) Parameters "Routing Type" registry - maintained by IANA: - - Suggested Description Reference - Value - ---------------------------------------------------------- - 4 Segment Routing Header (SRH) This document - - In addition, this document request IANA to create and maintain a new - Registry: "Segment Routing Header Type-Value Objects". The following - code-points are requested from the registry: - - Registry: Segment Routing Header Type-Value Objects - - Suggested Description Reference - Value - ----------------------------------------------------- - 1 Ingress Node TLV This document - 2 Egress Node TLV This document - 3 Opaque Container TLV This document - 4 Padding TLV This document - 5 HMAC TLV This document - -7. Manageability Considerations - - TBD - -8. Contributors - - Dave Barach, John Leddy, John Brzozowski, Pierre Francois, Nagendra - Kumar, Mark Townsley, Christian Martin, Roberta Maglione, James - Connolly, Aloys Augustin contributed to the content of this document. - -9. Acknowledgements - - The authors would like to thank Ole Troan, Bob Hinden, Fred Baker, - Brian Carpenter, Alexandru Petrescu and Punit Kumar Jaiswal for their - comments to this document. - - - - - - - -Previdi, et al. Expires August 5, 2017 [Page 24] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - -10. References - -10.1. Normative References - - [FIPS180-4] - National Institute of Standards and Technology, "FIPS - 180-4 Secure Hash Standard (SHS)", March 2012, - <http://csrc.nist.gov/publications/fips/fips180-4/ - fips-180-4.pdf>. - - [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate - Requirement Levels", BCP 14, RFC 2119, - DOI 10.17487/RFC2119, March 1997, - <http://www.rfc-editor.org/info/rfc2119>. - - [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 - (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460, - December 1998, <http://www.rfc-editor.org/info/rfc2460>. - - [RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)", - RFC 4303, DOI 10.17487/RFC4303, December 2005, - <http://www.rfc-editor.org/info/rfc4303>. - - [RFC5095] Abley, J., Savola, P., and G. Neville-Neil, "Deprecation - of Type 0 Routing Headers in IPv6", RFC 5095, - DOI 10.17487/RFC5095, December 2007, - <http://www.rfc-editor.org/info/rfc5095>. - - [RFC6407] Weis, B., Rowles, S., and T. Hardjono, "The Group Domain - of Interpretation", RFC 6407, DOI 10.17487/RFC6407, - October 2011, <http://www.rfc-editor.org/info/rfc6407>. - -10.2. Informative References - - [I-D.ietf-isis-segment-routing-extensions] - Previdi, S., Filsfils, C., Bashandy, A., Gredler, H., - Litkowski, S., Decraene, B., and j. jefftant@gmail.com, - "IS-IS Extensions for Segment Routing", draft-ietf-isis- - segment-routing-extensions-09 (work in progress), October - 2016. - - [I-D.ietf-ospf-ospfv3-segment-routing-extensions] - Psenak, P., Previdi, S., Filsfils, C., Gredler, H., - Shakir, R., Henderickx, W., and J. Tantsura, "OSPFv3 - Extensions for Segment Routing", draft-ietf-ospf-ospfv3- - segment-routing-extensions-07 (work in progress), October - 2016. - - - - -Previdi, et al. Expires August 5, 2017 [Page 25] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - - [I-D.ietf-spring-ipv6-use-cases] - Brzozowski, J., Leddy, J., Townsley, W., Filsfils, C., and - R. Maglione, "IPv6 SPRING Use Cases", draft-ietf-spring- - ipv6-use-cases-08 (work in progress), January 2017. - - [I-D.ietf-spring-resiliency-use-cases] - Filsfils, C., Previdi, S., Decraene, B., and R. Shakir, - "Resiliency use cases in SPRING networks", draft-ietf- - spring-resiliency-use-cases-08 (work in progress), October - 2016. - - [I-D.ietf-spring-segment-routing] - Filsfils, C., Previdi, S., Decraene, B., Litkowski, S., - and R. Shakir, "Segment Routing Architecture", draft-ietf- - spring-segment-routing-10 (work in progress), November - 2016. - - [I-D.ietf-spring-segment-routing-mpls] - Filsfils, C., Previdi, S., Bashandy, A., Decraene, B., - Litkowski, S., Horneffer, M., Shakir, R., - jefftant@gmail.com, j., and E. Crabbe, "Segment Routing - with MPLS data plane", draft-ietf-spring-segment-routing- - mpls-06 (work in progress), January 2017. - - [RFC1940] Estrin, D., Li, T., Rekhter, Y., Varadhan, K., and D. - Zappala, "Source Demand Routing: Packet Format and - Forwarding Specification (Version 1)", RFC 1940, - DOI 10.17487/RFC1940, May 1996, - <http://www.rfc-editor.org/info/rfc1940>. - - [RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed- - Hashing for Message Authentication", RFC 2104, - DOI 10.17487/RFC2104, February 1997, - <http://www.rfc-editor.org/info/rfc2104>. - - [RFC2827] Ferguson, P. and D. Senie, "Network Ingress Filtering: - Defeating Denial of Service Attacks which employ IP Source - Address Spoofing", BCP 38, RFC 2827, DOI 10.17487/RFC2827, - May 2000, <http://www.rfc-editor.org/info/rfc2827>. - - [RFC4942] Davies, E., Krishnan, S., and P. Savola, "IPv6 Transition/ - Co-existence Security Considerations", RFC 4942, - DOI 10.17487/RFC4942, September 2007, - <http://www.rfc-editor.org/info/rfc4942>. - - - - - - - -Previdi, et al. Expires August 5, 2017 [Page 26] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - - [RFC6554] Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6 - Routing Header for Source Routes with the Routing Protocol - for Low-Power and Lossy Networks (RPL)", RFC 6554, - DOI 10.17487/RFC6554, March 2012, - <http://www.rfc-editor.org/info/rfc6554>. - - [RFC7855] Previdi, S., Ed., Filsfils, C., Ed., Decraene, B., - Litkowski, S., Horneffer, M., and R. Shakir, "Source - Packet Routing in Networking (SPRING) Problem Statement - and Requirements", RFC 7855, DOI 10.17487/RFC7855, May - 2016, <http://www.rfc-editor.org/info/rfc7855>. - -Authors' Addresses - - Stefano Previdi (editor) - Cisco Systems, Inc. - Via Del Serafico, 200 - Rome 00142 - Italy - - Email: sprevidi@cisco.com - - - Clarence Filsfils - Cisco Systems, Inc. - Brussels - BE - - Email: cfilsfil@cisco.com - - - Brian Field - Comcast - 4100 East Dry Creek Road - Centennial, CO 80122 - US - - Email: Brian_Field@cable.comcast.com - - - Ida Leung - Rogers Communications - 8200 Dixie Road - Brampton, ON L6T 0C1 - CA - - Email: Ida.Leung@rci.rogers.com - - - - -Previdi, et al. Expires August 5, 2017 [Page 27] - -Internet-Draft IPv6 Segment Routing Header (SRH) February 2017 - - - Jen Linkova - Google - 1600 Amphitheatre Parkway - Mountain View, CA 94043 - US - - Email: furry@google.com - - - Ebben Aries - Facebook - US - - Email: exa@fb.com - - - Tomoya Kosugi - NTT - 3-9-11, Midori-Cho Musashino-Shi, - Tokyo 180-8585 - JP - - Email: kosugi.tomoya@lab.ntt.co.jp - - - Eric Vyncke - Cisco Systems, Inc. - De Kleetlaann 6A - Diegem 1831 - Belgium - - Email: evyncke@cisco.com - - - David Lebrun - Universite Catholique de Louvain - Place Ste Barbe, 2 - Louvain-la-Neuve, 1348 - Belgium - - Email: david.lebrun@uclouvain.be - - - - - - - - - - -Previdi, et al. Expires August 5, 2017 [Page 28]
\ No newline at end of file diff --git a/src/vnet/srv6/sr.h b/src/vnet/srv6/sr.h index 2353b284363..9ca0348cb87 100755 --- a/src/vnet/srv6/sr.h +++ b/src/vnet/srv6/sr.h @@ -302,11 +302,11 @@ ip6_sr_compute_rewrite_string_insert (ip6_address_t * sl) srh = (ip6_sr_header_t *) rs; srh->type = ROUTING_HEADER_TYPE_SR; srh->segments_left = vec_len (sl); - srh->first_segment = vec_len (sl); + srh->last_entry = vec_len (sl); srh->length = ((sizeof (ip6_sr_header_t) + ((vec_len (sl) + 1) * sizeof (ip6_address_t))) / 8) - 1; srh->flags = 0x00; - srh->reserved = 0x0000; + srh->tag = 0x0000; addrp = srh->segments + vec_len (sl); vec_foreach (this_address, sl) { diff --git a/src/vnet/srv6/sr_packet.h b/src/vnet/srv6/sr_packet.h index 7af4ad4d9c0..d2fb0898530 100755 --- a/src/vnet/srv6/sr_packet.h +++ b/src/vnet/srv6/sr_packet.h @@ -28,7 +28,7 @@ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | Next Header | Hdr Ext Len | Routing Type | Segments Left | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - * | First Segment | Flags | RESERVED | + * | Last Entry | Flags | Tag | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | | * | Segment List[0] (128 bits IPv6 address) | @@ -61,13 +61,12 @@ * * o Routing Type: TBD, to be assigned by IANA (suggested value: 4). * - * o Segments Left. Defined in [RFC2460], it contains the index, in + * o Segments Left. Defined in [RFC8200], it contains the index, in * the Segment List, of the next segment to inspect. Segments Left * is decremented at each segment. * - * o First Segment: contains the index, in the Segment List, of the - * first segment of the path which is in fact the last element of the - * Segment List. + * o Last Entry: contains the index (zero based), in the Segment List, + * of the the last element of the Segment List * * o Flags: 8 bits of flags. Following flags are defined: * @@ -94,8 +93,10 @@ * 36 octets of the SRH represent the HMAC information. See * Section 3.1.5 for details on the HMAC TLV. * - * o RESERVED: SHOULD be unset on transmission and MUST be ignored on - * receipt. + * o Tag: tag a packet as part of a class or group of packets, e.g., + * packets sharing the same set of properties. When tag is not used + * at source it MUST be set to zero on transmission. When tag is not + * used during SRH Processing it SHOULD be ignored. * * o Segment List[n]: 128 bit IPv6 addresses representing the nth * segment in the Segment List. The Segment List is encoded starting @@ -132,7 +133,7 @@ typedef struct u8 segments_left; /* Pointer to the first segment in the header */ - u8 first_segment; + u8 last_entry; /* Flag bits */ #define IP6_SR_HEADER_FLAG_PROTECTED (0x40) @@ -142,7 +143,7 @@ typedef struct /* values 0x0, 0x4 - 0x7 are reserved */ u8 flags; - u16 reserved; + u16 tag; /* The segment elts */ ip6_address_t segments[0]; diff --git a/src/vnet/srv6/sr_policy_rewrite.c b/src/vnet/srv6/sr_policy_rewrite.c index e9c42211209..aa2f0670c51 100755 --- a/src/vnet/srv6/sr_policy_rewrite.c +++ b/src/vnet/srv6/sr_policy_rewrite.c @@ -184,11 +184,11 @@ compute_rewrite_encaps (ip6_address_t * sl) srh->protocol = IP_PROTOCOL_IPV6; srh->type = ROUTING_HEADER_TYPE_SR; srh->segments_left = vec_len (sl) - 1; - srh->first_segment = vec_len (sl) - 1; + srh->last_entry = vec_len (sl) - 1; srh->length = ((sizeof (ip6_sr_header_t) + (vec_len (sl) * sizeof (ip6_address_t))) / 8) - 1; srh->flags = 0x00; - srh->reserved = 0x00; + srh->tag = 0x0000; addrp = srh->segments + vec_len (sl) - 1; vec_foreach (this_address, sl) { @@ -226,11 +226,11 @@ compute_rewrite_insert (ip6_address_t * sl) srh = (ip6_sr_header_t *) rs; srh->type = ROUTING_HEADER_TYPE_SR; srh->segments_left = vec_len (sl); - srh->first_segment = vec_len (sl); + srh->last_entry = vec_len (sl); srh->length = ((sizeof (ip6_sr_header_t) + ((vec_len (sl) + 1) * sizeof (ip6_address_t))) / 8) - 1; srh->flags = 0x00; - srh->reserved = 0x0000; + srh->tag = 0x0000; addrp = srh->segments + vec_len (sl); vec_foreach (this_address, sl) { @@ -265,11 +265,11 @@ compute_rewrite_bsid (ip6_address_t * sl) srh = (ip6_sr_header_t *) rs; srh->type = ROUTING_HEADER_TYPE_SR; srh->segments_left = vec_len (sl) - 1; - srh->first_segment = vec_len (sl) - 1; + srh->last_entry = vec_len (sl) - 1; srh->length = ((sizeof (ip6_sr_header_t) + (vec_len (sl) * sizeof (ip6_address_t))) / 8) - 1; srh->flags = 0x00; - srh->reserved = 0x0000; + srh->tag = 0x0000; addrp = srh->segments + vec_len (sl) - 1; vec_foreach (this_address, sl) { |