| SPRING | C. Filsfils, Ed. |
| Internet-Draft | P. Camarillo, Ed. |
| Intended status: Standards Track | Cisco Systems, Inc. |
| Expires: February 28, 2021 | J. Leddy |
| Individual Contributor | |
| D. Voyer | |
| Bell Canada | |
| S. Matsushima | |
| SoftBank | |
| Z. Li | |
| Huawei Technologies | |
| August 27, 2020 |
SRv6 Network Programming
draft-ietf-spring-srv6-network-programming-18
The SRv6 Network Programming framework enables a network operator or an application to specify a packet processing program by encoding a sequence of instructions in the IPv6 packet header.
Each instruction is implemented on one or several nodes in the network and identified by an SRv6 Segment Identifier in the packet.
This document defines the SRv6 Network Programming concept and specifies the base set of SRv6 behaviors that enables the creation of interoperable overlays with underlay optimization (Service Level Agreements).
This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.
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 https://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 February 28, 2021.
Copyright (c) 2020 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 (https://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.
Segment Routing [RFC8402] leverages the source routing paradigm. An ingress node steers a packet through an ordered list of instructions, called segments. Each one of these instructions represents a function to be called at a specific location in the network. A function is locally defined on the node where it is executed and may range from simply moving forward in the Segment List to any complex user-defined behavior. Network programming combines segment routing functions, both simple and complex, to achieve a networking objective that goes beyond mere packet routing.
This document defines the SRv6 Network Programming concept and specifies the main segment routing behaviors to enable the creation of interoperable overlays with underlay optimization (Service Level Agreement).
The companion document [I-D.filsfils-spring-srv6-net-pgm-illustration] illustrates the concepts defined in this document.
Familiarity with the Segment Routing Header is expected.
The following terms used within this document are defined in [RFC8402]: Segment Routing, SR Domain, Segment ID (SID), SRv6, SRv6 SID, SR Policy, Prefix SID and Adjacency SID.
The following terms used within this document are defined in [RFC8754]: SRH, SR Source Node, Transit Node, SR Segment Endpoint Node and Reduced SRH.
NH: Next-header field of the IPv6 header [RFC8200]. NH=SRH means that the next-header of the IPv6 header is Routing Header for IPv6(43) with the Type field set to 4.
SL: The Segments Left field of the SRH
FIB: Forwarding Information Base. A FIB lookup is a lookup in the forwarding table.
SA: Source Address
DA: Destination Address
SRv6 SID function: The function part of the SID is an opaque identification of a local behavior bound to the SID. It is formally defined in Section 3.1 of this document.
SRv6 Segment Endpoint behavior: A packet processing behavior executed at an SRv6 Segment Endpoint Node. Section 4 of this document defines SRv6 Segment Endpoint behaviors related to traffic-engineering and overlay use-cases. Other behaviors (e.g. service programming) are outside the scope of this document.
An SR Policy is resolved to a SID list. A SID list is represented as <S1, S2, S3> where S1 is the first SID to visit, S2 is the second SID to visit and S3 is the last SID to visit along the SR path.
(SA,DA) (S3, S2, S1; SL) represents an IPv6 packet with:
SRH[n]: A shorter representation of Segment List[n], as defined in [RFC8754].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.
RFC8402 defines an SRv6 Segment Identifier as an IPv6 address explicitly associated with the segment.
When an SRv6 SID is in the Destination Address field of an IPv6 header of a packet, it is routed through an IPv6 network as an IPv6 address.
Its processing is defined in [RFC8754] section 4.3 and reproduced here as a reminder.
This document formally defines behaviors and parameters for SRv6 SIDs.
This document defines an SRv6 SID as consisting of LOC:FUNCT:ARG, where a locator (LOC) is encoded in the L most significant bits of the SID, followed by F bits of function (FUNCT) and A bits of arguments (ARG). L, the locator length, is flexible, and an operator is free to use the locator length of their choice. F and A may be any value as long as L+F+A <= 128. When L+F+A is less than 128 then the remainder of the SID MUST be zero.
A locator may be represented as B:N where B is the SRv6 SID block (IPv6 subnet allocated for SRv6 SIDs by the operator) and N is the identifier of the parent node instantiating the SID.
When the LOC part of the SRv6 SIDs is routable, it leads to the node which instantiates the SID.
The FUNCT is an opaque identification of a local behavior bound to the SID.
The term "function" refers to the bit-string in the SRv6 SID. The term "behavior" identifies the behavior bound to the SID. The behaviors are defined in Section 4 of this document.
An SRv6 endpoint behavior MAY require additional information for its processing (e.g. related to the flow or service). This information may be encoded in the ARG bits of the SID.
In such a case, the semantics and format of the ARG bits are defined as part of the SRv6 endpoint behavior specification.
The ARG value of a routed SID SHOULD remain constant among packets in a given flow. Varying ARG values among packets in a flow may result in different ECMP hashing and cause re-ordering.
Locators are assigned consistent with IPv6 infrastructure allocation. For example, an network operator may:
As an example, one mobile service provider has commercially deployed SRv6 across more than 1000 commercial routers and 1800 whitebox routers. All these devices are enabled for SRv6 and advertise SRv6 SID's. The provider historically deployed IPv6 and assigned infrastructure address from a portion of the fc00::/7 prefix. They further subdivided the prefix into three /48 prefixes (Country X, Country Y, Country Z) to support their SRv6 infrastructure. From those /48 prefixes each router is assigned a /64 prefix from which all SIDs of that router are allocated.
In another example, a large mobile and fixed line service provider has commercially deployed SRv6 in their country-wide network. This provider is assigned a /20 prefix by a RIR. They sub-allocated a few /48 prefixes to their infrastructure to deploy SRv6. Each router is assigned a /64 prefix from which all SIDs of that router are allocated.
IPv6 address consumption in both these examples is minimum, representing one billionth and one millionth of the assigned address space respectively.
A service provider receiving the current minimum allocation of a /32 from a RIR may assign a /48 prefix to their infrastructure deploying SRv6, and subsequently allocate /64 prefixes for SIDs at each SRv6 node. The /48 assignment is one sixty five thousandth (1/2^16) of the usable IPv6 address space available for assignment by the provider.
When an operator instantiates a SID at a node, they specify a SID value B:N:FUNCT and the behavior bound to the SID using one of the IANA codepoints of the registry of SRv6 Endpoint Behaviors defined in this document.
The node advertises the SID, B:N:FUNCT, in the control-plane (see Section 8) together with the IANA Endpoint Behavior codepoint (see Table 4) identifying the behavior of the SID.
A remote node uses the IANA behavior codepoint to map the received SID (B:N:FUNCT) to a behavior.
A remote node selects a desired behavior at an advertising node by selecting the SID (B:N:FUNCT) advertised with the desired behavior.
A remote node cannot infer the behavior by examination of the FUNCT value of a SID.
Therefore the IANA Endpoint Behavior codepoint is advertised along with the SID in the control plane.
As an example, a network operator may:
Most often, the node N would advertise IPv6 prefix(es) matching the LOC parts covering its SIDs or shorter-mask prefix. The distribution of these advertisements and calculation of their reachability are routing protocol specific aspects that are outside the scope of this document.
An SRv6 SID is said to be routed if its SID belongs to an IPv6 prefix advertised via a routing protocol. An SRv6 SID that does not fulfill this condition is non-routed.
Let's provide a classic illustration:
Node N is configured explicitly with two SIDs: 2001:DB8:B:1:100:: and 2001:DB8:B:2:101::.
The network learns about a path to 2001:DB8:B:1::/64 via the IGP and hence a packet destined to 2001:DB8:B:1:100:: would be routed up to N. The network does not learn about a path to 2001:DB8:B:2::/64 via the IGP and hence a packet destined to 2001:DB8:B:2:101:: would not be routed up to N.
A packet could be steered to a non-routed SID 2001:DB8:B:2:101:: by using a SID list <...,2001:DB8:B:1:100::,2001:DB8:B:2:101::,...> where the non-routed SID is preceded by a routed SID to the same node. Routed and non-routed SRv6 SIDs are the SRv6 instantiation of global and local segments, respectively [RFC8402].
Each FIB entry indicates the behavior associated with a SID instance and its parameters.
This document defines a new set of behaviors in addition to that defined in RFC8754 Section 4.3.1.
Following is a set of well-known behaviors that can be associated with a SID.
End Endpoint function
The SRv6 instantiation of a prefix SID [RFC8402]
End.X Endpoint with Layer-3 cross-connect
The SRv6 instantiation of a Adj SID [RFC8402]
End.T Endpoint with specific IPv6 table lookup
End.DX6 Endpoint with decapsulation and IPv6 cross-connect
e.g. IPv6-L3VPN (equivalent to per-CE VPN label)
End.DX4 Endpoint with decaps and IPv4 cross-connect
e.g. IPv4-L3VPN (equivalent to per-CE VPN label)
End.DT6 Endpoint with decapsulation and IPv6 table lookup
e.g. IPv6-L3VPN (equivalent to per-VRF VPN label)
End.DT4 Endpoint with decapsulation and IPv4 table lookup
e.g. IPv4-L3VPN (equivalent to per-VRF VPN label)
End.DT46 Endpoint with decapsulation and IP table lookup
e.g. IP-L3VPN (equivalent to per-VRF VPN label)
End.DX2 Endpoint with decapsulation and L2 cross-connect
e.g. L2VPN use-case
End.DX2V Endpoint with decaps and VLAN L2 table lookup
e.g. EVPN Flexible cross-connect use-case
End.DT2U Endpoint with decaps and unicast MAC L2table lookup
e.g. EVPN Bridging unicast use-case
End.DT2M Endpoint with decapsulation and L2 table flooding
e.g. EVPN Bridging BUM use-case with ESI filtering
End.B6.Encaps Endpoint bound to an SRv6 policy with encapsulation
SRv6 instantiation of a Binding SID
End.B6.Encaps.RED End.B6.Encaps with reduced SRH
SRv6 instantiation of a Binding SID
End.BM Endpoint bound to an SR-MPLS Policy
SRv6 instantiation of an SR-MPLS Binding SID
The list is not exhaustive. In practice, any function can be attached to a local SID: e.g. a node N can bind a SID to a local VM or container which can apply any complex processing on the packet.
The following sub-sections detail the behaviors, introduced in this document, that a node (N) binds to a SID (S).
The pseudocode describing these behaviors detail local processing at a node. An implementation of the pseudocode is compliant as long as the externally observable wire protocol is as described by the pseudocode.
Section 4.16 defines flavors of some of these behaviors.
The Endpoint behavior ("End" for short) is the most basic behavior. It is the instantiation of a Prefix-SID [RFC8402].
When N receives a packet whose IPv6 DA is S and S is a local End SID, N does:
S01. When an SRH is processed {
S02. If (Segments Left == 0) {
S03. Proceed to process the next header in the packet,
whose type is identified by the Next Header field in
the routing header.
S04. }
S05. If (IPv6 Hop Limit <= 1) {
S06. Send an ICMP Time Exceeded message to the Source Address,
Code 0 (Hop limit exceeded in transit),
Interrupt packet processing and discard the packet.
S07. }
S08. max_LE = (Hdr Ext Len / 2) - 1
S09. If ((Last Entry > max_LE) or (Segments Left > Last Entry+1)) {
S10. Send an ICMP Parameter Problem to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field.
Interrupt packet processing and discard the packet.
S11. }
S12. Decrement Hop Limit by 1
S13. Decrement Segments Left by 1
S14. Update IPv6 DA with Segment List[Segments Left]
S15. Submit the packet to the egress IPv6 FIB lookup and
transmission to the new destination
S16. }
Notes:
The End behavior operates on the same FIB table (i.e. VRF, L3 relay id) associated to the packet. Hence the FIB lookup on line S15 is done in the same FIB table as the ingress interface.
When processing the Upper-layer Header of a packet matching a FIB entry locally instantiated as an SRv6 End SID, if Upper-layer Header processing is allowed by local configuration (e.g. ICMPv6), then process the upper-layer header. Otherwise, send an ICMP parameter problem message to the Source Address and discard the packet. Error code 4 (SR Upper-layer Header Error) and Pointer set to the offset of the upper-layer header.
The "Endpoint with cross-connect to an array of layer-3 adjacencies" behavior (End.X for short) is a variant of the End behavior.
It is the SRv6 instantiation of an Adjacency-SID [RFC8402] and it is required to express any traffic-engineering policy.
Any SID instance of this behavior is associated with a set, J, of one or more Layer-3 adjacencies.
When N receives a packet destined to S and S is a local End.X SID, the line S15 from the End processing is replaced by the following:
S15. Submit the packet to the IPv6 module for transmission
to the new destination via a member of J
Notes:
S15. If the set J contains several L3 adjacencies, then one element of the set is selected based on a hash of the packet's header Section 6.2.
If a node N has 30 outgoing interfaces to 30 neighbors, usually the operator would explicitly instantiate 30 End.X SIDs at N: one per layer-3 adjacency to a neighbor. Potentially, more End.X could be explicitly defined (groups of layer-3 adjacencies to the same neighbor or to different neighbors).
Note that if N has an outgoing interface bundle I to a neighbor Q made of 10 member links, N may allocate up to 11 End.X local SIDs: one for the bundle(LAG) itself and then up to one for each Layer-2 member link.
When the End.X behavior is associated with a BGP Next-Hop, it is the SRv6 instantiation of the BGP Peering Segments [RFC8402].
The "Endpoint with specific IPv6 table lookup" behavior (End.T for short) is a variant of the End behavior.
The End.T behavior is used for multi-table operation in the core. For this reason, an instance of the End.T behavior is associated with an IPv6 FIB table T.
When N receives a packet destined to S and S is a local End.T SID, the line S15 from the End processing is replaced by the following:
S15.1. Set the packet's associated FIB table to T
S15.2. Submit the packet to the egress IPv6 FIB lookup and
transmission to the new destination
The "Endpoint with decapsulation and cross-connect to an array of IPv6 adjacencies" behavior (End.DX6 for short) is a variant of the End.X behavior.
One of the applications of the End.DX6 behavior is the L3VPNv6 use-case where a FIB lookup in a specific tenant table at the egress Provider Edge (PE) is not required. This is equivalent to the per-CE VPN label in MPLS [RFC4364].
The End.DX6 SID MUST be the last segment in a SR Policy, and it is associated with one or more L3 IPv6 adjacencies J.
When N receives a packet destined to S and S is a local End.DX6 SID, N does the following processing:
S01. When an SRH is processed {
S02. If (Segments Left != 0) {
S03. Send an ICMP Parameter Problem to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field.
Interrupt packet processing and discard the packet.
S04. }
S05. Proceed to process the next header in the packet
S06. }
When processing the Upper-layer header of a packet matching a FIB entry locally instantiated as an SRv6 End.DX6 SID, the following is done:
S01. If (Upper-Layer Header type != 41) {
S02. Process as per Section 4.1.1
S03. }
S04. Remove the outer IPv6 Header with all its extension headers
S05. Forward the exposed IPv6 packet to the L3 adjacency J
Notes:
S01. 41 refers to IPv6 encapsulation as defined by IANA allocation for Internet Protocol Numbers.
S05. If the End.DX6 SID is bound to an array of L3 adjacencies, then one entry of the array is selected based on the hash of the packet's header Section 6.2.
The "Endpoint with decapsulation and cross-connect to an array of IPv4 adjacencies" behavior (End.DX4 for short) is a variant of the End.X behavior.
One of the applications of the End.DX4 behavior is the L3VPNv4 use-case where a FIB lookup in a specific tenant table at the egress PE is not required. This is equivalent to the per-CE VPN label in MPLS [RFC4364].
The End.DX4 SID MUST be the last segment in a SR Policy, and it is associated with one or more L3 IPv4 adjacencies J.
When N receives a packet destined to S and S is a local End.DX4 SID, N does the following processing:
S01. When an SRH is processed {
S02. If (Segments Left != 0) {
S03. Send an ICMP Parameter Problem to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field.
Interrupt packet processing and discard the packet.
S04. }
S05. Proceed to process the next header in the packet
S06. }
When processing the Upper-layer header of a packet matching a FIB entry locally instantiated as an SRv6 End.DX4 SID, the following is done:
S01. If (Upper-Layer Header type != 4) {
S02. Process as per Section 4.1.1
S03. }
S04. Remove the outer IPv6 Header with all its extension headers
S05. Forward the exposed IPv4 packet to the L3 adjacency J
Notes:
S01. 4 refers to IPv4 encapsulation as defined by IANA allocation for Internet Protocol Numbers
S05. If the End.DX4 SID is bound to an array of L3 adjacencies, then one entry of the array is selected based on the hash of the packet's header Section 6.2.
The "Endpoint with decapsulation and specific IPv6 table lookup" behavior (End.DT6 for short) is a variant of the End.T behavior.
One of the applications of the End.DT6 behavior is the L3VPNv6 use-case where a FIB lookup in a specific tenant table at the egress PE is required. This is equivalent to the per-VRF VPN label in MPLS [RFC4364].
Note that an End.DT6 may be defined for the main IPv6 table in which case and End.DT6 supports the equivalent of an IPv6inIPv6 decapsulation (without VPN/tenant implication).
The End.DT6 SID MUST be the last segment in a SR Policy, and a SID instance is associated with an IPv6 FIB table T.
When N receives a packet destined to S and S is a local End.DT6 SID, N does the following processing:
S01. When an SRH is processed {
S02. If (Segments Left != 0) {
S03. Send an ICMP Parameter Problem to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field.
Interrupt packet processing and discard the packet.
S04. }
S05. Proceed to process the next header in the packet
S06. }
When processing the Upper-layer header of a packet matching a FIB entry locally instantiated as an SRv6 End.DT6 SID, N does the following:
S01. If (Upper-Layer Header type != 41) {
S02. Process as per Section 4.1.1
S03. }
S04. Remove the outer IPv6 Header with all its extension headers
S05. Set the packet's associated FIB table to T
S06. Submit the packet to the egress IPv6 FIB lookup and
transmission to the new destination
The "Endpoint with decapsulation and specific IPv4 table lookup" behavior (End.DT4 for short) is a variant of the End behavior.
One of the applications of the End.DT4 behavior is the L3VPNv4 use-case where a FIB lookup in a specific tenant table at the egress PE is required. This is equivalent to the per-VRF VPN label in MPLS [RFC4364].
Note that an End.DT4 may be defined for the main IPv4 table in which case an End.DT4 supports the equivalent of an IPv4inIPv6 decapsulation (without VPN/tenant implication).
The End.DT4 SID MUST be the last segment in a SR Policy, and a SID instance is associated with an IPv4 FIB table T.
When N receives a packet destined to S and S is a local End.DT4 SID, N does the following processing:
S01. When an SRH is processed {
S02. If (Segments Left != 0) {
S03. Send an ICMP Parameter Problem to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field.
Interrupt packet processing and discard the packet.
S04. }
S05. Proceed to process the next header in the packet
S06. }
When processing the Upper-layer header of a packet matching a FIB entry locally instantiated as an SRv6 End.DT4 SID, N does the following:
S01. If (Upper-Layer Header type != 4) {
S02. Process as per Section 4.1.1
S03. }
S04. Remove the outer IPv6 Header with all its extension headers
S05. Set the packet's associated FIB table to T
S06. Submit the packet to the egress IPv4 FIB lookup and
transmission to the new destination
The "Endpoint with decapsulation and specific IP table lookup" behavior (End.DT46 for short) is a variant of the End.DT4 and End.DT6 behavior.
One of the applications of the End.DT46 behavior is the L3VPN use-case where a FIB lookup in a specific IP tenant table at the egress PE is required. This is equivalent to single per-VRF VPN label (for IPv4 and IPv6) in MPLS[RFC4364].
Note that an End.DT46 may be defined for the main IP table in which case an End.DT46 supports the equivalent of an IPinIPv6 decapsulation(without VPN/tenant implication).
The End.DT46 SID MUST be the last segment in a SR Policy, and a SID instance is associated with an IPv4 FIB table T4 and an IPv6 FIB table T6.
When N receives a packet destined to S and S is a local End.DT46 SID, N does the following processing:
S01. When an SRH is processed {
S02. If (Segments Left != 0) {
S03. Send an ICMP Parameter Problem to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field.
Interrupt packet processing and discard the packet.
S04. }
S05. Proceed to process the next header in the packet
S06. }
When processing the Upper-layer header of a packet matching a FIB entry locally instantiated as an SRv6 End.DT46 SID, N does the following:
S01. If (Upper-layer Header type == 4) {
S02. Remove the outer IPv6 Header with all its extension headers
S03. Set the packet's associated FIB table to T4
S04. Submit the packet to the egress IPv4 FIB lookup and
transmission to the new destination
S05. } Else if (Upper-layer Header type == 41) {
S06. Remove the outer IPv6 Header with all its extension headers
S07. Set the packet's associated FIB table to T6
S08. Submit the packet to the egress IPv6 FIB lookup and
transmission to the new destination
S09. } Else {
S10. Process as per Section 4.1.1
S11. }
The "Endpoint with decapsulation and Layer-2 cross-connect to an outgoing L2 interface (OIF)" (End.DX2 for short) is a variant of the endpoint behavior.
One of the applications of the End.DX2 behavior is the L2VPN/EVPN VPWS [RFC7432][RFC8214] use-case.
The End.DX2 SID MUST be the last segment in a SR Policy, and it is associated with one outgoing interface I.
When N receives a packet destined to S and S is a local End.DX2 SID, N does:
S01. When an SRH is processed {
S02. If (Segments Left != 0) {
S03. Send an ICMP Parameter Problem to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field.
Interrupt packet processing and discard the packet.
S04. }
S05. Proceed to process the next header in the packet
S06. }
When processing the Upper-layer header of a packet matching a FIB entry locally instantiated as an SRv6 End.DX2 SID, the following is done:
S01. If (Upper-Layer Header type != 143) {
S02. Process as per Section 4.1.1
S03. }
S04. Remove the outer IPv6 Header with all its extension headers and
forward the Ethernet frame to the OIF I.
Notes:
S04. An End.DX2 behavior could be customized to expect a specific IEEE header (e.g. VLAN tag) and rewrite the egress IEEE header before forwarding on the outgoing interface.
The "Endpoint with decapsulation and specific VLAN table lookup" behavior (End.DX2V for short) is a variant of the End.DX2 behavior.
One of the applications of the End.DX2V behavior is the EVPN Flexible cross-connect use-case. The End.DX2V behavior is used to perform a lookup of the Ethernet frame VLANs in a particular L2 table. Any SID instance of this behavior is associated with an L2 Table T.
When N receives a packet whose IPv6 DA is S and S is a local End.DX2 SID, the processing is identical to the End.DX2 behavior except for the Upper-layer header processing which is modified as follows:
S04. Remove the outer IPv6 Header with all its extension headers,
lookup the exposed VLANs in L2 table T, and forward
via the matched table entry.
Notes:
An End.DX2V behavior could be customized to expect a specific VLAN format and rewrite the egress VLAN header before forwarding on the outgoing interface.
The "Endpoint with decapsulation and specific unicast MAC L2 table lookup" behavior (End.DT2U for short) is a variant of the End behavior.
One of the applications of the End.DT2U behavior is the EVPN Bridging unicast. Any SID instance of the End.DT2U behavior is associated with an L2 Table T.
When N receives a packet whose IPv6 DA is S and S is a local End.DT2U SID, the processing is identical to the End.DX2 behavior except for the Upper-layer header processing which is as follows:
S01. If (Upper-Layer Header type != 143) {
S02. Process as per Section 4.1.1
S03. }
S04. Remove the IPv6 header and all its extension headers
S05. Learn the exposed MAC Source Address in L2 Table T
S06. Lookup the exposed MAC Destination Address in L2 Table T
S07. If (matched entry in T) {
S08. Forward via the matched table T entry
S09. } Else {
S10. Forward via all L2 OIFs entries in table T
S11. }
Notes:
S05. In EVPN, the learning of the exposed MAC Source Address is done via the control plane.
The "Endpoint with decapsulation and specific L2 table flooding" behavior (End.DT2M for short) is a variant of the End.DT2U behavior.
Two of the applications of the End.DT2M behavior are the EVPN Bridging of broadcast, unknown and multicast (BUM) traffic with Ethernet Segment Identifier (ESI) filtering and the EVPN ETREE use-cases.
Any SID instance of this behavior is associated with a L2 table T. Additionally the behavior MAY take an argument: "Arg.FE2". It is an argument specific to EVPN ESI filtering and EVPN-ETREE used to exclude specific OIF (or set of OIFs) from L2 table T flooding.
When N receives a packet whose IPv6 DA is S and S is a local End.DT2M SID, the processing is identical to the End.DX2 behavior except for the Upper-layer header processing which is as follows:
S01. If (Upper-Layer Header type != 143) {
S02. Process as per Section 4.1.1
S03. }
S04. Remove the IPv6 header and all its extension headers
S05. Learn the exposed MAC Source Address in L2 Table T
S06. Forward via all L2 OIFs excluding the one specified in Arg.FE2
Notes:
S05. In EVPN, the learning of the exposed MAC Source Address is done via control plane
Arg.FE2 is encoded in the SID as an (k*x)-bit value. These bits represent a list of up to k OIFs, each identified with an x-bit value. Values k and x are defined on a per End.DT2M SID basis. The interface identifier 0 indicates an empty entry in the interface list.
This is a variation of the End behavior.
One of its applications is to express scalable traffic-engineering policies across multiple domains. It is one of the SRv6 instantiations of a Binding SID [RFC8402].
Any SID instance of this behavior is associated with an SR Policy B and a source address A.
When N receives a packet whose IPv6 DA is S and S is a local End.B6.Encaps SID, does:
S01. When an SRH is processed {
S02. If (Segments Left == 0) {
S03. Proceed to process the next header in the packet,
whose type is identified by the Next Header field in
the routing header.
S04. }
S05. If (IPv6 Hop Limit <= 1) {
S06. Send an ICMP Time Exceeded message to the Source Address,
Code 0 (Hop limit exceeded in transit),
Interrupt packet processing and discard the packet.
S07. }
S08. max_LE = (Hdr Ext Len / 2) - 1
S09. If ((Last Entry > max_LE) or (Segments Left > (Last Entry+1)) {
S10. Send an ICMP Parameter Problem to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field.
Interrupt packet processing and discard the packet.
S11. }
S12. Decrement Hop Limit by 1
S13. Decrement Segments Left by 1
S14. Update IPv6 DA with Segment List[Segments Left]
S15. Push a new IPv6 header with its own SRH containing B
S16. Set the outer IPv6 SA to A
S17. Set the outer IPv6 DA to the first SID of B
S18. Set the outer PayloadLength, Traffic Class, FlowLabel and
Next-Header fields
S19. Submit the packet to the egress IPv6 FIB lookup and
transmission to the new destination
S20. }
Notes:
S14. The SRH MAY be omitted when the SRv6 Policy B only contains one SID and there is no need to use any flag, tag or TLV.
S17. The Payload Length, Traffic Class and Next-Header fields are set as per [RFC2473]. The Flow Label is computed as per [RFC6437].
When processing the Upper-layer header of a packet matching a FIB entry locally instantiated as an SRv6 End.B6.Encaps SID, process the packet as per Section 4.1.1.
This is an optimization of the End.B6.Encaps behavior.
End.B6.Encaps.Red reduces the size of the SRH by one SID by excluding the first SID in the SRH of the new IPv6 header. Thus the first segment is only placed in the IPv6 Destination Address of the new IPv6 header and the packet is forwarded according to it.
The SRH Last Entry field is set as defined in Section 4.1.1 of [RFC8754].
The SRH MAY be omitted when the SRv6 Policy only contains one segment and there is no need to use any flag, tag or TLV.
The "Endpoint bound to an SR-MPLS Policy" is a variant of the End behavior.
The End.BM behavior is required to express scalable traffic-engineering policies across multiple domains where some domains support the MPLS instantiation of Segment Routing. This is an SRv6 instantiation of an SR-MPLS Binding SID [RFC8402].
Any SID instance of this behavior is associated with an SR-MPLS Policy B.
When N receives a packet whose IPv6 DA is S and S is a local End.BM SID, does:
S01. When an SRH is processed {
S02. If (Segments Left == 0) {
S03. Proceed to process the next header in the packet,
whose type is identified by the Next Header field in
the routing header.
S04. }
S05. If (IPv6 Hop Limit <= 1) {
S06. Send an ICMP Time Exceeded message to the Source Address,
Code 0 (Hop limit exceeded in transit),
Interrupt packet processing and discard the packet.
S07. }
S08. max_LE = (Hdr Ext Len / 2) - 1
S09. If ((Last Entry > max_LE) or (Segments Left > (Last Entry+1)) {
S10. Send an ICMP Parameter Problem to the Source Address,
Code 0 (Erroneous header field encountered),
Pointer set to the Segments Left field.
Interrupt packet processing and discard the packet.
S11. }
S12. Decrement Hop Limit by 1
S13. Decrement Segments Left by 1
S14. Update IPv6 DA with Segment List[Segments Left]
S15. Push the MPLS label stack for B
S16. Submit the packet to the MPLS engine for transmission to the
topmost label.
S17. }
When processing the Upper-layer header of a packet matching a FIB entry locally instantiated as an SRv6 End.BM SID, process the packet as per Section 4.1.1.
The PSP, USP and USD flavors are variants of the End, End.X and End.T behaviors. For each of these behaviors these flavors MAY be supported for a SID either individually or in combinations.
SR Segment Endpoint Nodes advertise the SIDs instantiated on them via control plane protocols as described in Section 8. Different behavior ids are allocated for flavored and unflavored SIDs (see Table 4).
An SR Segment Endpoint Node that offers both PSP and non-PSP flavored behavior advertises them as two different SIDs.
The SR Segment Endpoint Node only advertises the PSP flavor if the operator enables this capability at the node.
The PSP operation is deterministically controlled by the SR Source Node.
A PSP-flavored SID is used by the Source SR Node when it needs to instruct the penultimate SR Segment Endpoint Node listed in the SRH to remove the SRH from the IPv6 header.
SR Segment Endpoint Nodes receive the IPv6 packet with the Destination Address field of the IPv6 Header equal to its SID address.
A penultimate SR Segment Endpoint Node is one that, as part of the SID processing, copies the last SID from the SRH into the IPv6 Destination Address and decrements Segments Left value from one to zero.
The PSP operation only takes place at a penultimate SR Segment Endpoint Node and does not happen at any Transit Node. When a SID of PSP-flavor is processed at a non-penultimate SR Segment Endpoint Node, the PSP behavior is not performed as described in the pseudocode below since Segments Left would not be zero.
The SRH processing of the End, End.X and End.T behaviors are modified: after the instruction "S14. Update IPv6 DA with Segment List[Segments Left]" is executed, the following instructions must be executed as well:
S14.1. If (Segments Left == 0) {
S14.2. Update the Next Header field in the preceding header to the
Next Header value of the SRH
S14.3. Decrease the IPv6 header Payload Length by the Hdr Ext Len
value of the SRH
S14.4. Remove the SRH from the IPv6 extension header chain
S14.5. }
The usage of PSP does not increase the MTU of the IPv6 packet and hence does not have any impact on the PMTU discovery mechanism.
As a reminder, [RFC8754] defines in section 5 the SR Deployment Model within the SR Domain [RFC8402]. Within this framework, the Authentication Header (AH) is not used to secure the SRH as described in Section 7.5 of [RFC8754].
The End, End.X and End.T behaviors with PSP do not contravene Section 4 of [RFC8200] because the destination address of the incoming packet is the address of the node executing the behavior.
One use-case for the PSP functionality is streamlining the operation of an egress border router.
+----------------------------------------------------+
| |
+-+-+ +--+ +--+ +--+ +-+-+
|iPE+-------->+R2+-------->+R3+-------->+R4+-------->+ePE|
| R1| +--+ +--+ +--+ |R5 |
+-+-+ +-----+ +-----+ +-----+ +-----+ +-+-+
| |IPv6 | |IPv6 | |IPv6 | |IPv6 | |
| |DA=R3| |DA=R3| |DA=R5| |DA=R5| |
| +-----+ +-----+ +-----+ +-----+ |
| | SRH | | SRH | | IP | | IP | |
| |SL=1 | |SL=1 | +-----+ +-----+ |
| | R5 | | R5 | |
| +-----+ +-----+ |
| | IP | | IP | |
| +-----+ +-----+ |
| |
+----------------------------------------------------+
Figure 1: PSP use-case topology
In the above illustration, for a packet sent from iPE to ePE, node R3 is an intermediate traffic engineering waypoint and is the penultimate segment endpoint router; the node that copies the last segment from the SRH into the IPv6 Destination Address and decrements segments left to 0. The SDN controller knows that no-other node after R3 needs to inspect the SRH, and it instructs R3 to remove the exhausted SRH from the packet by using a PSP-flavored SID.
The benefits for the egress PE are straightforward:
The SRH processing of the End, End.X and End.T behaviors are modified: the instructions S02-S04 are substituted by the following ones:
S02. If (Segments Left == 0) {
S03.1. Update the Next Header field in the preceding header to the
Next Header value of the SRH
S03.2. Decrease the IPv6 header Payload Length by the Hdr Ext Len
value of the SRH
S03.3. Remove the SRH from the IPv6 extension header chain
S03.4. Proceed to process the next header in the packet
S04. }
The Upper-layer header processing of the End, End.X and End.T behaviors are modified as follows:
End:
S01. If (Upper-layer Header type == 41 || 4) {
S02. Remove the outer IPv6 Header with all its extension headers
S03. Submit the packet to the egress IP FIB lookup and
transmission to the new destination
S04. } Else {
S05. Process as per Section 4.1.1
S06. }
End.T:
S01. If (Upper-layer Header type == 41 || 4) {
S02. Remove the outer IPv6 Header with all its extension headers
S03. Set the packet's associated FIB table to T
S04. Submit the packet to the egress IP FIB lookup and
Transmission to the new destination
S05. } Else {
S06. Process as per Section 4.1.1
S07. }
End.X:
S01. If (Upper-layer Header type == 41 || 4) {
S02. Remove the outer IPv6 Header with all its extension headers
S03. Forward the exposed IP packet to the L3 adjacency J
S04. } Else {
S05. Process as per Section 4.1.1
S06. }
An implementation that supports the USD flavor in conjunction with the USP flavor MAY optimize the packet processing by first looking whether the conditions for the USD flavor are met, in which case it can proceed with USD processing else do USP processing.
This section describes a set of SR Policy Headend behaviors.
H.Encaps SR Headend Behavior with Encapsulation in an SR Policy
H.Encaps.Red H.Encaps with Reduced Encapsulation
H.Encaps.L2 H.Encaps Applied to Received L2 Frames
H.Encaps.L2.Red H.Encaps.Red Applied to Received L2 Frames
This list can be expanded in case any new functionality requires it.
Node N receives two packets P1=(A, B2) and P2=(A,B2)(B3, B2, B1; SL=1). B2 is neither a local address nor SID of N.
N steers the transit packets P1 and P2 into an SR Policy with a Source Address T and a Segment list <S1, S2, S3>.
The H.Encaps encapsulation behavior is defined as follows:
S01. Push an IPv6 header with its own SRH (S3, S2, S1; SL=2)
S02. Set outer IPv6 SA = T and outer IPv6 DA = S1
S03. Set outer payload length, traffic class and flow label
S04. Set the outer Next-Header value
S05. Decrement inner Hop Limit or TTL
S06. Submit the packet to the IPv6 module for transmission to S1
After the H.Encaps behavior, P1' and P2' respectively look like:
The received packet is encapsulated unmodified (with the exception of the TTL or Hop Limit that is decremented as described in [RFC2473]).
The H.Encaps behavior is valid for any kind of Layer-3 traffic. This behavior is commonly used for L3VPN with IPv4 and IPv6 deployments. It may be also used for TI-LFA [I-D.ietf-rtgwg-segment-routing-ti-lfa] at the point of local repair.
The push of the SRH MAY be omitted when the SRv6 Policy only contains one segment and there is no need to use any flag, tag or TLV.
S03: As described in [RFC6437] (IPv6 Flow Label Specification)
The H.Encaps.Red behavior is an optimization of the H.Encaps behavior.
H.Encaps.Red reduces the length of the SRH by excluding the first SID in the SRH of the pushed IPv6 header. The first SID is only placed in the Destination Address field of the pushed IPv6 header.
After the H.Encaps.Red behavior, P1' and P2' respectively look like:
The push of the SRH MAY be omitted when the SRv6 Policy only contains one segment and there is no need to use any flag, tag or TLV.
The H.Encaps.L2 behavior encapsulates a received Ethernet [IEEE.802.3_2012] frame and its attached VLAN header, if present, in an IPv6 packet with an SRH. The Ethernet frame becomes the payload of the new IPv6 packet.
The Next Header field of the SRH MUST be set to 143.
The push of the SRH MAY be omitted when the SRv6 Policy only contains one segment and there is no need to use any flag, tag or TLV.
The encapsulating node MUST remove the preamble or frame check sequence (FCS) from the Ethernet frame upon encapsulation and the decapsulating node MUST regenerate the preamble or FCS before forwarding Ethernet frame.
The H.Encaps.L2.Red behavior is an optimization of the H.Encaps.L2 behavior.
H.Encaps.L2.Red reduces the length of the SRH by excluding the first SID in teh SRH of the pushed IPv6 header. The first SID is only places in the Destination Address field of the pushed IPv6 header.
The push of the SRH MAY be omitted when the SRv6 Policy only contains one segment and there is no need to use any flag, tag or TLV.
A node supporting this document SHOULD implement a combined traffic counter (packets and bytes) per local SID entry, for traffic that matched that SID and was processed correctly. The retrieval of these counters via MIB, NETCONF/YANG or any other means is outside the scope of this document.
When a flow-based selection within a set needs to be performed, the source address, the destination address and the flow label MUST be included in the flow-based hash.
This occurs when a FIB lookup is performed and multiple ECMP paths exist to the updated destination address.
This occurs when End.X, End.DX4, or End.DX6 are bound to an array of adjacencies.
This occurs when the packet is steered in an SR policy whose selected path has multiple SID lists.
Additionally, any transit router in an SRv6 domain includes the outer flow label in its ECMP load-balancing hash [RFC6437].
The security considerations for Segment Routing are discussed in [RFC8402]. More specifically for SRv6 the security considerations and the mechanisms for securing an SR domain are discussed in [RFC8754]. Together, they describe the required security mechanisms that allow establishment of an SR domain of trust to operate SRv6-based services for internal traffic while preventing any external traffic from accessing or exploiting the SRv6-based services.
This document introduces SRv6 Endpoint and SR Policy Headend behaviors for implementation on SRv6 capable nodes in the network. As such, this document does not introduce any new security considerations.
In an SDN environment, one expects the controller to explicitly provision the SIDs and/or discover them as part of a service discovery function. Applications residing on top of the controller could then discover the required SIDs and combine them to form a distributed network program.
The concept of "SRv6 network programming" refers to the capability for an application to encode any complex program as a set of individual functions distributed through the network. Some functions relate to underlay SLA, others to overlay/tenant, others to complex applications residing in VM and containers.
While not necessary for an SDN control plane, the remainder of this section provides a high-level illustrative overview of how control-plane protocols may be involved with SRv6. Their specification is outside the scope of this document.
The End, End.T and End.X SIDs express topological behaviors and hence are expected to be signaled in the IGP together with the flavors PSP, USP and USD. The IGP should also advertise the maximum SRv6 SID depth (MSD) capability of the node for each type of SRv6 operation. In particular, the SR source (e.g., H.Encaps), intermediate endpoint (e.g., End, End.X) and final endpoint (e.g., End.DX4, End.DT6) behaviors. These capabilities are factored in by an SR Source Node (or a controller) during the SR Policy computation.
The presence of SIDs in the IGP do not imply any routing semantics to the addresses represented by these SIDs. The routing reachability to an IPv6 address is solely governed by the, non-SID-related, IGP prefix reachability information that includes locators. Routing is not governed neither influenced in any way by a SID advertisement in the IGP.
These SIDs provide important topological behaviors for the IGP to build TI-LFA [I-D.ietf-rtgwg-segment-routing-ti-lfa] based FRR solutions and for TE processes relying on IGP topology database to build SR policies.
BGP-LS provides the functionality for topology discovery that includes the SRv6 capabilities of the nodes, their locators and locally instantiated SIDs. This enables controllers or applications to build an inter-domain topology that can be used for computation of SR Policies using the SRv6 SIDs.
The End.DX4, End.DX6, End.DT4, End.DT6, End.DT46, End.DX2, End.DX2V, End.DT2U and End.DT2M SIDs can be signaled in BGP.
The following table summarizes behaviors for SIDs that can be signaled in which each respective control plane protocol.
| IGP | BGP-LS | BGP IP/VPN/EVPN | |
|---|---|---|---|
| End (PSP, USP, USD) | X | X | |
| End.X (PSP, USP, USD) | X | X | |
| End.T (PSP, USP, USD) | X | X | |
| End.DX6 | X | X | X |
| End.DX4 | X | X | X |
| End.DT6 | X | X | X |
| End.DT4 | X | X | X |
| End.DT46 | X | X | X |
| End.DX2 | X | X | |
| End.DX2V | X | X | |
| End.DT2U | X | X | |
| End.DT2M | X | X | |
| End.B6.Encaps | X | ||
| End.B6.Encaps.Red | X | ||
| End.B6.BM | X |
The following table summarizes which SR Policy Headend capabilities are signaled in which signaling protocol.
| IGP | BGP-LS | BGP IP/VPN/EVPN | |
|---|---|---|---|
| H.Encaps | X | X | |
| H.Encaps.Red | X | X | |
| H.Encaps.L2 | X | ||
| H.Encaps.L2.Red | X |
The previous table describes generic capabilities. It does not describe specific instantiated SR policies.
For example, a BGP-LS advertisement of H.Encaps behavior would describe the capability of node N to perform a H.Encaps behavior, specifically it would describe how many SIDs could be pushed by N without significant performance degradation.
As a reminder, an SR policy is always assigned a Binding SID [RFC8402]. BSIDs are also advertised in BGP-LS as shown in Table 1. Hence, the Table 2 only focuses on the generic capabilities related to H.Encaps.
This document requests IANA to allocate, in the "Protocol Numbers" registry (https://www.iana.org/assignments/protocol-numbers/protocol-numbers.xhtml), a new value for "Ethernet" with the following definition: The value 143 in the Next Header field of an IPv6 header or any extension header indicates that the payload is an Ethernet [IEEE.802.3_2012].
IANA has done a temporary allocation of Protocol Number 143.
This document requests IANA to create a new top-level registry called "Segment Routing Parameters". This registry is being defined to serve as a top-level registry for keeping all other Segment Routing sub-registries.
Additionally, a new sub-registry "SRv6 Endpoint Behaviors" is to be created under top-level "Segment Routing Parameters" registry. This sub-registry maintains 16-bit identifiers for the SRv6 Endpoint behaviors. This registry is established to provide consistency for control plane protocols which need to refer to these behaviors. These values are not encoded in the function bits within a SID.
The range of the registry is 0-65535 (0x0000 - 0xFFFF) and has the following registration rules and allocation policies:
| Range | Hex | Registration procedure | Notes |
|---|---|---|---|
| 0 | 0x0000 | Reserved | Not to be allocated |
| 1-32767 | 0x0001-0x7FFF | FCFS | |
| 32768-65534 | 0x8000-0xFFFE | Reserved | |
| 65535 | 0xFFFF | Reserved | Opaque |
Requests for allocation from within the FCFS range must include a point of contact and preferably also a brief description of how the value will be used. This information may be provided with a reference to an Internet Draft or an RFC or in some other documentation that is permanently and readily available.
The initial registrations for the sub-registry are as follows:
| Value | Hex | Endpoint behavior | Reference |
|---|---|---|---|
| 0 | 0x0000 | Reserved | Not to be allocated |
| 1 | 0x0001 | End (no PSP, no USP) | [This.ID] |
| 2 | 0x0002 | End with PSP | [This.ID] |
| 3 | 0x0003 | End with USP | [This.ID] |
| 4 | 0x0004 | End with PSP&USP | [This.ID] |
| 5 | 0x0005 | End.X (no PSP, no USP) | [This.ID] |
| 6 | 0x0006 | End.X with PSP | [This.ID] |
| 7 | 0x0007 | End.X with USP | [This.ID] |
| 8 | 0x0008 | End.X with PSP&USP | [This.ID] |
| 9 | 0x0009 | End.T (no PSP, no USP) | [This.ID] |
| 10 | 0x000A | End.T with PSP | [This.ID] |
| 11 | 0x000B | End.T with USP | [This.ID] |
| 12 | 0x000C | End.T with PSP&USP | [This.ID] |
| 14 | 0x000E | End.B6.Encaps | [This.ID] |
| 15 | 0x000F | End.BM | [This.ID] |
| 16 | 0x0010 | End.DX6 | [This.ID] |
| 17 | 0x0011 | End.DX4 | [This.ID] |
| 18 | 0x0012 | End.DT6 | [This.ID] |
| 19 | 0x0013 | End.DT4 | [This.ID] |
| 20 | 0x0014 | End.DT46 | [This.ID] |
| 21 | 0x0015 | End.DX2 | [This.ID] |
| 22 | 0x0016 | End.DX2V | [This.ID] |
| 23 | 0x0017 | End.DT2U | [This.ID] |
| 24 | 0x0018 | End.DT2M | [This.ID] |
| 25 | 0x0019 | Reserved | [This.ID] |
| 27 | 0x001B | End.B6.Encaps.Red | [This.ID] |
| 28 | 0x001C | End with USD | [This.ID] |
| 29 | 0x001D | End with PSP&USD | [This.ID] |
| 30 | 0x001E | End with USP&USD | [This.ID] |
| 31 | 0x001F | End with PSP, USP & USD | [This.ID] |
| 32 | 0x0020 | End.X with USD | [This.ID] |
| 33 | 0x0021 | End.X with PSP&USD | [This.ID] |
| 34 | 0x0022 | End.X with USP&USD | [This.ID] |
| 35 | 0x0023 | End.X with PSP, USP & USD | [This.ID] |
| 36 | 0x0024 | End.T with USD | [This.ID] |
| 37 | 0x0025 | End.T with PSP&USD | [This.ID] |
| 38 | 0x0026 | End.T with USP&USD | [This.ID] |
| 39 | 0x0027 | End.T with PSP, USP & USD | [This.ID] |
| 40-32766 | Unassigned | ||
| 32767 | 0x7FFF | The SID defined in RFC8754 | [This.ID] [RFC8754] |
| 32768-65534 | Reserved | ||
| 65535 | 0xFFFF | Opaque | [This.ID] |
The authors would like to acknowledge Stefano Previdi, Dave Barach, Mark Townsley, Peter Psenak, Thierry Couture, Kris Michielsen, Paul Wells, Robert Hanzl, Dan Ye, Gaurav Dawra, Faisal Iqbal, Jaganbabu Rajamanickam, David Toscano, Asif Islam, Jianda Liu, Yunpeng Zhang, Jiaoming Li, Narendra A.K, Mike Mc Gourty, Bhupendra Yadav, Sherif Toulan, Satish Damodaran, John Bettink, Kishore Nandyala Veera Venk, Jisu Bhattacharya, Saleem Hafeez and Brian Carpenter.
Daniel Bernier
Bell Canada
Canada
Email: daniel.bernier@bell.ca
Dirk Steinberg
Lapishills Consulting Limited
Cyprus
Email: dirk@lapishills.com
Robert Raszuk
Bloomberg LP
United States of America
Email: robert@raszuk.net
Bruno Decraene
Orange
France
Email: bruno.decraene@orange.com
Bart Peirens
Proximus
Belgium
Email: bart.peirens@proximus.com
Hani Elmalky
Google
United States of America
Email: helmalky@google.com
Prem Jonnalagadda
Barefoot Networks
United States of America
Email: prem@barefootnetworks.com
Milad Sharif
SambaNova Systems
United States of America
Email: milad.sharif@sambanova.ai
David Lebrun
Google
Belgium
Email: dlebrun@google.com
Stefano Salsano
Universita di Roma "Tor Vergata"
Italy
Email: stefano.salsano@uniroma2.it
Ahmed AbdelSalam
Gran Sasso Science Institute
Italy
Email: ahmed.abdelsalam@gssi.it
Gaurav Naik
Drexel University
United States of America
Email: gn@drexel.edu
Arthi Ayyangar
Arrcus, Inc
United States of America
Email: arthi@arrcus.com
Satish Mynam
Arrcus, Inc
United States of America
Email: satishm@arrcus.com
Wim Henderickx
Nokia
Belgium
Email: wim.henderickx@nokia.com
Shaowen Ma
Juniper
Singapore
Email: mashao@juniper.net
Ahmed Bashandy
Individual
United States of America
Email: abashandy.ietf@gmail.com
Francois Clad
Cisco Systems, Inc.
France
Email: fclad@cisco.com
Kamran Raza
Cisco Systems, Inc.
Canada
Email: skraza@cisco.com
Darren Dukes
Cisco Systems, Inc.
Canada
Email: ddukes@cisco.com
Patrice Brissete
Cisco Systems, Inc.
Canada
Email: pbrisset@cisco.com
Zafar Ali
Cisco Systems, Inc.
United States of America
Email: zali@cisco.com
Ketan Talaulikar
Cisco Systems, Inc.
India
Email: ketant@cisco.com
| [IEEE.802.3_2012] | IEEE, "802.3-2012", IEEE 802.3-2012, DOI 10.1109/ieeestd.2012.6419735, January 2013. |
| [RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997. |
| [RFC2473] | Conta, A. and S. Deering, "Generic Packet Tunneling in IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473, December 1998. |
| [RFC6437] | Amante, S., Carpenter, B., Jiang, S. and J. Rajahalme, "IPv6 Flow Label Specification", RFC 6437, DOI 10.17487/RFC6437, November 2011. |
| [RFC8174] | Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017. |
| [RFC8200] | Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", STD 86, RFC 8200, DOI 10.17487/RFC8200, July 2017. |
| [RFC8402] | Filsfils, C., Previdi, S., Ginsberg, L., Decraene, B., Litkowski, S. and R. Shakir, "Segment Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, July 2018. |
| [RFC8754] | Filsfils, C., Dukes, D., Previdi, S., Leddy, J., Matsushima, S. and D. Voyer, "IPv6 Segment Routing Header (SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020. |