| < draft-ietf-ospf-segment-routing-msd-07.txt | draft-ietf-ospf-segment-routing-msd-08.txt > | |||
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| skipping to change at page 1, line 14 ¶ | skipping to change at page 1, line 14 ¶ | |||
| Internet-Draft Individual | Internet-Draft Individual | |||
| Intended status: Standards Track U. Chunduri | Intended status: Standards Track U. Chunduri | |||
| Expires: June 17, 2018 Huawei Technologies | Expires: June 17, 2018 Huawei Technologies | |||
| S. Aldrin | S. Aldrin | |||
| Google, Inc | Google, Inc | |||
| P. Psenak | P. Psenak | |||
| Cisco Systems | Cisco Systems | |||
| December 14, 2017 | December 14, 2017 | |||
| Signaling MSD (Maximum SID Depth) using OSPF | Signaling MSD (Maximum SID Depth) using OSPF | |||
| draft-ietf-ospf-segment-routing-msd-07 | draft-ietf-ospf-segment-routing-msd-08 | |||
| Abstract | Abstract | |||
| This document proposes a way to signal Maximum SID Depth (MSD) | This document proposes a way to signal Maximum SID Depth (MSD) | |||
| supported by a node at node and/or link granularity by an OSPF | supported by a node at node and/or link granularity by an OSPF | |||
| Router. In a Segment Routing (SR) enabled network a centralized | Router. In a Segment Routing (SR) enabled network a centralized | |||
| controller that programs SR tunnels needs to know the MSD supported | controller that programs SR tunnels needs to know the MSD supported | |||
| by the head-end at node and/or link granularity to impose the SID | by the head-end at node and/or link granularity to impose the SID | |||
| stack of an appropriate depth. MSD is relevant to the head-end of a | stack of an appropriate depth. MSD is relevant to the head-end of a | |||
| SR tunnel or Binding-SID anchor node where Binding-SID expansions | SR tunnel or Binding-SID anchor node where Binding-SID expansions | |||
| skipping to change at page 3, line 21 ¶ | skipping to change at page 3, line 21 ¶ | |||
| appropriate depth, so it could be read by transit nodes. MSD in | appropriate depth, so it could be read by transit nodes. MSD in | |||
| contrary signals ability to impose SID's stack of a particular depth. | contrary signals ability to impose SID's stack of a particular depth. | |||
| MSD of type 1 (IANA Registry), called Base MSD is used to signal the | MSD of type 1 (IANA Registry), called Base MSD is used to signal the | |||
| total number of SIDs a node is capable of imposing, to be used by a | total number of SIDs a node is capable of imposing, to be used by a | |||
| path computation element/controller. In case, there are additional | path computation element/controller. In case, there are additional | |||
| SIDs (e.g. service) that are to be imposed to the stack - this would | SIDs (e.g. service) that are to be imposed to the stack - this would | |||
| be signaled with an another MSD type (TBD), no adjustment to the Base | be signaled with an another MSD type (TBD), no adjustment to the Base | |||
| MSD should be made. In the future, new MSD types could be defined to | MSD should be made. In the future, new MSD types could be defined to | |||
| signal additional capabilities: entropy labels, SIDs that can be | signal additional capabilities: entropy labels, SIDs that can be | |||
| imposed thru recirculation, or another dataplane e.g IPv6. | imposed thru recirculation, or another dataplane e.g. IPv6. | |||
| 1.1. Conventions used in this document | 1.1. Conventions used in this document | |||
| 1.1.1. Terminology | 1.1.1. Terminology | |||
| BGP-LS: Distribution of Link-State and TE Information using Border | BGP-LS: Distribution of Link-State and TE Information using Border | |||
| Gateway Protocol | Gateway Protocol | |||
| OSPF: Open Shortest Path First | OSPF: Open Shortest Path First | |||
| skipping to change at page 5, line 29 ¶ | skipping to change at page 5, line 29 ¶ | |||
| Figure 2: Link MSD Sub-TLV | Figure 2: Link MSD Sub-TLV | |||
| The Type (2 bytes) of this TLV: | The Type (2 bytes) of this TLV: | |||
| For OSPFv2, the Link level MSD value is advertised as an optional | For OSPFv2, the Link level MSD value is advertised as an optional | |||
| Sub-TLV of OSPFv2 Extended Link TLV as defined in [RFC7684], and has | Sub-TLV of OSPFv2 Extended Link TLV as defined in [RFC7684], and has | |||
| value of 6. | value of 6. | |||
| For OSPFv3, the Link level MSD value is advertised as an optional | For OSPFv3, the Link level MSD value is advertised as an optional | |||
| Sub-TLV of the Router-Link TLV as defined in | Sub-TLV of the Router-Link TLV as defined in | |||
| [I-D.ietf-ospf-ospfv3-lsa-extend], and has value of 3 (Suggested | [I-D.ietf-ospf-ospfv3-lsa-extend], and has value of 16 (Suggested | |||
| value - to be assigned by IANA). | value - to be assigned by IANA). | |||
| Length is variable and similar to what is defined in Section 3. | Length is variable and similar to what is defined in Section 3. | |||
| Value field consists of a 1 octet sub-type (IANA Registry) and 1 | Value field consists of a 1 octet sub-type (IANA Registry) and 1 | |||
| octet value. | octet value. | |||
| Sub-Type 1 (IANA Section), MSD and the Value field contains Link MSD | Sub-Type 1 (IANA Section), MSD and the Value field contains Link MSD | |||
| of the router originating the corresponding LSA as specified for | of the router originating the corresponding LSA as specified for | |||
| OSPFv2 and OSPFv3. Link MSD is a number in the range of 0-254. 0 | OSPFv2 and OSPFv3. Link MSD is a number in the range of 0-254. 0 | |||
| skipping to change at page 6, line 10 ¶ | skipping to change at page 6, line 10 ¶ | |||
| 5. Node MSD vs Link MSD conflict resolution | 5. Node MSD vs Link MSD conflict resolution | |||
| When both Node MSD and Link MSD are present, the value in the Link | When both Node MSD and Link MSD are present, the value in the Link | |||
| MSD MUST be used. | MSD MUST be used. | |||
| 6. IANA Considerations | 6. IANA Considerations | |||
| This document includes a request to IANA to allocate TLV type codes | This document includes a request to IANA to allocate TLV type codes | |||
| for the new TLV proposed in Section 3 of this document from OSPF | for the new TLV proposed in Section 3 of this document from OSPF | |||
| Router Information (RI) TLVs Registry as defined by [RFC4970]. For | Router Information (RI) TLVs Registry as defined by [RFC4970]. For | |||
| THE link MSD, we request IANA to allocate new sub-TLV codes as | the link MSD, we request IANA to allocate new sub-TLV codes as | |||
| proposed in Section 4 from OSPFv2 Extended Link TLV Sub-TLVs registry | proposed in Section 4 from OSPFv2 Extended Link TLV Sub-TLVs registry | |||
| and from Router-Link TLV defined in OSPFv3 Extend-LSA Sub-TLV | and from Router-Link TLV defined in OSPFv3 Extend-LSA Sub-TLV | |||
| registry. | registry. | |||
| This document also requests IANA to create a new Sub-type registry as | This document also requests IANA to create a new Sub-type registry as | |||
| proposed in Section 3, Section 4. | proposed in Section 3, Section 4. | |||
| Value Name Reference | Value Name Reference | |||
| ----- --------------------- ------------- | ----- --------------------- ------------- | |||
| 0 Reserved This document | 0 Reserved This document | |||
| End of changes. 4 change blocks. | ||||
| 4 lines changed or deleted | 4 lines changed or added | |||
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