draft-ietf-lsr-dynamic-flooding-01.txt | draft-ietf-lsr-dynamic-flooding-02.txt | |||
---|---|---|---|---|
Internet Engineering Task Force T. Li, Ed. | Internet Engineering Task Force T. Li, Ed. | |||
Internet-Draft Arista Networks | Internet-Draft Arista Networks | |||
Intended status: Standards Track P. Psenak, Ed. | Intended status: Standards Track P. Psenak, Ed. | |||
Expires: November 22, 2019 L. Ginsberg | Expires: November 28, 2019 L. Ginsberg | |||
Cisco Systems, Inc. | Cisco Systems, Inc. | |||
T. Przygienda | T. Przygienda | |||
Juniper Networks, Inc. | Juniper Networks, Inc. | |||
D. Cooper | D. Cooper | |||
CenturyLink | CenturyLink | |||
L. Jalil | L. Jalil | |||
Verizon | Verizon | |||
S. Dontula | S. Dontula | |||
ATT | ATT | |||
May 21, 2019 | May 27, 2019 | |||
Dynamic Flooding on Dense Graphs | Dynamic Flooding on Dense Graphs | |||
draft-ietf-lsr-dynamic-flooding-01 | draft-ietf-lsr-dynamic-flooding-02 | |||
Abstract | Abstract | |||
Routing with link state protocols in dense network topologies can | Routing with link state protocols in dense network topologies can | |||
result in sub-optimal convergence times due to the overhead | result in sub-optimal convergence times due to the overhead | |||
associated with flooding. This can be addressed by decreasing the | associated with flooding. This can be addressed by decreasing the | |||
flooding topology so that it is less dense. | flooding topology so that it is less dense. | |||
This document discusses the problem in some depth and an | This document discusses the problem in some depth and an | |||
architectural solution. Specific protocol changes for IS-IS, OSPFv2, | architectural solution. Specific protocol changes for IS-IS, OSPFv2, | |||
skipping to change at page 1, line 47 ¶ | skipping to change at page 1, line 47 ¶ | |||
Internet-Drafts are working documents of the Internet Engineering | Internet-Drafts are working documents of the Internet Engineering | |||
Task Force (IETF). Note that other groups may also distribute | Task Force (IETF). Note that other groups may also distribute | |||
working documents as Internet-Drafts. The list of current Internet- | working documents as Internet-Drafts. The list of current Internet- | |||
Drafts is at https://datatracker.ietf.org/drafts/current/. | Drafts is at https://datatracker.ietf.org/drafts/current/. | |||
Internet-Drafts are draft documents valid for a maximum of six months | Internet-Drafts are draft documents valid for a maximum of six months | |||
and may be updated, replaced, or obsoleted by other documents at any | and may be updated, replaced, or obsoleted by other documents at any | |||
time. It is inappropriate to use Internet-Drafts as reference | time. It is inappropriate to use Internet-Drafts as reference | |||
material or to cite them other than as "work in progress." | material or to cite them other than as "work in progress." | |||
This Internet-Draft will expire on November 22, 2019. | This Internet-Draft will expire on November 28, 2019. | |||
Copyright Notice | Copyright Notice | |||
Copyright (c) 2019 IETF Trust and the persons identified as the | Copyright (c) 2019 IETF Trust and the persons identified as the | |||
document authors. All rights reserved. | document authors. All rights reserved. | |||
This document is subject to BCP 78 and the IETF Trust's Legal | This document is subject to BCP 78 and the IETF Trust's Legal | |||
Provisions Relating to IETF Documents | Provisions Relating to IETF Documents | |||
(https://trustee.ietf.org/license-info) in effect on the date of | (https://trustee.ietf.org/license-info) in effect on the date of | |||
publication of this document. Please review these documents | publication of this document. Please review these documents | |||
skipping to change at page 3, line 6 ¶ | skipping to change at page 3, line 6 ¶ | |||
5.2.1. OSPF Area Leader Sub-TLV . . . . . . . . . . . . . . 18 | 5.2.1. OSPF Area Leader Sub-TLV . . . . . . . . . . . . . . 18 | |||
5.2.2. OSPF Dynamic Flooding Sub-TLV . . . . . . . . . . . . 19 | 5.2.2. OSPF Dynamic Flooding Sub-TLV . . . . . . . . . . . . 19 | |||
5.2.3. OSPFv2 Dynamic Flooding Opaque LSA . . . . . . . . . 19 | 5.2.3. OSPFv2 Dynamic Flooding Opaque LSA . . . . . . . . . 19 | |||
5.2.4. OSPFv3 Dynamic Flooding LSA . . . . . . . . . . . . . 21 | 5.2.4. OSPFv3 Dynamic Flooding LSA . . . . . . . . . . . . . 21 | |||
5.2.5. OSPF Area Router ID TLVs . . . . . . . . . . . . . . 22 | 5.2.5. OSPF Area Router ID TLVs . . . . . . . . . . . . . . 22 | |||
5.2.5.1. OSPFv2 Area Router ID TLV . . . . . . . . . . . . 22 | 5.2.5.1. OSPFv2 Area Router ID TLV . . . . . . . . . . . . 22 | |||
5.2.5.2. OSPFv3 Area Router ID TLV . . . . . . . . . . . . 24 | 5.2.5.2. OSPFv3 Area Router ID TLV . . . . . . . . . . . . 24 | |||
5.2.6. OSPF Flooding Path TLV . . . . . . . . . . . . . . . 26 | 5.2.6. OSPF Flooding Path TLV . . . . . . . . . . . . . . . 26 | |||
5.2.7. OSPF Flooding Request Bit . . . . . . . . . . . . . . 27 | 5.2.7. OSPF Flooding Request Bit . . . . . . . . . . . . . . 27 | |||
5.2.8. OSPF LEEF Advertisement . . . . . . . . . . . . . . . 28 | 5.2.8. OSPF LEEF Advertisement . . . . . . . . . . . . . . . 28 | |||
6. Behavioral Specification . . . . . . . . . . . . . . . . . . 28 | 6. Behavioral Specification . . . . . . . . . . . . . . . . . . 29 | |||
6.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 29 | 6.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 29 | |||
6.2. Flooding Topology . . . . . . . . . . . . . . . . . . . . 29 | 6.2. Flooding Topology . . . . . . . . . . . . . . . . . . . . 29 | |||
6.3. Leader Election . . . . . . . . . . . . . . . . . . . . . 29 | 6.3. Leader Election . . . . . . . . . . . . . . . . . . . . . 29 | |||
6.4. Area Leader Responsibilities . . . . . . . . . . . . . . 30 | 6.4. Area Leader Responsibilities . . . . . . . . . . . . . . 30 | |||
6.5. Distributed Flooding Topology Calculation . . . . . . . . 30 | 6.5. Distributed Flooding Topology Calculation . . . . . . . . 30 | |||
6.6. Use of LANs in the Flooding Topology . . . . . . . . . . 30 | 6.6. Use of LANs in the Flooding Topology . . . . . . . . . . 31 | |||
6.6.1. Use of LANs in Centralized mode . . . . . . . . . . . 30 | 6.6.1. Use of LANs in Centralized mode . . . . . . . . . . . 31 | |||
6.6.2. Use of LANs in Distributed Mode . . . . . . . . . . . 31 | 6.6.2. Use of LANs in Distributed Mode . . . . . . . . . . . 31 | |||
6.6.2.1. Partial flooding on a LAN in IS-IS . . . . . . . 31 | 6.6.2.1. Partial flooding on a LAN in IS-IS . . . . . . . 31 | |||
6.6.2.2. Partial Flooding on a LAN in OSPF . . . . . . . . 31 | 6.6.2.2. Partial Flooding on a LAN in OSPF . . . . . . . . 32 | |||
6.7. Flooding Behavior . . . . . . . . . . . . . . . . . . . . 32 | 6.7. Flooding Behavior . . . . . . . . . . . . . . . . . . . . 32 | |||
6.8. Treatment of Topology Events . . . . . . . . . . . . . . 33 | 6.8. Treatment of Topology Events . . . . . . . . . . . . . . 33 | |||
6.8.1. Temporary Addition of Link to Flooding Topology . . . 33 | 6.8.1. Temporary Addition of Link to Flooding Topology . . . 33 | |||
6.8.2. Local Link Addition . . . . . . . . . . . . . . . . . 33 | 6.8.2. Local Link Addition . . . . . . . . . . . . . . . . . 34 | |||
6.8.3. Node Addition . . . . . . . . . . . . . . . . . . . . 34 | 6.8.3. Node Addition . . . . . . . . . . . . . . . . . . . . 35 | |||
6.8.4. Failures of Link Not on Flooding Topology . . . . . . 35 | 6.8.4. Failures of Link Not on Flooding Topology . . . . . . 35 | |||
6.8.5. Failures of Link On the Flooding Topology . . . . . . 35 | 6.8.5. Failures of Link On the Flooding Topology . . . . . . 35 | |||
6.8.6. Node Deletion . . . . . . . . . . . . . . . . . . . . 35 | 6.8.6. Node Deletion . . . . . . . . . . . . . . . . . . . . 36 | |||
6.8.7. Local Link Addition to the Flooding Topology . . . . 36 | 6.8.7. Local Link Addition to the Flooding Topology . . . . 36 | |||
6.8.8. Local Link Deletion from the Flooding Topology . . . 36 | 6.8.8. Local Link Deletion from the Flooding Topology . . . 36 | |||
6.8.9. Treatment of Disconnected Adjacent Nodes . . . . . . 36 | 6.8.9. Treatment of Disconnected Adjacent Nodes . . . . . . 37 | |||
6.8.10. Failure of the Area Leader . . . . . . . . . . . . . 36 | 6.8.10. Failure of the Area Leader . . . . . . . . . . . . . 37 | |||
6.8.11. Recovery from Multiple Failures . . . . . . . . . . . 37 | 6.8.11. Recovery from Multiple Failures . . . . . . . . . . . 37 | |||
6.8.12. Rate Limiting Temporary Flooding . . . . . . . . . . 37 | 6.8.12. Rate Limiting Temporary Flooding . . . . . . . . . . 38 | |||
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 38 | 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 38 | |||
7.1. IS-IS . . . . . . . . . . . . . . . . . . . . . . . . . . 38 | 7.1. IS-IS . . . . . . . . . . . . . . . . . . . . . . . . . . 38 | |||
7.2. OSPF . . . . . . . . . . . . . . . . . . . . . . . . . . 39 | 7.2. OSPF . . . . . . . . . . . . . . . . . . . . . . . . . . 39 | |||
7.2.1. OSPF Dynamic Flooding LSA TLVs Registry . . . . . . . 40 | 7.2.1. OSPF Dynamic Flooding LSA TLVs Registry . . . . . . . 41 | |||
7.2.2. OSPF Link Attributes Sub-TLV Bit Values Registry . . 41 | 7.2.2. OSPF Link Attributes Sub-TLV Bit Values Registry . . 41 | |||
7.3. IGP . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 | 7.3. IGP . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 | |||
8. Security Considerations . . . . . . . . . . . . . . . . . . . 42 | 8. Security Considerations . . . . . . . . . . . . . . . . . . . 42 | |||
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 42 | 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 43 | |||
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 42 | 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 43 | |||
10.1. Normative References . . . . . . . . . . . . . . . . . . 42 | 10.1. Normative References . . . . . . . . . . . . . . . . . . 43 | |||
10.2. Informative References . . . . . . . . . . . . . . . . . 44 | 10.2. Informative References . . . . . . . . . . . . . . . . . 45 | |||
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 45 | Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 46 | |||
1. Introduction | 1. Introduction | |||
In recent years, there has been increased focus on how to address the | In recent years, there has been increased focus on how to address the | |||
dynamic routing of networks that have a bipartite (a.k.a. spine-leaf | dynamic routing of networks that have a bipartite (a.k.a. spine-leaf | |||
or leaf-spine), Clos [Clos], or Fat Tree [Leiserson] topology. | or leaf-spine), Clos [Clos], or Fat Tree [Leiserson] topology. | |||
Conventional Interior Gateway Protocols (IGPs, i.e., IS-IS | Conventional Interior Gateway Protocols (IGPs, i.e., IS-IS | |||
[ISO10589], OSPFv2 [RFC2328], and OSPFv3 [RFC5340]) under-perform, | [ISO10589], OSPFv2 [RFC2328], and OSPFv3 [RFC5340]) under-perform, | |||
redundantly flooding information throughout the dense topology, | redundantly flooding information throughout the dense topology, | |||
leading to overloaded control plane inputs and thereby creating | leading to overloaded control plane inputs and thereby creating | |||
skipping to change at page 23, line 8 ¶ | skipping to change at page 23, line 8 ¶ | |||
the area. This TLV may also occur in multiple OSPFv2 Dynamic | the area. This TLV may also occur in multiple OSPFv2 Dynamic | |||
Flooding Opaque LSAs so that all Router IDs can be advertised. | Flooding Opaque LSAs so that all Router IDs can be advertised. | |||
Each entry in the OSPFv2 Area Router IDs TLV represents either a node | Each entry in the OSPFv2 Area Router IDs TLV represents either a node | |||
or a Broadcast/NBMA network identifier. An entry has the following | or a Broadcast/NBMA network identifier. An entry has the following | |||
format: | format: | |||
0 1 2 3 | 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 | 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 | |||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | |||
| Conn Type | Reserved | | | Conn Type | Number of IDs | Reserved | | |||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ||||
| Originating Router ID/DR Address | | ||||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | |||
| | | ||||
+- Originating Router ID/DR Address -+ | ||||
| ... | | ||||
where | where | |||
Conn Type - 1 byte | Conn Type - 1 byte | |||
The following values are defined: | The following values are defined: | |||
1 - Router | 1 - Router | |||
2 - Designated Router | 2 - Designated Router | |||
Reserved - 3 bytes | Number of IDs - 2 bytes | |||
Reserved - 1 byte | ||||
MUST be transmitted as 0 and MUST be ignored on receipt | MUST be transmitted as 0 and MUST be ignored on receipt | |||
Originating Router ID/DR Address - 4 bytes | Originating Router ID/DR Address - (4 * Number of IDs) bytes | |||
As indicated by the ID Type | As indicated by the ID Type | |||
OSPFv2 Router IDs TLV Entry | OSPFv2 Router IDs TLV Entry | |||
The format of the Area Router IDs TLV is: | The format of the Area Router IDs TLV is: | |||
0 1 2 3 | 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 | 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 | | | Type | Length | | |||
skipping to change at page 23, line 46 ¶ | skipping to change at page 24, line 4 ¶ | |||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | |||
| | | | | | |||
+- OSPFv2 Router ID TLV Entry -+ | +- OSPFv2 Router ID TLV Entry -+ | |||
| ... | | | ... | | |||
OSPFv2 Area Router IDs TLV | OSPFv2 Area Router IDs TLV | |||
TLV Type: 1 | TLV Type: 1 | |||
TLV Length: 4 + (8 * the number TLV entries) | TLV Length: 4 + (8 * the number TLV entries) | |||
Starting index: The index of the first Router/Designated Router ID | ||||
that appears in this TLV. | ||||
Starting index: The index of the first Router ID that appears in | L (Last): This bit is set if the index of the last Router/ | |||
this TLV. | Designated ID that appears in this TLV is equal to the last index | |||
in the full list of Rourer IDs for the area. | ||||
L (Last): This bit is set if the index of the last system ID that | ||||
appears in this TLV is equal to the last index in the full list of | ||||
Rourer IDs for the area. | ||||
OSPFv2 Router ID TLV Entries: A concatenated list of Router ID TLV | OSPFv2 Router ID TLV Entries: A concatenated list of Router ID TLV | |||
Entries for the area. | Entries for the area. | |||
If there are multiple OSPFv2 Area Router ID TLVs with the L bit set | If there are multiple OSPFv2 Area Router ID TLVs with the L bit set | |||
advertised by the same router, the TLV which specifies the smaller | advertised by the same router, the TLV which specifies the smaller | |||
maximum index is used and the other TLV(s) with L bit set are | maximum index is used and the other TLV(s) with L bit set are | |||
ignored. TLVs which specify Router IDs with indices greater than | ignored. TLVs which specify Router IDs with indices greater than | |||
that specified by the TLV with the L bit set are also ignored. | that specified by the TLV with the L bit set are also ignored. | |||
skipping to change at page 25, line 5 ¶ | skipping to change at page 25, line 5 ¶ | |||
Because the space in a single OSPFv3 Area Router ID TLV is limited, | Because the space in a single OSPFv3 Area Router ID TLV is limited, | |||
more than one TLV may be required to encode all of the Router IDs in | more than one TLV may be required to encode all of the Router IDs in | |||
the area. This TLV may also occur in multiple OSPFv3 Dynamic | the area. This TLV may also occur in multiple OSPFv3 Dynamic | |||
Flooding Opaque LSAs so that all Router IDs can be advertised. | Flooding Opaque LSAs so that all Router IDs can be advertised. | |||
Each entry in the OSPFv3 Area Router IDs TLV represents either a | Each entry in the OSPFv3 Area Router IDs TLV represents either a | |||
router or a Broadcast/NBMA network identifier. An entry has the | router or a Broadcast/NBMA network identifier. An entry has the | |||
following format: | following format: | |||
0 1 2 3 | 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 | 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 | |||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | |||
| Conn Type | Reserved | | | Conn Type | Number of IDs | Reserved | | |||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | |||
| Originating Router ID (always present) | | | | | |||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +- Originating ID Entry -+ | |||
| Interface ID (present for DRs) | | | ... | | |||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ||||
where | where | |||
Conn Type - 1 byte | Conn Type - 1 byte | |||
The following values are defined: | The following values are defined: | |||
1 - Router | 1 - Router | |||
2 - Designated Router | 2 - Designated Router | |||
Reserved - 3 bytes | Number of IDs - 2 bytes | |||
MUST be transmitted as 0 and MUST be ignored on receipt | ||||
Originating Router ID - 4 bytes | Reserved - 1 byte | |||
MUST be transmitted as 0 and MUST be ignored on receipt | ||||
Interface ID - 4 bytes | Originating ID Entry takes one of the following forms: | |||
This field MUST be present when Conn Type indicates Designated | ||||
Router. | Router: | |||
This field MUST NOT be present when Conn Type indicates Router. | 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 | ||||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ||||
| Originating Router ID | | ||||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ||||
Length of Originating ID Entry is 4 * Number of IDs) bytes | ||||
Designated Router: | ||||
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 | ||||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ||||
| Originating Router ID | | ||||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ||||
| Interface ID | | ||||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ||||
Length of Originating ID Entry is (8 * Number of IDs) bytes | ||||
OSPFv3 Router ID TLV Entry | OSPFv3 Router ID TLV Entry | |||
The format of the OSPFv3Area Router IDs TLV is: | The format of the OSPFv3Area Router IDs TLV is: | |||
0 1 2 3 | 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 | 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 | | | Type | Length | | |||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | |||
skipping to change at page 26, line 4 ¶ | skipping to change at page 26, line 19 ¶ | |||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | |||
| Starting Index |L| Flags | Reserved | | | Starting Index |L| Flags | Reserved | | |||
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | |||
| | | | | | |||
+- OSPFv3 Router ID TLV Entry -+ | +- OSPFv3 Router ID TLV Entry -+ | |||
| ... | | | ... | | |||
OSPFv3 Area Router IDs TLV | OSPFv3 Area Router IDs TLV | |||
TLV Type: 1 | TLV Type: 1 | |||
TLV Length: 4 + sum of the lengths of all TLV entries | TLV Length: 4 + sum of the lengths of all TLV entries | |||
Starting index: The index of the first Router ID that appears in | Starting index: The index of the first Router/Designated Router ID | |||
this TLV. | that appears in this TLV. | |||
L (Last): This bit is set if the index of the last router ID that | L (Last): This bit is set if the index of the last Router/ | |||
appears in this TLV is equal to the last index in the full list of | Designated Router ID that appears in this TLV is equal to the last | |||
Router IDs for the area. | index in the full list of Router IDs for the area. | |||
OSPFv2 Router ID TLV Entries: A concatenated list of Router ID TLV | OSPFv3 Router ID TLV Entries: A concatenated list of Router ID TLV | |||
Entries for the area. | Entries for the area. | |||
If there are multiple OSPFv3 Area Router ID TLVs with the L bit set | If there are multiple OSPFv3 Area Router ID TLVs with the L bit set | |||
advertised by the same router, the TLV which specifies the smaller | advertised by the same router, the TLV which specifies the smaller | |||
maximum index is used and the other TLV(s) with L bit set are | maximum index is used and the other TLV(s) with L bit set are | |||
ignored. TLVs which specify Router IDs with indices greater than | ignored. TLVs which specify Router IDs with indices greater than | |||
that specified by the TLV with the L bit set are also ignored. | that specified by the TLV with the L bit set are also ignored. | |||
5.2.6. OSPF Flooding Path TLV | 5.2.6. OSPF Flooding Path TLV | |||
skipping to change at page 30, line 10 ¶ | skipping to change at page 30, line 16 ¶ | |||
that do not advertise their eligibility to become Area Leader are not | that do not advertise their eligibility to become Area Leader are not | |||
eligible. Amongst the eligible nodes, the node with the numerically | eligible. Amongst the eligible nodes, the node with the numerically | |||
highest priority is the Area Leader. If multiple nodes all have the | highest priority is the Area Leader. If multiple nodes all have the | |||
highest priority, then the node with the numerically highest system | highest priority, then the node with the numerically highest system | |||
identifier in the case of IS-IS, or Router-ID in the case of OSPFv2 | identifier in the case of IS-IS, or Router-ID in the case of OSPFv2 | |||
and OSPFv3 is the Area Leader. | and OSPFv3 is the Area Leader. | |||
6.4. Area Leader Responsibilities | 6.4. Area Leader Responsibilities | |||
If the Area Leader operates in centralized mode, it MUST advertise | If the Area Leader operates in centralized mode, it MUST advertise | |||
algorithm 0 in its Area Leader Sub-TLV. It also MUST compute and | algorithm 0 in its Area Leader Sub-TLV. In order for Dynamic | |||
advertise a flooding topology for the area. The Area Leader may | Flooding to be enabled it also MUST compute and advertise a flooding | |||
update the flooding topology at any time, however, it should not | topology for the area. The Area Leader may update the flooding | |||
destabilize the network with undue or overly frequent topology | topology at any time, however, it should not destabilize the network | |||
changes. | with undue or overly frequent topology changes. If the Area Leader | |||
operates in centralized mode and needs to advertise a new flooding | ||||
topology, it floods the new flooding topology on both the new and old | ||||
flooding topologies. | ||||
If the Area Leader operates in centralized mode and needs to | If the Area Leader operates in distributed mode, it MUST advertise a | |||
advertises a new flooding topology, it floods a new flooding topology | non-zero algorithm in its Area Leader Sub-TLV. | |||
on both the new and old flooding topologies. | ||||
When the Area Leader advertises algorithm 0 in its Area Leader Sub- | ||||
TLV and does not advertise a flooding topology, Dynamic Flooding is | ||||
disabled for the area. Note this applies whether the Area Leader | ||||
intends to operate in centralized mode or in distributed mode. | ||||
Note that once Dynamic Flooding is enabled, disabling it risks | ||||
destabilizing the network. | ||||
6.5. Distributed Flooding Topology Calculation | 6.5. Distributed Flooding Topology Calculation | |||
If the Area Leader advertises a non-zero algorithm in its Area Leader | If the Area Leader advertises a non-zero algorithm in its Area Leader | |||
Sub-TLV, all nodes in the area that support Dynamic Flooding and the | Sub-TLV, all nodes in the area that support Dynamic Flooding and the | |||
value of algorithm advertised by the Area Leader MUST compute the | value of algorithm advertised by the Area Leader MUST compute the | |||
flooding topology based on the Area Leader's advertised algorithm. | flooding topology based on the Area Leader's advertised algorithm. | |||
Nodes that do not support the value of algorithm advertised by the | Nodes that do not support the value of algorithm advertised by the | |||
Area Leader MUST continue to use standard flooding mechanism as | Area Leader MUST continue to use standard flooding mechanism as | |||
skipping to change at page 31, line 19 ¶ | skipping to change at page 31, line 34 ¶ | |||
therefore possible to assign only a subset of the nodes connected to | therefore possible to assign only a subset of the nodes connected to | |||
the LAN to use the LAN as part of the flooding topology. Doing so | the LAN to use the LAN as part of the flooding topology. Doing so | |||
may further optimize flooding by reducing the amount of redundant | may further optimize flooding by reducing the amount of redundant | |||
flooding on a LAN. However, support of flooding only by a subset of | flooding on a LAN. However, support of flooding only by a subset of | |||
the nodes connected to a LAN requires some modest - but backwards | the nodes connected to a LAN requires some modest - but backwards | |||
compatible - changes in the way flooding is performed on a LAN. | compatible - changes in the way flooding is performed on a LAN. | |||
6.6.2.1. Partial flooding on a LAN in IS-IS | 6.6.2.1. Partial flooding on a LAN in IS-IS | |||
Designated Intermediate System (DIS) for a LAN MUST use standard | Designated Intermediate System (DIS) for a LAN MUST use standard | |||
flooding behavior: | flooding behavior. | |||
Non-DIS nodes whose connection to the LAN is included in the flooding | Non-DIS nodes whose connection to the LAN is included in the flooding | |||
topology MUST use standard flooding behavior. | topology MUST use standard flooding behavior. | |||
Non-DIS nodes whose connection to the LAN is NOT included in the | Non-DIS nodes whose connection to the LAN is NOT included in the | |||
flooding topology behave as follows: | flooding topology behave as follows: | |||
o Received CSNPs from the DIS are ignored | o Received CSNPs from the DIS are ignored | |||
o PSNPs are NOT originated on the LAN | o PSNPs are NOT originated on the LAN | |||
skipping to change at page 37, line 5 ¶ | skipping to change at page 37, line 26 ¶ | |||
check if there are any adjacent nodes that are disconnected from the | check if there are any adjacent nodes that are disconnected from the | |||
current flooding topology. Temporary flooding MUST be enabled | current flooding topology. Temporary flooding MUST be enabled | |||
towards a subset of the disconnected nodes. | towards a subset of the disconnected nodes. | |||
6.8.10. Failure of the Area Leader | 6.8.10. Failure of the Area Leader | |||
The failure of the Area Leader can be detected by observing that it | The failure of the Area Leader can be detected by observing that it | |||
is no longer reachable. In this case, the Area Leader election | is no longer reachable. In this case, the Area Leader election | |||
process is repeated and a new Area Leader is elected. | process is repeated and a new Area Leader is elected. | |||
In the centralized mode, the new Area Leader will compute a new | In order to minimize disruption to Dynamic Flooding if the Area | |||
flooding topology and flood it using the new flooding topology. | Leader becomes unreachable, the node which has the second highest | |||
priority for becoming Area Leader (including the system identifier/ | ||||
Router-ID tie breaker if necessary) SHOULD advertise the same | ||||
algorithm in its Area Leader Sub-TLV as the Area Leader and (in | ||||
centralized mode) SHOULD advertise a flooding topology. This SHOULD | ||||
be done even when the Area Leader is reachable. | ||||
As an optimization, applicable to centralized mode, the new Area | In centralized mode, the new Area Leader will compute a new flooding | |||
Leader MAY compute a new flooding topology that has as much in common | topology and flood it using the new flooding topology. To minimze | |||
disruption, the new flooding topology SHOULD have as much in common | ||||
as possible with the old flooding topology. This will minimize the | as possible with the old flooding topology. This will minimize the | |||
risk of over-flooding. | risk of over-flooding. | |||
In the distributed mode, the new flooding topology will be calculated | In the distributed mode, the new flooding topology will be calculated | |||
on all nodes that support the algorithm that is advertised by the new | on all nodes that support the algorithm that is advertised by the new | |||
Area Leader. Nodes that do not support the algorithm advertised by | Area Leader. Nodes that do not support the algorithm advertised by | |||
the new Area Leader will no longer participate in Dynamic Flooding | the new Area Leader will no longer participate in Dynamic Flooding | |||
and will revert to standard flooding. | and will revert to standard flooding. | |||
6.8.11. Recovery from Multiple Failures | 6.8.11. Recovery from Multiple Failures | |||
End of changes. 35 change blocks. | ||||
72 lines changed or deleted | 107 lines changed or added | |||
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