Internet Engineering Task Force H. Chen, Ed. Internet-Draft Huawei Technologies Intended status: Experimental R. Torvi, Ed. Expires: August 17, 2018 Juniper Networks February 13, 2018 Extensions to RSVP-TE for LSP Ingress FRR Protection draft-ietf-teas-rsvp-ingress-protection-13.txt Abstract This document describes extensions to Resource Reservation Protocol - Traffic Engineering (RSVP-TE) for locally protecting the ingress node of a Point-to-Point (P2P) or Point-to-Multipoint (P2MP) Traffic Engineered (TE) Label Switched Path (LSP). The procedures described in this document are experimental. Status of this Memo This Internet-Draft is submitted to IETF 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 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 17, 2018. Copyright Notice Copyright (c) 2018 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 Chen & Torvi Expires August 17, 2018 [Page 1] Internet-Draft LSP Ingress Protection February 2018 described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Ingress Local Protection . . . . . . . . . . . . . . . . . 4 2. Ingress Failure Detection . . . . . . . . . . . . . . . . . . 5 2.1. Source Detects Failure . . . . . . . . . . . . . . . . . . 5 2.2. Backup and Source Detect Failure . . . . . . . . . . . . . 5 3. Backup Forwarding State . . . . . . . . . . . . . . . . . . . 6 3.1. Forwarding State for Backup LSP . . . . . . . . . . . . . 6 4. Protocol Extensions . . . . . . . . . . . . . . . . . . . . . 7 4.1. INGRESS_PROTECTION Object . . . . . . . . . . . . . . . . 7 4.1.1. Subobject: Backup Ingress IPv4 Address . . . . . . . . 8 4.1.2. Subobject: Backup Ingress IPv6 Address . . . . . . . . 9 4.1.3. Subobject: Ingress IPv4 Address . . . . . . . . . . . 9 4.1.4. Subobject: Ingress IPv6 Address . . . . . . . . . . . 10 4.1.5. Subobject: Traffic Descriptor . . . . . . . . . . . . 10 4.1.6. Subobject: Label-Routes . . . . . . . . . . . . . . . 11 5. Behavior of Ingress Protection . . . . . . . . . . . . . . . . 11 5.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . 11 5.1.1. Relay-Message Method . . . . . . . . . . . . . . . . . 12 5.1.2. Proxy-Ingress Method . . . . . . . . . . . . . . . . . 12 5.2. Ingress Behavior . . . . . . . . . . . . . . . . . . . . . 13 5.2.1. Relay-Message Method . . . . . . . . . . . . . . . . . 14 5.2.2. Proxy-Ingress Method . . . . . . . . . . . . . . . . . 15 5.3. Backup Ingress Behavior . . . . . . . . . . . . . . . . . 16 5.3.1. Backup Ingress Behavior in Off-path Case . . . . . . . 16 5.3.2. Backup Ingress Behavior in On-path Case . . . . . . . 18 5.3.3. Failure Detection and Refresh PATH Messages . . . . . 19 5.4. Revertive Behavior . . . . . . . . . . . . . . . . . . . . 20 5.4.1. Revert to Primary Ingress . . . . . . . . . . . . . . 20 5.4.2. Global Repair by Backup Ingress . . . . . . . . . . . 20 6. Security Considerations . . . . . . . . . . . . . . . . . . . 21 7. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 21 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 9. Co-authors and Contributors . . . . . . . . . . . . . . . . . 22 10. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 24 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 24 11.1. Normative References . . . . . . . . . . . . . . . . . . . 24 11.2. Informative References . . . . . . . . . . . . . . . . . . 25 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 25 Chen & Torvi Expires August 17, 2018 [Page 2] Internet-Draft LSP Ingress Protection February 2018 1. Introduction For a MPLS TE LSP, protecting the failures of its transit nodes using fast-reroute (FRR) is covered in RFC 4090 for P2P LSP and RFC 4875 for P2MP LSP. However, protecting the failure of its ingress node using FRR is not covered in either RFC 4090 or RFC 4875. The MPLS Transport Profile (MPLS-TP) Linear Protection described in RFC 6378 can provide a protection against the failure of any transit node of a LSP between the ingress node and the egress node of the LSP, but cannot protect against the failure of the ingress node. To protect against the failure of the (primary) ingress node of a primary end to end P2MP (or P2P) TE LSP, a typical existing solution is to set up a secondary backup end to end P2MP (or P2P) TE LSP from a backup ingress node, which is different from the primary ingress node, to the backup egress nodes (or node), which are (or is) different from the primary egress nodes (or node) of the primary LSP. For a P2MP TE LSP, on each of the primary (and backup) egress nodes, a P2P LSP is created from the egress node to its primary (backup) ingress node and configured with BFD. This is used to detect the failure of the primary (backup) ingress node for the receiver to switch to the backup (or primary) egress node to receive the traffic after the primary (or backup) ingress node fails when both the primary LSP and the secondary LSP carry the traffic. In addition, FRR may be used to provide protections against the failures of the transit nodes and the links of the primary and secondary end to end TE LSPs. There are a number of issues in this solution, which are briefed as follows: o It consumes lots of network resources. Double states need to be maintained in the network since two end to end TE LSPs are created. Double link bandwidth is reserved and used when both the primary and the secondary end to end TE LSPs carry the traffic at the same time. o More operations are needed, which include the configurations of two end to end TE LSPs and BFDs from each of the egress nodes to its corresponding ingress node. o The detection of the failure of the ingress node may not be reliable. Any failure on the path of the BFD from an egress node to an ingress node may cause the BFD down to indicate the failure of the ingress node. Chen & Torvi Expires August 17, 2018 [Page 3] Internet-Draft LSP Ingress Protection February 2018 o The speed of protection against the failure of the ingress node may be slow. This specification defines a simple extension to RSVP-TE for local protection (FRR) of the ingress node of a P2MP or P2P LSP to resolve these issues. Ingress local protection and ingress FRR protection will be used exchangeably. Note that this document is experimental. Two different approaches are proposed to transfer the information for ingress protection. They both use the same new INGRESS_PROTECTION object, which is sent in both PATH and RESV messages between a primary ingress and a backup ingress. One approach is Relay-Message Method (refer to section 5.1.1 and 5.2.1), the other is Proxy-Ingress Method (refer to section 5.1.2 and 5.2.2). Each of them has its advantages and disadvantages. It is hard to decide which one is used as a standard approach now. After one approach is selected, the document SHOULD become proposed standard. 1.1. Ingress Local Protection Figure 1 shows an example of using a backup P2MP LSP to locally protect the ingress of a primary P2MP LSP, which is from ingress Ia to three egresses: L1, L2 and L3. The backup LSP is from backup ingress Ib to the next hops R2 and R4 of ingress Ia. ******* ******* S Source [R2]-----[R3]-----[L1] Ix Ingress */ & Rx Transit */ & Lx Egress */ & *** Primary LSP */ & &&& Backup LSP across */ & logical hop */ & */ ******** ******** ******* [S]---[Ia]--------[R4]------[R5]-----[L2] \ | & & *\ \ | & & *\ \ | & & *\ \ | & & *\ \ | & & *\ \ |& & *\ [Ib]&&& [L3] Figure 1: Ingress Local Protection In normal operations, source S sends the traffic to primary ingress Chen & Torvi Expires August 17, 2018 [Page 4] Internet-Draft LSP Ingress Protection February 2018 Ia. Ia imports the traffic into the primary LSP. When source S detects the failure of Ia, it switches the traffic to backup ingress Ib, which imports the traffic from S into the backup LSP to Ia's next hops R2 and R4, where the traffic is merged into the primary LSP, and then sent to egresses L1, L2 and L3. Note that the backup ingress is one logical hop away from the ingress. A logical hop is a direct link or a tunnel such as a GRE tunnel, over which RSVP-TE messages may be exchanged. 2. Ingress Failure Detection Exactly how to detect the failure of the ingress is out of scope. However, it is necessary to discuss different modes for detecting the failure because they determine what is the required behavior for the source and backup ingress. 2.1. Source Detects Failure Source Detects Failure or Source-Detect for short means that the source is responsible for fast detecting the failure of the primary ingress of an LSP. The backup ingress is ready to import the traffic from the source into the backup LSP(s) after the backup LSP(s) is up. In normal operations, the source sends the traffic to the primary ingress. When the source detects the failure of the primary ingress, it switches the traffic to the backup ingress, which delivers the traffic to the next hops of the primary ingress through the backup LSP(s), where the traffic is merged into the primary LSP. For an LSP, after the primary ingress fails, the backup ingress MUST use a method to reliably detect the failure of the primary ingress before the PATH message for the LSP expires at the next hop of the primary ingress. After reliably detecting the failure, the backup ingress sends/refreshes the PATH message to the next hop through the backup LSP as needed. The method may detect the failure of the primary ingress slowly such as in seconds. After the primary ingress fails, it will not be reachable after routing convergence. Thus checking whether the primary ingress (address) is reachable is a possible method. 2.2. Backup and Source Detect Failure Backup and Source Detect Failure or Backup-Source-Detect for short means that both the backup ingress and the source are concurrently Chen & Torvi Expires August 17, 2018 [Page 5] Internet-Draft LSP Ingress Protection February 2018 responsible for fast detecting the failure of the primary ingress. In normal operations, the source sends the traffic to the primary ingress. It switches the traffic to the backup ingress when it detects the failure of the primary ingress. The backup ingress does not import any traffic from the source into the backup LSP in normal operations. When it detects the failure of the primary ingress, it imports the traffic from the source into the backup LSP to the next hops of the primary ingress, where the traffic is merged into the primary LSP. The source-detect is preferred. It is simpler than the backup- source-detect, which needs both the source and the backup ingress detect the ingress failure quickly. 3. Backup Forwarding State Before the primary ingress fails, the backup ingress is responsible for creating the necessary backup LSPs. These LSPs might be multiple bypass P2P LSPs that avoid the ingress. Alternately, the backup ingress could choose to use a single backup P2MP LSP as a bypass or detour to protect the primary ingress of a primary P2MP LSP. The backup ingress may be off-path or on-path of an LSP. If a backup ingress is not any node of the LSP, we call it is off-path. If a backup ingress is a next-hop of the primary ingress of the LSP, we call it is on-path. When a backup ingress for protecting the primary ingress is configured or computed, the backup ingress MUST not be on the LSP except for it is the next hop of the primary ingress. If it is on-path, the primary forwarding state associated with the primary LSP SHOULD be clearly separated from the backup LSP(s) state. 3.1. Forwarding State for Backup LSP A forwarding entry for a backup LSP is created on the backup ingress after the LSP is set up. Depending on the failure-detection mode (e.g., source-detect), it may be used to forward received traffic or simply be inactive (e.g., backup-source-detect) until required. In either case, when the primary ingress fails, this entry is used to import the traffic into the backup LSP to the next hops of the primary ingress, where the traffic is merged into the primary LSP. The forwarding entry for a backup LSP is a local implementation issue. In one device, it may have an inactive flag. This inactive forwarding entry is not used to forward any traffic normally. When the primary ingress fails, it is changed to active, and thus the Chen & Torvi Expires August 17, 2018 [Page 6] Internet-Draft LSP Ingress Protection February 2018 traffic from the source is imported into the backup LSP. 4. Protocol Extensions A new object INGRESS_PROTECTION is defined for signaling ingress local protection. It is backward compatible. 4.1. INGRESS_PROTECTION Object The INGRESS_PROTECTION object with the FAST_REROUTE object in a PATH message is used to control the backup for protecting the primary ingress of a primary LSP. The primary ingress MUST insert this object into the PATH message to be sent to the backup ingress for protecting the primary ingress. It has the following format: Class-Num = TBD C-Type = 1 for INGRESS_PROTECTION_IPv4 C-Type = 2 for INGRESS_PROTECTION_IPv6 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Length (bytes) | Class-Num | C-Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved (zero) | NUB | Flags | Options | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ (Subobjects) ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ NUB Number of Unprotected Branches Flags 0x01 Ingress local protection available 0x02 Ingress local protection in use 0x04 Bandwidth protection Options 0x01 Revert to Ingress 0x02 P2MP Backup For protecting the ingress of a P2MP LSP, if the backup ingress doesn't have a backup LSP to each of the next hops of the primary ingress, it SHOULD clear "Ingress local protection available" and set NUB to the number of the next hops to which there is no backup LSP. The flags are used to communicate status information from the backup ingress to the primary ingress. Chen & Torvi Expires August 17, 2018 [Page 7] Internet-Draft LSP Ingress Protection February 2018 o Ingress local protection available: The backup ingress MUST set this flag after backup LSPs are up and ready for locally protecting the primary ingress. The backup ingress sends this to the primary ingress to indicate that the primary ingress is locally protected. o Ingress local protection in use: The backup ingress MUST set this flag when it detects a failure in the primary ingress and actively redirects the traffic into the backup LSPs. The backup ingress keeps it and does not send it to the primary ingress since the primary ingress is down. o Bandwidth protection: The backup ingress MUST set this flag if the backup LSPs guarantee to provide desired bandwidth for the protected LSP against the primary ingress failure. The options are used by the primary ingress to specify the desired behavior to the backup ingress. o Revert to Ingress: The primary ingress sets this option indicating that the traffic for the primary LSP successfully re-signaled will be switched back to the primary ingress from the backup ingress when the primary ingress is restored. o P2MP Backup: This option is set to ask for the backup ingress to use P2MP backup LSP to protect the primary ingress. The INGRESS_PROTECTION object may contain some sub objects of 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 (zero)| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Contents/Body of subobject | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ where Type is the type of a sub object, Length is the total size of the sub object in bytes, including Type, Length and Contents fields. 4.1.1. Subobject: Backup Ingress IPv4 Address When the primary ingress of a protected LSP sends a PATH message with an INGRESS_PROTECTION object to the backup ingress, the object MUST have a Backup Ingress IPv4 Address sub object containing an IPv4 address belonging to the backup ingress if IPv4 is used. The Type of Chen & Torvi Expires August 17, 2018 [Page 8] Internet-Draft LSP Ingress Protection February 2018 the sub object is TBD1 (the exact number to be assigned by IANA), and the body of the sub object is given below: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Backup ingress IPv4 address (4 bytes) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Backup ingress IPv4 address: An IPv4 host address of backup ingress 4.1.2. Subobject: Backup Ingress IPv6 Address When the primary ingress of a protected LSP sends a PATH message with an INGRESS_PROTECTION object to the backup ingress, the object MUST have a Backup Ingress IPv6 Address sub object containing an IPv6 address belonging to the backup ingress if IPv6 is used. The Type of the sub object is TBD2, the body of the sub object is given below: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Backup ingress IPv6 address (16 bytes) | ~ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Backup ingress IPv6 address: An IPv6 host address of backup ingress 4.1.3. Subobject: Ingress IPv4 Address The INGRESS_PROTECTION object may have an Ingress IPv4 Address sub object containing an IPv4 address belonging to the primary ingress if IPv4 is used. The Type of the sub object is TBD3. The sub object has the following body: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Ingress IPv4 address (4 bytes) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Ingress IPv4 address: An IPv4 host address of ingress Chen & Torvi Expires August 17, 2018 [Page 9] Internet-Draft LSP Ingress Protection February 2018 4.1.4. Subobject: Ingress IPv6 Address The INGRESS_PROTECTION object may have an Ingress IPv6 Address sub object containing an IPv6 address belonging to the primary ingress if IPv6 is used. The Type of the sub object is TBD4. The sub object has the following body: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Ingress IPv6 address (16 bytes) | ~ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Ingress IPv6 address: An IPv6 host address of ingress 4.1.5. Subobject: Traffic Descriptor The INGRESS_PROTECTION object may have a Traffic Descriptor sub object describing the traffic to be mapped to the backup LSP on the backup ingress for locally protecting the primary ingress. The Type of the sub object is TBD5, TBD6, TBD7 or TBD8 for Interface, IPv4 Prefix, IPv6 Prefix or Application Identifier respectively. The sub object has the following body: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Traffic Element 1 | ~ ~ | Traffic Element n | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The Traffic Descriptor sub object may contain multiple Traffic Elements of same type as follows: o Interface Traffic (Type TBD5): Each of the Traffic Elements is a 32 bit index of an interface, from which the traffic is imported into the backup LSP. o IPv4 Prefix Traffic (Type TBD6): Each of the Traffic Elements is an IPv4 prefix, containing an 8-bit prefix length followed by an IPv4 address prefix, whose length, in bits, is specified by the prefix length, padded to a byte boundary. Chen & Torvi Expires August 17, 2018 [Page 10] Internet-Draft LSP Ingress Protection February 2018 o IPv6 Prefix Traffic (Type TBD7): Each of the Traffic Elements is an IPv6 prefix, containing an 8-bit prefix length followed by an IPv6 address prefix, whose length, in bits, is specified by the prefix length, padded to a byte boundary. o Application Traffic (Type TBD8): Each of the Traffic Elements is a 32 bit identifier of an application, from which the traffic is imported into the backup LSP. 4.1.6. Subobject: Label-Routes The INGRESS_PROTECTION object in a PATH message from the primary ingress to the backup ingress will have a Label-Routes sub object containing the labels and routes that the next hops of the ingress use. The Type of the sub object is TBD9. The sub object has the following body: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ Subobjects ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The Subobjects in the Label-Routes are copied from those in the RECORD_ROUTE objects in the RESV messages that the primary ingress receives from its next hops for the primary LSP. They MUST contain the first hops of the LSP, each of which is paired with its label. 5. Behavior of Ingress Protection 5.1. Overview There are four parts of ingress protection: 1) setting up the necessary backup LSP forwarding state based on the information for ingress protection; 2) identifying the failure and providing the fast repair (as discussed in Sections 3 and 4); 3) maintaining the RSVP-TE control plane state until a global repair is done; and 4) performing the global repair(see Section 6.4). There are two different proposed signaling approaches to transfer the information for ingress protection. They both use the same new INGRESS_PROTECTION object. The object is sent in both PATH and RESV messages. Chen & Torvi Expires August 17, 2018 [Page 11] Internet-Draft LSP Ingress Protection February 2018 5.1.1. Relay-Message Method The primary ingress relays the information for ingress protection of an LSP to the backup ingress via PATH messages. Once the LSP is created, the ingress of the LSP sends the backup ingress a PATH message with an INGRESS_PROTECTION object with Label-Routes subobject, which is populated with the next-hops and labels. This provides sufficient information for the backup ingress to create the appropriate forwarding state and backup LSP(s). The ingress also sends the backup ingress all the other PATH messages for the LSP with an empty INGRESS_PROTECTION object. An INGRESS_PROTECTION object without any Traffic-Descriptor sub-object is called an empty INGRESS_PROTECTION object. Thus, the backup ingress has access to all the PATH messages needed for modification to refresh control-plane state after a failure. The empty INGRESS_PROTECTION object is for efficient process of ingress protection for a P2MP LSP. For a P2MP LSP, its primary ingress may have more than one PATH messages, each of which is sent to a next hop along a branch of the P2MP LSP. The PATH message along a branch will be selected and sent to the backup ingress with an INGRESS_PROTECTION object containing the Traffic-Descriptor sub- object; all the PATH messages along the other branches will be sent to the backup ingress containing an INGRESS_PROTECTION object without any Traffic-Descriptor sub-object (empty INGRESS_PROTECTION object). For a P2MP LSP, the backup ingress only needs one Traffic-Descriptor. The advantages of this method include: 1) the primary LSP is independent of the backup ingress; 2) simple; 3) less configuration; and 4) less control traffic. 5.1.2. Proxy-Ingress Method Conceptually, a proxy ingress is created that starts the RSVP signaling. The explicit path of the LSP goes from the proxy ingress to the backup ingress and then to the real ingress. The behavior and signaling for the proxy ingress is done by the real ingress; the use of a proxy ingress address avoids problems with loop detection. Note that the proxy ingress MUST reside within the same router as the real ingress. Chen & Torvi Expires August 17, 2018 [Page 12] Internet-Draft LSP Ingress Protection February 2018 [ traffic source ] *** Primary LSP $ $ --- Backup LSP $ $ $$ Link $ $ [ proxy ingress ] [ backup ] [ & ingress ] | * | *****[ MP ]----| Figure 2: Example Protected LSP with Proxy Ingress Node The backup ingress MUST know the merge points or next-hops and their associated labels. This is accomplished by having the RSVP PATH and RESV messages go through the backup ingress, although the forwarding path need not go through the backup ingress. If the backup ingress fails, the ingress simply removes the INGRESS_PROTECTION object and forwards the PATH messages to the LSP's next-hop(s). If the ingress has its LSP configured for ingress protection, then the ingress can add the backup ingress and itself to the ERO and start forwarding the PATH messages to the backup ingress. Slightly different behavior can apply for the on-path and off-path cases. In the on-path case, the backup ingress is a next hop node after the ingress for the LSP. In the off-path, the backup ingress is not any next-hop node after the ingress for all associated sub- LSPs. The key advantage of this approach is that it minimizes the special handling code requires. Because the backup ingress is on the signaling path, it can receive various notifications. It easily has access to all the PATH messages needed for modification to be sent to refresh control-plane state after a failure. 5.2. Ingress Behavior The primary ingress MUST be configured with a couple of pieces of information for ingress protection. o Backup Ingress Address: The primary ingress MUST know an IP address for it to be included in the INGRESS_PROTECTION object. o Proxy-Ingress-Id (only needed for Proxy-Ingress Method): The Proxy-Ingress-Id is only used in the Record Route Object for recording the proxy-ingress. If no proxy-ingress-id is specified, then a local interface address that will not otherwise be included in the Record Route Object can be used. A similar technique is used in [RFC4090 Sec 6.1.1]. Chen & Torvi Expires August 17, 2018 [Page 13] Internet-Draft LSP Ingress Protection February 2018 o Application Traffic Identifier: The primary ingress and backup ingress MUST both know what application traffic should be directed into the LSP. If a list of prefixes in the Traffic Descriptor sub-object will not suffice, then a commonly understood Application Traffic Identifier can be sent between the primary ingress and backup ingress. The exact meaning of the identifier should be configured similarly at both the primary ingress and backup ingress. The Application Traffic Identifier is understood within the unique context of the primary ingress and backup ingress. o A connection between backup ingress and primary ingress: If there is not any direct link between the primary ingress and the backup ingress, a tunnel MUST be configured between them. With this additional information, the primary ingress can create and signal the necessary RSVP extensions to support ingress protection. 5.2.1. Relay-Message Method To protect the primary ingress of an LSP, the primary ingress MUST do the following after the LSP is up. 1. Select a PATH message P0 for the LSP. 2. If the backup ingress is off-path (the backup ingress is not the next hop of the primary ingress for P0), then send it a PATH message P0' with the content from P0 and an INGRESS_PROTECTION object; else (the backup ingress is a next hop, i.e., on-path case) add an INGRESS_PROTECTION object into the existing PATH message to the backup ingress (i.e., the next hop). The object contains the Traffic-Descriptor sub-object, the Backup Ingress Address sub-object and the Label-Routes sub-object. The options is set to indicate whether a Backup P2MP LSP is desired. The Label-Routes sub-object contains the next-hops of the primary ingress and their labels. Note that for on-path case, there is an existing PATH message to the backup ingress (i.e., the next hop), and we just add an INGRESS_PROTECTION object into the existing PATH message to be sent to the backup ingress. We do not send a separate PATH message to the backup ingress for this existing PATH message. 3. For each Pi of the other PATH messages for the LSP, send the backup ingress a PATH message Pi' with the content copied from Pi and an empty INGRESS_PROTECTION object. For every PATH message Pj' (i.e., P0'/Pi') to be sent to the backup ingress, it has the same SESSION as Pj (i.e., P0/Pi). If the backup Chen & Torvi Expires August 17, 2018 [Page 14] Internet-Draft LSP Ingress Protection February 2018 ingress is off-path, the primary ingress updates Pj' according to the backup ingress as its next hop before sending it. It adds the backup ingress to the beginning of the ERO, and sets RSVP_HOP based on the interface to the backup ingress. The primary ingress MUST NOT set up any forwarding state to the backup ingress if the backup ingress is off-path. 5.2.2. Proxy-Ingress Method The primary ingress is responsible for starting the RSVP signaling for the proxy-ingress node. To do this, the following MUST be done for the RSVP PATH message. 1. Compute the EROs for the LSP as normal for the ingress. 2. If the selected backup ingress node is not the first node on the path (for all sub-LSPs), then insert at the beginning of the ERO first the backup ingress node and then the ingress node. 3. In the PATH RRO, instead of recording the ingress node's address, replace it with the Proxy-Ingress-Id. 4. Leave the HOP object populated as usual with information for the ingress-node. 5. Add the INGRESS_PROTECTION object to the PATH message. Include the Backup Ingress Address (IPv4 or IPv6) sub-object and the Traffic-Descriptor sub-object. Set or clear the options indicating that a Backup P2MP LSP is desired. 6. Optionally, add the FAST-REROUTE object [RFC4090] to the Path message. Indicate whether one-to-one backup is desired. Indicate whether facility backup is desired. 7. The RSVP PATH message is sent to the backup node as normal. If the ingress detects that it can't communicate with the backup ingress, then the ingress SHOULD instead send the PATH message to the next-hop indicated in the ERO computed in step 1. Once the ingress detects that it can communicate with the backup ingress, the ingress SHOULD follow the steps 1-7 to obtain ingress failure protection. When the ingress node receives an RSVP PATH message with an INGRESS_PROTECTION object and the object specifies that node as the ingress node and the PHOP as the backup ingress node, the ingress node SHOULD remove the INGRESS_PROTECTION object from the PATH message before sending it out. Additionally, the ingress node MUST store that it will install ingress forwarding state for the LSP Chen & Torvi Expires August 17, 2018 [Page 15] Internet-Draft LSP Ingress Protection February 2018 rather than midpoint forwarding. When an RSVP RESV message is received by the ingress, it uses the NHOP to determine whether the message is received from the backup ingress or from a different node. The stored associated PATH message contains an INGRESS_PROTECTION object that identifies the backup ingress node. If the RESV message is not from the backup node, then ingress forwarding state SHOULD be set up, and the INGRESS_PROTECTION object MUST be added to the RESV before it is sent to the NHOP, which SHOULD be the backup node. If the RESV message is from the backup node, then the LSP SHOULD be considered available for use. If the backup ingress node is on the forwarding path, then a RESV is received with an INGRESS_PROTECTION object and an NHOP that matches the backup ingress. In this case, the ingress node's address will not appear after the backup ingress in the RRO. The ingress node SHOULD set up ingress forwarding state, just as is done if the LSP weren't ingress-node protected. 5.3. Backup Ingress Behavior An LER determines that the ingress local protection is requested for an LSP if the INGRESS_PROTECTION object is included in the PATH message it receives for the LSP. The LER can further determine that it is the backup ingress if one of its addresses is in the Backup Ingress Address sub-object of the INGRESS_PROTECTION object. The LER as the backup ingress will assume full responsibility of the ingress after the primary ingress fails. In addition, the LER determines that it is off-path if it is not any node of the LSP. The LER determines whether it uses Relay-Message Method or Proxy-Ingress Method according to configurations. 5.3.1. Backup Ingress Behavior in Off-path Case The backup ingress considers itself as a PLR and the primary ingress as its next hop and provides a local protection for the primary ingress. It behaves very similarly to a PLR providing fast-reroute where the primary ingress is considered as the failure-point to protect. Where not otherwise specified, the behavior given in [RFC4090] for a PLR applies. The backup ingress MUST follow the control-options specified in the INGRESS_PROTECTION object and the flags and specifications in the FAST-REROUTE object. This applies to providing a P2MP backup if the "P2MP backup" is set, a one-to-one backup if "one-to-one desired" is set, facility backup if the "facility backup desired" is set, and backup paths that support the desired bandwidth, and administrative- colors that are requested. Chen & Torvi Expires August 17, 2018 [Page 16] Internet-Draft LSP Ingress Protection February 2018 If multiple non empty INGRESS_PROTECTION objects have been received via multiple PATH messages for the same LSP, then the most recent one MUST be the one used. The backup ingress creates the appropriate forwarding state for the backup LSP tunnel(s) to the merge point(s). When the backup ingress sends a RESV message to the primary ingress, it MUST add an INGRESS_PROTECTION object into the message. It MUST set or clear the flags in the object to report "Ingress local protection available", "Ingress local protection in use", and "bandwidth protection". If the backup ingress doesn't have a backup LSP tunnel to each of the merge points, it SHOULD clear "Ingress local protection available" and set NUB to the number of the merge points to which there is no backup LSP. When the primary ingress fails, the backup ingress redirects the traffic from a source into the backup P2P LSPs or the backup P2MP LSP transmitting the traffic to the next hops of the primary ingress, where the traffic is merged into the protected LSP. In this case, the backup ingress MUST keep the PATH message with the INGRESS_PROTECTION object received from the primary ingress and the RESV message with the INGRESS_PROTECTION object to be sent to the primary ingress. The backup ingress MUST set the "local protection in use" flag in the RESV message, indicating that the backup ingress is actively redirecting the traffic into the backup P2P LSPs or the backup P2MP LSP for locally protecting the primary ingress failure. Note that the RESV message with this piece of information will not be sent to the primary ingress because the primary ingress has failed. If the backup ingress has not received any PATH message from the primary ingress for an extended period of time (e.g., a cleanup timeout interval) and a confirmed primary ingress failure did not occur, then the standard RSVP soft-state removal SHOULD occur. The backup ingress SHALL remove the state for the PATH message from the primary ingress, and tear down the one-to-one backup LSPs for protecting the primary ingress if one-to-one backup is used or unbind the facility backup LSPs if facility backup is used. When the backup ingress receives a PATH message from the primary ingress for locally protecting the primary ingress of a protected LSP, it MUST check to see if any critical information has been changed. If the next hops of the primary ingress are changed, the backup ingress SHALL update its backup LSP(s) accordingly. Chen & Torvi Expires August 17, 2018 [Page 17] Internet-Draft LSP Ingress Protection February 2018 5.3.1.1. Relay-Message Method When the backup ingress receives a PATH message with an non empty INGRESS_PROTECTION object, it examines the object to learn what traffic associated with the LSP. It determines the next-hops to be merged to by examining the Label-Routes sub-object in the object. The backup ingress MUST store the PATH message received from the primary ingress, but NOT forward it. The backup ingress responds with a RESV message to the PATH message received from the primary ingress. If the backup ingress is off- path, the LABEL object in the RESV message contains IMPLICIT-NULL. If the INGRESS_PROTECTION object is not "empty", the backup ingress SHALL send the RESV message with the state indicating protection is available after the backup LSP(s) are successfully established. 5.3.1.2. Proxy-Ingress Method The backup ingress determines the next-hops to be merged to by collecting the set of the pair of (IPv4/IPv6 sub-object, Label sub- object) from the Record Route Object of each RESV that are closest to the top and not the Ingress router; this should be the second to the top pair. If a Label-Routes sub-object is included in the INGRESS_PROTECTION object, the included IPv4/IPv6 sub-objects are used to filter the set down to the specific next-hops where protection is desired. A RESV message MUST have been received before the Backup Ingress can create or select the appropriate backup LSP. When the backup ingress receives a PATH message with the INGRESS_PROTECTION object, the backup ingress examines the object to learn what traffic associated with the LSP. The backup ingress forwards the PATH message to the ingress node with the normal RSVP changes. When the backup ingress receives a RESV message with the INGRESS_PROTECTION object, the backup ingress records an IMPLICIT- NULL label in the RRO. Then the backup ingress forwards the RESV message to the ingress node, which is acting for the proxy ingress. 5.3.2. Backup Ingress Behavior in On-path Case An LER as the backup ingress determines that it is on-path if one of its addresses is a next hop of the primary ingress (and for Proxy- Ingress Method the primary ingress is not its next hop via checking the PATH message with the INGRESS_PROTECTION object received from the primary ingress). The LER on-path MUST send the corresponding PATH messages without any INGRESS_PROTECTION object to its next hops. It Chen & Torvi Expires August 17, 2018 [Page 18] Internet-Draft LSP Ingress Protection February 2018 creates a number of backup P2P LSPs or a backup P2MP LSP from itself to the other next hops (i.e., the next hops other than the backup ingress) of the primary ingress. The other next hops are from the Label-Routes sub object. It also creates a forwarding entry, which sends/multicasts the traffic from the source to the next hops of the backup ingress along the protected LSP when the primary ingress fails. The traffic is described by the Traffic-Descriptor. After the forwarding entry is created, all the backup P2P LSPs or the backup P2MP LSP is up and associated with the protected LSP, the backup ingress MUST send the primary ingress the RESV message with the INGRESS_PROTECTION object containing the state of the local protection such as "local protection available" flag set to one, which indicates that the primary ingress is locally protected. When the primary ingress fails, the backup ingress sends/multicasts the traffic from the source to its next hops along the protected LSP and imports the traffic into each of the backup P2P LSPs or the backup P2MP LSP transmitting the traffic to the other next hops of the primary ingress, where the traffic is merged into protected LSP. During the local repair, the backup ingress MUST continue to send the PATH messages to its next hops as before, keep the PATH message with the INGRESS_PROTECTION object received from the primary ingress and the RESV message with the INGRESS_PROTECTION object to be sent to the primary ingress. It MUST set the "local protection in use" flag in the RESV message. 5.3.3. Failure Detection and Refresh PATH Messages As described in [RFC4090], it is necessary to refresh the PATH messages via the backup LSP(s). The Backup Ingress MUST wait to refresh the PATH messages until it can accurately detect that the ingress node has failed. An example of such an accurate detection would be that the IGP has no bi-directional links to the ingress node or a BFD session to the primary ingress' loopback address has failed and stayed failed after the network has reconverged. As described in [RFC4090 Section 6.4.3], the backup ingress, acting as PLR, MUST modify and send any saved PATH messages associated with the primary LSP to the corresponding next hops through backup LSP(s). Any PATH message sent will not contain any INGRESS_PROTECTION object. The RSVP_HOP object in the message contains an IP source address belonging to the backup ingress. The sender template object has the backup ingress address as its tunnel sender address. Chen & Torvi Expires August 17, 2018 [Page 19] Internet-Draft LSP Ingress Protection February 2018 5.4. Revertive Behavior Upon a failure event in the (primary) ingress of a protected LSP, the protected LSP is locally repaired by the backup ingress. There are a couple of basic strategies for restoring the LSP to a full working path. - Revert to Primary Ingress: When the primary ingress is restored, it re-signals each of the LSPs that start from the primary ingress. The traffic for every LSP successfully re-signaled is switched back to the primary ingress from the backup ingress. - Global Repair by Backup Ingress: After determining that the primary ingress of an LSP has failed, the backup ingress computes a new optimal path, signals a new LSP along the new path, and switches the traffic to the new LSP. 5.4.1. Revert to Primary Ingress If "Revert to Primary Ingress" is desired for a protected LSP, the (primary) ingress of the LSP SHOULD re-signal the LSP that starts from the primary ingress after the primary ingress restores. After the LSP is re-signaled successfully, the traffic SHOULD be switched back to the primary ingress from the backup ingress on the source node and redirected into the LSP starting from the primary ingress. The primary ingress can specify the "Revert to Ingress" control- option in the INGRESS_PROTECTION object in the PATH messages to the backup ingress. After receiving the "Revert to Ingress" control- option, the backup ingress MUST stop sending/refreshing PATH messages for the protected LSP. 5.4.2. Global Repair by Backup Ingress When the backup ingress has determined that the primary ingress of the protected LSP has failed (e.g., via the IGP), it can compute a new path and signal a new LSP along the new path so that it no longer relies upon local repair. To do this, the backup ingress MUST use the same tunnel sender address in the Sender Template Object and allocate a LSP ID different from the one of the old LSP as the LSP-ID of the new LSP. This allows the new LSP to share resources with the old LSP. Alternately, the Backup Ingress can create a new LSP with no bandwidth reservation that duplicates the path(s) of the protected LSP, move traffic to the new LSP, delete the protected LSP, and then resignal the new LSP with bandwidth. Chen & Torvi Expires August 17, 2018 [Page 20] Internet-Draft LSP Ingress Protection February 2018 6. Security Considerations In principle this document does not introduce new security issues. The security considerations pertaining to RFC 4090, RFC 4875 and other RSVP protocols remain relevant. 7. Compatibility This extension reuses and extends semantics and procedures defined in RFC 2205, RFC 3209, RFC 4090 and RFC 4875 to support ingress protection. One new object is defined to indicate ingress protection with class numbers in the form 0bbbbbbb. Per RFC 2205, a node not supporting this extension will not recognize the new class number and should respond with an "Unknown Object Class" error. The error message will propagate to the ingress, which can then take action to avoid the incompatible node as a backup ingress or may simply terminate the session. 8. IANA Considerations IANA maintains a registry called "Class Names, Class Numbers, and Class Types" under "Resource Reservation Protocol-Traffic Engineering (RSVP-TE) Parameters". Upon approval of this document, IANA is requested to assign a new Class Number of form 0bbbbbbb for new object INGRESS_PROTECTION located at , as follows: +====================+===============+============================+ | Class Names | Class Numbers | Class Types | +====================+===============+============================+ | INGRESS_PROTECTION | TBD | 1: INGRESS_PROTECTION_IPv4 | | |(124 suggested)+----------------------------+ | | | 2: INGRESS_PROTECTION_IPv6 | +--------------------+---------------+----------------------------+ When this document moves to standards track, IANA is requested to create and maintain a new registry under INGRESS_PROTECTION located at . o Sub-object type - TBD INGRESS_PROTECTION Initial values for the registry are given below. The future assignments are to be made through IETF Review. Chen & Torvi Expires August 17, 2018 [Page 21] Internet-Draft LSP Ingress Protection February 2018 Value Name Definition 1 BACKUP_INGRESS_IPv4_ADDRESS Section 4.1.1 2 BACKUP_INGRESS_IPv6_ADDRESS Section 4.1.2 3 INGRESS_IPv4_ADDRESS Section 4.1.3 4 INGRESS_IPv6_ADDRESS Section 4.1.4 5 TRAFFIC_DESCRIPTOR_INTERFACE Section 4.1.5 6 TRAFFIC_DESCRIPTOR_IPv4_PREFIX Section 4.1.5 7 TRAFFIC_DESCRIPTOR_IPv6_PREFIX Section 4.1.5 8 TRAFFIC_DESCRIPTOR_APPLICATION Section 4.1.5 9 LABEL_ROUTES Section 4.1.6 9. Co-authors and Contributors 1. Co-authors Autumn Liu Ciena USA Email: hliu@ciena.com Zhenbin Li Huawei Technologies Email: zhenbin.li@huawei.com Yimin Shen Juniper Networks 10 Technology Park Drive Westford, MA 01886 USA Email: yshen@juniper.net Tarek Saad Cisco Systems Email: tsaad@cisco.com Chen & Torvi Expires August 17, 2018 [Page 22] Internet-Draft LSP Ingress Protection February 2018 Fengman Xu Verizon 2400 N. Glenville Dr Richardson, TX 75082 USA Email: fengman.xu@verizon.com 2. Contributors Ning So Tata Communications 2613 Fairbourne Cir. Plano, TX 75082 USA Email: ningso01@gmail.com Mehmet Toy Verizon USA Email: mehmet.toy@verizon.com Lei Liu USA Email: liulei.kddi@gmail.com Renwei Li Huawei Technologies 2330 Central Expressway Santa Clara, CA 95050 USA Email: renwei.li@huawei.com Quintin Zhao Huawei Technologies Boston, MA USA Email: quintin.zhao@huawei.com Chen & Torvi Expires August 17, 2018 [Page 23] Internet-Draft LSP Ingress Protection February 2018 Boris Zhang Telus Communications 200 Consilium Pl Floor 15 Toronto, ON M1H 3J3 Canada Email: Boris.Zhang@telus.com Markus Jork Juniper Networks 10 Technology Park Drive Westford, MA 01886 USA Email: mjork@juniper.net 10. Acknowledgement The authors would like to thank Nobo Akiya, Rahul Aggarwal, Eric Osborne, Ross Callon, Loa Andersson, Daniel King, Michael Yue, Alia Atlas, Olufemi Komolafe, Rob Rennison, Neil Harrison, Kannan Sampath, Gregory Mirsky, and Ronhazli Adam for their valuable comments and suggestions on this draft. 11. References 11.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/ RFC2119, March 1997, . [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol Label Switching Architecture", RFC 3031, DOI 10.17487/ RFC3031, January 2001, . [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, . [RFC4090] Pan, P., Ed., Swallow, G., Ed., and A. Atlas, Ed., "Fast Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090, Chen & Torvi Expires August 17, 2018 [Page 24] Internet-Draft LSP Ingress Protection February 2018 DOI 10.17487/RFC4090, May 2005, . [RFC4875] Aggarwal, R., Ed., Papadimitriou, D., Ed., and S. Yasukawa, Ed., "Extensions to Resource Reservation Protocol - Traffic Engineering (RSVP-TE) for Point-to- Multipoint TE Label Switched Paths (LSPs)", RFC 4875, DOI 10.17487/RFC4875, May 2007, . 11.2. Informative References [RFC6378] Weingarten, Y., Ed., Bryant, S., Osborne, E., Sprecher, N., and A. Fulignoli, Ed., "MPLS Transport Profile (MPLS-TP) Linear Protection", RFC 6378, DOI 10.17487/ RFC6378, October 2011, . Authors' Addresses Huaimo Chen (editor) Huawei Technologies Boston, MA USA Email: huaimo.chen@huawei.com Raveendra Torvi (editor) Juniper Networks 10 Technology Park Drive Westford, MA 01886 USA Email: rtorvi@juniper.net Chen & Torvi Expires August 17, 2018 [Page 25]