--- 1/draft-akiya-mpls-entropy-lsp-ping-00.txt 2013-12-16 19:14:31.826046698 -0800 +++ 2/draft-akiya-mpls-entropy-lsp-ping-01.txt 2013-12-16 19:14:31.862047609 -0800 @@ -1,32 +1,38 @@ Internet Engineering Task Force N. Akiya Internet-Draft G. Swallow Updates: 4379,6790 (if approved) C. Pignataro Intended status: Standards Track Cisco Systems -Expires: April 24, 2014 October 21, 2013 +Expires: June 18, 2014 December 15, 2013 Label Switched Path (LSP) Ping/Trace over MPLS Network using Entropy Labels (EL) - draft-akiya-mpls-entropy-lsp-ping-00 + draft-akiya-mpls-entropy-lsp-ping-01 Abstract The Multiprotocol Label Switching (MPLS) Label Switched Path (LSP) Ping and Traceroute are used to exercise specific paths of Equal Cost - Multipath (ECMP). This ability has been lost on some scenarios which - makes use of [RFC6790]: Entropy Labels (EL). + Multipath (ECMP). When LSP is signaled to use Entropy Label (EL) + described in RFC6790, the ability for LSP Ping and Traceroute + operation to discover and exercise ECMP paths has been lost in + scenarios which LSRs apply deviating load balance techniques. One + such scenario is when some LSRs apply EL based load balancing while + other LSRs apply non-EL based load balancing (ex: IP). Another + scenario is when EL based LSP is stitched with another LSP which can + be EL based or non-EL based. This document extends the MPLS LSP Ping and Traceroute mechanisms to restore the ability of exercising specific paths of ECMP over LSP - which make use of Entropy Label. This document updates [RFC4379] and - [RFC6790]. + which make use of Entropy Label. This document updates RFC4379 and + RFC6790. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. Status of This Memo This Internet-Draft is submitted in full conformance with the @@ -35,23 +41,24 @@ 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 April 24, 2014. + This Internet-Draft will expire on June 18, 2014. Copyright Notice + Copyright (c) 2013 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 @@ -53,47 +60,49 @@ (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents - 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 + 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Multipath Type 9 . . . . . . . . . . . . . . . . . . . . . . 5 4. Initiating LSR Procedures . . . . . . . . . . . . . . . . . . 6 5. Responder LSR Procedures . . . . . . . . . . . . . . . . . . 7 - 5.1. IP Based Load Balancer & Not Imposing ELI/EL . . . . . . 7 - 5.2. IP Based Load Balancer & Imposing ELI/EL . . . . . . . . 8 - 5.3. Label Based Load Balancer & Not Imposing ELI/EL . . . . . 8 - 5.4. Label Based Load Balancer & Imposing ELI/EL . . . . . . . 9 - 5.5. FAT MS-PW Stitching LSR . . . . . . . . . . . . . . . . . 9 + 5.1. IP Based Load Balancer & Not Pushing ELI/EL . . . . . . . 8 + 5.2. IP Based Load Balancer & Pushes ELI/EL . . . . . . . . . 8 + 5.3. Label Based Load Balancer & Not Pushing ELI/EL . . . . . 9 + 5.4. Label Based Load Balancer & Pushes ELI/EL . . . . . . . . 9 + 5.5. FAT MS-PW Stitching LSR . . . . . . . . . . . . . . . . . 10 6. Entropy Label FEC . . . . . . . . . . . . . . . . . . . . . . 10 - 7. DS Flags: L and E . . . . . . . . . . . . . . . . . . . . . . 10 - 8. New Multipath Information Type: 10 . . . . . . . . . . . . . 11 + 7. DS Flags: L and E . . . . . . . . . . . . . . . . . . . . . . 11 + 8. New Multipath Information Type: 10 . . . . . . . . . . . . . 12 9. Unsupported Cases . . . . . . . . . . . . . . . . . . . . . . 13 - 10. Security Considerations . . . . . . . . . . . . . . . . . . . 13 - 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 - 11.1. DS Flags . . . . . . . . . . . . . . . . . . . . . . . . 13 - 11.2. Multipath Information Types . . . . . . . . . . . . . . 13 - 11.3. Entropy Label FEC . . . . . . . . . . . . . . . . . . . 13 - 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14 - 13. Contributing Authors . . . . . . . . . . . . . . . . . . . . 14 - 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 - 14.1. Normative References . . . . . . . . . . . . . . . . . . 14 - 14.2. Informative References . . . . . . . . . . . . . . . . . 14 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 + 10. Security Considerations . . . . . . . . . . . . . . . . . . . 14 + 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 + 11.1. New Sub-Registries . . . . . . . . . . . . . . . . . . . 14 + 11.1.1. DS Flags . . . . . . . . . . . . . . . . . . . . . . 14 + 11.1.2. Multipath Type . . . . . . . . . . . . . . . . . . . 15 + 11.2. Entropy Label FEC . . . . . . . . . . . . . . . . . . . 15 + 12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15 + 13. Contributing Authors . . . . . . . . . . . . . . . . . . . . 15 + 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 16 + 14.1. Normative References . . . . . . . . . . . . . . . . . . 16 + 14.2. Informative References . . . . . . . . . . . . . . . . . 16 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 1. Introduction + Section 3.3.1 of [RFC4379] specifies multipath information encoding which can be used by LSP Ping initiator to trace and validate all ECMP paths between ingress and egress. These encodings are sufficient when all the LSRs along the path(s), between ingress and egress, consider same set of "keys" as input for load balancing algorithm: all IP based or all label based. With introduction of [RFC6790], it is quite normal to see set of LSRs performing load balancing based on EL/ELI while others still follow the traditional way (IP based). This results in LSP Ping initiator @@ -93,117 +102,125 @@ sufficient when all the LSRs along the path(s), between ingress and egress, consider same set of "keys" as input for load balancing algorithm: all IP based or all label based. With introduction of [RFC6790], it is quite normal to see set of LSRs performing load balancing based on EL/ELI while others still follow the traditional way (IP based). This results in LSP Ping initiator not be able to trace and validate all ECMP paths in following scenarios: - o One or more transit LSRs along ELI/EL imposed LSP do not perform - ECMP load balancing based on EL (hashes based on "keys" including - IP destination address). This scenario is not only possible but - quite common due transit LSRs not implementing [RFC6790] or - transit LSRs implementing [RFC6790] but not implementing suggested - transit LSR behavior in Section 4.3 of [RFC6790]. + o One or more transit LSRs along LSP with ELI/EL in label stack do + not perform ECMP load balancing based on EL (hashes based on + "keys" including IP destination address). This scenario is not + only possible but quite common due transit LSRs not implementing + [RFC6790] or transit LSRs implementing [RFC6790] but not + implementing suggested transit LSR behavior in Section 4.3 of + [RFC6790]. - o Two or more LSPs stitched together with at least one LSP being ELI - /EL imposing LSP. Such scenarios are described in + o Two or more LSPs stitched together with at least one of these LSP + pushing ELI/EL in label stack. Such scenarios are described in [I-D.ravisingh-mpls-el-for-seamless-mpls]. These scenarios will be quite common because every deployment of [RFC6790] will invariably end up with nodes that support ELI/EL and nodes that do not. There will typically be areas that support ELI/EL and areas that do not. As pointed out in [RFC6790] the procedures of [RFC4379] with respect to multipath information type {9} are incomplete. However [RFC6790] does not actually update [RFC4379]. Further the specific EL location - is not clearly defined, particularly in the case of FAT Pseudowires - [RFC6391]. Herein is defined a new FEC Stack sub-TLV for the Entropy - Label. Section 3 of this document updates the procedures for - multipath information type {9}. + is not clearly defined, particularly in the case of Flow-Aware + Transport Pseudowires [RFC6391]. This document defines a new FEC + Stack sub-TLV for the Entropy Label. Section 3 of this document + updates the procedures for multipath information type {9} described + in [RFC4379] Rest of this document describes extensions required to + restore ECMP discovery and tracing capabilities for scenarios + described. 2. Overview - [RFC4379] describes LSP traceroute as an operation performed through - initiating LSR sending LSP Ping packet (LSP echo request) with - incrementing TTL, starting with TTL of one. Initiating LSR discovers - and exercises ECMP by obtaining multipath information from each - transit LSR and using specific destination IP address or specific - entropy label. + [RFC4379] describes LSP traceroute as an operation where the + initiating LSR send a series of MPLS echo requests towards the same + destination. The first packet in the series have the TTL set to 1. + When the echo reply is received from the LSR one hop away the second + echo request in the series is sent with the TTL set to 2, for each + echo request the TLL is incremented by one until a response is + received from the intended destination. Initiating LSR discovers and + exercises ECMP by obtaining multipath information from each transit + LSR and using specific destination IP address or specific entropy + label. - LSP Ping initiating LSR sends LSP echo request with multipath + LSP Ping initiating LSR sends MPLS echo request with multipath information. This multipath information is described in DSMAP/DDMAP TLV of echo request, and can contain set of IP addresses or set of labels today. Multipath information types {2, 4, 8} carry set of IP addresses and multipath information type {9} carries set of labels. - Responder LSR (receiver of LSP echo request) is to determine subset + Responder LSR (receiver of MPLS echo request) is to determine subset of initiator specified multipath information which load balances to - each downstream (outgoing interface). Responder LSR sends LSP echo + each downstream (outgoing interface). Responder LSR sends MPLS echo reply with resulting multipath information per downstream (outgoing interface) back to the initiating LSR. Initiating LSR is then able to use specific IP destination address or specific label to exercise specific ECMP path on the responder LSR. Current behavior is problematic in following scenarios: o Initiating LSR sends IP multipath information, but responder LSR load balances on labels. o Initiating LSR sends label multipath information, but responder LSR load balances on IP addresses. - o Initiating LSR sends any of existing multipath information to ELI/ - EL imposing LSR, but initiating LSR can only continue to discover - and exercise specific path of ECMP if ELI/EL imposing LSR responds - with both IP addresses and associated EL corresponding to each IP - address. This is because: + o Initiating LSR sends one of existing multipath information to LSR + which pushes ELI/EL in label stack, but initiating LSR can only + continue to discover and exercise specific path of ECMP if LSR + which pushes ELI/EL responds with both IP addresses and associated + EL corresponding to each IP address. This is because: - * ELI/EL imposing LSR that is a stitching point will load balance + * ELI/EL pushing LSR that is a stitching point will load balance based on IP address. - * Downstream LSR(s) of ELI/EL imposing LSR may load balance based + * Downstream LSR(s) of ELI/EL pushing LSR may load balance based on ELs. - o Initiating LSR sends any of existing multipath information to ELI/ - EL imposing LSR, but initiating LSR can only continue to discover - and exercise specific path of ECMP if ELI/EL imposing LSR responds + o Initiating LSR sends one of existing multipath information to ELI/ + EL pushing LSR, but initiating LSR can only continue to discover + and exercise specific path of ECMP if ELI/EL pushing LSR responds with both labels and associated EL corresponding to label. This is because: - * ELI/EL imposing LSR that is a stitching point will load balance - based on EL from previous LSP and imposes new EL. + * ELI/EL pushing LSR that is a stitching point will load balance + based on EL from previous LSP and pushes new EL. - * Downstream LSR(s) of ELI/EL imposing LSR may load balance based + * Downstream LSR(s) of ELI/EL pushing LSR may load balance based on new ELs. The above scenarios point to how the existing multipath information is insufficient when LSP traceroute is operated on an LSP with Entropy Labels described by [RFC6790]. Therefore, this document defines a multipath information type to be used in the DSMAP/DDMAP of - LSP echo request/reply packets in Section 8. + MPLS echo request/reply packets in Section 8. In addition, responder LSR can reply with empty multipath information if no IP address set or label set from received multipath information matched load balancing to a downstream. Empty return is also possible if initiating LSR sends multipath information of one type, IP address or label, but responder LSR load balances on the other type. To disambiguate between the two results, this document introduces new flags in the DSMAP/DDMAP TLV to allow responder LSR to describe the load balance technique being used. It is required that all LSRs along the LSP understand new flags as well as new multipath information type. It is also required that initiating LSR can select both IP destination address and label to - use on transmitting LSP echo request packets. Two additional DS + use on transmitting MPLS echo request packets. Two additional DS Flags are defined for the DSMAP and DDMAP TLVs in Section 7. 3. Multipath Type 9 [RFC4379] defined multipath type {9} for tracing of LSPs where label based load-balancing is used. However, as pointed out in [RFC6790], the procedures for using this type are incomplete. First, the specific location of the label was not defined. What was assumed, but not spelled out, was that the presence of multipath type {9} meant the responder should act as if the payload of the received @@ -227,56 +244,56 @@ When an MPLS echo request message is received containing a FEC-Stack with an EL-FEC at the bottom of the FEC stack and is not preceded by an entropy label, the responder must behave (for load balancing purposes) as if the first word of the message were a Pseudowire Control Word. In order to trace a non-FAT pseudowire, instead of including the appropriate PW-FEC in the FEC-Stack, an EL-FEC is included. Tracing in this way will cause compliant routers to return the proper outgoing interface. Note that this procedure only traces to the end - of the MPLS transport LSP (e.g. LDP and/or RSVP). To actually verify - the PW-FEC or in the case of a MS-PW, to determine the next - pseudowire label value, the initiator MUST repeat that step of the - trace, (i.e., repeating the TTL value used) but with the FEC-Stack - modified to contain the appropriate PW-FEC. + of the MPLS LSP at transport layer (e.g. LDP and/or RSVP). To + actually verify the PW-FEC or in the case of a MS-PW, to determine + the next pseudowire label value, the initiator MUST repeat that step + of the trace, (i.e., repeating the TTL value used) but with the FEC- + Stack modified to contain the appropriate PW-FEC. - In order to trace a FAT pseudowire, the initiator includes an EL-FEC - at the bottom of the FEC-Stack and pushes the appropriate PW-FEC onto - the FEC-Stack. + In order to trace a Flow-Aware Transport Pseudowire, the initiator + includes an EL-FEC at the bottom of the FEC-Stack and pushes the + appropriate PW-FEC onto the FEC-Stack. 4. Initiating LSR Procedures In order to facilitate the flow of the following text we speak in terms of a boolean called EL_LSP maintained by the initiating LSR. This value controls the multipath information type to be used in transmitted echo request packets. When the initiating LSR is transmitting an echo request packet with DSMAP/DDMAP with a non-zero multipath information type, then EL_LSP boolean MUST be consulted to determine the multipath information type to use. In addition to procedures described in [RFC4379] as updated by Section 3 and [RFC6424], initiating LSR MUST operate with following procedures. - o When initiating LSR is IP based load balancer (not imposing ELI/ + o When initiating LSR is IP based load balancer (not pushing ELI/ EL), initialize EL_LSP=False. - o When initiating LSR imposes ELI/EL, initialize EL_LSP=True. + o When initiating LSR pushes ELI/EL, initialize EL_LSP=True. o When initiating LSR is transmitting non-zero multipath information type: - If (EL_LSP) initiating LSR MUST use multipath information type + * If (EL_LSP) initiating LSR MUST use multipath information type {10}. - Else initiating LSR MUST use multipath information type {2, 4, + * Else initiating LSR MUST use multipath information type {2, 4, 8, 9}. o When initiating LSR is transmitting multipath information type {10}, both "IP Multipath Information" and "Label Multipath Information" MUST be included, and "IP Associated Label Multipath Information" MUST be omitted (NULL). o When initiating LSR receives echo reply with {L=0, E=1} in DS flags with valid contents, set EL_LSP=True. @@ -296,141 +313,143 @@ contain associated label multipath information. o IP multipath information types {2, 4, 8} sent, and received echo reply with {L=1, E=0} in DS flags. o Multipath information type {10} sent, and received echo reply with multipath information type other than {10}. 5. Responder LSR Procedures - Common Procedures: Responder LSR receiving LSP echo request packet + Common Procedures: Responder LSR receiving MPLS echo request packet with multipath information type {10} MUST validate following contents. Any deviation MUST result in responder LSR to consider the packet as malformed and return code 1 (Malformed echo request - received) in LSP echo reply packet. + received) in MPLS echo reply packet. o IP multipath information MUST be included. o Label multipath information MUST be included. o IP associated label multipath information MUST be omitted (NULL). Following subsections describe expected responder LSR procedures when echo reply is to include DSMAP/DDMAP TLVs, based on local load balance technique being employed. In case responder LSR performs deviating load balance techniques per downstream basis, appropriate procedures matching to each downstream load balance technique MUST be operated. -5.1. IP Based Load Balancer & Not Imposing ELI/EL +5.1. IP Based Load Balancer & Not Pushing ELI/EL o Responder MUST set {L=0, E=0} in DS flags. o If multipath information type {2, 4, 8} is received, responder MUST comply with [RFC4379]/[RFC6424]. o If multipath information type {9} is received, responder MUST reply with multipath type {0}. o If multipath information type {10} is received, responder MUST reply with multipath information type {10}. "Label Multipath Information" and "Associated Label Multipath Information" sections MUST be omitted (NULL). If no matching IP address is found, then "IPMultipathType" field MUST be set to multipath information type {0} and "IP Multipath Information" section MUST also be omitted (NULL). If at least one matching IP address is found, then "IPMultipathType" field MUST be set to appropriate multipath information type {2, 4, 8} and "IP Multipath Information" section MUST be included. -5.2. IP Based Load Balancer & Imposing ELI/EL +5.2. IP Based Load Balancer & Pushes ELI/EL o Responder MUST set {L=0, E=1} in DS flags. o If multipath information type {9} is received, responder MUST reply with multipath type {0}. o If multipath type {2, 4, 8, 10} is received, responder MUST - respond with multipath type {10}. "Label Multipath Information" - section MUST be omitted (NULL). IP address set specified in + respond with multipath type {10}. See Section 8 for details of + multipath type {10}. "Label Multipath Information" section MUST be + omitted (i.e. is it not there). IP address set specified in received IP multipath information MUST be used to determine the returning IP/Label pairs. If received multipath information type was {10}, received "Label Multipath Information" sections MUST NOT be used to determine the associated label portion of returning IP/ Label pairs. If no matching IP address is found, then "IPMultipathType" field MUST be set to multipath information type - {0} and "IP Multipath Information" section MUST be omitted (NULL). - In addition, "Assoc Label Multipath Length" MUST be set to 0, and + {0} and "IP Multipath Information" section MUST be omitted. In + addition, "Assoc Label Multipath Length" MUST be set to 0, and "Associated Label Multipath Information" section MUST also be - omitted (NULL). If at least one matching IP address is found, - then "IPMultipathType" field MUST be set to appropriate multipath + omitted. If at least one matching IP address is found, then + "IPMultipathType" field MUST be set to appropriate multipath information type {2, 4, 8} and "IP Multipath Information" section MUST be included. In addition, "Associated Label Multipath Information" section MUST be populated with list of labels corresponding to each IP address specified in "IP Multipath Information" section. "Assoc Label Multipath Length" MUST be set - to appropriate value. + to a value representing length in octets of "Associated Label + Multipath Information" field. -5.3. Label Based Load Balancer & Not Imposing ELI/EL +5.3. Label Based Load Balancer & Not Pushing ELI/EL o Responder MUST set {L=1, E=0} in DS flags. o If multipath information type {2, 4, 8} is received, responder MUST reply with multipath type {0}. o If multipath information type {9} is received, responder MUST comply with [RFC4379] /[RFC6424] as updated by Section 3. o If multipath information type {10} is received, responder MUST reply with multipath information type {10}. "IP Multipath Information" and "Associated Label Multipath Information" sections MUST be omitted (NULL). If no matching label is found, then "LbMultipathType" field MUST be set to multipath information type {0} and "Label Multipath Information" section MUST also be omitted (NULL). If at least one matching label is found, then "LbMultipathType" field MUST be set to appropriate multipath information type {9} and "Label Multipath Information" section MUST be included. -5.4. Label Based Load Balancer & Imposing ELI/EL +5.4. Label Based Load Balancer & Pushes ELI/EL o Responder MUST set {L=1, E=1} in DS flags. o If multipath information type {2, 4, 8} is received, responder MUST reply with multipath type {0}. o If multipath type {9, 10} is received, responder MUST respond with multipath type {10}. "IP Multipath Information" section MUST be - omitted (NULL). Label set specified in received label multipath + omitted. Label set specified in received label multipath information MUST be used to determine the returning Label/Label pairs. If received multipath information type was {10}, received "Label Multipath Information" sections MUST NOT be used to determine the associated label portion of returning Label/Label pairs. If no matching label is found, then "LbMultipathType" field MUST be set to multipath information type {0} and "Label - Multipath Information" section MUST be omitted (NULL). In - addition, "Assoc Label Multipath Length" MUST be set to 0, and - "Associated Label Multipath Information" section MUST also be - omitted (NULL). If at least one matching label is found, then - "LbMultipathType" field MUST be set to appropriate multipath - information type {9} and "Label Multipath Information" section - MUST be included. In addition, "Associated Label Multipath - Information" section MUST be populated with list of labels - corresponding to each label specified in "Label Multipath - Information" section. "Assoc Label Multipath Length" MUST be set - to appropriate value. + Multipath Information" section MUST be omitted. In addition, + "Assoc Label Multipath Length" MUST be set to 0, and "Associated + Label Multipath Information" section MUST also be omitted. If at + least one matching label is found, then "LbMultipathType" field + MUST be set to appropriate multipath information type {9} and + "Label Multipath Information" section MUST be included. In + addition, "Associated Label Multipath Information" section MUST be + populated with list of labels corresponding to each label + specified in "Label Multipath Information" section. "Assoc Label + Multipath Length" MUST be set to a value representing length in + octets of "Associated Label Multipath Information" field. 5.5. FAT MS-PW Stitching LSR - MS-PW stitching LSR that xconnects flow-aware pseudowires behaves in - one of two ways: + Stitching LSR that xconnects Flow-Aware Transport Pseudowires behave + in one of two ways: o Load balances on previous flow label, and carries over same flow label. For this case, stitching LSR is to behave as procedures described in Section 5.3. o Load balances on previous flow label, and replaces flow label with newly computed. For this case, stitching LSR is to behave as procedures described in Section 5.4. 6. Entropy Label FEC @@ -477,38 +496,37 @@ Flag Name and Meaning ---- ---------------- L Label based load balance indicator This flag MUST be set to zero in the echo request. LSR which performs load balancing on a label MUST set this flag in the echo reply. LSR which performs load balancing on IP MUST NOT set this flag in the echo reply. - E ELI/EL imposer indicator + E ELI/EL push indicator This flag MUST be set to zero in the echo request. LSR - which imposes ELI/EL MUST set this flag in the echo - reply. LSR which does not impose ELI/EL MUST NOT set + which pushes ELI/EL MUST set this flag in the echo + reply. LSR which does not push ELI/EL MUST NOT set this flag in the echo reply. Two flags result in four load balancing techniques which echo reply generating LSR can indicate: - o {L=0, E=0} LSR load balances based on IP and does not impose ELI/ - EL. + o {L=0, E=0} LSR load balances based on IP and does not push ELI/EL. - o {L=0, E=1} LSR load balances based on IP and imposes ELI/EL. + o {L=0, E=1} LSR load balances based on IP and pushes ELI/EL. - o {L=1, E=0} LSR load balances based on label and does not impose - ELI/EL. + o {L=1, E=0} LSR load balances based on label and does not push ELI/ + EL. - o {L=1, E=1} LSR load balances based on label and imposes ELI/EL. + o {L=1, E=1} LSR load balances based on label and pushes ELI/EL. 8. New Multipath Information Type: 10 One new multipath information type is added to be used in DSMAP/DDMAP TLVs. New multipath type has value of 10. Key Type Multipath Information --- ---------------- --------------------- 10 IP and label set IP addresses and label prefixes @@ -534,98 +552,165 @@ | (Label Multipath Information) | ~ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved(MBZ) | Assoc Label Multipath Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ ~ | (Associated Label Multipath Information) | ~ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + o IPMultipathType + + * 0 when "IP Multipath Information" is omitted. Otherwise one of + IP multipath information values: {2, 4, 8}. + o IP Multipath Information + * This section is omitted when "IPMultipathType" is 0. Otherwise + this section reuses IP multipath information from [RFC4379]. + Specifically, multipath information for values {2, 4, 8} can be + used. - This section reuses IP multipath information from [RFC4379]. - Specifically, values {0, 2, 4, 8} can be used. + o LbMultipathType + + * 0 when "Label Multipath Information" is omitted. Otherwise + label multipath information value {9}. o Label Multipath Information - This section reuses label multipath information from [RFC4379]. - Specifically, values {0, 9} can be used. + * This section is omitted when "LbMultipathType" is 0. Otherwise + this section reuses label multipath information from [RFC4379]. + Specifically, multipath information for value {9} can be used. o Associated Label Multipath Information - "Assoc Label Multipath Length" is a 16 bit field of multipath + * "Assoc Label Multipath Length" is a 16 bit field of multipath information which indicates length in octets of the associated label multipath information. - "Associated Label Multipath Information" is a list of labels + * "Associated Label Multipath Information" is a list of labels with each label described in 24 bits. This section MUST be - omitted (NULL) in an MPLS Echo Request message. A midpoint - which imposes ELI/EL labels SHOULD include "Assoc Label - Multipath Information" in its MPLS Echo Reply message, along - with either "IP Multipath Information" or "Label Multipath - Information". Each specified associated label described in - this section maps to specific IP address OR label described in - the "IP Multipath Information" section or "Label Multipath - Information" section. For example, if 3 IP addresses are - specified in the "IP Multipath Information" section, then there - MUST be 3 labels described in this section. First label maps - to the lowest IP address specified, second label maps to the - second lowest IP address specified and third label maps to the - third lowest IP address specified. + omitted in an MPLS echo request message. A midpoint which + pushes ELI/EL labels SHOULD include "Assoc Label Multipath + Information" in its MPLS echo reply message, along with either + "IP Multipath Information" or "Label Multipath Information". + Each specified associated label described in this section maps + to specific IP address OR label described in the "IP Multipath + Information" section or "Label Multipath Information" section. + For example, if 3 IP addresses are specified in the "IP + Multipath Information" section, then there MUST be 3 labels + described in this section. First label maps to the lowest IP + address specified, second label maps to the second lowest IP + address specified and third label maps to the third lowest IP + address specified. 9. Unsupported Cases There are couple of scenarios where LSP path tracing mechanics are not supported in this draft revision. o When one or more LSP transit node(s) performs label based load balancing on a label that is not bottom-of-stack label when Entropy Label Indicator is not included. o When one or more LSP transit node(s) performs label based load balancing on a label other than Entropy Label when Entropy Label Indicator and Entropy Label pair is included. 10. Security Considerations - Beyond those specified in [RFC4379], [RFC6424] and [RFC6790], there - are no further security measured required. + This document extends LSP Traceroute mechanism to discover and + exercise ECMP paths when LSP uses ELI/EL in label stack. Additional + processings are required for responder and initiator nodes. + Responder node that pushes ELI/EL will need to compute and return + multipath data including associated EL. Initiator node will need to + store and handle both IP multipath and label multipath information, + and include destination IP addresses and/or ELs in MPLS echo request + packet as well as in carried multipath information to downstream + nodes. Due to additional processing, it is critical that proper + security measures described in [RFC4379] and [RFC6424] are followed. 11. IANA Considerations -11.1. DS Flags +11.1. New Sub-Registries - DS flags ... not maintained by IANA. Should it be? + [RFC4379] defines the Downstream Mapping TLV, which has the Type 2 + assigned from the "Multi-Protocol Label Switching (MPLS) Label + Switched Paths (LSPs) Ping Parameters - TLVs" registry. [RFC6424] + defines the Downstream Detailed Mapping TLV, which has the Type 20 + assigned from the "Multi-Protocol Label Switching (MPLS) Label + Switched Paths (LSPs) Ping Parameters - TLVs" registry. Both TLVs + shares two fields: "DS Flags" and "Multipath Type". This document + requires allocation of new values in both the "DS Flags" and + "Multipath Type" fields, which are not maintained by IANA today. + Therefore, this document requests IANA to create new registries + within [IANA-MPLS-LSP-PING] protocol to maintain "DS Flags" and + "Multipath Type" fields. Name of registries and initial values are + described in immediate sub-sections to follow. -11.2. Multipath Information Types +11.1.1. DS Flags - Multipath information types ... not maintained by IANA. Should it - be? + Bit number Name Reference + ---------- ---------------------------------------- --------- + 7 N: Treat as a Non-IP Packet RFC4379 + 6 I: Interface and Label Stack Object Request RFC4379 + 5 E: ELI/EL push indicator this document + 4 L: Label based load balance indicator this document + 3-0 Unassigned -11.3. Entropy Label FEC + Assignments of DS Flags are via Standards Action [RFC5226] or IESG + Approval [RFC5226]. - IANA is requested to assign a new sub-TLV from the "Sub-TLVs for TLV - Types 1 and 16" section from "TLVs" sub-registry within the "Multi- - Protocol Label Switching (MPLS) Label Switched Paths (LSPs) Ping - Parameters" registry. + Note that "DS Flags" is a field included in two TLVs defined in + "Multi-Protocol Label Switching (MPLS) Label Switched Paths (LSPs) + Ping Parameters - TLVs" registry: Downstream Mapping TLV (value 2) + and Downstream Detailed Mapping TLV (value 20). Modification to "DS + Flags" registry will affect both TLVs. - Following value appears to be next available sub-TLV value. - Requesting IANA to allow specified value as early allocation. +11.1.2. Multipath Type Value Meaning Reference - ----- ------- --------- - 26 Entropy Label FEC this document + ---------- ---------------------------------------- --------- + 0 no multipath RFC4379 + 1 Unassigned + 2 IP address RFC4379 + 3 Unassigned + 4 IP address range RFC4379 + 5-7 Unassigned + 8 Bit-masked IP address set RFC4379 + 9 Bit-masked label set RFC4379 + 10 IP and label set this document + 11-255 Unassigned + + Assignments of Multipath Type are via IETF Review [RFC5226] or IESG + Approval [RFC5226]. + + Note that "Multipath Type" is a field included in two TLVs defined in + "Multi-Protocol Label Switching (MPLS) Label Switched Paths (LSPs) + Ping Parameters - TLVs" registry: Downstream Mapping TLV (value 2) + and Downstream Detailed Mapping TLV (value 20). Modification to + "Multipath Type" registry will affect both TLVs. + +11.2. Entropy Label FEC + + IANA is requested to assign a new sub-TLV from the "Sub-TLVs for TLV + Types 1 and 16" section from "Multi-Protocol Label Switching (MPLS) + Label Switched Paths (LSPs) Ping Parameters - TLVs" registry. + + Sub-Type Sub-TLV Name Reference + -------- ------------ --------- + TBD1 Entropy Label FEC this document 12. Acknowledgements - TBD + Authors would like to thank Loa Andersson for performing thorough + review and providing valuable comments. 13. Contributing Authors Nagendra Kumar Cisco Systems Email: naikumar@cisco.com 14. References 14.1. Normative References @@ -639,21 +724,31 @@ [RFC6790] Kompella, K., Drake, J., Amante, S., Henderickx, W., and L. Yong, "The Use of Entropy Labels in MPLS Forwarding", RFC 6790, November 2012. 14.2. Informative References [I-D.ravisingh-mpls-el-for-seamless-mpls] Singh, R., Shen, Y., and J. Drake, "Entropy label for seamless MPLS", draft-ravisingh-mpls-el-for-seamless- - mpls-00 (work in progress), February 2013. + mpls-01 (work in progress), October 2013. + + [IANA-MPLS-LSP-PING] + IANA, "Multi-Protocol Label Switching (MPLS) Label + Switched Paths (LSPs) Ping Parameters", + . + + [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an + IANA Considerations Section in RFCs", BCP 26, RFC 5226, + May 2008. [RFC6391] Bryant, S., Filsfils, C., Drafz, U., Kompella, V., Regan, J., and S. Amante, "Flow-Aware Transport of Pseudowires over an MPLS Packet Switched Network", RFC 6391, November 2011. [RFC6424] Bahadur, N., Kompella, K., and G. Swallow, "Mechanism for Performing Label Switched Path Ping (LSP Ping) over MPLS Tunnels", RFC 6424, November 2011.