draft-ietf-mpls-egress-tlv-for-nil-fec-01.txt   draft-ietf-mpls-egress-tlv-for-nil-fec-02.txt 
Routing area D. Rathi, Ed. Routing area D. Rathi, Ed.
Internet-Draft K. Arora Internet-Draft K. Arora
Intended status: Standards Track S. Hegde Intended status: Standards Track S. Hegde
Expires: April 23, 2022 Juniper Networks Inc. Expires: June 6, 2022 Juniper Networks Inc.
Z. Ali Z. Ali
N. Nainar N. Nainar
Cisco Systems, Inc. Cisco Systems, Inc.
October 20, 2021 December 3, 2021
Egress TLV for Nil FEC in Label Switched Path Ping and Traceroute Egress TLV for Nil FEC in Label Switched Path Ping and Traceroute
Mechanisms Mechanisms
draft-ietf-mpls-egress-tlv-for-nil-fec-01 draft-ietf-mpls-egress-tlv-for-nil-fec-02
Abstract Abstract
MPLS ping and traceroute mechanism as described in RFC 8029 and MPLS ping and traceroute mechanism as described in RFC 8029 and
related extensions for SR as defined in RFC 8287 is very useful to related extensions for SR as defined in RFC 8287 is very useful to
precisely validate the control plane and data plane synchronization. precisely validate the control plane and data plane synchronization.
There is a possibility that all intermediate or transit nodes may not There is a possibility that all intermediate or transit nodes may not
have been upgraded to support these validation procedures. A simple have been upgraded to support these validation procedures. A simple
mpls ping and traceroute mechanism comprises of ability to traverse mpls ping and traceroute mechanism comprises of ability to traverse
any path without having to validate the control plane state. RFC any path without having to validate the control plane state. RFC
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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 April 23, 2022. This Internet-Draft will expire on June 6, 2022.
Copyright Notice Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the Copyright (c) 2021 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
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Request message. Its an optional TLV and should appear before FEC- Request message. Its an optional TLV and should appear before FEC-
stack TLV in the MPLS Echo Request packet. In case multiple Nil FEC stack TLV in the MPLS Echo Request packet. In case multiple Nil FEC
is present in Target FEC Stack TLV, Egress TLV should be added is present in Target FEC Stack TLV, Egress TLV should be added
corresponding to the ultimate egress of the label-stack. It can be corresponding to the ultimate egress of the label-stack. It can be
use for any kind of path with Egress TLV added corresponding to the use for any kind of path with Egress TLV added corresponding to the
end-point of the path. Explicit Path can be created using node-sid, end-point of the path. Explicit Path can be created using node-sid,
adj-sid, binding-sid etc, EGRESS TLV prefix will be derived from path adj-sid, binding-sid etc, EGRESS TLV prefix will be derived from path
egress/destination and not based on labels used in the path to reach egress/destination and not based on labels used in the path to reach
the destination. The format is as specified below: the destination. The format is as specified below:
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 = TBD1 (EGRESS TLV) | Length | | Type = 28 (EGRESS TLV) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix (4 or 16 octets) | | Prefix (4 or 16 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type : TBD1 (Section 7.1) Type : 28 (Section 7.1)
Length : variable based on IPV4/IPV6 prefix. Length excludes the Length : variable based on IPV4/IPV6 prefix. Length excludes the
length of Type and length field. Length will be 4 octets for IPv4 length of Type and length field. Length will be 4 octets for IPv4
and 16 octets for IPv6. and 16 octets for IPv6.
Prefix : This field carries the valid IPv4 prefix of length 4 octets Prefix : This field carries the valid IPv4 prefix of length 4 octets
or valid IPv6 Prefix of length 16 octets. It can be obtained from or valid IPv6 Prefix of length 16 octets. It can be obtained from
egress of Nil FEC corresponding to last label in the label-stack or egress of Nil FEC corresponding to last label in the label-stack or
SR-TE policy endpoint field [I.D-ietf-idr-segment-routing-te-policy]. SR-TE policy endpoint field [I.D-ietf-idr-segment-routing-te-policy].
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Stack sub-TLV at FEC-stack-depth is Nil FEC, set Best-return-code to Stack sub-TLV at FEC-stack-depth is Nil FEC, set Best-return-code to
8 ("Label switched at stack-depth") and Best-return-subcode to Label- 8 ("Label switched at stack-depth") and Best-return-subcode to Label-
stack-depth to report transit switching in MPLS Echo Reply message. stack-depth to report transit switching in MPLS Echo Reply message.
2. If the Label-stack-depth is 0 and the Target FEC Stack sub-TLV at 2. If the Label-stack-depth is 0 and the Target FEC Stack sub-TLV at
FEC-stack-depth is Nil FEC then do the look up for an exact match of FEC-stack-depth is Nil FEC then do the look up for an exact match of
the EGRESS TLV prefix to any of locally configured interfaces or the EGRESS TLV prefix to any of locally configured interfaces or
loopback addresses. loopback addresses.
2a. If EGRESS TLV prefix look up succeeds, set Best-return-code to 2a. If EGRESS TLV prefix look up succeeds, set Best-return-code to
TBD2 ("Replying router is an egress for the prefix in EGRESS-TLV") 36 ("Replying router is an egress for the prefix in EGRESS-TLV")
(Section 7.2) and Best-return-subcode to 1 to report egress ok in (Section 7.2) and Best-return-subcode to 1 to report egress ok in
MPLS Echo Reply message. MPLS Echo Reply message.
2b. If EGRESS TLV prefix look up fails, set the Best-return-code to 2b. If EGRESS TLV prefix look up fails, set the Best-return-code to
10, "Mapping for this FEC is not the given label at stack-depth" and 10, "Mapping for this FEC is not the given label at stack-depth" and
Best-return-subcode to 1. Best-return-subcode to 1.
5. Backward Compatibility 5. Backward Compatibility
The extension proposed in this document is backward compatible with The extension proposed in this document is backward compatible with
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TBD TBD
7. IANA Considerations 7. IANA Considerations
7.1. New TLV 7.1. New TLV
IANA need to assign new value for EGRESS TLV in the "Multi-Protocol IANA need to assign new value for EGRESS TLV in the "Multi-Protocol
Label Switching (MPLS) Label Switched Paths (LSPs) Ping Parameters" Label Switching (MPLS) Label Switched Paths (LSPs) Ping Parameters"
in "TLVs" sub-registry [IANA]. in "TLVs" sub-registry [IANA].
+----------------+-------------+---------------+ +-------+-------------+---------------+
| Value | Description | Reference | | Value | Description | Reference |
+----------------+-------------+---------------+ +-------+-------------+---------------+
| TBD1 | EGRESS TLV | Section 3 | | 28 | EGRESS TLV | Section 3 |
| (suggested 28) | | This document | | | | This document |
+----------------+-------------+---------------+ +-------+-------------+---------------+
Table 1: TLVs Sub-Registry Table 1: TLVs Sub-Registry
7.2. New Return code 7.2. New Return code
IANA need to assign new Return Code for "Replying router is an egress IANA need to assign new Return Code for "Replying router is an egress
for the prefix in EGRESS-TLV" in the "Multi-Protocol Label Switching for the prefix in EGRESS-TLV" in the "Multi-Protocol Label Switching
(MPLS) Label Switched Paths (LSPs) Ping Parameters" in "Return Codes" (MPLS) Label Switched Paths (LSPs) Ping Parameters" in "Return Codes"
sub-registry. [IANA]. sub-registry. [IANA].
+----------------+------------------------------+---------------+ +-------+------------------------------+---------------+
| Value | Description | Reference | | Value | Description | Reference |
+----------------+------------------------------+---------------+ +-------+------------------------------+---------------+
| TBD2 | Replying router is an egress | Section 4.2 | | 36 | Replying router is an egress | Section 4.2 |
| (suggested 36) | for the prefix in EGRESS-TLV | This document | | | for the prefix in EGRESS-TLV | This document |
+----------------+------------------------------+---------------+ +-------+------------------------------+---------------+
Table 2: Return code Sub-Registry Table 2: Return code Sub-Registry
8. Acknowledgements 8. Acknowledgements
TBD. TBD.
9. References 9. References
9.1. Normative References 9.1. Normative References
 End of changes. 9 change blocks. 
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