OSPF Traffic Engineering (TE) Metric Extensions
draft-ietf-ospf-te-metric-extensions-04
The information below is for an old version of the document.
Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 7471.
Expired & archived
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Authors | Spencer Giacalone , David Ward , John Drake , Alia Atlas , Stefano Previdi | ||
Last updated | 2013-12-05 (Latest revision 2013-06-03) | ||
Replaces | draft-ospf-te-metric-extensions | ||
RFC stream | Internet Engineering Task Force (IETF) | ||
Formats | |||
Reviews |
GENART Telechat review
(of
-09)
by Martin Thomson
Ready w/nits
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Additional resources | Mailing list discussion | ||
Stream | WG state | WG Document | |
Document shepherd | (None) | ||
IESG | IESG state | Became RFC 7471 (Proposed Standard) | |
Consensus boilerplate | Unknown | ||
Telechat date | (None) | ||
Responsible AD | (None) | ||
Send notices to | (None) |
draft-ietf-ospf-te-metric-extensions-04
Internet-Draft OSPF TE Metric Extensions June 2013 4. Sub TLV Details 4.1. Unidirectional Link Delay Sub-TLV This sub-TLV advertises the average link delay between two directly connected OSPF neighbors. The delay advertised by this sub-TLV MUST be the delay from the local neighbor to the remote one (i.e. the forward path latency). The format of this sub-TLV is shown in the following diagram: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TBD1 | 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |A| RESERVED | Delay | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 4.1.1. Type This sub-TLV has a type of TBD1. 4.1.2. Length The length is 4. 4.1.3. A bit This field represents the Anomalous (A) bit. The A bit is set when the measured value of this parameter exceeds its configured maximum threshold. The A bit is cleared when the measured value falls below its configured reuse threshold. If the A bit is clear, the sub-TLV represents steady state link performance. 4.1.4. Reserved This field is reserved for future use. It MUST be set to 0 when sent and MUST be ignored when received. 4.1.5. Delay Value This 24-bit field carries the average link delay over a configurable interval in micro-seconds, encoded as an integer value. When set to the maximum value 16,777,215 (16.777215 sec), then the delay is at least that value and may be larger. If there is no value to send Giacalone, et al Expires December 3, 2013 [Page 7] Internet-Draft OSPF TE Metric Extensions June 2013 (unmeasured and not statically specified), then the sub-TLV should not be sent or be withdrawn. 4.2. Min/Max Unidirectional Link Delay Sub-TLV This sub-TLV advertises the minimum and maximum delay values between two directly connected OSPF neighbors. The delay advertised by this sub-TLV MUST be the delay from the local neighbor to the remote one (i.e. the forward path latency). The format of this sub-TLV is shown in the following diagram: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TBD2 | 8 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |A| RESERVED | Min Delay | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RESERVED | Max Delay | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 4.2.1. Type This sub-TLV has a type of TBD2. 4.2.2. Length The length is 8. 4.2.3. A bit This field represents the Anomalous (A) bit. The A bit is set when one or more measured values exceed a configured maximum threshold. The A bit is cleared when the measured value falls below its configured reuse threshold. If the A bit is clear, the sub-TLV represents steady state link performance. 4.2.4. Reserved This field is reserved for future use. It MUST be set to 0 when sent and MUST be ignored when received. Giacalone, et al Expires December 3, 2013 [Page 8] Internet-Draft OSPF TE Metric Extensions June 2013 4.2.5. Low Delay This 24-bit field carries minimum measured link delay value (in microseconds) over a configurable interval, encoded as an integer value. Implementations MAY also permit the configuration of a static (non dynamic) offset value (in microseconds) to be added to the measured delay value, to facilitate the communication of operator specific delay constraints. When set to the maximum value 16,777,215 (16.777215 sec), then the delay is at least that value and may be larger. 4.2.6. High Delay This 24-bit field carries the maximum measured link delay value (in microseconds) over a configurable interval, encoded as an integer value. Implementations MAY also permit the configuration of a static (non dynamic) offset value (in microseconds) to be added to the measured delay value, to facilitate the communication of operator specific delay constraints. It is possible for the high delay and low delay to be the same value. When the delay value is set to maximum value 16,777,215 (16.777215 sec), then the delay is at least that value and may be larger. 4.2.7. Reserved This field is reserved for future use. It MUST be set to 0 when sent and MUST be ignored when received. When only an average delay value is sent, this field is not present in the TLV. 4.3. Unidirectional Delay Variation Sub-TLV This sub-TLV advertises the average link delay variation between two directly connected OSPF neighbors. The delay variation advertised by this sub-TLV MUST be the delay from the local neighbor to the remote one (i.e. the forward path latency). The format of this sub-TLV is shown in the following diagram: Giacalone, et al Expires December 3, 2013 [Page 9] Internet-Draft OSPF TE Metric Extensions June 2013 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TBD3 | 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | RESERVED | Delay Variation | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 4.3.1. Type This sub-TLV has a type of TBD3. 4.3.2. Length The length is 4. 4.3.3. Reserved This field is reserved for future use. It MUST be set to 0 when sent and MUST be ignored when received. 4.3.4. Delay Variation This 24-bit field carries the average link delay variation over a configurable interval in micro-seconds, encoded as an integer value. When set to 0, it has not been measured. When set to the maximum value 16,777,215 (16.777215 sec), then the delay is at least that value and may be larger. 4.4. Unidirectional Link Loss Sub-TLV This sub-TLV advertises the loss (as a packet percentage) between two directly connected OSPF neighbors. The link loss advertised by this sub-TLV MUST be the packet loss from the local neighbor to the remote one (i.e. the forward path loss). The format of this sub-TLV is shown in the following diagram: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TBD4 | 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Giacalone, et al Expires December 3, 2013 [Page 10] Internet-Draft OSPF TE Metric Extensions June 2013 |A| RESERVED | Link Loss | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 4.4.1. Type This sub-TLV has a type of TBD4 4.4.2. Length The length is 4. 4.4.3. A bit This field represents the Anomalous (A) bit. The A bit is set when the measured value of this parameter exceeds its configured maximum threshold. The A bit is cleared when the measured value falls below its configured reuse threshold. If the A bit is clear, the sub-TLV represents steady state link performance. 4.4.4. Reserved This field is reserved for future use. It MUST be set to 0 when sent and MUST be ignored when received. 4.4.5. Link Loss This 24-bit field carries link packet loss as a percentage of the total traffic sent over a configurable interval. The basic unit is 0.000003%, where (2^24 - 2) is 50.331642%. This value is the highest packet loss percentage that can be expressed (the assumption being that precision is more important on high speed links than the ability to advertise loss rates greater than this, and that high speed links with over 50% loss are unusable). Therefore, measured values that are larger than the field maximum SHOULD be encoded as the maximum value. When set to a value of all 1s (2^24 - 1), the link packet loss has not been measured. 4.5. Unidirectional Residual Bandwidth Sub-TLV This TLV advertises the residual bandwidth (defined in section 4.5.3. between two directly connected OSPF neighbors. The residual bandwidth advertised by this sub-TLV MUST be the residual bandwidth from the system originating the LSA to its neighbor. Giacalone, et al Expires December 3, 2013 [Page 11] Internet-Draft OSPF TE Metric Extensions June 2013 The format of this sub-TLV is shown in the following diagram: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TBD5 | 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Residual Bandwidth | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 4.5.1. Type This sub-TLV has a type of TBD5. 4.5.2. Length The length is 4. 4.5.3. Residual Bandwidth This field carries the residual bandwidth on a link, forwarding adjacency [RFC4206], or bundled link in IEEE floating point format with units of bytes per second. For a link or forwarding adjacency, residual bandwidth is defined to be Maximum Bandwidth [RFC3630] minus the bandwidth currently allocated to RSVP-TE LSPs. For a bundled link, residual bandwidth is defined to be the sum of the component link residual bandwidths. The calculation of Residual Bandwidth is different than that of Unreserved Bandwidth [RFC3630]. Residual Bandwidth subtracts tunnel reservations from Maximum Bandwidth (i.e. the link capacity) [RFC3630] and provides an aggregated remainder across QoS classes. Unreserved Bandwidth [RFC3630], on the other hand, is subtracted from the Maximum Reservable Bandwidth (the bandwidth that can theoretically be reserved) [RFC3630] and provides per-QoS-class remainders. Residual Bandwidth and Unreserved Bandwidth [RFC3630] can be used concurrently, and each has a separate use case (e.g. the former can be used for applications like Weighted ECMP while the latter can be used for call admission control). Giacalone, et al Expires December 3, 2013 [Page 12] Internet-Draft OSPF TE Metric Extensions June 2013 4.5. Unidirectional Available Bandwidth Sub-TLV This TLV advertises the available bandwidth (defined in section 4.5.6. ) between two directly connected OSPF neighbors. The available bandwidth advertised by this sub-TLV MUST be the available bandwidth from the system originating the LSA to its neighbor. The format of this sub-TLV is shown in the following diagram: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | TBD6 | 4 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Available Bandwidth | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 4.5.4. Type This sub-TLV has a type of TBD6. 4.5.5. Length The length is 4. 4.5.6. Available Bandwidth This field carries the available bandwidth on a link, forwarding adjacency, or bundled link in IEEE floating point format with units of bytes per second. For a link or forwarding adjacency, available bandwidth is defined to be residual bandwidth (see section 4.5. ) minus the measured bandwidth used for the actual forwarding of non- RSVP-TE LSP packets. For a bundled link, available bandwidth is defined to be the sum of the component link available bandwidths. 5. Announcement Thresholds and Filters The values advertised in all sub-TLVs (except min/max delay and residual bandwidth) MUST represent an average over a period or be obtained by a filter that is reasonably representative of an average. For example, a rolling average is one such filter. Low or high delay MAY be the lowest and/or highest measured value over a measurement interval or MAY make use of a filter, or other Giacalone, et al Expires December 3, 2013 [Page 13] Internet-Draft OSPF TE Metric Extensions June 2013 technique to obtain a reasonable representation of a low and high value representative of the interval with compensation for outliers. The measurement interval, any filter coefficients, and any advertisement intervals MUST be configurable per sub-TLV. In addition to the measurement intervals governing re-advertisement, implementations SHOULD provide per sub-TLV configurable accelerated advertisement thresholds, such that: 1. If the measured parameter falls outside a configured upper bound for all but the min delay metric (or lower bound for min-delay metric only) and the advertised sub-TLV is not already outside that bound or, 2. If the difference between the last advertised value and current measured value exceed a configured threshold then, 3. The advertisement is made immediately. 4. For sub-TLVs which include an A-bit (except low/high delay), an additional threshold SHOULD be included corresponding to the threshold for which the performance is considered anomalous (and sub-TLVs with the A bit are sent). The A-bit is cleared when the sub-TLV's performance has been below (or re-crosses) this threshold for an advertisement interval(s) to permit fail back. To prevent oscillations, only the high threshold or the low threshold (but not both) may be used to trigger any given sub-TLV that supports both. Additionally, once outside of the bounds of the threshold, any readvertisement of a measurement within the bounds would remain governed solely by the measurement interval for that sub-TLV. 6. Announcement Suppression When link performance values change by small amounts that fall under thresholds that would cause the announcement of a sub-TLV, implementations SHOULD suppress sub-TLV readvertisement and/or lengthen the period within which they are refreshed. Only the accelerated advertisement threshold mechanism described in section 6 may shorten the re-advertisement interval. Giacalone, et al Expires December 3, 2013 [Page 14] Internet-Draft OSPF TE Metric Extensions June 2013 All suppression and re-advertisement interval backoff timer features SHOULD be configurable. 7. Network Stability and Announcement Periodicity Sections 6 and 7 provide configurable mechanisms to bound the number of re-advertisements. Instability might occur in very large networks if measurement intervals are set low enough to overwhelm the processing of flooded information at some of the routers in the topology. Therefore care SHOULD be taken in setting these values. Additionally, the default measurement interval for all sub-TLVs SHOULD be 30 seconds. Announcements MUST also be able to be throttled using configurable inter-update throttle timers. The minimum announcement periodicity is 1 announcement per second. The default value SHOULD be set to 120 seconds. Implementations SHOULD NOT permit the inter-update timer to be lower than the measurement interval. Furthermore, it is RECOMMENDED that any underlying performance measurement mechanisms not include any significant buffer delay, any significant buffer induced delay variation, or any significant loss due to buffer overflow or due to active queue management. 8. Enabling and Disabling Sub-TLVs Implementations MUST make it possible to individually enable or disable each sub-TLV based on configuration. 9. Static Metric Override Implementations SHOULD permit the static configuration and/or manual override of dynamic measurements data on a per sub-TLV, per metric basis in order to simplify migrations and to mitigate scenarios where measurements are not possible across an entire network. Giacalone, et al Expires December 3, 2013 [Page 15] Internet-Draft OSPF TE Metric Extensions June 2013 10. Compatibility As per (RFC3630), unrecognized TLVs should be silently ignored 11. Security Considerations This document does not introduce security issues beyond those discussed in [RFC3630] and [RFC5329]. 12. IANA Considerations IANA maintains the registry for the sub-TLVs. OSPF TE Metric Extensions will require one new type code per sub-TLV defined in this document. 13. References 13.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3630] Katz, D., Kompella, K., Yeung, D., "Traffic Engineering (TE) Extensions to OSPF Version 2", RFC 3630, September 2003. [RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay Measurement for MPLS Networks", RFC 6374, September 2011. 13.2. Informative References [RFC2328] Moy, J, "OSPF Version 2", RFC 2328, April 1998 [RFC3031] Rosen, E., Viswanathan, A., Callon, R., "Multiprotocol Label Switching Architecture", January 2001 Giacalone, et al Expires December 3, 2013 [Page 16] Internet-Draft OSPF TE Metric Extensions June 2013 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels", RFC 3209, December 2001. [RFC5250] Berger, L., Bryskin I., Zinin, A., Coltun, R., "The OSPF Opaque LSA Option", RFC 5250, July 2008. [RFC6375] Frost, D. and S. Bryant, "A Packet Loss and Delay Measurement Profile for MPLS-Based Transport Networks", RFC 6375, September 2011. [Alto] R. Alimi R. Penno Y. Yang, "ALTO Protocol" 14. Acknowledgments The authors would like to recognize Ayman Soliman, Nabil Bitar, David McDysan, Edward Crabbe, and Don Fedyk for their contributions. The authors also recognize Curtis Villamizar for significant comments and direct content collaboration. This document was prepared using 2-Word-v2.0.template.dot. 15. Author's Addresses Spencer Giacalone Thomson Reuters 195 Broadway New York, NY 10007, USA Email: Spencer.giacalone@thomsonreuters.com Dave Ward Cisco Systems 170 West Tasman Dr. San Jose, CA 95134, USA Email: dward@cisco.com Giacalone, et al Expires December 3, 2013 [Page 17] Internet-Draft OSPF TE Metric Extensions June 2013 John Drake Juniper Networks 1194 N. Mathilda Ave. Sunnyvale, CA 94089, USA Email: jdrake@juniper.net Alia Atlas Juniper Networks 1194 N. Mathilda Ave. Sunnyvale, CA 94089, USA Email: akatlas@juniper.net Stefano Previdi Cisco Systems Via Del Serafico 200 00142 Rome Italy Email: sprevidi@cisco.com Giacalone, et al Expires December 3, 2013 [Page 18]