PANET Working Group Shankar Raman INTERNET-DRAFT Balaji Venkat Venkataswami Intended Status: Experimental RFC Prof.Kamakoti Veezhinathan Expires: July 2013 IIT Madras January 2013 Computing Power Saving Paths using TCAM Power Ratio draft-mjsraman-panet-tcam-power-ratio-01 Abstract A power saving scheme for switching of TCAM banks of fine granularity is discussed in [ID-TCAM-POWER-EFF]. This scheme switches of TCAM banks of fine granularity and their corresponding SRAM banks depending on the occupancy of routes and their rewrites within the TCAM of a intelligent router line card (where one or more such TCAM entities along with their SRAM banks may reside) by using an algorithm specified in [ID-TCAM-POWER-EFF]. This takes care of switching off TCAM and SRAM banks within a router's line card and correspondingly saves power when the traffic matrix is not large with respect to the routes the packets lookup where the occupancy of such routes is low in the line card. This is with reference to both single and multi-chassis devices. The algorithm specified therein tends to switch off banks which are not in use. The aim of this draft is to use the device level characteristic in the form of a TCAM Power Ratio and disseminate it as a metric within an area or an Autonomous system (where multiple such areas exist within an AS) to compute power saving paths through the set of routers where the TCAM-POWER-RATIO is low. The TCAM-POWER-RATIO is arrived at by dividing the number of bits in the TCAM banks that are switched off by the Total Available TCAM bank space in bits. This ratio is then subjected to the SPF algorithm as in a link state protocol like OSPF or IS-IS with available utilization on the links also being a factor. This way those routers that have more TCAM banks switched off are avoided and those with higher power consumption but with available bandwidth are used hence not increasing the total power consumed within the area and hence within the AS. 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), its areas, and its working groups. Note that other groups may also distribute working documents as Shankar et.al Expires July 2013 [Page 1] INTERNET DRAFT Power saving paths using TCAM power ratio January 2013 Internet-Drafts. 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." 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Table of Contents 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Methodology of the Proposal . . . . . . . . . . . . . . . . . 3 2.1 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . 6 3 Security Considerations . . . . . . . . . . . . . . . . . . . . 7 4 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7 5 References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5.1 Normative References . . . . . . . . . . . . . . . . . . . 7 5.2 Informative References . . . . . . . . . . . . . . . . . . 7 APPENDIX - A : References for power saving related material . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 Shankar et.al Expires July 2013 [Page 2] INTERNET DRAFT Power saving paths using TCAM power ratio January 2013 1 Introduction A power saving scheme for switching of TCAM banks of fine granularity is discussed in [ID-TCAM-POWER-EFF]. This scheme switches of TCAM banks of fine granularity and their corresponding SRAM banks depending on the occupancy of routes and their rewrites within the TCAM of a intelligent router line card (where one or more such TCAM entities along with their SRAM banks may reside) by using an algorithm specified in [ID-TCAM-POWER-EFF]. This takes care of switching of TCAM and SRAM banks within a router's line card and correspondingly saves power when the traffic matrix is not large with respect to the routes the packets lookup where the occupancy of such routes is low in the line card. This is with reference to both single and multi-chassis devices. The algorithm specified therein tends to switch off banks which are not in use. The aim of this draft is to use the device level characteristic in the form of a TCAM Power Ratio and disseminate it as a metric within an area or an Autonomous system (where multiple such areas exist within an AS) to compute power saving paths through the set of routers where the TCAM-POWER-RATIO is low. The TCAM-POWER-RATIO is arrived at by dividing the number of bits in the TCAM banks that are switched off by the Total Available TCAM bank space in bits. This ratio is then subjected to the SPF algorithm as in a link state protocol like OSPF or IS-IS with available utilization on the links also being a factor. This way those routers that have more TCAM banks switched off are avoided and those with higher power consumption but with available bandwidth are used hence not increasing the total power consumed within the area and hence within the AS. 1.1 Terminology 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]. 2. Methodology of the Proposal Consider a topology shown in Figure 1.0 that comprises several chassis devices (in this case single chassis ones) that have multiple line cards within each of them each of them having ports and respective TCAM banks along with their corresponding SRAM banks that contain the next-hop information and necessary re-write information. The TCAM banks contain the routes where packets are subject to longest prefix match lookup. Shankar et.al Expires July 2013 [Page 3] INTERNET DRAFT Power saving paths using TCAM power ratio January 2013 Consider the following topology... Router A Router B Router C +---+---+ +---+---+ +-------+ | | | | | | | | | |LC1|LC2| |LC1|LC2| |LC1|LC2| | | | | | | L11 | | | | P1| P1| | P1| P1|-------------- P1| P1|---+ | P2| P2|--+ | P2| P2| L12 | P2| P2| | | P3| P3| | L4 | P3| P3|-------------- P3| P3| | | P4| P4|--+----------- P4| P4| +---- P4| P4| | | P5| P5| | +----P5| P5--+ L5 | | P5| P5| | | | | | | | | | | | | | | | | | | +-|-+-|-+ |L3 | +---+---+ | | +---+-|-+ | L13 | | | +------------+-------+ | | | |L2 | L5 | | | | +----+------------+ | | | | | | | | | |L1 | | |L6 | | | | Router D | | Router E L12| | Router F | | +---+---+ | | +---+---+ | |+-------+ | | | | | |L2 | | | | | || | |L | | |LC1|LC2| | | |LC1|LC2| | ||LC1|LC2|1 | | | | | | | | | | | || | |4.. | +-| P1| P1---+ | | P1| P1|------+ || P1| P1|-> | | P2| P2| L7 +--- P2| P2| +--P2| P2|-> | | P3| P3|-------------- P3| P3| L10 | P3| P3|-> +----------| P4| P4| +---- P4| P4|-------------- P4| P4| | P5| P5| | +-- P5| P5| +----- P5| P5| | | | | | | | | | | | | | +-|-+---+ L8 | | +---+---+ L9 | +---+---+ +---------------+ +------------------+ It is given that the power-saving scheme in [ID-TCAM-POWER-EFF] is in vogue in each of these routers. It is possible that some of them are not running the algorithm specified in the [ID-TCAM-POWER-EFF]. Each of these routers consolidate the total number of bits in the TCAM banks that have been switched off and the total number of bits available in the TCAM banks. The above 2 pieces of information or data are used to compute the following TCAM-POWER-RATIO. Here TCAM-POWER-RATIO = Bits in TCAM Banks switched off --------------------------------- Total number of Bits in TCAM Banks. Shankar et.al Expires July 2013 [Page 4] INTERNET DRAFT Power saving paths using TCAM power ratio January 2013 The said ratio is further fed into a computation which is as follows. Link-Power-Metric = TCAM-POWER-RATIO ------------------ Available bandwidth of the said link on the line card on which TCAM-POWER-RATIO is calculated. The Link-Power-Metric is calculated for all the links on the line cards within a router and advertised using a suitable TLV in the opaque LSA or LSP packet in the IGP (Interior Gateway Protocol) such as OSPF or IS-IS as a link metric. The advertised Link-Power-Metric has 2 attached end-points for a link in the above mentioned topology. The overall Link-Power-Metric for a link is arrived at by assigning the Link-Power-Metric between the 2 attached end-points in the ingress direction towards the router which is a candidate next-hop towards the prefix to be reached. This is then used in the SPF algorithm to choose the least cost power path in the topology through which the packet can travel from the head-end to tail-end within the area of the AS. This is primarily an area specific calculation which ends up calculating the paths through those routers in the area that are in lesser power saving mode compared to other routers who are in more power saving mode and have shut off more than their fair share of TCAM banks and their corresponding SRAM banks. Those routers that do not employ this scheme are given a TCAM-POWER- RATIO of 1 since they are not employing the power saving scheme as outlined in [ID-TCAM-POWER-EFF]. It is important to note that the TCAM banks switched off are not used in the ratio as a discrete quantity but rather as in an interval of thresholds. The Available bandwidth as well are calculated not in discrete quantities but in intervals of thresholds. These intervals are uniformly to be undertaken in all the routers where the scheme is deployed. Shankar et.al Expires July 2013 [Page 5] INTERNET DRAFT Power saving paths using TCAM power ratio January 2013 2.1 Discussion Consider the following topology with the appropriate Link-Power- Metric assigned to the links contained within it. The shortest path is through A,B,D,X rather than through A,C,E,D and X. This primarily owing to the reason that the Link-Power-Metric that takes the TCAM-POWER-RATIO and the Available bandwidth on those links is the least in the SPF path. 0.2 0.1 0.2 (A).....>(B).....>(D).....>(X) | ^ |0.2 0.02 | 0.2 +--->(C)-------->(E) It is to be noted that if the prefix for the traffic whose Longest prefix match entry is not loaded in the TCAM bank which is in ON state in any of the chosen routers along the path, the usual scheme in [ID-TCAM-POWER-EFF] kicks in and loads the prefix and its associated re-write information on the traffic hitting the router in the chosen power saving path. For more information read the reference for scheme in [ID-TCAM-POWER-EFF]. Shankar et.al Expires July 2013 [Page 6] INTERNET DRAFT Power saving paths using TCAM power ratio January 2013 3 Security Considerations There are no new security considerations within the scope of this document. 4 IANA Considerations A suitable TLV to carry the Link-Power-Metric is to be defined for this purpose. 5 References 5.1 Normative References 5.2 Informative References [ID-TCAM-POWER-EFF] Shankar Raman et.al, "TCAM power reduction and optimization in Routers", draft-mjsraman- panet-tcam-power-efficiency-00 (work in progress), 2012. APPENDIX - A : References for power saving related material S.Raman, B.V. Venkataswami, K. Veezhinathan, G. Raina, "TCAM power reduction and optimization in Routers", draft- mjsraman-panet-tcam-power-efficiency-00 (work in progress) M. Zhang, J. Dong, B. Zhang, "Use Cases for Power-Aware Networks", draft-zhang-panet-use-cases (work in progress) B. Nordman, K. Christensen, "Nanogrids", draft-nordman- nanogrids-00 (work in progress) T. Suzuki, T. Tarui, "Requirements for an Energy-Efficient Network System", draft-suzuki-eens-requirements (work in progress) Z. Cao, "Synchronization Layer: an Implementation Method for Energy Efficient Sensor Stack", draft-cao-lwig-syn- layer (work in progress) A. Junior, R. Sofia, "Energy-awareness metrics global applicability guideline", draft-ajunior-energy-awareness- 00 (work in progress) B. Zhang, J. Shi, M. Zhang, J. Dong, "Power-aware Routing Shankar et.al Expires July 2013 [Page 7] INTERNET DRAFT Power saving paths using TCAM power ratio January 2013 and Traffic Engineering: Requirements, Approaches, and Issues", draft-zhang- greennet (work in progress) T. Suganuma, N. Nakamura, S. Izumi, H. Tsunoda, M. Matsuda, K. Ohta, "Green Usage Monitoring Information Base", draft-suganuma-greenmib (work in progress) S. Raman, B. V. Venkataswami, G. Raina, V. Srini, "Power Based Topologies and TE-Shortest Power Paths in OSPF", draft-mjsraman- rtgwg-ospf-power-topo-01 (work in progress) S. Raman, B. V. Venkataswami, G. Raina, V. Srini, "Building power optimal Multicast Trees", draft-mjsraman- rtgwg-pim-power-02 (work in progress) S. Raman, B. V. Venkataswami, G. Raina, "Reducing Power Consumption using BGP", draft-mjsraman-rtgwg-inter-as-psp- 03 (work in progress) S. Raman, B. V. Venkataswami, G. Raina, "Building power shortest inter-Area TE LSPs using pre-computed paths", draft-mjsraman-rtgwg- intra-as-psp-te-leak-02 (work in progress) S. Raman, B. V. Venkataswami, G. Raina, V. Srini, "Reducing Power Consumption using BGP path selection", draft-mjsraman-rtgwg-bgp- power-path-02 (work in progress) Authors' Addresses Shankar Raman Department of Computer Science and Engineering IIT Madras Chennai - 600036 TamilNadu India EMail: mjsraman@cse.iitm.ac.in Balaji Venkat Venkataswami Department of Electrical Engineering, IIT Madras Chennai - 600036 TamilNadu India Shankar et.al Expires July 2013 [Page 8] INTERNET DRAFT Power saving paths using TCAM power ratio January 2013 EMail: balajivenkat299@gmail.com Prof.Kamakoti Veezhinathan Department of Computer Science and Engineering IIT Madras Chennai - 600036 TamilNadu India Email: kama@cse.iitm.ac.in Shankar et.al Expires July 2013 [Page 9]