Internet DRAFT - draft-mjsraman-panet-ospf-power-topo
draft-mjsraman-panet-ospf-power-topo
PANET Working Group Shankar Raman
INTERNET-DRAFT Balaji Venkat Venkataswami
Intended Status: Experimental RFC Gaurav Raina
Expires: September 28, 2013 Vasan Srini
IIT Madras
March 27, 2013
Power Based Topologies and TE-Shortest Power Paths in OSPF
draft-mjsraman-panet-ospf-power-topo-02
Abstract
In a Interior Gateway Protocol like OSPF (Open Shortest Path First)
the computation of the Constrained shortest path to destinations is
computed for an area say a backbone or a non-backbone area using the
TE-metrics advertised in the area. With importance given to the
reduction of power within a network it becomes important to provide a
solution that reduces the power consumed amongst routers and links
that make up the network (in this case an area or a collection of
areas including the backbone and non-backbone areas). This proposal
aims at providing such a solution by producing a power topology of
the area / areas. This power topology is constructed by assigning
metrics to links based on the power consumed by the linecards (and
hence their respective ports in an indirect way) of adjacent routers
that are interconnected by each such link.
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
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."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/1id-abstracts.html
Shankar Raman et.al, Expires September 2013 [Page 1]
INTERNET DRAFT Power based Topologies using CSPF in OSPF March 2013
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html
Copyright and License Notice
Copyright (c) 2012 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
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Low-power routers and switches . . . . . . . . . . . . . . . 3
1.3 Power reduction using routing and traffic engineering . . . 3
2. Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.0.1 ERRATA . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.1 Power Bias . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.1.1 Advertising Available POWER . . . . . . . . . . . . . . 8
2.2 ECMP links . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.3 Dampening the side effects of constant change . . . . . . . 9
2.4 Calculating power shortest paths in an Area . . . . . . . . 9
2.4.1 Power profiles of Routers and Switches . . . . . . . . . 10
2.4.1.3 Need to advertise both available power and
consumed power . . . . . . . . . . . . . . . . . . . 14
2.4.2 Power to Available Bandwidth ratio in a TLV . . . . . . 14
3. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 16
3 Security Considerations . . . . . . . . . . . . . . . . . . . . 17
4 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 17
5 References . . . . . . . . . . . . . . . . . . . . . . . . . . 17
5.1 Normative References . . . . . . . . . . . . . . . . . . . 17
5.2 Informative References . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18
Shankar Raman et.al, Expires September 2013 [Page 2]
INTERNET DRAFT Power based Topologies using CSPF in OSPF March 2013
1. Introduction
Estimates of power consumption for the Internet predict a 300%
increase, as access speeds increase from 10 Mbps to 100 Mbps [3],
[8]. Access speeds are likely to increase as new video, voice and
gaming devices get added to the Internet. Various approaches have
been proposed to reduce the power consumption of the Internet such as
designing low-power routers and switches, and optimizing the network
topology using traffic engineering methods [2].
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].
1.2 Low-power routers and switches
Low-power router and switch design aim at reducing the power consumed
by hardware architectural components such as transmission link,
lookup tables and memory. In [4] it is shown that the router's link
power consumption can vary by 20 Watts between idle and traffic
scenarios. Hence the authors suggest having more line cards and
running them to capacity: operating the router at full throughput
will lead to less power per bit, and hence larger packet lengths will
consume lower power. The two important components in routers that
have received attention for high power consumption are buffers and
TCAMs. Buffers are built using dynamic RAM (DRAM) or static RAM
(SRAM). SRAMs are limited in size and consume more power, but have
low access times. Guido [1] states that a 40Gb/s line card would
require more than 300 SRAM chips and consume 2.5kW. DRAM access times
prevent them from being used on high speed line cards. Sometimes the
buffering of packets in DRAM is done at the back end, while SRAM is
used at the front end for fast data access. But these schemes cannot
scale with increasing line speeds. Some variants of TCAMs have been
proposed for increasing line speeds and for reduced power consumption
[7].
1.3 Power reduction using routing and traffic engineering
At the Internet level, creating a topology that allows route
adaptation, capacity scaling and power-aware service rate tuning,
will reduce power consumption. In [8] the author has proposed a
technique to traffic engineer the data packets in such a way that the
link capacity between routers is optimized. Links which are not
utilized are moved to the idle state. Power consumption can be
reduced by trading off performance related measures like latency. For
Shankar Raman et.al, Expires September 2013 [Page 3]
INTERNET DRAFT Power based Topologies using CSPF in OSPF March 2013
example, power savings while switching from 1 Gbps to 100 Mbps is
approximately 4 W and from 100 Mbps to 10 Mbps around 0:1 Watts.
Hence instead of operating at 1 Gbps the link speed could be reduced
to a lower bandwidth under certain conditions for reduced power
consumption.
Multi layer traffic engineering based methods make use of parameters
such as resource usage, bandwidth, throughput and QoS measures, for
power reduction. In [6] an approach for reducing Intra-AS power
consumption for optical networks that uses Djikstra's shortest path
algorithm is proposed. The input to this method assumes the existence
of a network topology using which an auxiliary graph is constructed.
Power optimization is done on the auxiliary graph and traffic is
routed through the low-power links. However, the algorithm expects
the topology to be available for getting the auxiliary graph. While
[6] handles optical networks and their corresponding power
consumption, it does not take into account other link layer
technologies. It is specialized for optical and not for heterogenous
links that will exist in common OSPF domains.
The proposal we make in this document indicates ways to solve the
power reduction problem, by calculating a POWER metric whose
importance is highlighted in the below mentioned sections. This POWER
metric is obtained by including the factors such as power consumed by
a linecard on a single chassis or multi-chassis router and
consequently a port on that linecard by proportionally calculating
power consumed for that port and hence for the link. The other factor
that is taken into account is the Available Bandwidth on that port
and hence on that link.
2. Methodology
For each router / switch there exist linecards and each linecard has
a set of ports or sometimes just one port of high capacity. This
usually applies on routers and switches that are either single
chassis or multi-chassis in their characterisation. By single chassis
we mean that there exists a single chassis and slots for the Route
Processor Card (one or more of these) typically upto to two of them,
and one or more slots for linecards each having their respective
characteristics such as number of ports (port density), type of such
ports (SONET, ethernet, ATM etc..) usually depending on the link
layer technology they support. Links are connections between ports on
these linecards to other ports on linecards of other single chassis
or multi-chassis system. A multi-chassis system is one that has
multiple such chassis interconnceted amongst each other to form a
single logical view of the system. Both single and multi-chassis have
Shankar Raman et.al, Expires September 2013 [Page 4]
INTERNET DRAFT Power based Topologies using CSPF in OSPF March 2013
linecards and respective ports on these linecards. Multi-chassis
typically have a switch fabric chassis which connects each of these
chassis to each other or to chassis of other multi-chassis or single
chassis systems.
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 | +---+---+
+---------------+ +------------------+
Shankar Raman et.al, Expires September 2013 [Page 5]
INTERNET DRAFT Power based Topologies using CSPF in OSPF March 2013
The table of links between the various routers (which are assumed to
be single chassis systems) is as follows...
+--------+----------+-----------+-----------+-----------+----------+
| Links | Routers | LC <> LC | Port Conn.| Capacity |Available |
| | | | | |Bandwidth |
+--------+----------+-----------+-----------+-----------+----------+
| L1 | A <> D | LC1<>LC1 | P5<>P4 | 10G | 7.5 |
| L2 | A <> D | LC2<>LC2 | P5<>P1 | 10G | 6.0 |
| L3 | A <> D | LC2<>LC1 | P2<>P1 | 10G | 4.0 |
| L4 | A <> B | LC2<>LC1 | P4<>P4 | 10G | 3.0 |
| L5 | B <> C | LC1<>LC1 | P5<>P4 | 10G | 3.5 |
| L6 | B <> E | LC1<>LC1 | P6<>P2 | 10G | 1.0 |
| L7 | D <> E | LC2<>LC1 | P3<>P3 | 10G | 6.0 |
| L8 | D <> E | LC1<>LC1 | P5<>P4 | 10G | 1.5 |
| L9 | E <> F | LC1<>LC2 | P5<>P5 | 100G | 20.0 |
| L10 | E <> F | LC2<>LC1 | P4<>P4 | 10G | 2.5 |
| L11 | B <> C | LC2<>LC1 | P1<>P1 | 10G | 3.0 |
| L12 | E <> C | LC2<>LC2 | P1<>P5 | 10G | 2.0 |
| L13 | C <> F | LC2<>LC1 | P1<>P2 | 10G | 1.0 |
| L14 | F <> OA | LC2<> | P1<> | | |
| | | | | | |
+--------+----------+-----------+-----------+------------+---------+
In the above topology assume all point-to-point links between the
routers. For now we will deal with P2P links alone and not venture
into Broadcast Multi-access links or Non-Broadcast Multi-access links
etc.. It is suffice to show how the scheme works for P2P links and
then move more specifically to other types of networks to demonstrate
this method of calculating the power topology of the network in the
figure.
Each linecard consumes a certain amount of power and it is vendor
dependent as to how the power consumed relates to the Available
Bandwidth on any of the links to which the linecard connects to. It
is possible that the said topology of routers come from one vendor or
from multiple vendors. It is assumed that the algorithm proposed will
have the power consumed by a linecard available as a readable value
in terms of W or kW or whichever measurable metric that is provided
by the vendor.
It is possible that some of the Linecards are more capable than the
others. Consider that Router A is a more capable router with more
powerful linecards with higher port density. This is not shown in the
figure, but assume so. LC1, LC2 on Router A could be consuming more
power than the other Linecards on other routers. The main reason
could be that LC1 and LC2 may have higher port density or higher
Shankar Raman et.al, Expires September 2013 [Page 6]
INTERNET DRAFT Power based Topologies using CSPF in OSPF March 2013
speed ports than the other routers. In order to calculate the power
consumed on a link by a linecard it is important that we normalize
the power as power consumed per port. Here the ports are normalized
to lowest common denominator. If all links in the topology have 10G
port capacity then the power calculated should be in terms power
consumed per 10G port.
Assuming we have done this normalization we go on to calculate the
POWER metric for each of the ports involved in a link which is
derived as follows...
POWER metric = Power consumed per XG (normalized bandwidth) port
for a given -------------------------------------------------
Port on a LC Available Bandwidth on that port
Assume link L1. The ports concerned are both 10G and the ports are P5
on Router A and P4 on Router D. For calculating the POWER metric for
a link which we will call PWRLINK we calculate the POWER metric for
each side of the link and average the two to get PWRLINK.
So PWRLINK for L1 = POWER for P5 on LC1 + Power for P4 on LC1
on Router A on Router D
============================================
2
The above can also be weighted if there is a multi-capacity port on
one side of the link and not on the other. A multi-capacity link is
one which provides multiple bandwidth capabilities such (1G/10G/100G)
for example but auto-negotiates with other end to provide a lesser
than highest capacity service.
The PWRLINK metrices once calculated are flooded in already defined
OSPF-TE-LSA as an adapted TE-metric and is typically flooded as a
link characteristic.
It is important to note that the denominator for POWER metric is
Available Bandwidth instead of Available Bandwidth on that port. The
Available Bandwidth is measured in terms of intervals and not as
discrete quantities. This is in order not to flood PWRLINK metrics
into the OSPF area in LSAs very frequently as Bandwidth may
constantly change. The same applies to POWER metric as well.
Once the LSAs have been flooded the Routers run CSPF on the graph of
the topology with PWRLINKs assigned to the links and calculate the
PWRLINK based paths which consume the least power. The shortest power
paths based on this topology can be used for forwarding high
bandwidth streams and to optimally use power within the area.
Shankar Raman et.al, Expires September 2013 [Page 7]
INTERNET DRAFT Power based Topologies using CSPF in OSPF March 2013
The Available Bandwidth column shows the Available bandwidth of the
link corresponding to the row and column intersection. This figure is
used as the numerator in the POWER metric computation for that port.
2.0.1 ERRATA
ERRATA : Previously the experiments were carried out with Available
Utilization since only 10G and 100G ports were considered. This
baselines the metric to 10G ports and proportionality thereof. But in
reality the actual Available Bandwidth needs to be considered for
real world experiments. Hence this draft has been changed to reflect
the Available Bandwidth to be taken as the denominator of the formula
thereof.
In our previous experiments the 100G link if it showed a utilization
of 0.2 would end up as a high POWER metric and hence would be totally
avoided. In reality this link may have been a more power optimal link
given that if it had a first power profile (Please refer section on
Power Profiles). Dividing the Power consumed or Available Power by
the Available Bandwidth gives a better picture of how much power cost
per Gb is consumed and normalizes the metric amongst links of varying
bandwidth.
2.1 Power Bias
Assume in the figure that there exist Routers A and D and that there
is a bias on the link L1 in such a way that Router D computes a POWER
metric of 10 and the Router D computes a POWER metric of 2 on the
ports P5 and P4 respectively. Now the PWRLINK would be 6 for that
link L1. Thus even if one side is excessively power guzzling then the
PWRLINK moves up and thus is less preferred in the CSPF algorithm and
path computation based on the Power topology.
If there is no bias and both the sides of the link are optimal in
their power usage then the metric stays low even if more streams are
sent on it. This is the main objective that is set out for router and
switch manufacturers in the single chassis and multi-chassis world,
in that they are incentivised to manufacture linecards that are not
power hungry even if the number of packets flowing through them is
high and thus the Bandwidth Available is also reasonably on the
higher side compared to other routers.
For those manufacturers who set a high power value for even minimal
traffic, the vendors that dont would win out in the end.
2.1.1 Advertising Available POWER
Please see section 2.4.1 for more information on why Available POWER
Shankar Raman et.al, Expires September 2013 [Page 8]
INTERNET DRAFT Power based Topologies using CSPF in OSPF March 2013
plays a crucial role in determining the choice of routers based on
the Power metric.
2.2 ECMP links
It is possible that multiple links would have the same PWRLINK metric
after a computation cycle. In such a case load-balancing techniques
can be used to keep the ECMP links in a steady state with respect to
each other. Depending on the Available Bandwidth thereafter it is
possible that the ECMP links may no longer be Equal cost but UCMP or
Unequal Cost Paths.
2.3 Dampening the side effects of constant change
It is recommended in this draft that the implementation of the
proposal be adaptive, infrequent in computation to the extent
possible without sacrificing adapting to the dynamism and also reduce
any frequent oscillations. The actual methods to adopt for this
computation are outside the scope of this document.
2.4 Calculating power shortest paths in an Area
Assume the following topology where A,B,C etc.. are routers and
corresponding labelled edges with weights are the links. These
weights are the current values of the PWRLINK attribute that has been
flooded in the LSAs through the Area concerned. Assume B is the ABR
for Area 1 and the routers A and C are the Area 0 core routers. The
rest of the routers are assumed to be in Area 1. Once the power
topology of the Area 1 has been calculated as shown below with the
PWRLINK attributes being assigned to the links, Constrained shortest
path can be run from the ABR to any of the other routers say H, E , X
etc.. The CSPF algorithm takes the constraint in terms of the PWRLINK
attributes along with other attributes to construct a power shortest
path from say router B to other routers in Area 1.
0.5
(C) +----------------+
0.5| / |
| / |
0.05 V/ 0.1 0.03 0.2 V
(A)--->(B)--->(D)--->(G)--->(H)
| | |
| 0.5| | 0.1
| V V
+----------->(E)--->(X)
0.5 0.3
Shankar Raman et.al, Expires September 2013 [Page 9]
INTERNET DRAFT Power based Topologies using CSPF in OSPF March 2013
Once the path has been computed it is possible to use RSVP-TE to
construct the power shortest path with the TE-LSP being instantiated
with the labels appropriately placed in the routers on the power
shortest path. In this topology, assume one would want to construct a
path from B to X then the dotted path shows the path constructed and
to be used by a set of flows or streams of packets belonging to
multiple flows as seen fit by the router B. If the PWRLINK metrics
change after due course of time then another power shortest path that
possibly traverses the same path (if the SUM of PWRLINKs doesnt
exceed any other path's metrics' SUM) or some other path would be
constructed. Specifically this method makes use of traffic-
engineering signalling protocols as the method to place the streams
from point X to point Y (where X and Y are routers).
0.5
(C) +----------------+
0.5| / |
| / |
0.05 V/ 0.1 0.03 0.2 V
(A)--->(B)...>(D)...>(G)...>(H)
| | .
| 0.5| . 0.1
| V V
+----------->(E)--->(X)
0.5 0.3
2.4.1 Power profiles of Routers and Switches
It has been experimented and from several sources found that there
exist routers which have different power profiles. The power profile
of a router is the curve of power consumption to available bandwidth.
Mentioned below are a few of these prominent ones that have to be
taken into consideration.
The first profile that we will consider is the flattening curve. The
power consumed to available bandwidth curve takes the shape of a
steep one initially and then tapers off to a plateau. The point at
which it begins to give a delta-C (delta in Power Consumed) to delta-
B (Available Bandwidth exhausted) is the inflection point that tapers
off to a plateau. Here the delta-C/delta-B begins to slow down or
decrease rapidly. The more the traffic that is added onto the device
the lesser it draws power.
Shankar Raman et.al, Expires September 2013 [Page 10]
INTERNET DRAFT Power based Topologies using CSPF in OSPF March 2013
^
|
P | .
o | .
w | .
e | .
r | .
| .
c | .
o | .
n | .
s | .
u.| .
------------------------------------>
| Available Bandwidth exhausted
The second profile that we will consider is the exponential curve.
The power consumed to available bandwidth curve takes the shape of an
ever increasing steep curve as shown below. Here the delta-C/delta-B
begins to increase as more traffic is thrown onto it as the Available
bandwidth exhausted increases. This power curve beyond a point is
intolerable with respect to power guzzling.
^
|
P | .
o | .
w | .
e | .
r | .
| .
c | .
o | .
n | .
s | .
u.| .
------------------------------------>
| Available Bandwidth exhausted
Shankar Raman et.al, Expires September 2013 [Page 11]
INTERNET DRAFT Power based Topologies using CSPF in OSPF March 2013
The third profile that we will consider is a linear curve. In other
words just a straight line. Here delta-C/delta-B is a constant.
^
|
P | .
o | .
w | .
e | .
r | .
| .
c | .
o | .
n | .
s | .
u.| .
------------------------------------>
| Available Bandwidth exhausted
2.4.1.1 Concave and Convex power curves
Given that there are 3 kinds of major profiles in the router power
consumption, what line would we like to pick. This is an important
point when choosing the metric to pick the low power paths.
(a) If the confrontation is between 2 first profile routers the lower
of the 2 would be considered as shown below. The lower curve offers
better power savings for each GB of bandwidth transported.
^
|
P | .
o | .
w | . .
e | . .
r | . .
| . .
c | . .
o | . .
n | . .
s | . .
u.| .
------------------------------------>
| Available Bandwidth exhausted
Shankar Raman et.al, Expires September 2013 [Page 12]
INTERNET DRAFT Power based Topologies using CSPF in OSPF March 2013
(b) If the confrontation is between 2 second profile routers the
upper curve offers more power savings per GB of bandwidth.
^
|
P | . .
o | . .
w | . .
e | . .
r | . .
| . .
c | . .
o | . .
n | . .
s | .
u.| .
------------------------------------>
| Available Bandwidth exhausted
(c) When the confrontation is between a first profile curve and a
second profile curve, it would be optimal to pick (as shown below)
the lower of the curves because it gives us lesser power consumed for
every GB of traffic routed / switched. Here the exponential curve is
the one that offers lesser amount of power consumed per GB of traffic
is chosen. But when it gets to a point that the two curves intersect
it would be more optimal to pick the tapering curve. Thus at the
meeting point of the 2 curves the exponential curve becomes more
costly and the tapering one gives us more GB for the power buck. Thus
this switchover from one curve to the other (in other words from the
exponential curve to the tapering one) does the trick in terms of
finding an optimal solution.
Shankar Raman et.al, Expires September 2013 [Page 13]
INTERNET DRAFT Power based Topologies using CSPF in OSPF March 2013
^ .
| .
P | . .
o | (*)
w | . .
e | . .
r | . .
| . .
c | . .
o | . .
n | . .
s | . .
u.| ..
------------------------------------>
| Available Bandwidth exhausted
(*) Metric switchover point from Consumed Power to Available
Power.
2.4.1.3 Need to advertise both available power and consumed power
Thus the above sections have shown that both the available power and
the consumed power MUST be advertised so that case (c) can be
deciphered and the switchover of the curves be done and the
appropriate router be chosen for the rest of the bandwidth to be
switched over to.
Thus there will exist Consumed-Power to Available Bandwidth ratio and
the Available Power to Available Bandwidth ratio. Both the ratios are
computed and the lower value chosen. The Available Power can be
judged from the calibration process such as the one carried out by
independent test organizations as in [12]. An example of their
calibration is referred to in [12].
Here given below is the formula for calculating the Available Power
to Available Bandwidth ratio also called the Available POWER metric.
Available
POWER metric = Available Power consumed per XG
(normalized bandwidth) port
for a given ----------------------------------
Port on a LC Available Bandwidth on that port
2.4.2 Power to Available Bandwidth ratio in a TLV
As per [RFC3630] the Link TLV can be used to carry this power to
available Bandwidth ratio with an additional sub-TLV of the link TLV.
The sub-type number 11 is recommended to be defined for this purpose.
Shankar Raman et.al, Expires September 2013 [Page 14]
INTERNET DRAFT Power based Topologies using CSPF in OSPF March 2013
[RFC 3630] states in section 2.2.1 and we QUOTE ...
2.2.1 Link TLV
The Link TLV describes a single link. It is constructed of a set of
sub-TLVs. There are no ordering requirements for the sub-TLVs.
Only one Link TLV shall be carried in each LSA, allowing for fine
granularity changes in topology.
The Link TLV is type 2, and the length is variable.
The following sub-TLVs of the Link TLV are defined:
1 - Link type (1 octet)
2 - Link ID (4 octets)
3 - Local interface IP address (4 octets)
4 - Remote interface IP address (4 octets)
5 - Traffic engineering metric (4 octets)
6 - Maximum bandwidth (4 octets)
7 - Maximum reservable bandwidth (4 octets)
8 - Unreserved bandwidth (32 octets)
9 - Administrative group (4 octets)
10 - Power-to-Multicast-replication-capacity (4 octets)
11 - Consumed-Power-to-Available-Bandwidth (4 octets)
12 - Available-Power-to-Available-Bandwidth (4 octets)
This memo defines sub-Types 1 through 9. See the IANA Considerations
in [RFC3630] section for allocation of new sub-Types.
The Link Type and Link ID sub-TLVs are mandatory, i.e., must appear
exactly once. All other sub-TLVs defined here may occur at most
once. These restrictions need not apply to future sub-TLVs.
Unrecognized sub-TLVs are ignored.
Various values below use the (32 bit) IEEE Floating Point format. For
quick reference, this format is as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|S| Exponent | Fraction |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
S is the sign, Exponent is the exponent base 2 in "excess 127"
notation, and Fraction is the mantissa - 1, with an implied binary
point in front of it. Thus, the above represents the value:
Shankar Raman et.al, Expires September 2013 [Page 15]
INTERNET DRAFT Power based Topologies using CSPF in OSPF March 2013
(-1)**(S) * 2**(Exponent-127) * (1 + Fraction)
It is proposed that we use the Power-to-Available-Bandwidth ratio as
a 32 bit IEEE floating Point format field for the purpose of this
document.
3. Conclusion
Routers may have step levels in which they increase power consumption
when they additively are loaded with more large bandwidth consuming
multicast or unicast streams. Calibrating these levels may be useful
for implementing this scheme. It is possible that such calibrated
thresholds can be used for advertising the PWRLINK ratios in the OSPF
LSA advertisements. This would be useful for bringing down the
frequency of updates or advertisements from a line-card about its
PWRLINK ratio. When power consumption meanders within a certain given
interval these ratios need not be re-advertised even if further
unicast and/or multicast streams are added to it. The incentive is to
recognize a linecard that does not drastically change power
consumption even if large bandwidth streams are added onto it for
forwarding and thus give it credit for its power optimal functioning.
If a router tends to consume the highest level of power even when
carrying low amounts of unicast and multicast streams on its line
card, it would automatically have a poor ratio when compared to a
router that efficiently uses power when considering the Available
Bandwidth being observed. The best case would be a low power
consuming line-card or a router filled with such line cards that does
not leave its power interval no matter how much ever capacity is
sought to be used on it. But that would be an ideal condition but it
is definitely an idealistic scenario towards which the router
manufacturers should look at.
Shankar Raman et.al, Expires September 2013 [Page 16]
INTERNET DRAFT Power based Topologies using CSPF in OSPF March 2013
3 Security Considerations
<Security considerations text>
4 IANA Considerations
New requirements are required from IANA for a new type in the Link
TLV in order to carry the PWRLINK metric as well. This is needed for
both Consumed Power Ratio and Available Power Ratio.
5 References
5.1 Normative References
5.2 Informative References
[1] G. Appenzeller, Sizing router buffers, Doctoral
Thesis, Department of Electrical Engineering, Stanford
University, 2005.
[2] A. P. Bianzino, C. Chaudet, D. Rossi and J. L.
Rougier, A survey of green networking research, IEEE
Communications and Surveys Tutorials, preprint.
[3] J. Baliga, K. Hinton and R. S. Tucker, Energy
consumption of the internet, Proc. of joint international
conference on optical internet, June 2007, pp. 1-3.
[4] J. Chabarek, J. Sommers, P. Barford, C. Estan, D.
Tsiang and S. Wright, Power awareness in network design
and routing, Proc. of the IEEE INFOCOM 2008, April 2008,
pp. 457-465.
[5] B. Venkat et.al, Constructing disjoint and partially
disjoint InterAS TE-LSPs, USPTO Patent 7751318, Cisco
Systems, 2010.
[6] M. Xia et. al., Greening the optical backbone network:
A traffic engineering approach, IEEE ICC Proceedings, May
2010, pp. 1-5.
[7] W. Lu and S. Sahni, Low-power TCAMs for very large
forwarding tables, IEEE/ACM Transactions on Computer
Networks, June 2010, vol. 18, no. 3, pp. 948-959.
Shankar Raman et.al, Expires September 2013 [Page 17]
INTERNET DRAFT Power based Topologies using CSPF in OSPF March 2013
[8] B. Zhang, Routing Area Open Meeting, Proceedings of
the IETF 81, Quebec, Canada, July 2011.
[9] M.J.S Raman, V.Balaji Venkat, G.Raina, Reducing Power
consumption using the Border Gateway Protocol, IARIA
conferences ENERGY 2012.
[10] A.Cianfrani et al., An OSPF enhancement for energy
saving in IP Networks, IEEE INFOCOM 2011 Workshop on Green
Communications and Networking
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.
EMail: balajivenkat299@gmail.com
Prof.Gaurav Raina
Department of Electrical Engineering
IIT Madras
Chennai - 600036
TamilNadu
India.
EMail: gaurav@ee.iitm.ac.in
Shankar Raman et.al, Expires September 2013 [Page 18]
INTERNET DRAFT Power based Topologies using CSPF in OSPF March 2013
Vasan Srini
Department of Computer Science and Engineering
IIT Madras
Chennai - 600036
TamilNadu
India.
EMail: vasan.vs@gmail.com
Shankar Raman et.al, Expires September 2013 [Page 19]
