One document matched: draft-lee-network-stratum-query-problem-00.txt
Network Working Group Young Lee (Huawei)
Internet Draft Dave McDysan (Verizon)
Intended Status: Informational Ning So (UTD)
Greg Bernstein (Grotto)
Tae Yeon Kim (ETRI)
Kohei Shiomoto (NTT)
Oscar Gonzalez de Dios (Telefonica)
October 13, 2010
Problem Statement for Network Stratum Query
draft-lee-network-stratum-query-problem-00.txt
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Abstract
This document describes the general problem of network stratum query
for application optimization. Network Stratum query is an ability to
query the network from an application controller such as those used
in Data Centers so that application controller decisions such as
server assignment or virtual machine instantiation/migration could be
performed with better knowledge of the underlying network conditions.
As application servers are distributed geographically across Data
Centers, many application-related decisions such as which server to
assign a new client or where to instantiate/migrate virtual machines
will suffer from sub-optimality unless the underlying network
conditions are factored in the decision process. The lack of network
awareness may result in not meeting the end-user service objective
for some key applications like video gaming/conferencing that require
stringent latency and bandwidth requirement.
Table of Contents
1. Introduction...................................................2
2. Network Contexts...............................................4
3. Problem Statement..............................................7
4. High-level requirements........................................8
4.1. Data Center-Network Stratum Communication (NS Query)......8
4.1.1. Application Profile..................................8
4.1.2. Network Load Data to be queried......................9
4.1.3. Responses to NS Query from network to application...10
5. Security Considerations.......................................10
6. References....................................................10
Author's Addresses...............................................11
Intellectual Property Statement..................................11
Disclaimer of Validity...........................................12
1. Introduction
Cross Stratum Optimization is a joint optimization effort in
allocating resources to end-users that involves both the Application
Stratum and Network Stratum.
The application stratum is the functional block which manages and
controls application resources and provides application resources to
a variety of clients/end-users. Application resources are non-network
resources critical to achieving the application service
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functionality. Examples include: application specific servers,
storage, content, large data sets, and computing power. Data Centers
are regarded as tangible realization of the application stratum
architecture.
The network stratum is the functional block which manages and
controls network resources and provides transport of data between
clients/end-users to and among application resources. Network
Resources are resources of any layer 3 or below (L1/L2/L3) such as
bandwidth, links, paths, path processing (creation, deletion, and
management), network databases, path computation, admission control,
and resource reservation capability.
Application services offered by Data Centers by their very nature
utilize application resources (e.g., servers, storage, memory,
etc...) in Data Centers, and the underlying network resources
provided by LANs, MANs, and carrier's transport networks.
As the application servers are distributed geographically across many
Data Centers, decisions such as server assignment or new virtual
machine instantiation will suffer from sub-optimality unless the
underlying network conditions are factored in the decision process.
The lack of network awareness may result in not meeting the end-user
service objective for some key applications like video
gaming/conferencing that require stringent latency and bandwidth
requirement.
This document describes the general problem of network stratum query
(NS Query) in Data Center environments. Network Stratum query is an
ability to query the network from application controller in Data
Centers so that application server instantiation decision would be
jointly performed based on both the application resource/load status
and the network resource/load status.
The NS query is different from typical "horizontal" query
capabilities in the network. The horizontal query in the network is
carried by the head end (i.e., data source) that would "probe" the
network to test the capabilities for data flows to/from particular
point in the network. This is a horizontal scheme.
NS Query is a two-stage query that consists of two stages:
. A vertical query capability where an external point (i.e., the
Application Control Gateway (ACG) in Data Center) will query
the network (i.e., the Network Control Gateway (NCG)); and
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. A horizontal query capability where the NCG to gather the
collective information of a variety of horizontal schemes
(IPPM, IGP, RIB, etc.) implemented in the network stratum.
NS Query does not re-invent the wheel on existing network
capabilities but tries to reuse them where possible.
2. Network Contexts
Figure 1 shows a typical data center architecture where an end-user
(the point of consuming resource) needs to be connected for its
application (e.g., gaming) to a server located in one of the data
centers geographically spread.
---------------
---------- | DC 1 |
| End-user |. . . . .>| o o o |
| | | \|/ |
---------- | O |
| ----- --|------
| |
| |
| -----------------|-----------
| / | \
| / ..........O PE1 \ --------------
| | . | | o o o DC 2 |
| | PE4 . PE2 | | \|/ |
----|---O.........................O---|---|---O |
| . | | |
| . PE3 | --------------
\ ..........O Carrier /
\ | Network /
---------------|-------------
|
--------|------
| O |
| /|\ |
| o o o |
| DC 3 |
---------------
Figure 1. Data Center Architecture
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Figure 1 shows that the user application can be served by any of the
servers in DC1, DC2 and DC3. When the initial request arrives to the
proxy server in DC1, the proxy server (aka, the load balancer) would
ideally assign an "optimal" server based on both server resource/load
status and the network resources/load status. This server assignment
decision today, however, is limited due to the lack of network
awareness in this decision making process in the application.
For example, the server close to the user in Data Center 1 may find a
good server that can serve the application. Assume that this
particular application requires x amount of minimum bandwidth
guarantee and with less than y ms of latency limit. The route that
serves Data Center 1 traffic to the end-user (PE1 - PE4) may not have
enough capacity at a moment of service instantiation and therefore
the service objective of the end-user may not be satisfied had such
route been taken.
On the other hand, there may be good servers available in Data
Centers 2 and 3 and their routes (PE2-PE4 and PE3-PE4) may have
enough capacity to meet the service requirement.
This example illustrates the benefit of and the need for the joint
optimization across the application and network strata. NS Query is
the ability to query the network from an application to collect a
certain level of network information. No such mechanisms exist in the
today's Internet Protocol technologies.
Figure 2 shows the context of NS Query in a more detail within the
overarching data center architecture shown in Figure 1.
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--------------------------------------------
| Application Overlay |
| (Data Centers) |
| |
---------- | -------------- -------------- |
| End-User | | | Application |. . . .| Application | |
| |. . . >| | Control | | Processes | |
---------- | | Gateway (ACG)| -------------- |
| | | -------------- |
| ------------- . . . . | Application | |
| /\ | Related Data | |
| || -------------- |
----------||--------------------------------
||
|| Network Stratum Query (First Stage)
||
----------||--------------------------------
| \/ Network Underlay |
| |
| -------------- ---------------- |
| | Network |. . . | Network | |
| | Control | | Processes | |
| | Gateway (NCG)| ----------------
| | | ---------------- |
| ------------- | Network | |
| |------------->| Related Data | |
| (Second Stage) ---------------- |
-------------------------------------------
Figure 2. NS Query Architecture
Figure 2 shows key architectural components that enable NS Query
capability. The Application Control Gateway (ACG) is the proxy
gateway that interfaces with network and generate queries to network.
The ACG can query various metric values that may contribute to
meeting the overall service objective of an application. This is a
vertical query (Stage 1).
In the network stratum, the Network Control Gateway (NCG) serves as
the proxy gateway to the network. The NCG receives the query request
from the ACG, probes the network to test the capabilities for data
flow to/from particular point in the network, and gather the
collective information of a variety of horizontal schemes (IPPM,
IGP, MIB, TED, etc.) implemented in the network stratum. This is a
horizontal query (Stage 2).
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Further, the NCG provides the responses to the original query sent
from the ACG. The data collected by the NCG needs to be abstracted.
This abstraction is needed on two grounds.
First, the network does not usually reveal its details to the
outside entity. Although the Data Center providers and the carriers
are business partners in providing application services to the end-
users and to the application providers (e.g., gaming providers),
detail network data may not be leaked to the Data Centers, and vice
versa.
Second, detail network data may not be understood by the
application. Link or node level data in and of themselves may not
help the application to process the detail data. For instance,
latency or bandwidth on a link level is too detail for application
to handle. Instead, latency or bandwidth on a route level (i.e., PE1
- PE4 in Figure 1) will help the application make its server
selection/instantiation decision.
The abstraction function needs to be provided by the NCG. Note that
NCG plays a head end role within the network probing/collecting
network performance/management data (e.g., IPPM, MIB, etc.) or
routing data [MRT] (e.g., LSDB, TED, BGP-RIB, etc.) and others. Once
the basic data is collected, the NCG will need to abstract/summary
before it sends to the application.
3. Problem Statement
The current state-of-the art probing schemes from an external point
are based on ping or trace route like mechanisms based on the
assumption that the underlying transport network is L3 network and
that the routing is simple IP forwarding.
In reality, the carrier's routing schemes are likely to include IP
tunneling or MPLS tunneling on top of or in place of IP forwarding.
In some cases, the actual network may be VPN, MPLS-TE or GMPLS-TE
networks where trace route does not work.
This implies that network status estimation technique made from
application stratum cannot be accurate. Thus, application resource
allocation to end-users can suffer sub-optimality and fail to meet
performance objective for the application.
Currently, there is no standard "vertical" probing scheme that allows
an application control gateway in Data Center to query network
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stratum in a way suitable for a third party (i.e. an entity "outside"
the network).
In the network stratum, there is no mechanism for "a whole network
query of information at the network-stratum." A whole network query
is "a query to gather the topology of the network, the bandwidth
availability for the routes of interest, the capabilities and
congestion of links and routes, and an indication of the contribution
to delay and jitter that each link and route will contribute."
Note that there are existing mechanisms in the network such as IPPM,
PCE, PCN, IGP, etc. that can be reused for this purpose.
Further, even if the whole network query of information is available,
there is no abstraction mechanism today in the network stratum to
avoid the details of such information such as topology, link
bandwidth availability, latency, packet loss, etc., to the outside
entity. This warrants some works on abstraction from network side to
preserve the privacy of network stratum details from the application
stratum.
4. High-level requirements
This section discusses high-level requirements to support NS Query in
the Data Center environments.
4.1. Data Center-Network Stratum Communication (NS Query)
The ACG plays the key role functioning as an application gateway to
network and runs the NS Query. The ACG has access to the end-user
profile for the application and the candidate servers' locations
locally and remotely located. How the ACG access these information is
beyond the scope of this work.
4.1.1. Application Profile
The application Stratum needs to provide the application profile to
network.
Example service profile information that can be useful to network to
understand is as follows:
. End user IP address;
. User access router IP address;
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. Authentication Profile: Authentication Key;
. Bandwidth Profile: Minimum bandwidth required for the
application;
. Connectivity Profile: P-P, P-MP, Anycast (Multi-destination);
. Directionality of the connectivity: unidirectional, bi-
directional;
. Path Estimation Objective Function: Min latency, etc.
Additional profile information can be added depending on the network
capability.
4.1.2. Network Load Data to be queried
For a given location mapping information (i.e., from the server
location to end-user location), the query can ask the following
network load data:
. Type of networks and the technical capabilities of the networks;
. Bandwidth capabilities and availability;
. latency;
. jitter;
. packet loss;
. And other Network Performance Objective (NPO) as defined in
section 5 of [ITU-T Y.1541].
Note that this can be asked in a different way. For example, the
query can simply ask:
. Can you give me if you can route x amount of b/w (from server to
end-user) within y ms of latency?
. Can you give me if you can route x amount of b/w (from server to
end-user) with no packet loss?
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4.1.3. Responses to NS Query from network to application
Given the network query from application, the network should provide
the following mechanisms:
- For a given location mapping information from application (i.e.,
from the server location to end-user location), network needs to
derive its network graph and estimate the asked data (e.g.,
latency, b/w available, packet loss, etc.)
Note: How to estimate by network is beyond the scope of this work and
should be addressed in other pertinent WGs.
- The abstraction of the requested data in response to the NS Query
request from application.
5. Security Considerations
TBD
6. IANA Considerations
This informational document does not make any requests for IANA
action.
7. References
7.1. Informative References
[RFC2261] D. Harrington, et al., "An Architecture for Describing SNMP
Management Frameworks," January, 1998.
[RFC2265] B. Wijnen, et al., "View-based Access Control Model (VACM)
for the Simple Network Management Protocol (SNMP),"
January, 1998.
[Y.2011] General principles and general reference model for Next
Generation Networks, October, 2004.
[Y.2012] Functional Requirements and architecture of the NGN, April,
2010.
[MRT] L. Blunk, M. Karir, and C. Labovitz, "MRT routing
information export format," draft-ietf-grow-mrt, work in
progress.
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Author's Addresses
Young Lee
Huawei Technologies
1700 Alma Drive, Suite 500
Plano, TX 75075
USA
Phone: (972) 509-5599
Email: ylee@huawei.com
Ning So
Univerity of Texas at Dallas
Email: ningso@yahoo.com
Dave McDysan
Verizon Business
Email: dave.mcdysan@verizon.com
Greg M. Bernstein
Grotto Networking
Fremont California, USA
Phone: (510) 573-2237
Email: gregb@grotto-networking.com
Tae Yeon Kim
ETRI
tykim@etri.or.kr
Kohei Shiomoto
NTT
Email : shiomoto.kohei@lab.ntt.co.jp
Oscar Gonzalez de Dios
Telefonica
Email : ogondio@tid.es
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