Internet DRAFT - draft-chen-trill-te-applicability
draft-chen-trill-te-applicability
Network Working Group G. Chen
Internet-Draft C. Li
Intended status: Informational China Mobile
Expires: January 16, 2014 July 15, 2013
The Applicability Analysis of Traffic Engineering over Trill
draft-chen-trill-te-applicability-00
Abstract
This memo intended to describe the needs of Traffic Engineering (TE)
in a Data Center Network (DCN) in which Transparent Interconnection
of Lots of Links (Trill) has been adopted. Several use cases have
been proposed to demonstrate the usage while the feasibility of Trill
extension has been evaluated. It serves to motivate the normative
work subsequently.
Status of This Memo
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This Internet-Draft will expire on January 16, 2014.
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Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Motivations . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Bandwidth Ensuring . . . . . . . . . . . . . . . . . . . 3
3.2. Link Protections . . . . . . . . . . . . . . . . . . . . 4
3.3. Traffic Matrix . . . . . . . . . . . . . . . . . . . . . 4
3.4. Unequal Load Balancing . . . . . . . . . . . . . . . . . 5
4. Applicabilty Analysis . . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. Normative References . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction
Transparent Interconnection of Lots of Links (Trill) protocol is
targeted to improve link utilizations of switch networks. With the
growth of Data Center Network (DCN), this technology is widely used
and approved to be an essential component building layer-two
networks. The services in DCN could benefit from multi-path
forwarding for good flexibility and resilience. Shortest Path First
(SPF) is used to forward data frames. The selection of forwarding
path is inherited from a routing protocol, which may be optimized
based on a simple additive metric. Those algorithms are generally
topology-driven, so link utilizations and traffic features can't be
factors considered in data path decisions.
Traffic Engineering (TE) provided a useful feature to improve
the performance of the telecommunication networks. The ultimate
objective is to avoid congestion in the network by keeping its links
from being overloaded. Current uses are exclusively focused on the
applications of Multiprotocol Label Switching (MPLS). It's normally
deployed in a large Internet backbone. The adoption in a DCN
environment is worth to be investigated given the scale of large
Ethernet networks has been dramatically expanded.
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This document describes service characteristics in a DCN. The
deployment of traffic engineering would likely optimize the Quality
of Experiences. It motivates the work to populate TE functions into
Trill protocol. Several use cases help to elaborate the usages of
those technologies. The considerations of technical principle can
also be deduced from actual uses. This memo also provided the
possibilities of protocol design.
2. Motivations
Data centers are being heavily employed in enterprise and consumer
settings to run a variety of applications and cloud-based services.
These range from Internet-facing "sensitive" applications, such as,
Web services, instant messaging, stock updates, financial
applications and gaming, to storage intensive applications, such as,
data analysis, file sharing and scientific computing. The
performance of these applications crucially depends on the
functioning of the data center's network infrastructure. For
example, a congested data center network, where internal traffic is
routinely subjected to losses and poor throughput, could lead search
queries to take longer to complete, instant message to get delayed,
gaming experience to deteriorate, and POP mail services and Web
transactions to hang. The dissatisfied end-users and subscribers
could choose alternate providers, resulting in a significant loss in
revenues for the data center. TE mechanism likely could help the
situation by monitoring the link's loads and traffic growth trends.
It's desirable to introduce the technology into DCN even there is
constituted with a number of switch device.
Trill has been adopted in DCN in recent years. SPF-based algorithm
still can't provide satisfactory performance if congestions are
occurred on the links. Our preliminary study reveals that SPF-based
algorithm achieve only 80-85% of the performance achieved by an
optimal TE algorithm. It indicates that there is significant room
for improvement if TE functions could be integrated with Trill.
Those benefits could motivate new works on Trill-TE.
3. Use Cases
3.1. Bandwidth Ensuring
The Fig. 1 shown the case, in which different services, including
gaming, stroge backup and web browse are relied on a switch network.
There are two paths between ingress RB1 and egress RB3, i.e. RB1---
RB2---RB3 and RB1---RB4---RB5--RB6. Trill-TE is used to guarantee
the performance of gaming with low delay. And other services would
bypass the route gaming traversed so as to avoid congestions with
gaming. Therefore, RB1---RB2---RB3 are served as to transmit the
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gaming data. RB1---RB4---RB5--RB6 has been selected for other data
services.
+-----+ +-----+ +-----+
| RB4 |-------| RB5 |--------| RB6 |
+-----+ +-----+ +-----+
| |
+-----+ +-----+ +-----+
| RB1 |-------| RB2 |--------| RB3 |
+-----+ +-----+ +-----+
Ingress | | Egress
Figure 1: Bandwidth Ensuring with Trill-TE
3.2. Link Protections
The Fig.2 shows the topology. Ingress RB1 would go through the way
of RB1-- RB2--RB3--RB4 to RB8. If there is failure detected on the
path. Trill-TE would switch the traffic to the backup link, i.e.
RB1-- RB5--RB6--RB7--RB8. Once the above link is recovered, the
traffic would be switched back to below link.
+-----+ +-----+ +-----+
+------ | RB2 |-------| RB3 |--------| RB4 |-------+
| +-----+ +-----+ +-----+ |
+-----+ +-----+
| RB1 |Ingress | RB8 |Egress
+-----+ +-----+
| +-----+ +-----+ +-----+ |
+------ | RB5 |-------| RB6 |--------| RB7 |-------+
+-----+ +-----+ +-----+
Figure 2: Link Protections with Trill-TE
3.3. Traffic Matrix
Various traffic flows can be well gauged when the Trill is capable of
Traffic Engineering. Operators could get accurate traffic statistics
because the traffic is deterministically transmitted over the planned
data paths. The deployment of traffic engineering in a DCN helps to
form a traffic matrix, which provides the volume of traffic between
every pair of ingress and egress points over a given time interval.
Such information is critical inputs to network design, capacity
planning and business planning.
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3.4. Unequal Load Balancing
Unequal load balancing could help to utilize bandwidth resource
properly. Each link is vary in the exchange capability, for example
10GbE, 40GbE or 100GbE have been deployed on the route paths. The
traffic engineering in Trill could distribute the flow on the matched
link. It could optimize the network resource uses as a whole.
4. Applicabilty Analysis
The following is the features Trill-TE could leverage. Those can
verify the feasibility of this work.
o Multipath: Trill-TE must take advantage of the path diversity
available in the data center's network. Based on that, the
forwarding path can be decided via an global view of traffic.
o Metric transmission: IS-IS Extensions for Traffic Engineering is
already defined in [RFC5305]. Trill-TE may need to insert
Nicknames to the forwarding table for the TE routing path. The
existing Trill process would immune to those changes.
5. IANA Considerations
This document makes no request of IANA.
6. Security Considerations
TBD
7. Normative References
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, October 2008.
Authors' Addresses
Gang Chen
China Mobile
53A,Xibianmennei Ave.,
Xuanwu District,
Beijing 100053
China
Email: phdgang@gmail.com
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Chen Li
China Mobile
53A,Xibianmennei Ave.,
Xuanwu District,
Beijing 100053
China
Email: lichen@chinamobile.com
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