2012 International Conference on Information and Computer Applications (ICICA 2012)
IPCSIT vol. 24 (2012) © (2012) IACSIT Press, Singapore
GA-Ethernet: The Global Area Ethernet
SutheeSirisutthidechaa and KomwutWipusitwarakunb
School of Information, Computer, and Communication Technology,
Sirindhorn International Institute of Technology (SIIT),
Thammasat University, PathumThani 12121, Thailand
Email: a speedyaui@msn.com, b komwut@siit.tu.ac.th
Abstract. Recently, many researches in network virtualization have demonstrated the potential of building
virtualized networks over global network environment, like the Internet. However there is still no virtualized
network proposal for the most popular Ethernet network which can be easily utilized by most of applications
in all end-user devices. This paper explores the possibility of building Ethernet networks over the public
Internet, called Global Area Ethernet (GA-Ethernet). Pros and cons of having the GA-Ethernet have been
discussed. Existing proposed alternatives have been investigated. Finally, a novel GA-Ethernet which might
be suitable for the public Internet has been proposed.
Keywords: Network Virtualization, Global Area Ethernet, Overlay Network.
1. Introduction
Recently, many researches [1-10] in network virtualization have demonstrated the potential of building
virtualized networks on global network environment, like the Internet. For examples, L2VPN [1] and Pseudo
Wire [11] built virtual “Layer 2” network that emulated the operation of a "transparent wire" to carrying the
native service such as T1 Lease line, Frame relay, etc. those services are running on the MPLS/IP router
network which is practically provided by a single network service provider.
Internetworking researches [6-9] built virtual “IP” network over public Internet using application-level
overlay technique to enable virtual IP infrastructures, composed of tunneled links among set of the
components: hosts, routers and links. They provide a new playground to deploy, leverage, and evaluate
value-added network services which are not widely deployed in the real Internet but its activities and
communications are strictly confined within them.
EtherIP [12] proposed a way to send Ethernet frame across the Internet, using tunneling method to
encapsulate only Ethernet frame’s payload into IP datagram (IPv4). However, a full virtual Ethernet network
cannot be created over the Internet.
As to our knowledge, there is no network virtualization proposal addressing one of the most popular
networks, the Ethernet [13, 14]. Ethernet network is initially designed for LAN (Local Area Network).
Ethernet deals with the low level - Physical and Data Link Layers that make it be able to carry any packets
and any protocols of the upper layer (IP, IPX, NetBIOS, etc.) with all communication types (unicast,
multicast and broadcast). Ethernet serves as the basis for the IEEE 802.3 standard that seems to be the
standardized interface in all OS platforms.
Currently, Ethernet can be easily utilized by most of applications in all end-user devices. There are two
practical usages of Ethernet. Firstly, applications indirectly use Ethernet via the standard TCP/IP protocols.
Most of Internet Applications falls in this category. Secondly, non-IP applications use Ethernet directly,
based on their proprietary protocols. For example, Network neighborhood or SMB/CIFS [15,17] broadcast
Ethernet frames to find active nodes and services in the same LAN. This usage category is very popular in
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workgroup (LAN) networks which can be easily setup by end users themselves, including both wired and
wireless Ethernet. The following examples show some popular LAN applications,
•
•
•
Messaging and Collaboration Systems (MS Exchange, Lotus Notes) [16]
Files and Print sharing [17]
IEEE 802.1 Audio/Video Bridging (AVB): These allowed time-synchronized low latency streaming
services, audio and video data, through IEEE 802.x networks. [18]
Even though, Ethernet is very popular but it was designed for Local Area Network with short coverage
distance [19] and fixed type of physical medium [19].
This paper explores the possibility of building virtual Ethernet networks over the public Internet, called
Global Area Ethernet (GA-Ethernet). Figure 1 illustrates a general idea of the GA-Ethernet with the
following characteristics.
•
•
G
AEt
h
M
G
AC
AEt
h
M
U
D
AC
P
Ap
p
•
The users can setup an Ethernet network on global area coverage.
Application still uses the same Ethernet interface as if it is the LAN Ethernet.
Public Internet is utilized as the very long distance medium for transferring Ethernet frames across
the globe via any Internet access technology.
Fig. 1: Global Area Ethernet (GA-Ethernet)
Fig. 2: System Model of the GA-Ethernet
By using GA-Ethernet, users will get all benefits of working on a workgroup network such as LAN [19]
or VLAN [20]. Since GA-Ethernet provides native Ethernet API, all existing applications including non-IP
applications can run over the GA-Ethernet without any modification. Multicast and Broadcast application
such as file sharing and Network neighborhood [16-17] will be usable over the Internet easily without any
addition of network infrastructure elements such as multicast router [21]. Users can utilize all applications
from anywhere, independent to their Internet access technology. The mobility feature of Internet technology
will seamlessly inherit to the GA-Ethernet, then finally to the applications. This eases application
development process since the developer does not have to change their codes whenever physical (access)
networks or access technologies changes.
However there are several challenges need to be addressed since the characteristics of the public Internet
over which the proposed GA-Ethernet is built may not be suitable to the standard service model of the
Ethernet. One of the key challenges is how to emulate Ethernet broadcast domain over the unicasting Internet.
The other is that the system must support for heterogeneous end-point speeds due to various Internet access
technologies used by end users. In addition, a simple but effective set of GA-Ethernet management and
administrative protocols is required to setup GA-Ethernet workgroup (analogous to the VLAN) on demand
over the public Internet.
The rest of the paper has been organized as follows. Section II explains system overview of GA-Ethernet.
Section III presents its transmission and protocol interaction model. Section IV studies the technical
feasibility of realizing the GA-Ethernet. Finally, section V concludes the paper.
2. System Overview
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GA-Ethernet borrows the service model of VLAN[20], which is a group of logically networked hosts
with a single broadcast domain regardless of their physical connectivity, but works in scope of global area
Internet. Figure 2 shows the system model of the GA-Ethernet. Each host installs a physical Network
Interface Card (NIC) of any available Internet access technologies, e.g. wired/wireless Ethernet, 3G, Wimax,
FTTH or xDSLetc, with appropriate protocol stacks. Such installation will let the host physically connect and
send data over the public Internet. To create a GA-Ethernet workgroup (GAENet), the host will additionally
install a GA-Ethernet network Interface card (GAE-NIC). Then it will be plugged in one of GA-Ethernet
ports on a certain GA-Ethernet switch (GAE-SW), placed somewhere on the Internet, via the GA-Ethernet
cable (GAE-Cable). Both GAE-NIC and GAE-SW are virtual entities which are software-based
implementation while a GAE-Cable connecting between a GAE-NIC and the GAE-SW is the virtual cable
created by adaptive tunnels [22] carrying the GA-Ethernet MAC frame. The tunnel may be implemented by
any available Internet protocol such as UDP, TCP or even application layer protocol, which is agreed upon
by both GAE-NIC and GAE-SW when plugging them together. Note that a GAE-Cable can utilize multiple
tunnels with different carrier protocols concurrently in order to manage a GAENet more efficiently if
necessary. In a GAE-SW, the GA-Ethernet Filtering and Forwarding module (GAE-FF) will forward arrival
GA-Ethernet MAC frames to only the GAE-port corresponding with the destination MAC address in the
frame. In case of broadcast and multicast MAC address, the frame will be forwarded to every active port.
The GA-Ethernet configuration and administration module (GAE-CA) will take care of other necessary
works such as MAC address assignment, GAE-cable configuration and performance monitoring, frame
transmission shortcut control, etc. Since a GAE-SW is solely implemented as a set of software modules, one
may easily run multiple GAE-SWs on the shared server in the Internet. In the same manner, a host may run
multiple instances of GAE-NIC to join multiple GAENets simultaneously using the same shared physical
Internet access NIC.
3. Transmission and Protocol Interaction Model
In the proposed GA-Ethernet, a GAE-SW can serve only one GAENet which is comparable to a VLAN
in a standard Ethernet network. Each GAE-SW process instance configured with a unique GAENet ID is run
and bound to a specific UDP port number on the server. By specifying the IP address + the UDP port, GAENIC can contact to the GAE-SW for joining a GAENet.
3.1.
GAE-NIC Life Cycle
Each host who will join a GAENet needs to install the GAE-NIC software to emulate a standard Ethernet
Interface in its operating system. The GAE-NIC starts joining a specific GAENet by sending initialization
request to the GAE-SW specifying necessary information such as GAENet ID, authentication tokens, GAECable’s tunnel options etc. The GAE-CA module in the GAE-SW will reply the request with the allocated
resources such as the GAE-NIC’s MAC address, the usable GAE-SW’s port ID and the available GAECable’s tunnel options if the request passed the authentication process. Based on replied information, the
GAE-NIC will configure itself with the assigned MAC address and try to plug the GAE-Cable from itself in
the GAE-SW’s port by creating the most appropriate tunnel option. When the GAE-Cable has been
successfully connected, the state of the GAE-NIC will change to “cable plugged”. The GAE-NIC is now
prompt to send/receive GA Ethernet MAC frame and can be utilized as a standard Ethernet interface in the
host computer. Figure 3 shows the state transition diagram of GAE-NIC and its corresponding interaction
with GAE-SW to joining a GAENet. Note that the state of GAE-NIC may change forth and back between the
“cable plugged” and the “cable unplugged” if the GAE-Cable’s tunnel is broken and needed to be
reconstructed.
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Fig. 3: GAE-NIC’s state transition diagram Fig. 4: GA-Ethernet MAC frame structure and its interaction model
with GAE-SW
3.2.
GA Ethernet Frame Transmission
In a GAENet, its broadcast domain is created by relaying GA Ethernet frames through its GAE-SW.
Each GAE-NIC is connected to the GAE-SW via GAE-Cable, implemented by Internet tunnels. Since those
tunnels are usually the full-duplex virtual connection, the GAENet is a full-duplex switched network. Thus,
the MAC sublayer of the GA Ethernet will implement only MAC addressing mechanism. The channel access
control mechanism is not necessary in such full-duplex switched network [19, 20].
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th
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GA
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M
AC
M
AC
M
Eth
A-
th
A-E
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Eth
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AG
MA
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To be compatible with the standard Ethernet API in any OS, the format of GA Ethernet MAC address is
the standard MAC-48 or EUI-48 [19] which is used by most of wired/wireless Ethernet networks. When a
GAE-NIC is on the “cable plugged” state, data can be transmitted from itself to any other GAE-NIC in the
same GAENet. Figure 4 shows the GA Ethernet MAC frame structure. It consists of 5 fields which are frame
control, destination MAC address, source MAC address, payload sequence and frame body. The frame body
may carry either higher layer data (802.2 LLC sublayer) or GA Ethernet control information, whose type is
determined by the type bits in the frame control field. The payload sequence field specifies the sequence
number of the frame body’s payload. Since the GA Ethernet MAC sublayer may send a MAC frame over
multiple GAE-cables (Internet tunnels) concurrently, the payload sequence will let the receiving GAE-NIC
detect duplicate frames and, if necessary, reorder the arrival frames correctly. Figure 5 illustrates the GAEthernet MAC frame transmission in a GAENet. Both GAE-NIC and GAE-SW maintain a frame forwarding
table (FFT) for deciding which GAE-cable will be used to send out MAC frames for a specific destination
MAC address. Entries in the FFT will be updated when the GAE-cables have been set up or changed. By
default, there is only one entry in the FFT of a GAE-NIC, which points to the GAE-SW for any destination
MAC address. For the GAE-SW’s FFT, each destination MAC address will have its corresponding GAEcable entry when a specific GAE-NIC joins the GAENet. However if a GAE-NIC creates a GAE-cable by
constructing multiple tunnels, it is possible to have several correspondent entries for a specific destination
MAC address. Especially, when the transmission shortcut mode (described in the next section) has been
activated, the higher priority entry in the FFT will be selected to send frames with the matched unicast
destination MAC address. Note that frames with broadcast or multicast destination MAC address will always
be forwarded to the GAE-SW. Then, they will be duplicated and sent to every active entry in the GAE-SW’s
FFT table.
Fig. 5:GA-Ethernet MAC frame transmission
Fig. 6:Transmission Shortcut Control Protocol
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3.3.
Tran
nsmission Shortcut
S
C
Control
To incrrease perform
mance of MAC
M
frame transmission
t
n, a better shhortcut GAE
E-cable from
m the sourcee
GAE-NIC to
t the destinaation GAE-N
NIC might bee created on demand. Figgure 6 showss the interacttion betweenn
two GAE-N
NICs which are going too communiccate with eacch other. When
W
a GAE-NIC sends frames to a
specific desstination GA
AE-NIC at thhe first timee, the frames will be reelayed througgh the GAE
E-SW. If thee
transmissionn shortcut mode
m
of the GAE-NIC is
i set, the source GAE--NIC will sttart negotiatiing with thee
destination GAE-NIC to
t create a shortcut
s
GAE
E-cable by exchanging
e
t
transmission
n shortcut co
ontrol (TSC))
MAC framees. The TSC
C frames conntain necessaary info such
h as authentication tokenns and tunnell options forr
constructingg the direct Internet
I
tunnnel between both
b
GAE-N
NIC. Those TSC
T
frames are transmittted by usingg
default trannsmission moode via the GAE-SW.
G
W
When
the direect GAE-cabble has been created, its transmission
t
n
performance will be coompared withh the defaultt transmissio
on path usingg transmission performaance probingg
frames. If itt is better, thhe FFT of thhe GAE-NIC
C will be upd
dated to recoognize the nnew shortcut GAE-cable..
After that, data
d frames will
w be forwaarded directlly to the desttination GAE
E-NIC. Reguularly, the GA
AE-NIC willl
probe the performance
p
e of the shoortcut GAE-cable and will
w update, release or rrecreate the GAE-cablee
appropriatelly accordingg with its currrent state. The
T frame trransmission will
w be switcched back to
o the defaultt
mode if eithher the shorttcut entry in the FFT no longer existts or its perfo
formance deggrades to thee level lowerr
than the deffault transmission path.
4. Performance Evaluation
E
n
The GA
A-Ethernet siimulation model,
m
like sm
mall workgro
oup of Etherrnet networkk with star to
opology andd
full-duplex transmissionn, consists of
o a one GAE-SW and ten
t Hosts (G
GAE-NICs). D
Default GAE
E-Cable andd
shortcut GA
AE-Cable arre implemented by UDP
P-based tunn
neling techniique over IP
P networks with
w averagee
path delay varied
v
from 25 ms to 2550 ms. The GAE-MAC frame forwaarding delay in GAE-SW
W and GAE-NICs are on
o average 0.2 ms. Three appliications whiich are FTP
P, VOIP annd NetBIOS
S’s Networkk
Neighborhoood have beeen tested on the
t simulatedd GA-Ethern
net.
GAE-S
SW
GAE-Ca
able : l is
S
Dlix = flix (dip , pip , ol)
Llix = glix (pip , dip)
Sh
hortcut : lij
Host #1
Host #2
GAE -NIC
GAE-NIC
INTE
ERNET
Host 3
Host 10
Fig.7:GA-Etherneet simulation model
m
P
Fig. 9: Meeasurement off G.729 VOIP
Fig.8: Measurement
M
oof FTP Throug
ghput
M
o NetBIOS’s Network Neig
of
ghborhood
Fig.10: Measurement
M
file between a ppair of hostss using FTP
P
Figure 8 shows thee throughputt when transsferring 10 MByte
protocol ovver the simuulated GA-E
Ethernet.Therre are two type of GA
AE-MAC fraame transmisssion mode..
Default moode always relays
r
GAE--MAC framee through GAE-SW
G
whhile shortcut mode will forward thee
frame direcctly to the End host via direct GAE--Cable if po
ossible. In shhortcut modee,up to 600 kbps can bee
achieved whhen average IP network delay is aboout 5 ms. Th
he 5ms–IP neetwork may represent a sample coree
network in a country. However
H
the throughput
t
shharply decreases when IP
P network’s delay increasses. One cann
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get only 100 kbps of FTP throughput on the IP network with 250 ms network delay like the public Internet.
Based on this result, FTP additional speed enhancement of GA-Ethernet is required in order to meet FTP
user’s satisfaction.
Figure 9 shows the end-to-end delay of VOIP session with G.729 codec. High quality Voice with VOIP
packet delay lower than 150 msec can be maintain as long as the underlying IP network delay does not
exceed 35 msec.When network delay increases, VOIP quality linearly degrades until it becomes
unacceptable at network delay 100 msec for shortcut mode. Unlike FTP, it is difficult to improve VOIP
performance if the underlying IP network delay is higher than 100 msec. A possible way which can be done
is to let GAE-SW selectively creates GAE-Cable with low delay for a GAE-NIC running VOIP
application.The last figure shows the response time in searching for other computers running broadcastbased NetBIOS protocol. There is only default mode since all broadcasting MAC frames need to pass
through GAE-SW. The response time does not vary much when network delay changes. At 250 ms-network
delay, the response time is around 600 ms which is quite acceptable.
5. Conclusion
We present GA-Ethernet as a novel virtual Ethernet Network over IP network like the public Internet.
Users will get all benefits of working on a workgroup network like working on LAN environment. All
existing unicast, multicast and broadcast applications including non-IP applications can run over the GAEthernet without modification. The mobility feature of Internet technology will inherit to the GA-Ethernet
that allows user can work anywhere, anyplace. Although there are still some performance issues as shown by
our performance evaluation, it is feasible to improve performance by using additional speed-enhancement
technique such as multiple tunnel GAE-Cable.
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