U.S. patent application number 11/784307 was filed with the patent office on 2007-08-16 for station mobility between access points.
This patent application is currently assigned to Trapeze Networks, Inc.. Invention is credited to Stan Chesnutt, Dan Harkins, Edward S. JR. Harriman, Tim Kolar, Allan Thomson.
Application Number | 20070189222 11/784307 |
Document ID | / |
Family ID | 34838266 |
Filed Date | 2007-08-16 |
United States Patent
Application |
20070189222 |
Kind Code |
A1 |
Kolar; Tim ; et al. |
August 16, 2007 |
Station mobility between access points
Abstract
Various embodiments are discussed for approaches to transparent
mobility, which attempts to permit a wireless station to be handed
off between wireless access points without packet loss, without
noticeable delay to the station user, and/or without loss of
session continuity.
Inventors: |
Kolar; Tim; (San Jose,
CA) ; Harriman; Edward S. JR.; (Saratoga, CA)
; Chesnutt; Stan; (Berkeley, CA) ; Thomson;
Allan; (Pleasanton, CA) ; Harkins; Dan; (La
Selva Beach, CA) |
Correspondence
Address: |
PERKINS COIE LLP
P.O. BOX 2168
MENLO PARK
CA
94026
US
|
Assignee: |
Trapeze Networks, Inc.
|
Family ID: |
34838266 |
Appl. No.: |
11/784307 |
Filed: |
April 5, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10778901 |
Feb 13, 2004 |
7221927 |
|
|
11784307 |
Apr 5, 2007 |
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Current U.S.
Class: |
370/331 |
Current CPC
Class: |
H04L 63/0272 20130101;
H04W 84/12 20130101; H04W 36/0011 20130101; H04W 92/24 20130101;
H04L 12/4641 20130101 |
Class at
Publication: |
370/331 |
International
Class: |
H04Q 7/00 20060101
H04Q007/00 |
Claims
1. A wireless local area network method, comprising: in response to
a wireless station moving in a wireless local area network from a
first wireless area of a first access point of the wireless local
area network to a second wireless area of a second access point of
the wireless local area network, wherein the first access point is
connected to a first distribution system switch of the wireless
local area network and the second access point is connected to a
second distribution system switch of the wireless local area
network, wherein the first distribution system switch and the
second distribution system switch are at least part of an
interconnected distribution system of the wireless local area
network, and wherein the wireless station corresponds to at least a
first virtual local area network connected to at least the first
distribution system switch, tunneling the first virtual local area
network to the second distribution system switch.
2. The method of claim 1, further comprising: at least partly prior
to the wireless station moving from the first wireless area of the
first access point of the wireless local area network to the second
wireless area of the second access point of the wireless local area
network, communicating data of the first virtual local area network
to the wireless station via the first distribution system
switch.
3. The method of claim 1, wherein tunneling includes: at least
partly after the wireless station moving from the first wireless
area of the first access point of the wireless local area network
to the second wireless area of the second access point of the
wireless local area network, communicating data of the first
virtual local area network to the wireless station via the second
distribution system switch.
4. The method of claim 2, further comprising: at least partly prior
to communicating data of the first virtual local area network to
the wireless station via the first distribution system switch,
creating AAA data corresponding to the wireless station.
5. The method of claim 4, further comprising: storing the AAA data
corresponding to the wireless station at the first distribution
system switch.
6. The method of claim 1, further comprising: transferring, to the
second distribution system switch, AAA data corresponding to the
wireless station.
7. The method of claim 1, wherein tunneling includes tunneling the
first virtual local area network from the first distribution system
switch.
8. The method of claim 1, wherein tunneling includes tunneling the
first virtual local area network from a third distribution system
switch of the wireless local area network, the third distribution
system switch being at least part of the interconnected
distribution system of the wireless local area network, the first
virtual local area network connected to at least the third
distribution system switch.
9. The method of claim 1, wherein tunneling includes layer 3
tunneling of layer 2 virtual local area network data.
10. The method of claim 1, wherein tunneling the first virtual
local area network to the second distribution system switch occurs
if the second distribution system switch is not connected to the
first virtual local area network.
11. The method of claim 1, further comprising: detecting the
wireless station moving in the wireless local area network from the
first wireless area of the first access point of the wireless local
area network to the second wireless area of the second access point
of the wireless local area network.
12. A wireless local area network method, comprising: in response
to a wireless station moving in a wireless local area network from
a first wireless area of a first access point of the wireless local
area network to a second wireless area of a second access point of
the wireless local area network, wherein the first access point is
connected to a first distribution system switch of the wireless
local area network and the second access point is connected to a
second distribution system switch of the wireless local area
network, wherein the first distribution system switch and the
second distribution system switch are at least part of an
interconnected distribution system of the wireless local area
network, and wherein the wireless station corresponds to at least a
first virtual local area network connected to at least the first
distribution system switch and the second distribution system
switch, transferring AAA data corresponding to the wireless station
to the second distribution system switch.
13. The method of claim 12, further comprising: at least partly
prior to the wireless station moving from the first wireless area
of the first access point of the wireless local area network to the
second wireless area of the second access point of the wireless
local area network, communicating data of the first virtual local
area network to the wireless station via the first distribution
system switch.
14. The method of claim 12, further comprising: at least partly
after the wireless station moving from the first wireless area of
the first access point of the wireless local area network to the
second wireless area of the second access point of the wireless
local area network, communicating data of the first virtual local
area network to the wireless station via the second distribution
system switch.
15. The method of claim 12, wherein communicating data of the first
virtual local area network to the wireless station via the second
distribution system switch occurs without distribution system
switch.
16. The method of claim 13, further comprising: at least partly
prior to communicating data of the first virtual local area network
to the wireless station via the first distribution system switch,
creating AAA data corresponding to the wireless station.
17. The method of claim 16, further comprising: storing the AAA
data corresponding to the wireless station at the first
distribution system switch.
18. The method of claim 12, further comprising: detecting the
wireless station moving in the wireless local area network from the
first wireless area of the first access point of the wireless local
area network to the second wireless area of the second access point
of the wireless local area network.
19. A wireless local area network method, comprising: in response
to a wireless station attempting to communicate with a first
virtual local area network via a first access point of the wireless
local area network, wherein the first access point is connected to
a first distribution system switch of the wireless local area
network, recognizing that the first distribution system switch is
not connected to the first virtual local area network; recognizing
that a second distribution system switch is connected to the first
virtual local area network, wherein the first distribution system
switch and the second distribution system switch are at least part
of an interconnected distribution system of the wireless local area
network; and tunneling the first virtual local area network from
the second distribution system switch to the first distribution
system switch.
20. The method of claim 19, further comprising: communicating data
of the tunneled first virtual local area network to the wireless
station via the first distribution system switch.
Description
BACKGROUND
[0001] Transparent mobility permits a wireless station to be handed
off between wireless access points without packet loss, without
noticeable delay to the station user, and/or without loss of
session continuity. Enabling the transparent mobility of a station
among access points is a goal of Inter-Access Point Protocol
(IAPP). However, IAPP for years has been at the stage of an
unapproved draft IEEE standard 802.11f. In addition, 802.11f
support is uncertain for all the attributes necessary for
transparent mobility among access points, and extremely unlikely
with regard to mobile VLAN support, due to the lack of focus on the
distribution system in 802.11f. Thus, it would be desirable to
enable transparent mobility between access points, while
maintaining support for the VLANs utilized by a user of a mobile
station.
SUMMARY
[0002] Transparent mobility can be enabled by communicating session
data, including backed up packets and/or Authentication,
Authorization and Accounting (AAA) data, between access points,
and/or communicating tunneling VLAN data between the distribution
system managing the access points.
[0003] Communicating the AAA data, such as keys, between access
points is one element that enables the fast handoff of a station
from an old access point to a new access point, by eliminating the
time which would otherwise be spent at the new access point
reauthenticating the handed off station, etc.
[0004] In addition, a tunnel can automatically be created between
the distribution system switches. VLAN data is subsequently
tunneled between the switches of the distribution system. Tunneling
VLAN data also simplifies configuration of the distribution system
switches, because relevant VLAN can be configured on only some
switches of the distribution system, rather than on every switch of
the distribution system. Tunneling VLAN data from the correct
distribution system switch also saves bandwidth, as compared to
broadcasting the VLAN data to all switches of the distribution
system.
BRIEF DESCRIPTION OF FIGURES
[0005] FIG. 1 shows an example deployment of a WLAN.
[0006] FIG. 2 shows an embodiment of a wireless local area network
method that includes VLAN tunneling between distribution system
switches in response to detection of a moving wireless station.
[0007] FIG. 3 shows another embodiment of a wireless local area
network method, that includes the transfer of AAA data between
distribution system switches in response to detection of a moving
wireless station.
[0008] FIG. 4 shows another embodiment of a wireless local area
network method, including recognizing distribution system switches
connected and not connected to a VLAN, and VLAN tunneling between
distribution system switches.
[0009] FIGS. 5A, 5B, and 5C show examples of embodiments with VLAN
tunneling and AAA data transfer.
[0010] FIGS. 6A and 6B show an example of an embodiment with VLAN
tunneling, but no AAA transfer.
[0011] FIGS. 7A and 7B show an example of an embodiment with AAA
transfer, but no VLAN tunneling.
DETAILED DESCRIPTION
[0012] FIG. 1 shows an example deployment of a WLAN 100. The
distribution system 110 includes a first distribution system switch
DS1 112, a second distribution system switch DS2 114, and a
distribution system backbone 116 connecting the first distribution
system switch DS1 112 and the second distribution system switch DS2
114. In some embodiments, the distribution system switches can
support thin access points on at least some ports. A first extended
service set network ESS1 120 includes the first distribution system
switch DS1 112, access point AP1A 122, access point AP1B 124,
access point AP1C 126, and station 128. Access point AP1A 122,
access point AP1B 124, and access point AP1C 126 are connected to
the first distribution system switch DS1 112 by wired links 172,
174, and 176, respectively. Station 128 and access point AP1A 122
are connected via wireless link 192, and form a first basic service
set network BSS1 140. A second extended service set network ESS2
130 includes the second distribution system switch DS2 114, access
point AP2A 132, access point AP2B 134, access point AP2C 136, and
station 138. Access point AP2A 132, access point AP2B 134, and
access point AP2C 136 are connected to the second distribution
system switch DS2 114 by wired links 182, 184, and 186,
respectively. Station 138 and access point AP2B 134 are connected
via wireless link 194, and form a second basic service set network
BSS2 150. Station 160 is in process of being handed off between
access point AP1C 126 of the first extended service set network
ESS1 120 and access point AP2A 132 of the second extended service
set network ESS2 130, and thereby is associated with two wireless
links 196 and 198 to access point AP1C 126 and access point AP2A
132, respectively.
[0013] Various embodiments are shown. Each shown embodiment can be
modified, such as by adding, removing, and/or changing one or more
portions, and/or rearranging one or more portions.
[0014] Various types of user roaming can occur from a distribution
system switch in the same cluster, with different types of
"recognition".
[0015] In one case, roaming between distribution system switches in
the same cluster can use an 802.11 reassociation. A reassociation
packet includes the address of an access point that the user is
roaming from. A distribution system switch has a list (which can be
distributed beforehand) of all access point addresses, and the
particular distribution system switches in that cluster the AP is
attached to. A "roamed-to" distribution system switch can directly
contact a "roamed-from" distribution system switch.
[0016] In another case, a user can send an 802.11 associate packet.
The distribution system switch can send message to all other
cluster members asking if user is known (how broken clients
actually work that don't send reassociate packet) (broadcast
everytime user enters system)
[0017] FIG. 2 shows an embodiment of a wireless local area network
method that includes VLAN tunneling between distribution system
switches in response to detection of a moving wireless station.
[0018] In 210, AAA data are created corresponding to a wireless
station. This can occur at least partly prior to communicating data
of a first virtual local area network to the wireless station via a
first distribution system switch connected to the first virtual
local area network. The AAA data corresponding to the wireless
station can be stored at the first distribution system switch. The
AAA data corresponding to the wireless station can be transferred
to a second distribution system switch. The second distribution
system switch is connected to an access point which a wireless
station moves to.
[0019] AAA data include authentication data such as keys;
authorization data such as access lists and VLAN association
information (i.e. for network security), and whether or not a user
is permitted to connect to a particular distribution system switch
and/or access point; and accounting data, such as a complete or
incomplete session history including roams, total packets sent,
error packets, etc.
[0020] In 220, data of the first virtual local area network are
communicated to the wireless station via the first distribution
system switch. This occurs at least partly prior to the wireless
station moving from a first wireless area of a first access point
to a second wireless area of a second access point. Both the first
access point and the second access point belong to a wireless local
area network.
[0021] In 230, a moving wireless station is detected. More
particularly, it is detected that the wireless station moves in a
wireless local area network. The movement is from a first wireless
area to a second wireless area. The first wireless area corresponds
to a first access point, such that wireless stations in the first
wireless area can associate with the first access point. The second
wireless area corresponds a second access point, such that wireless
stations in the second wireless area can associate with the second
access point. The first wireless area and the second wireless area
can partly or completely overlap, and/or not overlap. Both the
first access point and the second access point are access points of
a wireless local area network. Detection of the movement can be
logical detection of movement. For example, the second access point
can be said to have detected movement of the wireless station upon
successful communication with the wireless station. Detection of
the movement can be physical. For example, movement of the wireless
station can be detected based upon measurements of the radio
emissions of the wireless station.
[0022] The wireless local area network can include an
interconnected distribution system, and multiple access points,
such as the first access point and the second access point. The
interconnected distribution system can include multiple
distribution system switches, such as a first distribution system
switch and a second distribution system switch. The first
distribution system switch is connected to the first access point.
The second distribution system switch is connected to the second
access point.
[0023] The wireless station can correspond to at least a first
virtual local area network of the wireless local area network. For
example, one or more users of the wireless station can be users of
the first virtual local area network. The first virtual local area
network is connected to at least the first distribution system
switch.
[0024] In 240, in response to the wireless station moving in the
wireless local area network, the first virtual local area network
is tunneled to the second distribution system switch. In some
embodiments, such tunneling can occur if the second distribution
system switch is not connected to the first virtual local area
network. One type of tunneling includes layer 3 tunneling of layer
2 virtual local area network data. Tunneling can include
communicating data of the first virtual local area network to the
wireless station via the second distribution system switch. This
can occur at least partly after the wireless station moves from the
first wireless area to the second wireless area. Tunneling can
include tunneling the first virtual local area network from the
first distribution system switch and/or from a third distribution
system switch. The third distribution system switch can be part of
the interconnected distribution system of the wireless local area
network, along with the first distribution system switch and the
second distribution system switch. The third distribution system
switch is connected to the first virtual local area network.
[0025] FIG. 3 shows another embodiment of a wireless local area
network method, that includes the transfer of AAA data between
distribution system switches in response to detection of a moving
wireless station.
[0026] In 310, data of the first virtual local area network are
communicated to the wireless station via the first distribution
system switch. This occurs at least partly prior to the wireless
station moving from a first wireless area of a first access point
to a second wireless area of a second access point. Both the first
access point and the second access point belong to a wireless local
area network.
[0027] In 320, a moving wireless station is detected. More
particularly, it is detected that the wireless station moves in a
wireless local area network. The movement is from a first wireless
area to a second wireless area. The first wireless area corresponds
to a first access point, such that wireless stations in the first
wireless area can associate with the first access point. The second
wireless area corresponds a second access point, such that wireless
stations in the second wireless area can associate with the second
access point. The first wireless area and the second wireless area
can partly or completely overlap, and/or not overlap. Both the
first access point and the second access point are access points of
a wireless local area network. Detection of the movement can be
logical detection of movement. For example, the second access point
can be said to have detected movement of the wireless station upon
successful communication with the wireless station. Detection of
the movement can be physical. For example, movement of the wireless
station can be detected based upon measurements of the radio
emissions of the wireless station.
[0028] The wireless local area network can include an
interconnected distribution system, and multiple access points,
such as the first access point and the second access point. The
interconnected distribution system can include multiple
distribution system switches, such as a first distribution system
switch and a second distribution system switch. The first
distribution system switch is connected to the first access point.
The second distribution system switch is connected to the second
access point.
[0029] The wireless station can correspond to at least a first
virtual local area network of the wireless local area network. For
example, one or more users of the wireless station can be users of
the first virtual local area network. The first virtual local area
network is connected to at least the first distribution system
switch and the first distribution system switch.
[0030] In 330, in response to the wireless station moving in the
wireless local area network, AAA data corresponding to the wireless
station are transferred to the second distribution system switch.
The AAA data corresponding to the wireless station can be stored at
the first distribution system switch. In some embodiments, the AAA
data corresponding to the wireless station can be created at least
partly prior to communicating data of the first virtual local area
network to the wireless station via the first distribution system
switch.
[0031] In 340, data of the first virtual local area network are
communicated to the wireless station via the second distribution
system switch. This occurs at least partly after the wireless
station moves from the first wireless area to the second wireless
area. In some embodiments, communicating data of the first virtual
local area network to the wireless station via the second
distribution system switch can occur without communicating the data
via the first distribution system switch.
[0032] FIG. 4 shows another embodiment of a wireless local area
network method, including recognizing distribution system switches
connected and not connected to a VLAN, and VLAN tunneling between
distribution system switches.
[0033] In 410, a wireless station attempting to communicate is
detected. Detection of attempting to communicate can be logical
and/or physical detection. More particularly, it is detected that
the wireless station is attempting to communicate with a first
virtual local area network via a first access point. The first
access point is an access point of a wireless local area network.
The first access point is connected to a first distribution system
switch of the wireless local area network.
[0034] In response to the wireless station attempting to
communicate, one or more events can occur.
[0035] In 420, AAA data corresponding to the wireless station are
created. The AAA data corresponding to the wireless station can be
stored at the first distribution system switch.
[0036] In 430, it is recognized that the first distribution system
switch is not connected to the first virtual local area
network.
[0037] In 440, it is recognized that a second distribution system
switch is connected to the first virtual local area network. The
first distribution system switch and the second distribution system
switch are at least part of an interconnected distribution system
of the wireless local area network. AAA data corresponding to the
wireless station can be transferred to the second distribution
system switch. For example, AAA data corresponding to the wireless
station can be communicated from the first distribution system
switch to the second distribution system switch.
[0038] In 450, the first virtual local area network is tunneled
from the second distribution system switch to the first
distribution system switch. This can occur after communicating AAA
data corresponding to the wireless station from the first
distribution system switch to the second distribution system
switch. The tunneling can include layer 3 tunneling of layer 2
virtual local area network data.
[0039] In 460, data of the tunneled first virtual local area
network are communicated to the wireless station via the first
distribution system switch. This can occur after AAA data
corresponding to the wireless station are communicated from the
first distribution system switch to the second distribution system
switch.
[0040] FIGS. 5A, 5B, and 5C show examples of embodiments with VLAN
tunneling and AAA data transfer.
[0041] In FIG. 5A, a wireless station 510 has a wireless link with
an access point 1 520. Access point 1 520 is connected to
distribution system switch 1 530. AAA data 540 corresponding to
wireless station 510 is at distribution system switch 1 530.
Wireless station 510 is associated with a VLAN 550 connected to
distribution system switch 1 530.
[0042] In FIG. 5B, a wireless station 510 has moved to have a
wireless link with another access point 2 560. Access point 2 560
is connected to distribution system switch 2 570. AAA data 540
corresponding to wireless station 510 is at distribution system
switch 2 570; AAA data 540 may have been transferred from
distribution system switch 1 530. Because distribution system
switch 2 570 is not connected to VLAN 550, VLAN 550 is tunneled 580
from distribution system switch 1 530 to distribution system switch
2 570. The tunnel 580 can be a newly created tunnel or an already
existing tunnel. This can be layer 3 tunneling of a layer 2
VLAN.
[0043] FIGS. 5A and 5B therefore show a seamless roam of the
wireless station 510 from distribution system switch 1 530 to
distribution system switch 2 570, with AAA data VLAN connection
taken care of.
[0044] FIG. 5C shows an alternative to FIG. 5B. A seamless roam of
the wireless station 510 from distribution system switch 1 530 to
distribution system switch 2 570 does not require the VLAN tunnel
580 to be from distribution system 1 530. Distribution system
switch 1 530, distribution system switch 2 570, and distribution
system switch 3 590, can be part a cluster mutually sharing
information about which VLANs are connected to which distribution
system switch. VLAN 550 is connected to both distribution system
switch 1 530 and distribution system switch 3 590. When wireless
station 510 roams from distribution system switch 1 530 to
distribution system switch 2 570, then VLAN 550 is tunneled 580
from distribution system switch 3 590 to distribution system switch
2 570.
[0045] Clusters can also share information about other distribution
system switches in the same cluster, such as known IP addresses of
other distribution system switches, and/or addresses of attached
access points, with other distribution system switches in the same
cluster.
[0046] FIGS. 6A and 6B show an example of an embodiment with VLAN
tunneling, but no AAA transfer.
[0047] In FIG. 6A, distribution system switch 1 630 finds out from
other distribution system switches in its cluster which VLANs are
connected to which distribution system switches. Distribution
system switch 1 630 thereby has the information that VLAN 650 is
connected to distribution system switch 2 670. Wireless station 610
forms a wireless link with access point 620 connected to
distribution system switch 1 630. Distribution system switch 1 630
determines from AAA data 640 that wireless station 610 should
connect to VLAN 650.
[0048] In FIG. 6B, distribution system switch 1 630 recognizes that
it is not connected to VLAN 650, and that distribution system
switch 2 670 is connected to VLAN 650. A VLAN tunnel 680 is used
from distribution system switch 2 670 to distribution system switch
1 630 for VLAN 650.
[0049] At the conclusion of FIGS. 6A and 6B, wireless station 610
has a wireless link with distribution system switch 1 630, and a
connection to VLAN 650.
[0050] FIGS. 7A and 7B show an example of an embodiment with AAA
transfer, but no VLAN tunneling.
[0051] In FIG. 7A, wireless station 710 has a wireless link with
access point 710 attached to distribution system switch 1 730. The
wireless station 710 has AAA state 740 at distribution system
switch 1 730. The wireless station 710 is associated with VLAN 750,
which is attached to distribution system switch 1 730.
[0052] In FIG. 7B, wireless station 710 roams to access point 2 760
attached to distribution system switch 2 770. Distribution system
switch 2 770 recognizes that wireless station 710 is from an access
point connected to distribution system switch 1 730. The AAA state
740 for wireless station 710 is transferred from distribution
system switch 1 730. Because VLAN 750 is already connected to
distribution system switch 2 770, no VLAN tunneling takes
place.
[0053] In another embodiment, a wireless station has a wireless
connection to a first access point connected to a first
distribution system switch. While a user roams to a second access
point connected to a second distribution system switch, packets
arrive at the first access point, and are queued, for example on
the first access point and/or the first distribution system switch.
When a user finishes roaming to the second distribution system
switch, packets are extracted from the queue, and inserted into the
transmit queue for the user on the second access point attached to
the second distribution system switch.
* * * * *