EXHIBIT A

Case 6:20-cv-00487-ADA Document 39 Filed 11/06/20 Page 1 of 13
(12) United States Patent 

Yin et al. 

USOO845 1839B2 

(10) Patent No.: US 8.451,839 B2 

(45) Date of Patent: May 28, 2013 

(54) METHOD AND APPARATUS FOR MANAGING 

ROUTEINFORMATION AND FORWARDING 

DATAN ACCESS DEVICES 

(75) Inventors: Qin Yin, Shanghai (CN); Yingzhong 

Miu, Shanghai (CN); Jianhua Zhu, Shanghai (CN); Yifeng Yao, Shanghai 

(CN) 

(73) Assignee: Alcatel Lucent, Paris (FR) 

(*) Notice: Subject to any disclaimer, the term of this 

patent is extended or adjusted under 35 

U.S.C. 154(b) by 322 days. 

(21) Appl. No.: 12/310,660 

(22) PCT Filed: Aug. 14, 2007 

(86). PCT No.: PCT/CN2007/002449 

S371 (c)(1), 

(2), (4) Date: May 29, 2009 

(87) PCT Pub. No.: WO2008/031319 

PCT Pub. Date: Mar. 20, 2008 

(65) Prior Publication Data 

US 2009/0323693 A1 Dec. 31, 2009 

(30) Foreign Application Priority Data 

Sep. 7, 2006 (CN) .......................... 2006 1 OO3O926 

(51) Int. Cl. 

H04L 2/56 (2006.01) 

(52) U.S. Cl. 

USPC .......................................................... 370/392 

(58) Field of Classification Search 

USPC ......... 370/351 357, 389, 392,395.5. 395.54, 

370/464 467 

See application file for complete search history. 

access device O 

client end devices P forwarding 

(56) References Cited 

U.S. PATENT DOCUMENTS 

5,922,049 A * 7/1999 Radia et al. ................... TO9.220 

6,697.360 B1* 2/2004 Gaiet al. ....... 370,389 

7,385,973 B1* 6/2008 Johnson et al. 370,389 

2002/01386.14 A1* 9, 2002 Hall .............................. 709,225 

2006, O140164 A1 6/2006 Patel et al. 

2008/0212598 A1* 9, 2008 Kolli et al. .................... 370/409 

FOREIGN PATENT DOCUMENTS 

JP 2002-217941 8, 2002 

KR 10-2004-001 1936 2, 2004 

OTHER PUBLICATIONS 

PowerConnect ApplicationNote #38, What is VLAN Routing?, Dell, 

5 pages, Feb. 2004.* 

* cited by examiner 

Primary Examiner — Frank Duong 

(74) Attorney, Agent, or Firm — Harness, Dickey & Pierce, 

P.L.C. 

(57) ABSTRACT 

The present invention provides a method for creating routes in 

access devices of the communication network by using access 

response messages. With the method provided by the present 

invention, services can be distinguished and forwarded based 

on destination IP sub-networks, so that different services can 

be distributed in access devices. In this way, on the premise that services are distinguished based on layer 3, the require 

ments for access devices are reduced and layer 2 networks on 

the user side are not required to carry out route protocols, 

which decreases administrators maintenance work and is the 

important condition for the realization of plug&play and 

reduces the requirements for marginal routers. 

12 Claims, 6 Drawing Sheets 

providing network services 

Sewe a 

sewer b 

service b g-gateway b voic Set W. C. 

marginal Otter service c wideo 

 

 

 

 

 

Case 6:20-cv-00487-ADA Document 39 Filed 11/06/20 Page 2 of 13
U.S. Patent May 28, 2013 Sheet 1 of 6 US 8.451,839 B2 

MAC IP header UDP DHCP DHCP 

header header header options 

Fig. 1 a 

one byte one byte multiple bytes 

S R N 

Fig. 1b 

Case 6:20-cv-00487-ADA Document 39 Filed 11/06/20 Page 3 of 13
U.S. Patent May 28, 2013 Sheet 2 of 6 US 8451,839 B2 

S11 receiving an access response 

message which is from a 

network configuration server 

and sent to a user terminal 

obtaining route-related information and a S12 

predefined using time from said access 

response message, the predefined time is 

used to indicate the using time of said 

route 

whether a route 

able item corresponding to said route 

elated information exists in said route 

whether the remaining 

time of Said route table item is shorter than 

said predefined using time S16 

yes creating item corresponding a route E/ to 

S15 said route - related updating the remaining time of information 

said route table item to said 

predefined using time 

end 

Fig. 2 

 

 

 

 

 

Case 6:20-cv-00487-ADA Document 39 Filed 11/06/20 Page 4 of 13
U.S. Patent May 28, 2013 Sheet 3 of 6 US 8451,839 B2 

providing network 

services 

Sewer a 

access device O 

DSLAM 

P 

forwarding Sewer C 

marginal 

Outer service c video 

Fig. 3a 

providing network 

services 

Seweta 

L harginal router 

80 gateway) a 

access device O 

D DSLAMD client end marginal router Service b devices IP 6 gateway b w WOCC forwarding 

service c 

video 

Fig. 3b 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Case 6:20-cv-00487-ADA Document 39 Filed 11/06/20 Page 5 of 13
U.S. Patent May 28, 2013 Sheet 4 of 6 US 8451,839 B2 

- first second First Second A. 

reveiving obtainin obtainin judging judging updating 

eaS 9. J caS CS 3S eaS eaS 

-144 

creating 

route maintenance CaS 

apparatus 14 route management apparatus 

Fig. 4 

 

Case 6:20-cv-00487-ADA Document 39 Filed 11/06/20 Page 6 of 13
U.S. Patent May 28, 2013 Sheet 5 of 6 US 8451,839 B2 

S21 

receiving a packet from a user terminal 

obtaining the source and destination network S22 

addresses from said packet 

based on the source and destination network S23 addresses of said packet, induiring and obtaining a 

gateway which can get to the destination network 

and matches said source network address, and a 

forwarding port corresponding to said gateway 

S24 

sending the packet to the gate way of Said 

corresponding sub-network via said forwarding port 

Fig. 5 

 

Case 6:20-cv-00487-ADA Document 39 Filed 11/06/20 Page 7 of 13
U.S. Patent May 28, 2013 Sheet 6 of 6 US 8451,839 B2 

23 24 

inquiring sending 

CaS CaS 

forwarding means 2 

21 22 

receiving obtaining 

aS eaS 

Fig. 6 

 

Case 6:20-cv-00487-ADA Document 39 Filed 11/06/20 Page 8 of 13
US 8,451,839 B2 

1. 

METHOD AND APPARATUS FOR MANAGING 

ROUTEINFORMATION AND FORWARDING 

DATAN ACCESS DEVICES 

TECHNICAL FIELD 

The present invention relates to the communication net 

work, particularly to the access network of the communica 

tion network. 

BACKGROUND OF THE INVENTION 

Currently, the requirements for layer 2 access devices put 

forward by telecom operators are higher and higher. Layer 2 

devices are required to distinguish services based on layer3 

information, so that different services, such as audio, video, 

Internet and so on, can be distributed in access devices like the 

Digital Subscriber Line-Access Multiplexer (DSLAM) and 

access to corresponding service networks via gateways cor 

responding to different services. Concretely, operators will 

generally plan service networks in advance, and different 

service providers possess different IP addresses. In this way, 

access devices can distinguish and forward services based on 

destination IP sub-networks. However, common access 

devices are only layer 2 devices and not used as user gate 

ways, therefore these access devices are transparent to users 

in the third layer. Moreover, they don't have dedicated IP 

addresses for forwarding data. Therefore, accordingly, the 

network can only create unnumbered IP interfaces to meet 

this requirement. And this is also used to cope with the 

requirement for saving IPv4 addresses which are becoming SCaC. 

Presently, there is a method for creating route tables by monitoring route protocol messages. But operators normally 

don’t enable route protocols on the ports on the user side. 

Route protocols based on link statuses (e.g. Open Shortest 

Path First) normally requires the correspondent node to have 

layer 3 addresses, however, this requirement can not be sat 

isfied. Although route protocols based on distance vectors 

(e.g. Routing Information Protocol) are usable, restrictions 

are put forward when operators choose route protocols, and 

employing route protocols in the user-end network increases 

the complexity of the network and the load of the layer 2 

network. Since layer 2 devices should support route protocols in this way, higher requirements are put forward for them. 

Generally, it is very difficult for layer 2 devices to obtain 

layer 3 route information. Configuring each Such access 

device statically not only leads to high work load, but also 

makes layer 2 devices lose their advantage of plug&play. 

Thus, this becomes a relative prominent problem. The present invention proposes a method and an apparatus for distinguishing services and forwarding data based on 

destination IP sub-networks by creating routes on layer 2 

devices via the use of access response messages generated by 

servers when terminal devices access to the network. Here, 

the access response message refers to the Dynamic Host 

Configuration Protocol (DHCP) response message. Below, a 

brief introduction will be made about the DHCP. 

Dynamic Host Configuration Protocol (DHCP): 

The DHCP can be divided into two parts: one is the server 

end, while the other is the client end. DHCP servers run 

centralized management of all IP network setting informa 

tion, and are responsible for dealing with DHCP requirements 

of the client end; while the client end uses IP environment 

information assigned from servers. 

1. Assignment Forms of DHCP 

At first, there must be at least one DHCP server working in 

the network. It monitors DHCP requirements of the network 

10 

15 

25 

30 

35 

40 

45 

50 

55 

60 

65 

2 

and negotiates with the client end about the setting environ 

ment of TCP/IP. Two kinds of IP positioning ways are pro 

vided: 

automatic assignment, its circumstance is: once the DHCP 

client end has successfully leased an IP address from the 

DHCP server for the first time, it will use this address for ever, 

dynamic assignment: once the DHCP client end has leased 

an IP address from the DHCP server for the first time, it 

doesn’t use this address for ever. As long as the lease expires, 

the client end should release this IP address, so as to provide 

it to other work stations. Of course, the client end can renew 

the lease with higher priorities than other hosts, or lease other 

IP addresses. 

2. Work Principle of DHCP 

Depending on whether it is the first time for the client end 

to log on the network, the working form of DHCP will be 

different. Below, the working form of DHCP when it is the 

first time for the client end to log on the network will be 

detailed described with reference to FIG. 1. 

Logging on the network for the first time: 

1) Searching Server. When the DHCP end client logs on the 

network for the first time, namely the client finds there is no IP 

information setting in the host, it will send a DHCPDIS 

COVER packet to the network. Since the client hasn’t known 

to which network it belongs yet, the source address of the 

packet is 0.0.0.0. and the destination address is 

255.255.255.255, then the packet is attached with DHCPDIS 

COVER information and broadcasted to the network. 

Under the circumstances of the Windows default setting, the waiting time of DHCPDISCOVER is preset as 1 second, 

namely after the client end has sent the first DHCPDIS 

COVER packet, if no response is obtained within 1 second, 

the second DHCPDISCOVER broadcast will be performed. 

Under the circumstances that no response is obtained all 

along, the client end will conduct totally four DHCPDIS 

COVER broadcasts (including the first DHCPDISCOVER 

broadcast), the waiting time for the first broadcast is 1 second, 

and the waiting time for the other three broadcasts is 9 sec 

onds, 13 seconds and 16 seconds respectively. If there is still 

no response of the DHCP server, the client end will display error information and declares the failure of DHCPDIS 

COVER. After that, based on the choice of the user, the 

system will continue to repeat the DHCPDISCOVER process 

once again after 5 minutes. 

2) Providing an IP lease address. After the DHCP server 

has monitored the DHCPDISCOVER broadcast sent by the 

client end, it will choose the most front unleased IP address 

from the range of the addresses which have not been leased, 

together with other TCP/IP settings, to form a DHCPDIS 

COVER packet and sent the same to the client end as a 

response. 

Since the client end doesn’t have IP address at the begin 

ning, there is MAC address information contained in the 

DHCPDISCOVER packet, and there is an XID number to 

identify this packet. Based on this information, the DHCPOF 

FER packet responded by the DHCP server is forwarded to 

the client needing the lease. According to the setting of the 

server end, the DHCPOFFER packet contains information of 

the lease term. 

3) Accepting an IP lease. If the client end receives 

responses of multiple DHCP servers in the network, it will 

only choose one of the DHCPOFFERs (generally the one that 

arrives earliest), and send a DHCPREQUEST broadcast 

packet to the network in order to tell all DHCP servers that it 

will accept the IP address provided by which server. 

At the same time, the client end will also send an ARP 

packet to the network to enquire whether there are any other 

Case 6:20-cv-00487-ADA Document 39 Filed 11/06/20 Page 9 of 13
US 8,451,839 B2 

3 

hosts using this IP address in the network; if it is found that 

this IP address has been occupied, the client end will send a 

DHCPDECLINE packet to the DHCP server, so as to decline 

to accept its DHCPOFFER and resend a DHCPDISCOVER 

message. 

4) Acknowledging the lease. After the DHCP server has 

received the DHCPREQUEST of the client end, it will senda 

DHCPACK response to the client end in order to acknowl 

edge that the IP lease has come into effect formally, namely a 

whole DHCP working process is completed. 

SUMMARY OF THE INVENTION 

The object of the present invention is to provide a method, 

in access devices of the communication network, for making 

use of access response messages to create routes, so as to 

distinguish services and forward based on destination IP sub 

networks and make different services distribute in access 

devices. 

According to the first aspect of the present invention, there 

is provided a method for managing route information in an access device of the communication network. The method 

comprises the steps of at first, receiving an access response 

message which is from the server and sent to a user terminal; 

then, extracting route-related information from said access 

response message, and creating or updating the route table 

based on said route-related information. 

According to the second aspect of the present invention, 

there is provided a route management apparatus for managing 

route information in an access device of the communication 

network. The route management apparatus comprises a 

receiving means, a first obtaining means and a route mainte 

nance means. The receiving means receives an access 

response message which is from the server and sent to a user 

terminal; the first obtaining means extracts route-related 

information from said access response information; the route 

maintenance means creates or updates the route table based on said route-related information. 

According to the third aspect of the present invention, there 

is provided a method for forwarding data in an access device 

of the communication network, wherein data from user ter 

minals belonging to different sub-networks is forwarded to 

corresponding Sub-network gateways. According to the fourth aspect of the present invention, there is provided a forwarding apparatus for forwarding data 

in an access device of the communication network, wherein 

data from user terminals belonging to different Sub-networks 

is forwarded to corresponding Sub network gateways. 

As compared with the prior art, the present invention has following advantages: 

1. Not influencing the choice of route protocols; 

2. Not requiring layer 2 network on the user side to execute 

route protocols; 3. Reducing the requirements for the marginal routers; 

4. Reducing the maintenance work of administrators, which is the important condition for realizing plug&play; 

5. Under the premise that services are distinguished based 

on layer 3, reducing the requirements for access devices. 

BRIEF DESCRIPTION OF THE DRAWINGS 

Other features, objects and advantages of the present 

invention will be apparent by reading the following detailed 

description of non-limiting exemplary embodiments with ref 

erence to appended drawings. 

FIG. 1a illustrates the frame structure of DHCP; 

FIG. 1b illustrates the option structure in the frame struc 

ture of DHCP; 

10 

15 

25 

30 

35 

40 

45 

50 

55 

60 

65 

4 

FIG. 2 illustrates the flowchart of the method for managing 

route information in an access device of the communication 

network according to an embodiment of the present inven 

tion; 

FIG. 3a illustrates a network topological structure of the 

access network according to an embodiment of the present 

invention; 

FIG.3b illustrates another network topological structure of 

the access network according to an embodiment of the present 

invention; 

FIG. 4 illustrates the block diagram of the route manage 

ment apparatus for managing route information in an access 

device of the communication network according to an 

embodiment of the present invention; 

FIG. 5 illustrates the flowchart of the method for forward 

ing data in an access device of the communication network 

according to an embodiment of the present invention; 

FIG. 6 illustrates the block diagram of the forwarding 

apparatus for forwarding data in an access device of the 

communication network according to an embodiment of the 

present invention. 

DETAILED DESCRIPTION OF THE 

EMBODIMENTS 

FIG. 1a illustrates the encapsulation format of a DHCP 

packet. All DHCP messages are encapsulated in UDP pack 

ets. The options in DHCP are vendor-specific area, so as to 

provide more setting information (e.g. Netmask, Gateway, 

DNS, etc.), and its length can be variable and there can be 

multiple options at the same time. The first byte of each option is the option code, its subsequent byte shows the length of the 

option content hereafter, and the rest is the option content, 

such as the option format in a DHCP message shown in FIG. 

1b. DHCP employs the option code 0x53 to set the packet 

type: 1 represents DHCP-DISCOVER, 2 represents DHCP 

OFFER, 3 represents DHCP-REQUEST, 4 represents 

DHCP-DECLINE, 5 represents DHCP-ACK, 6 represents 

DHCP-NACK and 7 represents DHCP-RELEASE. 

In the DHCP standard, three static route-related options are 

defined: option3, option 33 and option 121. Wherein, option 

3 is used to declare the gateway corresponding to the client. 

There can be multiple gateways in correspondence with the 

client, which are ordered according to the priority. Option 33 

is put forward relative early, and is used to declare static type 

route information. Option 121 comprises the former two. It 

declares all static routes, including default routes, and Sup 

ports Classless Inter-Domain Routing. These options are con 

figured to the client end at the same time when the server is 

assigning IP addresses, so that the client end can create the 

route table correctly. It is worth noting that, for the whole 

network, user gateways and planed addresses of service pro 

viders are not often changed. They are located at two ends of 

the IP addresses and are the end points of the network topol 

ogy and won't change with the network topology. Therefore, 

these routes can be regarded as static and can be pre-config 

ured in the server by administrators. The configuration load is 

also not very large. 

For an access device, it is located between the marginal 

router and the user and won't be influenced by the topology 

change. Hence, these static routes are Sufficient for the access 

device. 

Considering the current situation of the network, Classless 

Inter-Domain Routing has been widely used. An access 

device should learn and maintain the upstream route mainly depending on monitoring option 121 in each DHCP-ACK 

packet. 

Case 6:20-cv-00487-ADA Document 39 Filed 11/06/20 Page 10 of 13
US 8,451,839 B2 

5 

Below, the present invention will be further elucidated in 

conjunction with FIG. 2 to FIG. 6. 

FIG. 2 illustrates the flowchart of the method for managing 

route information in an access device of the communication 

network according to an embodiment of the present inven- 5 

tion. 

At first, in step S11, an access response message which is 

from a server and sent to a user terminal is received. 

Then, in step S12, route-related information is extracted 

from said route-related message. 10 

Finally, a route table item is created or updated based on 

said route-related information. 

If said access response message further comprises the pre 

defined using time indicating the time which can be used by said route, then in step S12, said predefined using time is 15 

obtained simultaneously; finally, the route table item is 

updated or created in conjunction with said route-related 

information and said predefined using time. 

Wherein the step in which said route table item is updated 

or created can be concretely divided into steps S13, S14, S15 20 

and S16. 

At first, in step S13, judging whether a route table item 

corresponding to said route-related information exists in said 

route table. 

If a route table item corresponding to said route-related 25 

information exists in said route table, then in step S14, judg ing whether the remaining time of said route table item is 

shorter than said predefined using time. 

If the remaining time of said route table item is shorter than 

said predefined using time, then updating the remaining time 30 

of said route item to the said predefined using time. 

If no route table item corresponding to said route-related 

information exists in said route table, then in step S16, creat 

ing a route-related item corresponding to said route-related 

information. 35 

If the virtual local area network (VLAN) configuration is 

employed between an access device and each Sub-network 

gateway (also referred to as a marginal router) connected with 

the access device, correlated information of said route table 

item and the VLAN is obtained from the address resolution 40 

protocol (ARP) message or the access response message. 

FIGS. 3a and 3b illustrates two network topological struc 

tures of the access network according to an embodiment of 

the present invention. In FIG. 3a, each VLAN has a server 

responding to user access requests. In FIG. 3b, three VLANs 45 

share a server responding to user access requests. 

In general cases, such as the network topological structure 

graphs shown in FIGS. 3a and 3b, the access device 0 can 

obtain information of the VLAN via the VLAN tag in the 

acknowledgment frame of the ARP from each sub-network 50 

gateway, and correlate the information with corresponding 

route. The detailed flow is as below: at first, the access device 

0 receives a packet from a user device. Assume that the packet 

is sent to the servicea (worldwide web). Based on the source 

network address and the destination network address in the 55 

packet, the access device 0 finds the destination network 

address of the next hop of the forwarding, then sends a ARP 

request frame to the host of the next hop (namely the marginal 

route a shown in FIGS.3a and3b) so as to inquire its link layer 

address. After receiving this request, the host of the next hop 60 

responds with an ARP response frame comprising a VLAN 

tag. When receiving said ARP response frame comprising a 

VLAN tag, the access device 0 extracts the information of the 

VLAN and correlates it with the route. 

If there is one (or more) server(s) in each VLAN which 65 

responds to user access requests, as shown in FIG. 3a, under 

such network configuration, information of the VLAN can 

6 

also be obtained by the VLAN tag in an access response 

message, and then correlated with the route-related informa 

tion. If multiple VLANs share one server responding to user 

access requests, as shown in FIG. 3b, then the VLAN infor 

mation correlated with the route-related information can not 

be obtained via the VLAN tag in the access response message. 

At this time, the VLAN information correlated with the route 

related information can only be obtained by the ARP mes 

Sage. 

In current network realizations, aforesaid access request 

message and access response message are DHCP messages, 

and said predefined using time is the lease time in the DHCP 

message. 

FIG. 4 illustrates the block diagram of the route manage 

ment apparatus 1 for managing route information in an access 

device of the communication network according to an 

embodiment of the present invention. The route management 

apparatus 1 comprises a receiving means 11, a first obtaining 

means 12, a second obtaining means 13 and a route mainte nance means 14. Wherein the route maintenance means 14 

comprises a first judging means 141, a second judging means 

142, an updating means 143 and a creating means 144. 

At first, the receiving means 11 receives an access response 

message which is from the server end and sent to the terminal. 

Then, the first obtaining means 12 obtains said route-re 

lated information from said access response message and 

obtains a predefined using time at the same time. The pre 

defined using time is used to indicate the using time of said 

rOute. 

If the VLAN configuration is employed between an access 

device and each sub-network gateway (also referred to as a 

marginal router) connected with the access device, the second 

obtaining means 13 obtains the correlated information of said 

route table item and the VLAN from the ARP message or the access response message. 

In general cases, as shown in FIGS. 3a and 3b, the infor 

mation of the VLAN can be obtained via the VLAN tag in the 

acknowledgment frame of the ARP from each sub-network 

gateway, and correlate the information with corresponding 

route. The detailed flow is as below: at first, the access device 

0 receives a packet from a user device. Assume that the packet 

is sent to the service a (worldwide web). Based on the source 

network address and the destination network address in the 

packet, the access device 0 finds the destination network 

address of the next hop of the forwarding, then sends a ARP 

request frame to the host of the next hop (namely the marginal 

route a shown in FIGS.3a and3b) so as to inquire its link layer address. After receiving this request, the host of the next hop 

responds with an ARP response frame comprising a VLAN 

tag. When receiving said ARP response frame comprising a 

VLAN tag, the access device 0 extracts the information of the 

VLAN and correlates it with the route. 

If there is one (or more) server(s) in each VLAN which 

responds to user access requests, as shown in FIG. 3a, under 

such network configuration, information of the VLAN can 

also be obtained by the VLAN tag in the access response 

message, and then correlated with the route-related informa 

tion. If multiple VLANs share one server responding to user 

access requests, as shown in FIG. 3b, then the VLAN infor 

mation correlated with the route-related information can not 

be obtained via the VLAN tag in the access response message. 

At this time, the VLAN information correlated with the route 

related information can only be obtained by the ARP mes 

Sage. 

Finally, the route maintenance means 14 creates or updates 

the route table based on said route-related information. 

Case 6:20-cv-00487-ADA Document 39 Filed 11/06/20 Page 11 of 13
US 8,451,839 B2 

7 

In a preferred embodiment of the route maintenance means 

14, according to the route-related information, the predefined 

using time obtained by the first obtaining means 12 and the 

VLAN information obtained by the second obtaining means 

13, the first judging means 141 first judges whether a route 

table item corresponding to said route-related information 

exists in said route table. 

If a route table item corresponding to said route-related 

information exists in said route table, the second judging 

means 142 judges whether the remaining time in said route 

table item is shorter than said predefined using time. 

If a route table item corresponding to said route-related 

information exists in said route table and the remaining time 

in said route table item is shorter than said predefined using time, the updating means 143 updates the remaining time of 

said route table item to the predefined using time. 

If no route table item corresponding to said route-related 

information exists in said route table, the creating means 144 

creates a route table item corresponding to said route-related 

information. 

In current network realizations, aforesaid access request 

message and access response message are DHCP messages, 

and said predefined using time is the lease time in the DHCP 

message. 

FIG. 5 illustrates the flowchart of the method for forward 

ing data in an access device of the communication network 

according to an embodiment of the present invention. The 

method consists in that data from user terminals belonging to 

different sub-networks is forwarded to corresponding sub 

network gateway. As shown in FIG. 5, the method can be 

divided into four steps. 

At first, in step S21, a packet from a user terminal is 

received. 

Then, in step S22, the source network address and the 

destination network address are obtained from the packet. 

After that, in step S23, based on the source network address 

and the destination network address of said packet, a gateway 

which can get to the destination network and matches the 

source network address is inquired from the route table. In 

addition, the forwarding port corresponding to said gateway 

is also obtained. 

Finally, in step S24, the packet is sent to the gateway of said 

corresponding Sub-network via said forwarding port. 

In current network realizations, aforesaid network 

addresses are IP addresses. 

In a preferred embodiment, an access device maintains a 

sub-network route table respectively for each sub-network. 

At first, a packet from a user terminal is received; then, based 

on the source IP address of said packet, a corresponding 

sub-network route table is inquired; after that, based on the 

destination IP address of said packet, the corresponding route 

table item is inquired from said corresponding Sub-network 

route table, so as to determine the forwarding port of said 

packet; finally, the packet is sent to the gateway of said cor 

responding Sub-network via said forwarding port. 

In another preferred embodiment, an access device only 

maintains one route table. At first, a packet coming from a 

user terminal is received; then based on the destination IP 

address of said packet, one or more route table items corre 

lated with said destination address are inquired from said 

route table; after that, by using the source IP address of said 

packet, the route table item corresponding to the gateway 

belonging to its Sub-network is determined from said one or more route table items correlated with said destination 

address, and the forwarding port of said packet is also deter 

mined; finally, the packet is sent to said corresponding Sub 

network's gateway via said forwarding port. 

5 

10 

15 

25 

30 

35 

40 

45 

50 

55 

60 

65 

8 

FIG. 6 illustrates the block diagram of the forwarding 

apparatus 2 for forwarding data in an access device of the 

communication network according to an embodiment of the 

invention. The forwarding apparatus 2 forwards data from 

user terminals of different sub-networks to the gateways of 

corresponding Sub-networks. 

The forwarding apparatus comprises a receiving means 21, 

an obtaining means 22, an inquiring means 23 and a sending means 24. 

At first, the receiving means 21 receives a packet from a user terminal. 

Then, the obtaining means 22 obtains the source network 

address and the destination network address from said packet. 

After that, based on the source network address and the 

destination network address of said packet, the inquiring 

means 23 inquires a gateway from the route table which can 

get to the destination network and match the source network 

address, and a forwarding port corresponding to said gateway. 

Finally, the sending means 24 sends said packet to the 

gateway of said corresponding Sub-network via said forward 

ing port. 

In current network realizations, 

addresses are IP addresses. 

In a preferred embodiment, an access device maintains a 

sub-network route table respectively for each sub-network. 

At first, the receiving means 21 receives a packet from a user 

terminal; then, the obtaining means 22 obtains the Source 

network address and the destination network address from 

said packet; after that, based on the destination IP address of 

said packet, the inquiring means 23 inquires its corresponding 

sub-network route table; and then, based on the destination IP 

address of said packet, the inquiring means 23 inquires the 

corresponding route table item from said corresponding Sub 

network route table, so as to determine the forwarding port of 

said packet; finally, the sending means 24 sends said packet to 

the gateway of said corresponding Sub-network via said for 

warding port. 

In another preferred embodiment, an access device only 

maintains one route table. At first, the receiving means 21 

receives a packet coming from a user terminal; then, the 

obtaining means 22 obtains the Source network address and 

the destination network address from said packet; after that, 

based on the destination IP address of said packet, the inquir 

ing means 23 inquires one or more route table items corre 

lated with said destination address from said route table; 

afterwards, by using the source IP address of said packet, the 

route table item corresponding to the gateway belonging to its 

sub-network is determined from said one or more route table 

items correlated with said destination address, and the for 

warding port of said packet is also determined; finally, the 

sending means sends said packet to the gateway said corre 

sponding Sub-network via said forwarding port. 

Above, embodiments of the present invention have been 

described. It should be understood that the present invention 

is not limited to aforementioned specific embodiments. Those 

skilled in the art can make various variations and modifica 

tions within the scope of the appended claims. 

What is claimed is: 

1. A method, in an access device of the communication 

network, for managing route information, comprising: receiving an access response message from a server; 

obtaining route-related information and a predefined using time from said access response message, said predefined 

using time indicates a using time of said route; and 

updating a route table item in a route table based on said 

route-related information and said predefined using 

time. 

aforesaid network 

Case 6:20-cv-00487-ADA Document 39 Filed 11/06/20 Page 12 of 13
US 8,451,839 B2 

9 

2. The method according to claim 1, wherein said access 

device is a Layer 2 access device. 

3. The method according to claim 1, further comprising: determining whether the route table item corresponding to 

said route-related information exists in said route table: 5 

updating a remaining time of the route table item if the 

determining determines that the route table item corre 

sponding to said route-related information exists in said 

route table and the remaining time of said route table 

item is shorter than said predefined using time; and 10 

creating a route table item corresponding to the route 

related information if the determining determines that 

the route table item corresponding to said route-related 

information does not exist in the route table. 

4. The method according to claim 1, further comprising: 15 

obtaining correlated information of said route table item 

and a virtual local area network from an address resolu 

tion protocol message or an access response message; 

wherein said virtual local area network configuration is 

employed between said access device and each marginal 20 

router connected with said access device. 

5. The method according to claim 1, wherein said access 

response message refers to a dynamic host configuration pro 

tocol response message, said predefined using time refers to 

the lease time in said dynamic host configuration protocol 25 

response message. 

6. A route management apparatus, in an access device of 

the communication network, for managing route information, comprising: 

a receiver configured to receive an access response mes- 30 

sage from a server; 

a first obtainer configured to obtain route-related informa 

tion and a predefined using time from said access 

response message, said predefined using time indicating 

the using time of said route; and 35 

a route maintainer configured to update a route table based 

on said route-related information and said predefined using time. 

7. The apparatus according to claim 6, wherein said access 

device is a Layer 2 access device. 

10 

8. The apparatus according to claim 6, wherein said route 

maintainer includes: 

a first judger configured to judge whether the route table 

item corresponding to said route-related information 

exists in said route table: 

a second judger configured to judge whether a remaining 

time of said route table item is shorter than said pre defined using time if the first judgerjudges that the route 

table item corresponding to said route-related informa 

tion exists in said route table; 

an updater configured to update the remaining time of said 

route table item to said predefined using time if the first 

judger judges that the route table item corresponding to 

said route-related information exists in said route table 

and the second judger judges that the remaining time of 

said route table item is shorter than said predefined using 

time; 

a creator configured to create the route table item corre 

sponding to said route-related information if the first 

judger judges that no route table item corresponding to 

said route-related information exists in said route table. 

9. The apparatus according to claim 6, further comprising: 

a second obtainer configured to obtain correlated informa 

tion of said route table item and a virtual local area 

network; 

wherein, said virtual local area network configuration is 

employed between said access device and each marginal 

routers connected with said access device. 

10. The apparatus according to claim 6, wherein said 

access response message refers to a dynamic host configura tion protocol, said predefined using time refers to the lease 

time in said dynamic host configuration protocol response 

message. 

11. An access device in the communication network, wherein said access device comprises a route management 

apparatus according to claim 6. 

12. The device according to claim 11, wherein said access 

device is a digital subscriber line-access multiplexer. ck ck ck ck ck 

Case 6:20-cv-00487-ADA Document 39 Filed 11/06/20 Page 13 of 13