ZyXEL Communications P-791R V2 Manual

P-791R v2 Support Notes
P-791R v2
G.SHDSL.bis Router
Support Notes
Version 3.40
04/2007
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All contents copyright © 2007 ZyXEL Communications Corporation.

P-791R v2 Support Notes
FAQ.................................................................................................................5
ZyNOS FAQ.................................................................................................5
1. What is ZyNOS?..........................................................................5
2. How do I access the P-791R v2 SMT menu?.............................5
3. How do I upload the ZyNOS firmware code via console? .......5
4. How do I upgrade/backup the ZyNOS firmware by using TFTP
client program via LAN?............................................................5
5. How do I upload ROMFILE via console port?...........................6
6. How do I restore P-791R v2 configurations by using TFTP
client program via LAN?............................................................6
7. What should I do if I forget the system password? .................6
8. How to use the Reset button?....................................................6
9. What is SUA? When should I use SUA? ...................................7
10. What is the difference between SUA and Full Feature NAT?..7
11. Is it possible to access a server running behind SUA from the
outside Internet? If possible, how?..........................................8
12. When do I need to select Full Feature NAT? ............................8
13. What IP/Port mapping does Multi-NAT support?.....................9
14. How many network users can the SUA/NAT support?..........10
15. What are Device filters and Protocol filters?..........................10
16. How can I protect against IP spoofing attacks?.....................10
Product FAQ.............................................................................................12
1. What is SHDSL, SHDSL.bis?....................................................12
2. How can I manage P-791R v2?.................................................12
3. What is the default password for Web Configurator? ...........12
4. What’s the difference between ‘Common User Account’ and
‘Administrator Account’?........................................................12
5. How do I know the P-791R v2's WAN IP address assigned by
the ISP?.....................................................................................13
6. What do I need before using the SHDSL?...............................13
7. What should I do when the power LED is off? .......................13
8. How to debug while DSL LED is off? ......................................14
9. How do I verify my PC's IP address assigned by the P-791R
v2？ ......................................................................................14
10. What is Traffic Shaping?..........................................................14
11. What do the parameters (PCR, SCR, MBS) mean? ................14
12. What do ATM QoS Types (CBR, UBR, VBR-nRT, VBR-RT)
mean? ........................................................................................15
13. Why do we perform traffic shaping in the P-791R v2? ..........15
14. The P-791R v2 supports Bridge and Router mode, what's the
difference between them?.......................................................15
15. How do I know I am using PPPoE? .........................................16
16. Why does my provider use PPPoE?........................................16
17. What is DDNS?..........................................................................16
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P-791R v2 Support Notes
18. When do I need DDNS service?...............................................16
19. What is DDNS wildcard? Does the P-791R v2 support DDNS
wildcard? ..................................................................................17
20. Can the P-791R v2's SUA handle IPSec packets sent by the
IPSec gateway? ........................................................................17
21. How do I setup my P-791R v2 for routing IPSec packets over
SUA? .........................................................................................17
22. What is Traffic Redirect?..........................................................18
23. What is Dial Backup?................................................................18
DSL FAQ ...................................................................................................19
1. How does DSL compare to Cable modems?..........................19
2. How do I know the DSL line is up?..........................................19
3. How does the P-791R v2 work on a noisy DSL? ....................19
4. Does the VC-based multiplexing perform better than the
LLC-based multiplexing? ........................................................19
5. How do I know the details of my DSL line statistics?............19
6. What are the signaling pins of the DSL connector? ..............20
Application Notes ........................................................................................21
General Application Notes ......................................................................21
1. Internet Access Using P-791R v2 under Bridge mode...........21
2. Internet Access Using P-791R v2 under Routing mode ........23
3. Internet Access scenarios........................................................26
4. Point-to-point scenarios...........................................................27
5. What is the checklist for making a point-to-point connection
over P-791R v2? .......................................................................27
6. Setup the P-791R v2 as a DHCP Relay....................................28
7. SUA Notes..................................................................................29
8. Using Full Feature NAT ............................................................38
9. Using the Dynamic DNS (DDNS)..............................................46
10. Network Management Using SNMP.........................................48
11. Using syslog..............................................................................51
12. Using IP Alias............................................................................51
13. Using IP Policy Routing............................................................54
14. Using Call Scheduling ..............................................................56
15. Using IP Multicast.....................................................................58
16. How to configure packet filter on P-791R v2?........................59
17. How to setup traffic redirect in P-791R v2?............................59
18. How to deal with Triangle toute and Traffic redirect?............62
19. How to setup Dial Backup?......................................................63
Support Tool.................................................................................................65
1. LAN/WAN Packet Trace............................................................65
2. Firmware/Configurations Uploading and Downloading using
TFTP..........................................................................................70
3. Firmware/Configurations Uploading and Downloading using
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P-791R v2 Support Notes
FTP ............................................................................................73
CI Command Reference ..............................................................................76
Reference .....................................................................................................77
1. PPP Numbers ............................................................................77
2. Port Numbers ............................................................................90
3. Protocol Numbers.....................................................................95
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P-791R v2 Support Notes
FAQ
ZyNOS FAQ
1. What is ZyNOS?
ZyNOS is ZyXEL's proprietary Network Operating System. It is the platform on
all P-791R v2 routers that delivers network services and applications. It is
designed in a modular fashion so it is easy for developers to add new features.
New ZyNOS software upgrades can be easily downloaded from our FTP sites
as they become available.
2. How do I access the P-791R v2 SMT menu?
The SMT interface is a menu driven interface, which can be accessed via a
console or a Telnet connection. To access the P-791R v2 via SMT console
port, a computer equipped with communication software such as
HyperTerminal must be configured to the following parameters.
zVT100 terminal emulation
z9600bps baud rate
zN81 data format (No Parity, 8 data bits, 1 stop bit)
The default console port baud rate is 9600bps, you can change it to
115200bps in Menu 24.2.2 to speed up access of the SMT.
3. How do I upload the ZyNOS firmware code via console?
The procedure for uploading via console is as follows.
(1) Enter debug mode when powering on the P-791R v2 using a terminal
emulator
(2) Enter 'ATUR' to start the uploading
(3) Use X-modem protocol to transfer the ZyNOS code
(4) Enter 'ATGO' to restart the P-791R v2
4. How do I upgrade/backup the ZyNOS firmware by using TFTP client
program via LAN?
The P-791R v2 allows you to transfer the firmware from/to P-791R v2 by using
TFTP program via LAN. The procedure for uploading via TFTP is as follows.
(1) Use the TELNET client program in your PC to login to your P-791R v2,
and use Menu 24.8 to enter CI command 'sys stdio 0' to disable
console idle timeout
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P-791R v2 Support Notes
(2) To upgrade firmware, use TFTP client program to put firmware in file
'ras' in the P-791R v2. After data transfer is finished, the P-791R v2 will
program the upgraded firmware into FLASH ROM and reboot itself.
(3) To backup your firmware, use the TFTP client program to get file 'ras'
from the P-791R v2.
5. How do I upload ROMFILE via console port?
In some situations, you may need to upload the ROMFILE, such as losing the
system password, or the need of resetting SMT to factory default.
The procedure for uploading via the console port is as follows.
Enter debug mode when powering on the P-791R v2 using a terminal emulator
Enter 'ATLC' to start the uploading
Use X-modem protocol to transfer ROMFILE
Enter 'ATGO' to restart the P-791R v2
6. How do I restore P-791R v2 configurations by using TFTP client
program via LAN?
(1) Use the TELNET client program in your PC to login to your P-791R v2.
(2) Enter CI command 'sys stdio 0' disable Stdio idle timeout
(3) To backup the P-791R v2 configurations, use TFTP client program to
get file 'rom-0' from the P-791R v2.
(4) To restore the P-791R v2 configurations, use the TFTP client program
to put your configuration in file rom-0 in the P-791R v2.
7. What should I do if I forget the system password?
In case you forget the system password, you can erase the current
configuration and restore factory defaults this way:
Use the RESET button on the rear panel of P-791R v2 to reset the router.
After the router is reset, the LAN IP address will be reset to '192.168.1.1', the
common user password will be reset to 'user', the dministrator password will
be reset to ‘1234’.
8. How to use the Reset button?
(1) Turn your P-791R v2 on. Make sure the POWER LED is on (not
blinking)
(2) Press the RESET button for six seconds and release it. If the POWER
LED begins to blink, the default configuration has been restored and
the P-791R v2 restarts.
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P-791R v2 Support Notes
9. What is SUA? When should I use SUA?
SUA (Single User Account) is a unique feature supported by P-791R v2 router
which allows multiple people to access Internet concurrently for the cost of a
single user account.
When P-791R v2 acts as SUA receives a packet from a local client destined
for the outside Internet, it replaces the source address in the IP packet header
with its own address and the source port in the TCP or UDP header with
another value chosen out of a local pool. It then recomputes the appropriate
header checksums and forwards the packet to the Internet as if it is originated
from P-791R v2 using the IP address assigned by ISP. When reply packets
from the external Internet are received by P-791R v2, the original IP source
address and TCP/UDP source port numbers are written into the destination
fields of the packet (since it is now moving in the opposite direction), the
checksums are recomputed, and the packet is delivered to its true destination.
This is because SUA keeps a table of the IP addresses and port numbers of
the local systems currently using it.
10. What is the difference between SUA and Full Feature NAT?
When you edit NAT in Web Configurator, Advanced Setup, Network -> NAT
-> General, there will be three options for you:
zInactive NAT
zSUA Only
zFull Feature
SUA (Single User Account) in previous ZyNOS versions is a NAT set with 2
rules: Many-to-One and Server. With SUA, 'visible' servers had to be mapped
to different ports, since the servers share only one global IP.
The P-791R v2 now has Full Feature NAT which supports five types of IP/Port
mapping: One to One, Many to One, Many to Many Overload, Many to Many
No Overload and Server. You can make special application when you select
Full Feature NAT. For example: With multiple global IP addresses, multiple
severs using the same port (e.g., FTP servers using port 21/20) are allowed on
the LAN for outside access.
You can edit Full Feature NAT in Network->NAT->Address Mapping
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P-791R v2 Support Notes
The P-791R v2 supports NAT sets on a remote node basis. They are reusable,
but only one set is allowed for each remote node. The P-791R v2 supports 8
sets since there are 8 remote nodes.
By fatory default, the NAT is select as SUA in Web Configurator, Advanced
Setup, Network -> NAT -> General -> NAT Setup.
11. Is it possible to access a server running behind SUA from the outside
Internet? If possible, how?
Yes, it is possible because P-791R v2 delivers the packet to the local server by
looking up to a SUA server table. Therefore, to make a local server accessible
to the outside users, the port number and the inside IP address of the server
must be configured. (You can configure it in Web Configurator, Advanced
Setup, Network -> NAT -> Port Forwarding.
12. When do I need to select Full Feature NAT?
•Make multiple local servers on the LAN accessible from outside with
multiple global IP addresses
With SUA, 'visible' servers had to be mapped to different ports, since the
servers share only one global IP. But when you select Full Feature, you can
make multiple local servers (mapping the same port or not) on the LAN
accessible from outside with multiple global IP addresses.
•Support Non-NAT Friendly Applications
Some servers providing Internet applications such as some MIRC servers do
not allow users to login using the same IP address. Thus, users on the same
network can not login to the same server simultaneously. In this case it is
better to use Many-to-Many No Overload or One-to-One NAT mapping types,
thus each user login to the server using a unique global IP address.
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P-791R v2 Support Notes
13. What IP/Port mapping does Multi-NAT support?
Multi-NAT supports five types of IP/port mapping: One to One, Many to One,
Many to Many Overload, Many to Many No Overload and Server. The details
of the mapping between ILA and IGA are described as below. Here we define
the local IP addresses as the Internal Local Addresses (ILA) and the global IP
addresses as the Inside Global Address (IGA),
•One to One: In One-to-One mode, the P-791R v2 maps one ILA to one
IGA.
•Many to One: In Many-to-One mode, the P-791R v2 maps multiple ILA
to one IGA. This is equivalent to SUA (i.e., PAT, port address
translation), ZyXEL's Single User Account feature that previous ZyNOS
routers supported (the SUA is optional in today's P-791R v2 routers).
•Many to Many Overload: In Many-to-Many Overload mode, the
P-791R v2 maps multiple ILA to shared IGA.
•Many One-to-One: In Many One-to-One mode, the P-791R v2 maps
each ILA to unique IGA.
•Server: In Server mode, the P-791R v2 maps multiple inside servers to
one global IP address. This allows us to specify multiple servers of
different types behind the NAT for outside access.
Note: if you want to map each server to one unique IGA please use the
one-to-One mode.
The following table summarizes the five types.
NAT Type IP Mapping
One-to-One ILA1<--->IGA1
Many-to-One
(SUA/PAT)
ILA1<--->IGA1
ILA2<--->IGA1
...
Many-to-Many
Overload
ILA1<--->IGA1
ILA2<--->IGA2
ILA3<--->IGA1
ILA4<--->IGA2
...
Many
One-to-One
ILA1<--->IGA1
ILA2<--->IGA2
ILA3<--->IGA3
ILA4<--->IGA4
...
Server Server 1 IP<--->IGA1
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P-791R v2 Support Notes
Server 2 IP<--->IGA1
14. How many network users can the SUA/NAT support?
The P-791R v2 does not limit the number of the users but the number of the
NAT sessions. The P-791R v2 supports 2048 sessions that you can use the 'ip
nat session' command in CLI to see. You can also use ‘ip nat hashTable
wanif0’ to view the current active NAT sessions.Or you can check it in below
WEB Configurator.
15. What are Device filters and Protocol filters?
In ZyNOS, the filters have been separated into two groups. One group is called
'device filter group', and the other is called 'protocol filter group'. Generic
filters belong to the 'device filter group', TCP/IP and IPX filters belong to the
'protocol filter group'. You can configure the filter rule in SMT.
Note: In ZyNOS, you can not mix different filter groups in the same filter
set.
16. How can I protect against IP spoofing attacks?
The P-791R v2's filter sets provide a means to protect against IP spoofing
attacks. The basic scheme is as follows:
For the input data filter:
•Deny packets from the outside that claim to be from the inside
•Allow everything that is not spoofing us
•Filter rule setup:
•Filter type =TCP/IP Filter Rule
•Active =Yes
•Source IP Addr =a.b.c.d
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P-791R v2 Support Notes
•Source IP Mask =w.x.y.z
•Action Matched =Drop
•Action Not Matched =Forward
Where a.b.c.d is an IP address on your local network and w.x.y.z is your
netmask:
For the output data filters:
•Deny bounce back packet
•Allow packets that originate from us
Filter rule setup:
•Filter Type =TCP/IP Filter Rule
•Active =Yes
•Destination IP Addr =a.b.c.d
•Destination IP Mask =w.x.y.z
•Action Matched =Drop
•Action No Matched =Forward
Where a.b.c.d is an IP address on your local network and w.x.y.z is your
netmask.
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P-791R v2 Support Notes
Product FAQ
1. What is SHDSL, SHDSL.bis?
SHDSL stands for Symmetric High-data-rate Digital Subscriber Line. SHDSL
bases on TC-PAM (Trellis Coded Pulse Amplitude Modulation) which offers
symmetrical transmission speed up to 2.30 Mbps (2-wire mode).
SHDSL.bis boots SHDSL performance to approximately 5.70 Mbps (2-wire
mode) or 11.4 Mbps (4-wire mode).
Note: P-791R v2 only support 2-wire mode.
2. How can I manage P-791R v2?
Multilingual Embedded Web GUI for Local and Remote management
SMT via console.
Telnet support (Administrator Password Protected ) for remote
configuration change and status monitoring
FTP/ TFTP sever, firmware upgrade and configuration backup and
restore are supported(Administrator Password Protected)
3. What is the default password for Web Configurator?
There are two different accounts for P-791R v2 Web Configurator: Common
User Account and Administrator Account.
By factory default the password for the two accounts are:
•Common User Account: user
•Administrator Account: 1234.
You can change the password after you logging in the Web Configurator.
Note: By default, the password is “user”.
4. What’s the difference between ‘Common User Account’ and
‘Administrator Account’?
For Common User Account, it can only access the status monitor of P-791R v2
and check the current system status.
For Administrator Account, besides accessing the status monitor of P-791R v2,
it can also access Winzard setup / Advanced setup of P-791R v2.
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P-791R v2 Support Notes
Moreover, only with Administrator Password, you could manage the P-791R
v2 via FTP/TFTP or Telnet.
5. How do I know the P-791R v2's WAN IP address assigned by the ISP?
You can view "IP Address: x.x.x.x" shown in Web Configurator ‘Status->Device
Information ->WAN Information’.
6. What do I need before using the SHDSL?
(1) You must order the SHDSL service from your telephone company and
choose the service category.
(2) Your telephone company must have tested the phone line for the
SHDSL transfer rate.
(3) You must have subscribed to an ISP ( Internet Service Provider)
already and have the following information:
•The user name and password for the connection
•VPI/VCI number (Virtual Path Indentifier/Virtual Circuit Identifier)
assigned by the Telecompany.
•The encapsulation protocol the service provider supports. It can
be PPP, RFC 1483, or ENET ENCAP.
•The DNS and gateway, and ENET ENCAP Gateway if the
encapsulation is ENET ENCAP.
7. What should I do when the power LED is off?
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P-791R v2 Support Notes
Make sure the P-791R v2 is connected to the power adapter, the power
adapter is plugged into a power outlet and the power switch is at the ON
position.
8. How to debug while DSL LED is off?
Check the connection between the P-791R v2's DSL port and the wall socket
or remote devices. If you use the back to back application, check the service
type and the Standard Mode in both P-791R v2s.
9. How do I verify my PC's IP address assigned by the P-791R v2?
Make sure you have the P-791R v2 powered on and then turn on your PC.
After the PC starts, select " Run..." from the windows "Start" menu. Enter
"cmd" and click OK.You may check IP of your PC with “ipconfig”. Verify your
cabling if the IP address box shows "0.0.0.0".
10. What is Traffic Shaping?
Traffic Shaping is a feature in the P-791R v2. It allocates the bandwidth to
WAN dynamically and aims at boosting the efficiency of the bandwidth. If there
are serveral VCs in the P-791R v2 but only one VC activated at one time, the
P-791R v2 allocates all the Bandwidth to the VC and the VC gets full
bandwidth. If another VCs are avtivated later, the bandwidth is yield to other
VCs after ward.
11. What do the parameters (PCR, SCR, MBS) mean?
Traffic shaping parameters (PCR, SCR, MBS) can be set in Menu 4 and Menu
11.6 and is valid for both incoming and outgoing direction since G.shdsl is
symmetric.
Peak Cell Rate(PCR): The maximum bandwidth allocated to this connection.
The VC connection throughput is limited by PCR.
Sustainable Cell Rate(SCR): The least guaranteed bandwidth of a VC.
When there are multi-VCs on the same line, the VC throughput is guaranteed
by SCR.
Maximum Burst Size(MBS): The amount of cells transmitted through this
VC at the Peak Cell Rate before yielding to other VCs. Total bandwidth of the
line is dedicated to single VC if there is only one VC on the line. However, as
the other VC asking the bandwidth, the MBS defines the maximum number of
cells transmitted via this VC with Peak Cell rate before yielding to other VCs.
The P-791R v2 holds the parameters for shaping the traffic among its virtual
channels. If you do not need traffic shaping, please set SCR = 0, MBS = 0 and
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P-791R v2 Support Notes
PCR as the maximum value according to the line rate (for example, 2.3 Mbps
line rate will result PCR as 5424 cell/sec.)
12. What do ATM QoS Types (CBR, UBR, VBR-nRT, VBR-RT) mean?
Constant bit rate(CBR): An ATM bandwidth-allocation service that requires
the user to determine a fixed bandwidth requirement at the time the connection
is set up so that the data can be sent in a steady stream. CBR service is often
used when transmitting fixed-rate uncompressed video.
Unspecified bit rate(UBR): An ATM bandwidth-allocation service that does
not guarantee any throughput levels and uses only available bandwidth. UBR
is often used when transmitting data that can tolerate delays, such as e-mail.
Variable bit rate(VBR): An ATM bandwidth-allocation service that allows
users to specify a throughput capacity (i.e., a peak rate) and a sustained rate
but data is not sent evenly. You can select VBR for bursty traffic and
bandwidth sharing with other applications. It contains two subclasses:
Variable bit rate nonreal time (VBR-nRT) and Variable bit rate real time
(VBR-RT).
13. Why do we perform traffic shaping in the P-791R v2?
The P-791R v2 must manage traffic fairly and provide bandwidth allocation for
different sorts of applications, such as voice, video, and data. All applications
have their own natural bit rate. Large data transactions have a fluctuating
natural bit rate. The P-791R v2 is able to support variable traffic among
different virtual connections. Certain traffic may be discarded if the virtual
connection experiences congestion. Traffic shaping defines a set of actions
taken by the P-791R v2 to avoid congestion; traffic shaping takes measures to
adapt to unpredictable fluctuations in traffic flows and other problems among
virtual connections.
14. The P-791R v2 supports Bridge and Router mode, what's the
difference between them?
When the ISP limits some specific computers to access Internet, which means
only the traffic to/from these computers will be forwarded and the other will be
filtered. In this case, we use bridge mode which works as an DSL modem to
connect to the ISP. The ISP will generally give one Internet account and limit
only one computer to access the Internet.
For most Internet users having multiple computers want to share an Internet
account for Internet access, they have to add another Internet sharing device,
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P-791R v2 Support Notes
like a router. In this case, we use the router mode which works as a general
Router plus a DSL Modem.
15. How do I know I am using PPPoE?
PPPoE requires a user account to login to the provider's server. If you need to
configure a user name and password on your computer to connect to the ISP
you are probably using PPPoE. If you are simply connected to the Internet
when you turn on your computer, you probably are not. You can also check
your ISP or the information sheet given by the ISP. Please choose PPPoE as
the encapsulation type in the P-791R v2 if the ISP uses PPPoE.
16. Why does my provider use PPPoE?
PPPoE emulates a familiar Dial-Up connection. It allows your ISP to provide
services using their existing network configuration over the broadband
connections. Besides, PPPoE supports a broad range of existing applications
and service including authentication, accounting, secure access and
configuration management.
17. What is DDNS?
The Dynamic DNS service allows you to alias a dynamic IP address to a static
hostname, allowing your computer to be more easily accessed from various
locations on the Internet. To use the service, you must first apply an account
from several free Web servers such as http://www.dyndns.org/.
Without DDNS, we always tell the users to use the WAN IP of the P-791R v2 to
reach our internal server. It is inconvenient for the users if this IP is dynamic.
With DDNS supported by the P-791R v2, you apply a DNS name (e.g.,
www.zyxel.com.tw) for your server (e.g., Web server) from a DDNS server.
The outside users can always access the web server using the
www.zyxel.com.tw regardless of the WAN IP of the P-791R v2.
When the ISP assigns the P-791R v2a new IP, the P-791R v2 updates this IP
to DDNS server so that the server can update its IP-to-DNS entry. Once the
IP-to-DNS table in the DDNS server is updated, the DNS name for your web
server (i.e., www.zyxel.com.tw) is still usable.
18. When do I need DDNS service?
When you want your internal server to be accessed by using DNS name rather
than using the dynamic IP address we can use the DDNS service. The DDNS
server allows to alias a dynamic IP address to a static hostname. Whenever
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P-791R v2 Support Notes
the ISP assigns you a new IP, the P-791R v2 sends this IP to the DDNS server
for its updates.
19. What is DDNS wildcard? Does the P-791R v2 support DDNS
wildcard?
Some DDNS servers support the wildcard feature which allows the hostname,
*.yourhost.dyndns.org, to be aliased to the same IP address as
yourhost.dyndns.org. This feature is useful when there are multiple servers
inside and you want users to be able to use things such as
www.yourhost.dyndns.org and still reach your hostname.
Yes, the P-791R v2 supports DDNS wildcard that http://www.dyndns.org/
supports. When using wildcard, you simply enter yourhost.dyndns.org in the
Host field in Menu 1.1 Configure Dynamic DNS.
20. Can the P-791R v2's SUA handle IPSec packets sent by the IPSec
gateway?
Yes, the P-791R v2's SUA can handle IPSec ESP Tunneling mode. We know
when packets go through SUA, SUA will change the source IP address and
source port for the host. To pass IPSec packets, SUA must understand the
ESP packet with protocol number 50, replace the source IP address of the
IPSec gateway to the router's WAN IP address. However, SUA should not
change the source port of the UDP packets which are used for key
managements. Because the remote gateway checks this source port during
connections, the port thus is not allowed to be changed.
21. How do I setup my P-791R v2 for routing IPSec packets over SUA?
For outgoing IPSec tunnels, no extra setting is required.
For forwarding the inbound IPSec ESP tunnel, A 'Default' server set is required.
You could configure it in Web Configurator, Advanced Setup, Network -> NAT
-> Port Forwarding -> Default Server Setup:
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P-791R v2 Support Notes
It is because SUA makes your LAN appear as a single machine to the outside
world. LAN users are invisible to outside users. So, to make an internal server
for outside access, we must specify the service port and the LAN IP of this
server in Web configurator. Thus SUA is able to forward the incoming packets
to the requested service behind SUA and the outside users access the server
using the P-791R v2's WAN IP address. So, we have to configure the internal
IPsec client as a default server (unspecified service port) when it acts a server
gateway.
Note: The NAT type should be SUA only, then you can edit port
forwarding.
22. What is Traffic Redirect?
Traffic Redirect forwards WAN traffic to a backup gateway when the
Prestige cannot connect to the Internet through its normal gateway.
Thus make your backup gateway as an auxiliary backup of your WAN
connection. Once Prestige detects its WAN connectivity is broken,
Prestige will try to forward outgoing traffic to backup gateway that users
specify in traffic redirect configuration menu.
23. What is Dial Backup?
It is Auto Fail-over and Fall-back WAN Backup Solution.
The P-791R v2 features a Fail-over and Fall-back WAN Backup Solution for
complete reliability. When the DSL connection fails, traffic is forwarded to
either a backup ISDN or analog modem to maintain data exchange. When the
DSL connection is re-established, traffic will be fully restored. The WAN
Backup Solution saves device maintenance cost and reduces loss from daily
operation.
In addition, P-791R v2 also performs backup functions by redirecting traffic to
a specific gateway to ensure availability of the Internet connection.
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All contents copyright © 2007 ZyXEL Communications Corporation.

P-791R v2 Support Notes
DSL FAQ
1. How does DSL compare to Cable modems?
DSL provides a dedicated service over a single telephone line; cable modems
offer a dedicated service over a shared media. While cable modems have
greater downstream bandwidth capabilities (up to 30 Mbps), that bandwidth is
shared among all users on a line, and will therefore vary, perhaps dramatically,
as more users in a neighborhood get online at the same time. Cable modem
upstream traffic will in many cases be slower than DSL, either because the
particular cable modem is inherently slower, or because of rate reductions
caused by contention for upstream bandwidth slots. The big difference
between DSL and cable modems, however, is the number of lines available to
each. There are no more than 12 million homes passed today that can support
two-way cable modem transmissions, and while the figure also grows steadily,
it will not catch up with telephone lines for many years. Additionally, many of
the older cable networks are not capable of offering a return channel;
consequently, such networks will need significant upgrading before they can
offer high bandwidth services.
2. How do I know the DSL line is up?
You can see the DSL LED on the P-791R v2's front panel is on Green when
the DSL physical layer is up.
3. How does the P-791R v2 work on a noisy DSL?
Depending on the line quality, the P-791R v2 uses "Fall Back" and "Fall
Forward" to automatically adjust the date rate.
4. Does the VC-based multiplexing perform better than the LLC-based
multiplexing?
Though the LLC-based multiplexing can carry multiple protocols over a single
VC, it requires extra header information to identify the protocol being carried
on the virtual circuit (VC). The VC-based multiplexing needs a separate VC for
carrying each protocol but it does not need the extra headers. Therefore, the
VC-based multiplexing is more efficient.
5. How do I know the details of my DSL line statistics?
In WEB Configurator, Maintenance -> Diagnostic -> DSL Line -> DSL Line
Status:
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All contents copyright © 2007 ZyXEL Communications Corporation.

P-791R v2 Support Notes
6. What are the signaling pins of the DSL connector?
The signaling pins on the P-791R v2's DSL connector RJ11 cable are pin 1
and 2 for 2-wire mode.
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All contents copyright © 2007 ZyXEL Communications Corporation.