[Cisco ccna in urdu] static routing part 2
[Cisco ccna in urdu] static routing Part 1
Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2
IPv6 configuration items
You can configure the following for the IPv6 protocol:
- IPv6 address
- Default router
- DNS server
By default, link-local addresses are automatically configured for each interface on each IPv6 node (host or router) with a unique link-local IPv6 address. If you want to communicate with IPv6 nodes that are not on attached links, the host must have additional site-local or global unicast addresses. Additional addresses for hosts are either obtained from router advertisements sent by a router or assigned manually. Additional addresses for routers must be assigned manually.
To communicate with IPv6 nodes on other network segments, IPv6 must use a default router. A default router is automatically assigned based on the receipt of a router advertisement. Alternately, you can add a default route to the IPv6 routing table. You do not need to configure a default router for a network that consists of a single network segment.
You can use a Domain Name System (DNS) server to resolve host names to IPv6 addresses. When an IPv6 host is configured with the address of a DNS server, the host sends DNS name queries to the server for resolution. AAAA (quad-A) resource records, which are stored on your DNS servers, enable mapping from a host name to its IPv6 address.
To enable DNS name resolution, configure an IPv6 router with forwarding enabled and a global prefix that is advertised to clients. You can do this by using the netsh interface ipv6 add route and netsh interface ipv6 set interface commands.
Configuring clients with the DNS server address
To provide communication between DNS clients and servers, you can configure the clients with the IPv6 address of the DNS server, or you can configure your DNS server with one of the three default DNS server IPv6 addresses that are automatically configured on all IPv6 clients.
You can configure clients with the IPv6 address of the DNS server by using the netsh interface ipv6 add dns command at each client computer or in a logon script that is run each time a client logs on to the network.
To configure the DNS server with one of the three IPv6 addresses that are available on IPv6 client computers by default, use the netsh interface ipv6 add address command. The three default DNS server addresses are:
- FEC0:0:0: FFFF::1
- FEC0:0:0: FFFF::2
If your DNS server is on a different subnet than your IPv6 clients, configure a static route to the DNS server on any IPv6 router that is available on the DNS server’s subnet.
Configuring the DNS server to listen on IPv6
You can configure the DNS server to listen for DNS name registration and resolution requests over IPv6. When your DNS server is configured to listen on both IPv4 and IPv6:
- Devices that function over IPv6 but not IPv4 will function properly with your DNS server.
- Computers and other devices that are configured with both IPv4 and IPv6 use IPv6 by default.
To configure your DNS server to listen over IPv6, do the following:
- Install Windows Support Tools.
For more information, see Install Windows Support Tools
- Open Command Prompt.
- Type the following command:
dnscmd /config /EnableIPv6 1
- Restart the DNS Server service.
The Purpose of the Configuration Register
The configuration register can be used to change router behavior in several ways, such as:
how the router boots (into ROMmon, NetBoot)
options while booting (ignore configuration, disable boot messages)
console speed (baud rate for a terminal emulation session)
The configuration register can be set from configuration mode using the config-register command. From ROMmon, use the confreg command. Issue the show version command to view the current setting of the configuration register:
Cisco Internetwork Operating System Software
IOS ™ 2500 Software (C2500-JS-L), Version 12.1(5), RELEASE SOFTWARE (fc1)
Copyright © 1986-2000 by cisco Systems, Inc.
Compiled Wed 25-Oct-00 05:18 by cmong
Image text-base: 0x03071DB0, data-base: 0x00001000
ROM: System Bootstrap, Version 5.2(8a), RELEASE SOFTWARE
BOOTFLASH: 3000 Bootstrap Software (IGS-RXBOOT), Version 10.2(8a), RELEASE SOFTWARE (fc1)
Router uptime is 7 minutes
System returned to ROM by reload
System image file is “flash:c2500-js-l_121-5.bin”
cisco 2500 (68030) processor (revision D) with 16384K/2048K bytes of memory.
Processor board ID 03867477, with hardware revision 00000000
X.25 software, Version 3.0.0.
SuperLAT software (copyright 1990 by Meridian Technology Corp).
TN3270 Emulation software.
1 Token Ring/IEEE 802.5 interface(s)
2 Serial network interface(s)
32K bytes of non-volatile configuration memory.
16384K bytes of processor board System flash (Read ONLY)
Configuration register is 0x2102
The factory-default setting for the configuration register is 0x2102. This indicates that the router should attempt to load a Cisco IOS® software image from Flash memory and load the startup configuration with a console speed of 9600 baud.
There have been many posts regarding SNR and Line Attenuation.
SNR means Signal to Noise Ratio. Simply put divide the Signal value by Noise Value and you get SNR. You need high SNR for a stable connection. In general, a higher signal to noise ratio will result in less errors.
- 6bB. or below = Bad and will experience no line synchronisation and frequent disconnections
- 7dB-10dB. = Fair but does not leave much room for variances in conditions.
- 11dB-20dB. = Good with little or no disconnection problems
- 20dB-28dB. = Excellent
- 29dB. or above = Outstanding
Note that most modems display value as SNR Margin and not pure SNR.
You can think of SNR margin as the measure of quality of the service; it defines the ability of the service to work error free during noise bursts.
This is a measure of the difference between your current SNR and the SNR that is required to keep a reliable service at your connection speed. If your SNR is very close to the minimum required SNR, you are more likely to suffer intermittent connection faults, or slowdowns. You need a high margin to ensure that bursts of interference don’t cause constant disconnections.
With traditional broadband, the higher the SNR Margin, the better. With MaxDSL the faster speeds are only available as a trade-off with what your line can reliably support. The Target SNR Margin is about 6dB. If your broadband is provided through an LLU (Local Loop Unbundled) network, this target SNR Margin may be as high as 12dB.
In gerneral, attenuation is the loss of signal over distance. Unfortunately, dB loss is not just dependent on distance. It also depends on cable type and gauge (which can differ over the length of the cable), the number and location other connection points on the cable.
- 20bB. and below = Outstanding
- 20dB-30dB. = Excellent
- 30dB-40dB. = Very Good
- 40dB-50dB. = Good
- 50dB-60dB. = Poor and may experience connectivity issues
- 60dB. and above = Bad and will experience connectivity issues
Line attenuation also affects your speed.
- 75 dB+: Out of range for broadband
- 60-75 dB: max speed up to 512kbps
- 43-60dB: max speed up to 1Mbps
- 0-42dB: speed up to 2Mbps+