Please Whitelist This Site?
I know everyone hates ads. But please understand that I am providing premium content for free that takes hundreds of hours of time to research and write. I don't want to go to a pay-only model like some sites, but when more and more people block ads, I end up working for free. And I have a family to support, just like you. :)
If you like The TCP/IP Guide, please consider the download version. It's priced very economically and you can read all of it in a convenient format without ads.
If you want to use this site for free, I'd be grateful if you could add the site to the whitelist for Adblock. To do so, just open the Adblock menu and select "Disable on tcpipguide.com". Or go to the Tools menu and select "Adblock Plus Preferences...". Then click "Add Filter..." at the bottom, and add this string: "@@||tcpipguide.com^$document". Then just click OK.
Thanks for your understanding!
Sincerely, Charles Kozierok
Author and Publisher, The TCP/IP Guide
|
NOTE: Using software to mass-download the site degrades the server and is prohibited. If you want to read The TCP/IP Guide offline, please consider licensing it. Thank you.
|
|
|
|
ICMPv4 Router Advertisement and Router Solicitation Messages
(Page 4 of 4)
Addressing and Use of Router Advertisement and Router Solicitation Messages
If possible, both Router Advertisement
and Router Solicitation messages are sent out multicast for efficiency.
Router Advertisements use the all devices multicast
address (224.0.0.1), since they are intended for hosts to hear, while
Router Solicitation messages use the all routers
multicast address (224.0.0.2). If the local network does not supports
multicast, messages are instead sent out broadcast (to address 255.255.255.255).
It is important to remember that
just like ICMP
Redirect messages, Router Advertisement
messages are not a generalized method for exchanging routing information.
They are a support mechanism only, used to inform hosts about the existence
of routers. Detailed information about routes is communicated between
routers using routing
protocols, like RIP
and OSPF.
I should also mention that while
I suggested router discovery was the alternative to manual configuration
of a host's default router, there are other alternatives as well. For
example, a host configuration protocol like DHCP
can allow a host to learn the address of a default router on the local
network.
Finally, note that when Mobile
IP is implemented, Router Advertisement
messages are used as the basis for Mobile-IP-aware routers to send Agent
Advertisements. One or more special extensions are added
to the regular Router Advertisement format to create an Agent
Advertisement. This is discussed extensively in the
topic on Mobile IP agent discovery.
Key Concept: ICMP Router Advertisement messages are sent regularly by IP routers to inform hosts of their presence and characteristics, so hosts know to use them for delivery of datagrams to distant hosts. A host that is new to a network and wants to find out immediately what routers are present may send a Router Solicitation, which will prompt listening routers to send out Router Advertisements. |
If you find The TCP/IP Guide useful, please consider making a small Paypal donation to help the site, using one of the buttons below. You can also donate a custom amount using the far right button (not less than $1 please, or PayPal gets most/all of your money!) In lieu of a larger donation, you may wish to consider purchasing a download license of The TCP/IP Guide. Thanks for your support! |
|
|
Home -
Table Of Contents - Contact Us
The TCP/IP Guide (http://www.TCPIPGuide.com)
Version 3.0 - Version Date: September 20, 2005
© Copyright 2001-2005 Charles M. Kozierok. All Rights Reserved.
Not responsible for any loss resulting from the use of this site.
|