Writing about current checks inc was indeed a spontaneous decision on my part. I solemnly hope that this was a wise decision that I had made.

A Featured current checks inc Article
Cisco CCNP / BCMSN Exam Tutorial: Multicasting And The RPF Check

Multicasting is a vital topic on your BCMSN, CCNP, and CCIE exams, and it can also be very confusing when you first start studying it. Multicasting uses concepts that are unlike anything you've run into in your routing protocol studies, and that can throw you at first. I speak from experience that multicasting is like any other Cisco technology - learn the basics, master the fundamentals, and then build your skills on that foundation.

One such fundamental is the RPF Check, or Reverse Path Forwarding Check.

A fundamental difference between unicasting and multicasting is that a unicast is routed by sending it toward the destination, while a multicast is routed by sending it away from its source.

"toward the destination" and "away from its source" sound like the same thing, but they're not. A unicast is going to follow a single path from source to destination. The only factor the routers care about is the destination IP address - the source IP address isn't a factor.

With multicast routing, the destination is a multicast IP group address. It's the multicast router's job to decide which paths will lead back to the source (upstream) and which paths are downstream from the source. Reverse Path Forwarding refers to the router's behavior of sending multicast packets away from the source rather than toward a specific destination.

The RPF Check is run against any incoming multicast packet. The multicast router examines the interface that the packet arrived on. If the packet comes in on an upstream interface - that is, an interface found on the reverse path that leads back to the source - the packet passes the check and will be forwarded. If the packet comes in on any other interface, the packet is dropped.

The RPF Check serves to verify the integrity of your multicasting network, and also serves as a reminder that the basic operation of multicasting is a lot different than unicasting!

About the Author

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage , home of free CCNA and CCNP tutorials! Pass the CCNA exam with Chris Bryant!

current checks inc Items For Viewing
EARTHJUSTICE


Earthjustice is a non-profit public interest law firm dedicated to protecting the magnificent places, natural resources, and wildlife of this earth and to defending the right of all people to a healthy environment. Earthjustice brings about far-reaching change by enforcing and strengthening environmental laws on behalf of hundreds of organizations and communities.


Price: 20.90



AMERICAN MUSEUM OF NATURAL HISTORY-CLASSIC CONSCIENCE


Your checks will increase awareness of the work of the American Museum of Natural History in its efforts to increase understanding and appreciation of the natural world. Your support will go directly to the American Museum of Natural History to help with their work in preserving biological and cultural diversity. Every check order supports important programs, exhibits and research.


Price: 20.90



AMERICAN MUSEUM OF NATURAL HISTORY-ONE EARTH


Your checks will increase awareness of the work of the American Museum of Natural History in its efforts to increase understanding and appreciation of the natural world. Your support will go directly to the American Museum of Natural History to help with their work in preserving biological and cultural diversity. Every check order supports important programs, exhibits and research.


Price: 20.90



LA LECHE LEAGUE INTERNATIONAL


An international, nonprofit, nonsectarian organization dedicated to providing education, information, support, and encouragement to women who want to breastfeed.


Price: 20.90



Current current checks inc News
FBI probes Ecorse deal that outsourced public works

Thu, 28 Aug 2008 18:49:43 GMT
Conflict of interest denied although officials' family and friends work for contractor that replaced DPW BY SARAH TOMPKINS * FREE PRESS STAFF WRITER * August 28, 2008 The FBI is investigating whether Ecorse's ...

Dover Saddlery Reports Second Quarter 2008 Financial Results - MarketWatch

Mon, 11 Aug 2008 20:39:31 GMT

Earthtimes (press release)

Dover Saddlery Reports Second Quarter 2008 Financial Results MarketWatch - Aug 11, 2008 DOVER SADDLERY, INC. AND SUBSIDIARIES CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Dollar amounts in thousands, except share data, unaudited) Three ... US Dataworks, Inc. Announces First Fiscal Quarter Financial Results PR Newswire (press release) all 518 news articles

here

Mon, 25 Aug 2008 07:00:00 GMT
I hear that there are many "regular Americans" slated to speak at the Democratic convention.