Re: QS: FIB and RIB: what is the difference

When you look at RIB and FIB you have to think of the 2 major and most
important components of routing:

   - Control Plane
   - Data Plane

 The control plane takes care of the routing information exchange, and in
MPLS environment, label exchange between adjacent devices.

What do we have and see in the control plane? Routing protocols, exchange of
routing information, RIB (Routing Information Table) and once again in an
MPLS environment you will also see a Label Exchange Protocol such as LDP.

So therefore control plane builds a routing table or RIB based on the
routing protocols.

The control plane builds/populates 2 forwarding tables: a FIB (Which is
built from the information in the RIB) and in MPLS networks an LFIB (Label
Forwarding Information Base). These (FIB and LFIB) exist and work in the
Data plane.

The data Plane is simply a forwarding engine that is* independent* of the
routing protocol or Label exchange protocol type; this Plane forwards
packets to the appropriate interface based on the info found in the FIB or
LFIB.

So the way I envision it:

You use a routing protocol to advertise routes upstreamand if any of the
upstream routers need to connect to the advertised networks, they connect
downstream toward the destination.

Now this is a very brief and *basic* explanation of the RIB, FIB and LFIB.

Now weather they are hardware based or software based I think is irrelevant
when you look at different platforms.

On Fri, Sep 25, 2009 at 9:24 AM, Tony Varriale
<tvarriale_at_flamboyaninc.com>wrote:

> That's making a poor assumption that the device you are speaking about is
> hardware based.
>
> More than half of people won't come in contact with those devices (with the
> exception of a 6500).
>
> tv
>
> -----Original Message-----
> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
> Anthony Sequeira
> Sent: Friday, September 25, 2009 10:13 AM
> To: Syed Khalid Ali
> Cc: ccielab_at_groupstudy.com
> Subject: Re: QS: FIB and RIB: what is the difference
>
> The Routing Information Base is the copy of the routing table stored
> in software on the Cisco device.
>
> The Forwarding Information Base is the copy of the routing table
> stored in hardware on the Cisco device.
>
> Thanks to Cisco Express Forwarding (CEF) and its use of the FIB,
> performance for Cisco routers is much improved.
>
> Warmest Regards,
>
> Anthony J. Sequeira, CCIE #15626
> http://www.INE.com <http://www.ine.com/>
>
> Test your Core Knowledge today!
> Q: What protocol supports load-balancing with first-hop redundancy?
> A: gateway load balancing protocol
> More Info:
>
>
http://www.cisco.com/en/US/docs/ios/12_2t/12_2t15/feature/guide/ft_glbp.html
>
>
> On Sep 25, 2009, at 10:47 AM, Syed Khalid Ali wrote:
>
> > dear group,
> >
> > I just started to prepare for R&S track. While going through the "ip
> > packet
> > debug command" these two terms just popped up.
> > What is the difference between these two?
> >
> > Thanks
> > Khalid
> >
> >
> >
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--
Narbik Kocharians
CCSI#30832, CCIE# 12410 (R&S, SP, Security)
www.MicronicsTraining.com
Sr. Technical Instructor
Blogs and organic groups at http://www.ccie.net