Re: MPLS FEC and LIB

RF

Good explanation, the more deep I'm getting into r&s the more interested in TE I'm getting, the SP track for this reason in intriguing!

--
BR
Tony
Sent from my iPad
On 18 Jan 2013, at 03:15, Routing Freak <routingfreak_at_gmail.com> wrote:
> Hey
> 
> The destination Prefixes present in the LIB are the FECs classified on the
> ingress LER ( iLER) These FECs ie the destination prefixes can be derived
> from various parameters such as same NEXT HOP, same QOS, Bandwidth and same
> end to end path
> 
> So in LDP by default it creates LSP for all the prefixes in the IGP table
> and it just derives the FECs just from prefixes and not on other
> parameters, So in LDP u cannot have control over the parameters tat i
> mentioned above.
> 
> So when u create RSVP LSPs , u can really control what prefixes should go
> via which LSP. U can specify parameters such as BW, Path, and QOS treatment
> for a particular LSP and make all ur Traffic go via tat particular LSP
> matching all the conditions end to end
> 
> So generally when designing ur LSPs u need to know the end to end and see
> which LSP suits to send Data , VOice or Video traffic, and make sure that u
> dont end up all ur traffic going via a single LSP and choke the LSP BW.
> 
> Hope this helps
> 
> 
> On Wed, Jan 16, 2013 at 4:27 PM, vishal bhugra <vishal.bhugra_at_gmail.com>wrote:
> 
>> Hello experts
>> 
>> While reading MPLS basics, I have a query :-
>> 
>> FEC says providing the same behavior to same kind of packet that is
>> allocating the same next hop, same egress interface.
>> 
>> AS book says - "In MPLS, the assignment of a particular packet to a
>> particular FEC is done just once, as the packet enters the network. The FEC
>> to which the packet is assigned is encoded as a short fixed length value
>> known as a "label". "
>> 
>> 
>> That mean classifying the packets and assigning the labels as per the
>> classification.
>> 
>> 
>> and for LIB book says - " The LIB functions in the control plane and is
>> used by the label distribution protocol where IP destination prefixes in
>> the routing table are mapped to next-hop labels that are received from
>> downstream neighbors, as well as local labels generated by the label
>> distribution protocol."
>> 
>> 
>> 
>> I am confused - FEC says classifying the packet and assigning the label and
>> LIB says destination prefixes are mapped to labels.
>> 
>> 
>> *If Destination prefixes need to mapped to labels then why do we need to
>> classify the packets and why do we need FEC ?*
>> 
>> *
>> *
>> 
>> *I know that I am missing something because books area already reviewed by
>> experts.*
>> 
>> 
>> Thanks&regards
>> Vishal
>> +91 8587900305
>> 
>> Best way to predict the future ..... is to create it
>> 
>> 
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>> 
> 
> 
> -- 
> Regards
> Routing Freak CCIE#35889 (SPv3)
> 
> 
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