Re: MPLS FEC and LIB

Hello

Thanks a lot, now I got the idea.

Sent from my iPhone

On Jan 18, 2013, at 8:45 AM, 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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Received on Sat Jan 19 2013 - 08:42:02 ART