Re: A good link for MPLS

Seriously is this list for people preparing for CCIE exams or is it for
beginner issues? I dont want to be the groupstudy police but why answer
questions like this on here? This list shouldnt be for questions like this
and anyone wanting to get their CCIE without any prior work experience, or
hence knowledge of a technical subject should start somewhere else quite
frankly.

On Wed, Nov 11, 2009 at 7:35 AM, Rick Mur <rmur_at_ipexpert.com> wrote:

> A FEC is indeed as you say the combination of a couple values (Dst IP, BGP
> Next Hop, IP Prec). These FEC's are just terms for clarification. It's not a
> technology.
>
> A router generates and advertises labels for each IGP learned prefix it
> knows of. That way you have determined your Destination IP's (prefixes) and
> BGP next hops (loopbacks from routers). The IP precedence value is copied to
> the EXP field in the MPLS header, so there are all your deviations of FEC's.
>
> Again the FEC is a term to let you understand on how traffic is matched in
> t he router when send out to be label switched (most times on destination
> subnet or BGP next hop). Different FEC's could have the same label, this is
> because when only the IP Precedence is different, the EXP field is
> different, but the label is the same as this is based on Destination subnet
> or BGP next hop.
>
> THe label is definitely not the same throughout the network (cloud), these
> label values are generated per router and could be all the same or all
> different.
>
>
>
> --
> Regards,
>
> Rick Mur
> CCIE2 #21946 (R&S / Service Provider)
> Sr. Support Engineer IPexpert, Inc.
> URL: http://www.IPexpert.com
>
>
> On 10 nov 2009, at 18:19, Naufal Jamal wrote:
>
>
>> Hi Friends,
>>
>> Found the below link interesting for a MPLS beginner.check it out.
>>
>>
>> http://www.cisco.com/en/US/tech/tk436/tk428/tsd_technology_support_protocol_h
>> ome.html
>>
>> I do have a doubt regrding FEC.
>>
>> FEC tells the first ingress router how to forward a particular packet
>> based on
>> certain criteria eg.destination ip subnet,BGP next hop,IP precedence value
>> etc.all the packets who match the criteria are forwarded the same way
>> through
>> out the cloud.
>>
>> how these criterias are defined or recognised by the router ? are these
>> being
>> done by manipulating the EXP bits inside a label?
>>
>> if i am correct, then all packets in a fec have same label but all same
>> labels
>> are not neccesarily under the same FEC.
>>
>> Kindly clarify or provide any link which could clarify the concept of FEC
>> as I
>> am a beginner to MPLS..
>>
>> Thanks
>> Naufal
>>
>>
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>>
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Received on Wed Nov 11 2009 - 07:55:05 ART