Re: RSVP and LDP

Thanks man.it is good info

2012/2/2, CCIE KID <eliteccie_at_gmail.com>:
> The order of labels will be VPN label exchanged and the RSVP TE label man.
>
> PE1-------------P3------------------P4----------------P5--------------P6-----------------P7------------------------PE4
>
> |
> |
>
> |
> |
>
> |
> |
>
> PE2
> PE3
>
>
>
> So in this scenario PE1 ,PE2 to P connections run LDP. From P3 to P7
> there will be RSVP....From P3 to P7 there will be Targeted LDP established
> to exchange the label for corresponding PE . lets see the thought process
>
> Here P7 will form a targeted LDP with P3 and exchange labels for PE3 and
> PE1 respectively.
>
> Now P3 will update PE1 about PE3 via its local label.. and now LSP from PE
> 1 to PE3 will be the LDP label given by P3 and when it reaches P3, it
> uses the Targeted LDP label recevied from P7 and to reach P7 it uses RSVP
> label given by P7 when forming the TE tunnel.
>
> So P4, P5 and P6 have no idea about PE1 and PE3
>
> So Over RSVP there will be LDP and this way it works
>
> LDP over RSVP solves the problem of creating many LSPs . For example u have
> to create as many LSPs as number of PE's
> Lets assume ur POP has 5 PE routers connected to 2 P routers connected to
> each other in each site. Think there are 7 sites. So totally 35 PE routers
> and 14 P .. So for each PE to PE there will be LSPs created. so in this
> case 35 PE's so 35*34 LSPs has to be formed
>
> When u use LDP over RSVP, there will be only 14*13 LSPs created
>
> So it basically avoids number of LSPs
>
>
>
>
> 2012/2/2 Mustafa Yadav <mustafa.yadav_at_gmail.com>
>
>> This makes sense and. I have found ldp over rsvp is used and there are
>> 3 labels are used.vpn rsvp and ldp label
>>
>> 2012/2/2, CCIE KID <eliteccie_at_gmail.com>:
>> > Good explanation Hemanth
>> >
>> > TE is used to engineer the traffic as u want to go through with the
>> > prioritized traffic in need of B.W. There many be different LSP's and
>> you
>> > assign different treatment for each LSP.
>> > And also u can do LDP over RSVP where u can do RSVP TE Tunnel from one P
>> to
>> > another P . So from PE to P u run LDP and have a targeted LDP over ur
>> RSVP
>> > So its basically hierarchical LDP over ur RSVP .
>> >
>> > On Thu, Feb 2, 2012 at 6:13 PM, HEMANTH RAJ <hemanthrj_at_gmail.com> wrote:
>> >
>> >> Hi Mustafa
>> >>
>> >> LDP has been designed for distributing labels exclusively, But RSVP has
>> >> been a Host based protocol to inform the transit routers that to
>> >> reserve
>> >> the bandwidth what the application needs.
>> >> So here in MPLS TE , RSVP is used as a signalling protocol to establish
>> a
>> >> BANDWIDTH DEFINED LSP from head end router to your Tail End Router
>> >>
>> >> In ur normal LDP , For each prefix u build a particular LSP . These
>> >> prefixes are distributed by ur CORE IGP. SO basically ur LDP is relying
>> on
>> >> ur IGP info for setting up a LSP for that prefix
>> >>
>> >> But in MPLS TE, RSVP will build a LSP with the Tail End Router with
>> >> some
>> >> constraints. So basically it is a Tunnel where ur Head End Router is
>> >> trying
>> >> to form with the Tail End and to switch packets on the Tunnel. It is a
>> >> unidirectional Tunnel.
>> >>
>> >> TE also uses ur CORE IGP to check whether the requirements to form a
>> >> tunnel are met. For example , If the TE Tunnel requires 500Kb of
>> bandwidth
>> >> ie ur Head End's routers requirement is 500Kbs of B.W end to end (
>> Assume
>> >> that there are some users sitting behind Head End Router which requires
>> a
>> >> 500kb feed from the server which is present behind ur Tail End Router )
>> So
>> >> now ur Head End has to know the end to end B.W capacity of each transit
>> >> router . This information is fed by our CORE IGP which can be ISIS or
>> OSPF
>> >> . ( These r the two protocol in use currently which has the capability
>> to
>> >> carry MPLS TE extended attributes . OSPF uses Opaque LSA and ISIS uses
>> >> extended TLVS for it )
>> >>
>> >> So TE Tunnel will be up only when it is met with these requirements and
>> >> after that it signals the RSVP Path and Tail End will send Reserve
>> >> Messages
>> >> to assign Labels ..
>> >> This is also same as ur LDP where ur Downstream router starts assigning
>> >> labels to the prefixes.
>> >>
>> >> So basically LDP is a prefix driven label assignment protocol but RSVP
>> is
>> >> all about how ur Head End wants the Constraint driven LSP with ur Tail
>> >> End
>> >> router and ( so u must know ur network and u know there is greedy hosts
>> >> which wants a feed and u configure the TE Tunnel accordingly )
>> >>
>> >> Without LDP also, RSVP will work .For RSVP u just need ur CORE IGP to
>> >> be
>> >> converged and has the capabilities to carry TE extended information (
>> >> So
>> >> no
>> >> RIP and EIGRP as of now ) RSVP Head End just sends Path message to ur
>> >> Tail
>> >> End router to signal each and every transit router that this is the
>> >> requirement
>> >>
>> >> Do not confuse between LDP and RSVP. LDP is always Prefix Driven From
>> IGP
>> >> .. RSVP is basically manually configured Constraint Driven LSP (
>> >> knowing
>> >> ur
>> >> network end to end )
>> >>
>> >> Hope this helps :)
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >> On Thu, Feb 2, 2012 at 5:43 PM, GAURAV MADAN <gauravmadan1177_at_gmail.com
>> >> >wrote:
>> >>
>> >> > I think things are being mixed up here .
>> >> >
>> >> > When RSVP is used with TE .. RSVP will do the label distribution .
>> >> > Hence role of LDP as a protocol for label distibution is eliminated
>> >> > as
>> >> you
>> >> > are doing same thing using RSVP .
>> >> >
>> >> > And also ; i believe that in MPLS L3 VPN scenario as well ; running
>> only
>> >> > RSVP and no LDP anywhere in core can achieve your goal .
>> >> >
>> >> > Regards
>> >> > Gaurav Madan
>> >> > CCIE
>> >> >
>> >> > On Thu, Feb 2, 2012 at 5:14 PM, Mustafa Yadav <
>> mustafa.yadav_at_gmail.com
>> >> > >wrote:
>> >> >
>> >> > > so when ldp is going down all te tunnles are going to be down?
>> >> > >
>> >> > > but in one of my case ldp goes down but te tunnels did not.
>> >> > >
>> >> > > Also I seee ldp neigbor is up for 4 hours but mpls te tunnel up for
>> 8
>> >> > > hours.and 4 hours ago ldp went down.
>> >> > >
>> >> > > On Thu, Feb 2, 2012 at 1:18 PM, sundeep sadhwani <
>> >> > > sundeep.sadhwani_at_gmail.com
>> >> > > > wrote:
>> >> > >
>> >> > > > Hi Mustafa,
>> >> > > >
>> >> > > > RSVP is used for reservation of bandwidth in TE environment( i am
>> >> > giving
>> >> > > u
>> >> > > > a very high level view). However plain MPLS-TE is not used in
>> >> > production
>> >> > > > scenario as SPs have MPLS-VPN as well. for that purpose we
>> >> > > > require
>> >> LDP
>> >> > as
>> >> > > > well to distribute IGP labels that will be required for PE to PE
>> >> > > > communication in case of MPLS-VPN.
>> >> > > >
>> >> > > > Regards
>> >> > > > Sundeep
>> >> > > >
>> >> > > > On Thu, Feb 2, 2012 at 4:41 PM, Mustafa Yadav <
>> >> mustafa.yadav_at_gmail.com
>> >> > > >wrote:
>> >> > > >
>> >> > > >> HD0,
>> >> > > >>
>> >> > > >>
>> >> > > >> In a cisco network I have seen mpls traffic engineneering
>> >> > > >> tunnels
>> >> are
>> >> > > >> being
>> >> > > >> used .So as far as I know rsvp must be configured .But I alos
>> >> > > >> see
>> >> that
>> >> > > ldp
>> >> > > >> is configured in all boxes.why is that?Is not rsvp enough for
>> >> > > distrbuting
>> >> > > >> labels?
>> >> > > >>
>> >> > > >>
>> >> > > >> Blogs and organic groups at http://www.ccie.net
>> >> > > >>
>> >> > > >>
>> >> >
>> _______________________________________________________________________
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>> _______________________________________________________________________
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>> _______________________________________________________________________
>> >> > Subscription information may be found at:
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>> >> >
>> >> >
>> >> >
>> >> >
>> >> >
>> >> >
>> >> >
>> >> >
>> >>
>> >>
>> >> --
>> >> Problems arise because we talk,problems are not solved because we don't
>> >> talk So good or bad talk to your affectionate one's freely.
>> >>
>> >> Yours Friendly,
>> >> H P HEMANTH RAJ
>> >> CCIE#28593 (R&S)
>> >> Cisco Systems
>> >>
>> >>
>> >> Blogs and organic groups at http://www.ccie.net
>> >>
>> >> _______________________________________________________________________
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>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >>
>> >
>> >
>> > --
>> > With Warmest Regards,
>> >
>> > CCIE KID
>> > CCIE#29992 (Security)
>> >
>>
>> --
>> Mobil cihaz}mdan gvnderildi
>>
>
>
>
> --
> With Warmest Regards,
>
> CCIE KID
> CCIE#29992 (Security)
>

-- 
Mobil cihaz}mdan gvnderildi
Blogs and organic groups at http://www.ccie.net