From: Jian Gu (guxiaojian@gmail.com)
Date: Wed Nov 26 2008 - 06:51:42 ARST
Simple, just do "show mpls forwarding <peer IP address>" if LSP is signaled
by LDP, you will see only outgoing label, if LSP to destination signalled by
RSVP, you will see tunnel information (show ip cef should tell you also).
You have no control over targetted LDP, it is implicitly used for L2VPN VC
FEC exchange, which has zero correlation for link LDP which is used for LSP
siginalling, i.e. prefix-FEC exchange. So removing LDP from interface will
have no impact as far as L2VPN signalling is concerned.
Benefit or running both LDP and RSVP? one benefit I can think of is if one
fails, application will be able pick up the other.
On Wed, Nov 26, 2008 at 12:34 AM, DENNIS UBOM <cciedreamz@gmail.com> wrote:
> Guys,
>
> if you running a network with both LDP/RSVP TE with services like
> MPLS VPN, MVPN, MPLS QOS etc.
> let say a network with RSVP TE PE-PE and LDP is enabled all the way down
> also from PE-PE.
> how can you tell which signalling is being used? RSVP OR LDP? I have a
> network running both and even targeted LDP on TE, been thinking about
> removing LDP.
> Also what should i be aware of before removing LDP session from production?
> Are there any benefit running Both LDP and RSVP?
>
> Thanks
>
> Dennis
>
>
>
> On Wed, Nov 26, 2008 at 2:20 AM, Jian Gu <guxiaojian@gmail.com> wrote:
>
>> Roman,
>>
>> The command "mpls traffic-eng multicast intact" was introduced* *to
>> enable
>> interoperability between* *Protocol-Independent Multicast (PIM) and
>> Multiprotocol Label Switching (MPLS) traffic engineering, it has nothing
>> to
>> do with MDT RPF check, it is introduced before mVPN is available.
>>
>> There are 3 RPF check happens in mVPN, 1) C-packets received from a PE
>> router customer interface in mVRF; 2) P-ackets received from a PE router
>> or
>> P router interface in the global routing table; and 3)C-Packets received
>> from MTI (multicast tunnel interface) in mVRF
>>
>> RPF check 1) is straightforwad.
>>
>> For RPF check 2), if MPLS TE tunnel is next hop between PEs, yes, you
>> will
>> need this command to make RPF check pass, but note that it is not a
>> necessity to have MPLS TE tunnel as IGP next hop between PEs, in fact, the
>> whole mVPN does not depend on MPLS at all (only PIM SM register/register
>> stop messages will ride on existing MPLS transport)
>>
>> For 3) IOS has internally changed the RPF check requirements such that if
>> MBGP has learned a prefix that contains C-source address, the RPF inteface
>> is set to MTI that is associated with that mVRF and RPF neighbor is also
>> modified to be the remote PE router,
>>
>> So you see, MDT has nothing to do with "mpls traffic-eng multicast
>> intact".
>>
>> Jian
>>
>> P.S. I highly doubt that OP is doing MDT though.
>>
>> On Tue, Nov 25, 2008 at 7:41 PM, Roman Rodichev <roman@iementor.com>
>> wrote:
>>
>> > When a multicast IP packet is received, IOS will perform RPF check on
>> the
>> > source of the multicast packet to make sure it arrived on the correct
>> > interface. MDT tunnels are sourced from loopback interfaces, same
>> loopbacks
>> > that are reachable via the TE tunnels. MDT tunnel packets destination is
>> > multicast. So when a PE receives an MDT packet on a physical interface,
>> it
>> > does an RPF check and says "Oh, this source is supposed to arrive on
>> this
>> > TE
>> > tunnel interface" and multicast breaks. That command fixes the problem
>> >
>> >
>> > Roman Rodichev
>> > 5xCCIE #7927 (R&S, Security, Voice, Storage, Service Provider)
>> > Instructor, Content Developer
>> > ieMentor Corporation http://www.iementor.com
>> > Y!M: roman7927
>> >
>> >
>> > -----Original Message-----
>> > From: Vin Mendoza (vinm) [mailto:vinm@cisco.com]
>> > Sent: Tuesday, November 25, 2008 9:37 PM
>> > To: Roman Rodichev; mreiks
>> > Cc: Cisco certification; Cisco certification
>> > Subject: RE: MPLS TE + RSVP+LDP
>> >
>> > What does multicast-intact do?
>> >
>> > Vin
>> >
>> > -----Original Message-----
>> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
>> > Roman Rodichev
>> > Sent: Tuesday, November 25, 2008 10:20 PM
>> > To: 'mreiks'
>> > Cc: 'Cisco certification'; 'Cisco certification'
>> > Subject: RE: MPLS TE + RSVP+LDP
>> >
>> > You are doing MDT?
>> >
>> >
>> >
>> > under router ospf or router isis in the core put:
>> >
>> >
>> >
>> > mpls traffic-eng multicast-intact
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> > Roman Rodichev
>> >
>> > 5xCCIE #7927 (R&S, Security, Voice, Storage, Service Provider)
>> >
>> > Instructor, Content Developer
>> >
>> > ieMentor Corporation http://www.iementor.com
>> >
>> > Y!M: roman7927
>> >
>> >
>> >
>> > From: mreiks [mailto:marakalas.molefe@gmail.com]
>> > Sent: Tuesday, November 25, 2008 9:15 PM
>> > To: Roman Rodichev
>> > Cc: Cisco certification; Cisco certification
>> > Subject: Re: MPLS TE + RSVP+LDP
>> >
>> >
>> >
>> > Hmm, my excitement was short-lived there. Now my multicast tunnel
>> > between the two PE routers is broken after disabling "mpls ip" on the
>> > interfaces.
>> > Any idea?
>> >
>> > On Wed, Nov 26, 2008 at 5:12 AM, mreiks <marakalas.molefe@gmail.com>
>> > wrote:
>> >
>> > Wow, tx a lot Roman, it's working now without "mpls ip" on the SP
>> > interfaces. I only had the TE tunnel configured only on the one PE. Much
>> > appreciated.
>> >
>> >
>> >
>> > On Wed, Nov 26, 2008 at 4:38 AM, Roman Rodichev <roman@iementor.com>
>> > wrote:
>> >
>> > Hello,
>> >
>> > You don't need LDP in order to run MPLS VPN over TE tunnels. When you
>> > say you "disable LDP on the interfaces", I assume you are disabling
>> > "mpls ip" on the physical interfaces. In a simple CE1 - PE1 - P - PE2 -
>> > CE2 network, make sure you have a TE tunnel from PE1 to PE2 and from PE2
>> > to PE1. Make sure you are using "tunnel mpls traff autoroute announce"
>> > so that PE1 and PE2 loopbacks are reachable via TE tunnels instead of
>> > the IGP path. You can remove LDP between PE1, P and PE2 router, and your
>> > MPLS L3VPN will work.
>> >
>> > By the way, you don't need "mpls ip" on the TE tunnel interfaces if
>> > their headends and tailends are on PE routers (not on P routers).
>> >
>> > If you have a specific scenario, please present.
>> >
>> > Roman Rodichev
>> > 5xCCIE #7927 (R&S, Security, Voice, Storage, Service Provider)
>> > Instructor, Content Developer ieMentor Corporation
>> > http://www.iementor.com
>> > Y!M: roman7927
>> >
>> >
>> > -----Original Message-----
>> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
>> > mreiks
>> > Sent: Tuesday, November 25, 2008 2:37 PM
>> > To: Cisco certification; Cisco certification
>> > Subject: MPLS TE + RSVP+LDP
>> >
>> > Hi
>> >
>> > I am finding it diffucult to understand whether RSVP TE can be run
>> > instead of LDP/TDP. I am able to establish the tunnel with TE but when I
>> > disable LDP on the interfaces, my VPN sites cannot ping each other,
>> > until such time I enable LDP. Is this normal? With MPLS VPNs do we
>> > always have to run either LDP/TDP and have RSVP also if we want TE?
>> >
>> > Tx.
>> >
>> >
>> >
>> > Blogs and organic groups at http://www.ccie.net
>> >
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>>
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