you should just post your questions to the IPExpert blog ;)
On Mon, Oct 12, 2009 at 10:49 PM, Marcel Lammerse <m.lammerse_at_mac.com>wrote:
> Thanks Bryan.
>
> I think we've reached the same conclusion :) For me it was a bit unexpected
> behavior, but I guess it makes more sense now. Especially when I get to the
> AtoM chapter in my MPLS books :)
>
>
> On 12/10/2009, at 11:47 , Bryan Bartik wrote:
>
> Marcel,
>>
>> There are a few exceptions, but in order to forward labeled packets over
>> an
>> interface you need "mpls ip" on the interface. A couple of exceptions are
>> when you are using another protocol to advertise labels over the interface
>> such as BGP + send-label or RSVP (in MPLS TE). Unlike these scenarios,
>> targeted hellos do not remove the need for configuring "mpls ip" on an
>> interface.
>>
>> Remember, targeted hellos are not only used by session protection. For
>> example, they are also used in AToM where you need to advertise one label
>> (VC label) across multiple hops.
>>
>> On Sun, Oct 11, 2009 at 1:47 AM, Marcel Lammerse <m.lammerse_at_mac.com>
>> wrote:
>>
>>
>>> Hi Bryan,
>>>
>>> yeah.. still wondering what's going on here.
>>>
>>> Someone suggested to me that targeted ldp is used more for mpls
>>> applications such as atom, not so much for plain label switching between
>>> directly connected routers. But, t-ldp is also mentioned as a way of
>>> making
>>> ldp sessions more resilient in case the directly connected interface
>>> between
>>> two ldp peers breaks.
>>>
>>> The way I understand it, there are two ways of configuring a protected
>>> ldp
>>> session.
>>>
>>> 1. 'mpls ldp neighbor <ip> targeted ldp' in global config mode
>>>
>>> 2. 'mpls ip' under the interface + 'mpls ldp session protection' in
>>> global config mode
>>>
>>> So really with ldp session protection, you have both a directly connected
>>> ldp session and a 'targeted' ldp session active at the same time.
>>>
>>> When I try option 1 and remove the 'mpls ip' command from the interface,
>>> the labels disappear from the lfib, but the targeted ldp sesions is up.
>>> If
>>> leave the 'mpls ip' command on the interface, I do receive the labels.
>>>
>>> So my questions are :
>>>
>>> 1. Why are there different commands to configure a protected ldp
>>> session, that seem to do the same thing?
>>> 2. When should I configure a targeted ldp session and what is it
>>> used
>>> for?
>>> 3. Why am I not receiving labels across a targeted ldp session
>>> between
>>> directly connected neighbors?
>>>
>>> PE4#sh mpls ldp neighbor
>>> Peer LDP Ident: 1.1.1.1:0; Local LDP Ident 4.4.4.4:0
>>> TCP connection: 1.1.1.1.646 - 4.4.4.4.13537
>>> State: Oper; Msgs sent/rcvd: 15/15; Downstream
>>> Up time: 00:00:15
>>> LDP discovery sources:
>>> FastEthernet1/0, Src IP addr: 172.16.14.1
>>> Addresses bound to peer LDP Ident:
>>> 1.1.1.1 172.16.12.1 172.16.14.1
>>> Peer LDP Ident: 3.3.3.3:0; Local LDP Ident 4.4.4.4:0
>>> TCP connection: 3.3.3.3.646 - 4.4.4.4.14581
>>> State: Oper; Msgs sent/rcvd: 15/15; Downstream
>>> Up time: 00:00:13
>>> LDP discovery sources:
>>> FastEthernet3/0, Src IP addr: 172.16.34.3
>>> Addresses bound to peer LDP Ident:
>>> 3.3.3.3 172.16.13.3 172.16.23.3 172.16.34.3
>>>
>>> PE4#sh mpls forwarding-table 192.168.2.0
>>> Local Outgoing Prefix Bytes Label Outgoing Next Hop
>>> Label Label or VC or Tunnel Id Switched interface
>>> 23 25 192.168.2.0/24 0 Fa1/0
>>> 172.16.14.1
>>> 19 192.168.2.0/24 0 Fa3/0 172.16.34.3
>>> PE4#
>>>
>>>
>>> PE4#sh run int fastEthernet 1/0
>>> Building configuration...
>>>
>>> Current configuration : 105 bytes
>>> !
>>> interface FastEthernet1/0
>>> ip address 172.16.14.4 255.255.255.0
>>> duplex auto
>>> speed auto
>>> mpls ip
>>> end
>>>
>>> PE4#sh run int fastEthernet 3/0
>>> Building configuration...
>>>
>>> Current configuration : 105 bytes
>>> !
>>> interface FastEthernet3/0
>>> ip address 172.16.34.4 255.255.255.0
>>> duplex auto
>>> speed auto
>>> mpls ip
>>> end
>>>
>>> PE4#
>>>
>>> PE4#conf t
>>> Enter configuration commands, one per line. End with CNTL/Z.
>>> PE4(config)#int fastEthernet 3/0
>>> PE4(config-if)#no mpls ip
>>> PE4(config)#int fastEthernet 1/0
>>> PE4(config-if)#no mpls ip
>>> PE4(config-if)#exit
>>> PE4(config)#mpls ldp neighbor 1.1.1.1 targeted ldp
>>> PE4(config)#mpls ldp neighbor 3.3.3.3 targeted ldp
>>> PE4(config)#
>>>
>>> PE4#sh mpls ldp neighbor
>>> *Oct 11 17:37:53.215: %SYS-5-CONFIG_I: Configured from console by console
>>> Peer LDP Ident: 3.3.3.3:0; Local LDP Ident 4.4.4.4:0
>>> TCP connection: 3.3.3.3.646 - 4.4.4.4.28418
>>> State: Oper; Msgs sent/rcvd: 268/268; Downstream
>>> Up time: 03:41:25
>>> LDP discovery sources:
>>> Targeted Hello 4.4.4.4 -> 3.3.3.3, active, passive
>>> Addresses bound to peer LDP Ident:
>>> 3.3.3.3 172.16.13.3 172.16.23.3 172.16.34.3
>>> Peer LDP Ident: 1.1.1.1:0; Local LDP Ident 4.4.4.4:0
>>> TCP connection: 1.1.1.1.646 - 4.4.4.4.24502
>>> State: Oper; Msgs sent/rcvd: 35/36; Downstream
>>> Up time: 00:18:32
>>> LDP discovery sources:
>>> Targeted Hello 4.4.4.4 -> 1.1.1.1, active, passive
>>> Addresses bound to peer LDP Ident:
>>> 1.1.1.1 172.16.12.1 172.16.14.1
>>> PE4#
>>>
>>>
>>> PE4#sh mpls forwarding-table 192.168.2.0
>>> Local Outgoing Prefix Bytes Label Outgoing Next Hop
>>> Label Label or VC or Tunnel Id Switched interface
>>> 23 No Label 192.168.2.0/24 0 Fa1/0
>>> 172.16.14.1
>>> No Label 192.168.2.0/24 0 Fa3/0 172.16.34.3
>>> PE4#
>>>
>>> PE4#sh mpls forwarding-table
>>> Local Outgoing Prefix Bytes Label Outgoing Next Hop
>>> Label Label or VC or Tunnel Id Switched interface
>>> 16 No Label 3.3.3.3/32 41402 Fa3/0
>>> 172.16.34.3
>>> 17 No Label 2.2.2.2/32 0 Fa1/0
>>> 172.16.14.1
>>> No Label 2.2.2.2/32 0 Fa3/0 172.16.34.3
>>> 18 No Label 1.1.1.1/32 0 Fa1/0
>>> 172.16.14.1
>>> 19 No Label 172.16.24.0/24 0 Fa1/0
>>> 172.16.14.1
>>> No Label 172.16.24.0/24 0 Fa3/0 172.16.34.3
>>> 20 No Label 172.16.13.0/24 0 Fa3/0
>>> 172.16.34.3
>>> 21 No Label 172.16.12.0/24 0 Fa1/0
>>> 172.16.14.1
>>> 22 No Label 172.16.23.0/24 0 Fa3/0
>>> 172.16.34.3
>>> 23 No Label 192.168.2.0/24 0 Fa1/0
>>> 172.16.14.1
>>> No Label 192.168.2.0/24 0 Fa3/0 172.16.34.3
>>> 24 No Label 12.12.12.2/32 0 Fa1/0
>>> 172.16.14.1
>>> No Label 12.12.12.2/32 0 Fa3/0 172.16.34.3
>>> PE4#
>>>
>>>
>>> Attached a topology diagram. The link between PE1 and PE2 was shut during
>>> the lab :
>>>
>>> PE4#sh ip int brief
>>> Interface IP-Address OK? Method Status
>>> Protocol
>>> FastEthernet0/0 unassigned YES NVRAM administratively
>>> down
>>> down
>>> FastEthernet1/0 172.16.14.4 YES NVRAM up
>>> up
>>> FastEthernet1/1 unassigned YES NVRAM administratively
>>> down
>>> down
>>> FastEthernet2/0 172.16.24.4 YES NVRAM administratively
>>> down
>>> down
>>> FastEthernet2/1 unassigned YES NVRAM administratively
>>> down
>>> down
>>> FastEthernet3/0 172.16.34.4 YES NVRAM up
>>> up
>>> FastEthernet3/1 unassigned YES NVRAM administratively
>>> down
>>> down
>>> FastEthernet4/0 unassigned YES NVRAM up
>>> up
>>> FastEthernet4/1 unassigned YES NVRAM administratively
>>> down
>>> down
>>> SSLVPN-VIF0 unassigned NO unset up
>>> up
>>> Loopback0 4.4.4.4 YES NVRAM up
>>> up
>>> PE4#
>>>
>>>
>>>
>>>
>>>
>>> On 11/10/2009, at 10:18 , Bryan Bartik wrote:
>>>
>>> Marcel,
>>>
>>>>
>>>> Are you still having this issue? Can you post configs and topology?
>>>>
>>>> On Wed, Oct 7, 2009 at 6:13 PM, Marcel Lammerse <m.lammerse_at_mac.com>
>>>> wrote:
>>>>
>>>> Experts,
>>>>
>>>>>
>>>>> here I have a load-balanced path between directly connected ldp
>>>>> speakers
>>>>> :
>>>>>
>>>>> PE4#sh mpls forwarding-table 192.168.2.0
>>>>> Local Outgoing Prefix Bytes Label Outgoing Next
>>>>> Hop
>>>>> Label Label or VC or Tunnel Id Switched interface
>>>>> 22 25 192.168.2.0/24 0 Fa1/0
>>>>> 172.16.14.1
>>>>> 23 192.168.2.0/24 0 Fa3/0 172.16.34.3
>>>>> PE4#
>>>>>
>>>>> PE4#sh mpls ldp bindings 192.168.2.0 24 detail
>>>>> lib entry: 192.168.2.0/24, rev 22, chkpt: none
>>>>> local binding: label: 22 (owner LDP)
>>>>> Advertised to:
>>>>> 1.1.1.1:0 3.3.3.3:0
>>>>> remote binding: lsr: 1.1.1.1:0, label: 25
>>>>> remote binding: lsr: 3.3.3.3:0, label: 23
>>>>> route information: state: none, table: default,
>>>>> next-hop: 172.16.14.1, remote label: 25
>>>>> route information: state: none, table: default,
>>>>> next-hop: 172.16.34.3, remote label: 23
>>>>>
>>>>> If I change the ldp sessions to t-ldp, and keep everything else the
>>>>> same,
>>>>> the labels seem to disappear and traffic appears to go out untagged :
>>>>>
>>>>> PE4#sh mpls forwarding-table 192.168.2.0
>>>>> Local Outgoing Prefix Bytes Label Outgoing Next
>>>>> Hop
>>>>> Label Label or VC or Tunnel Id Switched interface
>>>>> 22 No Label 192.168.2.0/24 0 Fa1/0
>>>>> 172.16.14.1
>>>>> No Label 192.168.2.0/24 0 Fa3/0 172.16.34.3
>>>>> PE4#
>>>>>
>>>>> PE4#sh mpls ldp bindings 192.168.2.0 24 detail
>>>>> lib entry: 192.168.2.0/24, rev 22, chkpt: none
>>>>> local binding: label: 22 (owner LDP)
>>>>> Advertised to:
>>>>> 3.3.3.3:0 1.1.1.1:0
>>>>> remote binding: lsr: 3.3.3.3:0, label: 23
>>>>> remote binding: lsr: 1.1.1.1:0, label: 25
>>>>> route information: state: none, table: default,
>>>>> next-hop: 172.16.14.1, remote label: <----- no label
>>>>> route information: state: none, table: default,
>>>>> next-hop: 172.16.34.3, remote label: <----- no label
>>>>> PE4#
>>>>>
>>>>> I'm a bit confused by this. I would have expected the traffic to
>>>>> continue
>>>>> to be labeled and the labels to remain the same.
>>>>>
>>>>> Can anyone shed some light on why this happens?
>>>>>
>>>>> Thanks,
>>>>> Marcel
>>>>>
>>>>>
>>>>> Blogs and organic groups at http://www.ccie.net
>>>>>
>>>>> _______________________________________________________________________
>>>>> Subscription information may be found at:
>>>>> http://www.groupstudy.com/list/CCIELab.html
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>> --
>>>> Bryan Bartik
>>>> CCIE #23707 (R&S), CCNP
>>>> Sr. Support Engineer - IPexpert, Inc.
>>>> URL: http://www.IPexpert.com
>>>>
>>>>
>>>> Blogs and organic groups at http://www.ccie.net
>>>>
>>>> _______________________________________________________________________
>>>> Subscription information may be found at:
>>>> http://www.groupstudy.com/list/CCIELab.html
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>
>> --
>> Bryan Bartik
>> CCIE #23707 (R&S), CCNP
>> Sr. Support Engineer - IPexpert, Inc.
>> URL: http://www.IPexpert.com
>>
>>
>> Blogs and organic groups at http://www.ccie.net
>>
>> _______________________________________________________________________
>> Subscription information may be found at:
>> http://www.groupstudy.com/list/CCIELab.html
>>
>
>
> Blogs and organic groups at http://www.ccie.net
>
> _______________________________________________________________________
> Subscription information may be found at:
> http://www.groupstudy.com/list/CCIELab.html
Blogs and organic groups at http://www.ccie.net
Received on Tue Oct 13 2009 - 00:22:37 ART
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