Re: vpn label understanding required

Hi,

sh mpls forwarding-table detail
Local Outgoing Prefix Bytes Label Outgoing Next Hop
21 No Label 150.1.7.7/32[V] 0 Fa0/0 10.1.37.7
<<<<<<<<<<<<<<
Local Outgoing Prefix Bytes Label Outgoing Next Hop
Label Label or VC or Tunnel Id Switched interface
        MAC/Encaps=0/0, MRU=1504, Label Stack{}
        VPN route: SW1-BB1

Is that VPN LABEL 21 will be there on the packet once it reaches this router
and it sees

VPN route: SW1-BB1 and Fa0/0 10.1.37.7 .... Based on this it forwards
the packet.
BUT NOW A NEW Q ARISES - I m sorry for that , what makes router keep in
record it has already given 21 label to a prefix, don't use it.

Regards
J.Daniels

On Thu, Jun 25, 2009 at 10:21 PM, Bryan Bartik <bbartik_at_ipexpert.com> wrote:

> Jack,
>
> "Show mpls forwarding-table detail" shows the label, prefix and the VRF.
>
>
> On Thu, Jun 25, 2009 at 10:43 AM, jack daniels <jckdaniels12_at_gmail.com>wrote:
>
>> Hi,
>>
>> If that is the case , so router must be keeping a database of label to VRF
>> , how can we see that ....( command)
>>
>> Regards
>> J.Daniels
>>
>> On Thu, Jun 25, 2009 at 10:01 PM, Bryan Bartik <bbartik_at_ipexpert.com>wrote:
>>
>>> Yes, that is right.
>>>
>>>
>>> On Thu, Jun 25, 2009 at 10:25 AM, jack daniels <jckdaniels12_at_gmail.com>wrote:
>>>
>>>> Hi,
>>>>
>>>> so it means LFIB lookup is done , which sees [V] VPN label and forwards
>>>> to the appropriarate VRF. so if a router has 200 VRF and each VRF is
>>>> orignating 2 routes so it means 400 UNIQUE LABELS will identify which VRF to
>>>> forward the traffic.
>>>>
>>>> Regards
>>>> J.daniels
>>>>
>>>> On Thu, Jun 25, 2009 at 9:28 PM, Bryan Bartik <bbartik_at_ipexpert.com>wrote:
>>>>
>>>>> Jack,
>>>>>
>>>>> I see what you mean, good question. If you so "show mpls
>>>>> fowarding-table detail" you will see the VPN. I think this would be a
>>>>> function of looking up the label in the LFIB when the prefix is listed with
>>>>> [V].
>>>>>
>>>>>
>>>>> On Thu, Jun 25, 2009 at 9:47 AM, jack daniels <jckdaniels12_at_gmail.com>wrote:
>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> I got that but my querrie still stands - let me put it other way
>>>>>>
>>>>>> ( 1.1.1.0/24)CE1--VRF <http://1.1.1.0/24%29CE1--VRF>K--PE1----P1----PE2----CE2
>>>>>> packet from CE2 reaches PE1 with VPN label , now what will hapen ....
>>>>>> will router say it has stamp of label Y which is for VRF X ?
>>>>>>
>>>>>> Regards
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Thu, Jun 25, 2009 at 8:45 PM, Bryan Bartik <bbartik_at_ipexpert.com>wrote:
>>>>>>
>>>>>>> Jack,
>>>>>>>
>>>>>>> Yes, each prefix learned in the VRF would have a different label. I
>>>>>>> would not associate labels with VRFs, but rather with the prefix learned in
>>>>>>> the VRF. The bottom label corresponds to the egress PE, the inner label
>>>>>>> corresponds to the prefix in the VRF.
>>>>>>>
>>>>>>> On Thu, Jun 25, 2009 at 7:06 AM, jack daniels <
>>>>>>> jckdaniels12_at_gmail.com> wrote:
>>>>>>>
>>>>>>>> Hi group,
>>>>>>>>
>>>>>>>> I have routers
>>>>>>>>
>>>>>>>> ( 1.1.1.0/24)CE1--VRF <http://1.1.1.0/24%29CE1--VRF>K--PE1----P1----PE2----CE2
>>>>>>>>
>>>>>>>> now when pkt is forwarded from CE2 for 1.1.1.0/24 it has VPN label
>>>>>>>> Y. On
>>>>>>>> reaching PE1 it sees label Y = VRF K....
>>>>>>>> so it means that if a router has 2000 vrf on it , so it will asign
>>>>>>>> unique
>>>>>>>> labels per vrf for each prefix to advertise in vrf ?
>>>>>>>>
>>>>>>>> Regards
>>>>>>>> J.Daniels
>>>>>>>>
>>>>>>>>
>>>>>>>> Blogs and organic groups at http://www.ccie.net
>>>>>>>>
>>>>>>>>
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>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> Bryan Bartik
>>>>>>> CCIE #23707 (R&S), CCNP
>>>>>>> Sr. Support Engineer - IPexpert, Inc.
>>>>>>> URL: http://www.IPexpert.com <http://www.ipexpert.com/>
>>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Bryan Bartik
>>>>> CCIE #23707 (R&S), CCNP
>>>>> Sr. Support Engineer - IPexpert, Inc.
>>>>> URL: http://www.IPexpert.com <http://www.ipexpert.com/>
>>>>>
>>>>
>>>>
>>>
>>>
>>> --
>>> Bryan Bartik
>>> CCIE #23707 (R&S), CCNP
>>> Sr. Support Engineer - IPexpert, Inc.
>>> URL: http://www.IPexpert.com <http://www.ipexpert.com/>
>>>
>>
>>
>
>
> --
> Bryan Bartik
> CCIE #23707 (R&S), CCNP
> Sr. Support Engineer - IPexpert, Inc.
> URL: http://www.IPexpert.com <http://www.ipexpert.com/>

Blogs and organic groups at http://www.ccie.net
Received on Thu Jun 25 2009 - 22:42:42 ART