MPLS LDP LSP

Created: Sep 10, 2019 19:26:55Latest reply: Sep 11, 2019 07:02:04 223 10 0 0
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MPLS

Hi ,,, when i run the command "Display mpls ldp lsp" show multiple labels for the same route as above picture...like for 1.1.1.1 we have out label Null & 1024 what it means.?..


and anyone explains me that what actually meaning of in/out labels? & liberal label means? upstream peer,next-hop? 127.0.0.1?


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Featured Answers
chenhui
Admin Created Sep 11, 2019 02:13:15 Helpful(0) Helpful(0)

Posted by LuizPuppin at 2019-09-11 00:49 The in label is what you announce to neighboor indicating what label you spect to receive for a rout ...
@LSA hello,
(like for 1.1.1.1 we have out label Null & 1024 what it means) the different out labels are distributed by the different routers, for example, In/Outlabel 3/NULL means it is distributed by the router itself, In/Outlabel Liberal/1024, this is a backup LSP, it's used in the LDP FRR. You are kindly advised to review the distribution rules of the LDP.
in/out label is a pair of label which guide the router to deal with the labeled packets. Liberal label indicates the corresponding entry is a backup LSP, it's used in LDP FRR, when the main LSP turns down, the IGP protocol will switch to the backup path, then the LSP path switchover, but there might be labeled data discarded, so the LDP FRR is introduced, it generates a backup path so that it could switch to the backup LSP path rapidly.
UpstreamPeer means the upsteam peer of the LSP, just as the words itsself indicates.
Next-hop is opposite to the upstreampeer, it indicates the downstream peer.
127.0.0.1 indicates the router itself, with the next-hop 127.0.0.1, it means the packets should be hand over to the router itself.
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All Answers
LuizPuppin
LuizPuppin MVE Created Sep 11, 2019 00:49:28 Helpful(0) Helpful(0)

The in label is what you announce to neighboor indicating what label you spect to receive for a route. The OUT is what you receive from your neighboor to a specific route.
NULL indicates that you will not use label on this out packet. This is to a packet directed by out of MPLS network.
UPStream Peer is the nighboor who will receive the mpls packet.
NextHop 127.0.0.1 indicates that the packet is direct by this router
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jason_hu
jason_hu Admin Created Sep 11, 2019 01:07:47 Helpful(0) Helpful(0)

Hello@LSA
A label is a short, fixed-length (4 bytes) identifier that is only locally significant. A label identifies an FEC to which a packet belongs. In some cases, such as load balancing, a FEC can be mapped to multiple incoming labels. Each label, however, represents only one FEC on a device
You can refer to this:

Item

Description

DestAddress/Mask

Destination address and mask of an LSP.

In/OutLabel

Values of the incoming and outgoing labels.

An asterisk (*) before In/OutLabel indicates that the LSP is in the Stale state and needs to be restored.

UpstreamPeer

Upstream peer of an LSP.

An asterisk (*) before UpstreamPeer indicates that the session is in the GR state.

NextHop

Next hop IP address.

An asterisk (*) before NextHop indicates that the LSP is a FRR LSP.

DS is short for DownStream. The address next to DS/ is the LSR ID of a downstream peer.

OutInterface

Name of an outbound interface.



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chenhui
chenhui Admin Created Sep 11, 2019 02:13:15 Helpful(0) Helpful(0)

Posted by LuizPuppin at 2019-09-11 00:49 The in label is what you announce to neighboor indicating what label you spect to receive for a rout ...
@LSA hello,
(like for 1.1.1.1 we have out label Null & 1024 what it means) the different out labels are distributed by the different routers, for example, In/Outlabel 3/NULL means it is distributed by the router itself, In/Outlabel Liberal/1024, this is a backup LSP, it's used in the LDP FRR. You are kindly advised to review the distribution rules of the LDP.
in/out label is a pair of label which guide the router to deal with the labeled packets. Liberal label indicates the corresponding entry is a backup LSP, it's used in LDP FRR, when the main LSP turns down, the IGP protocol will switch to the backup path, then the LSP path switchover, but there might be labeled data discarded, so the LDP FRR is introduced, it generates a backup path so that it could switch to the backup LSP path rapidly.
UpstreamPeer means the upsteam peer of the LSP, just as the words itsself indicates.
Next-hop is opposite to the upstreampeer, it indicates the downstream peer.
127.0.0.1 indicates the router itself, with the next-hop 127.0.0.1, it means the packets should be hand over to the router itself.
  • x
  • convention:

LSA
LSA Created Sep 11, 2019 05:15:31 Helpful(0) Helpful(0)

Posted by chenhui at 2019-09-11 02:13 @LSA hello,(like for 1.1.1.1 we have out label Null & 1024 what it means) the different out labels ...
the different out labels are distributed by the different routers,) but label are distributed only peer not ..indireclty router are advetised label to indirectly router.....as we have only two types of label Local & remote like in/out in huawei..mens any route in router have only two label local & remote...but why here multiple...?
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LSA
LSA Created Sep 11, 2019 05:18:34 Helpful(0) Helpful(0)

Posted by jason_hu at 2019-09-11 01:07 Hello@LSAA label is a short, fixed-length (4 bytes) identifier that is only locally significant. A l ...
thanks for reply....A label identifies an FEC to which a packet belongs) can you clarify this sentence in simple words, not understand what it means??& what is acutallly FEC you define...??
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LSA
LSA Created Sep 11, 2019 05:25:07 Helpful(0) Helpful(0)

Posted by chenhui at 2019-09-11 02:13 @LSA hello,(like for 1.1.1.1 we have out label Null & 1024 what it means) the different out labels ...
But some label we have no upstream peer ...like 2.2.2.2 NULL/3 ----..what it means.??
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LSA
LSA Created Sep 11, 2019 05:27:44 Helpful(0) Helpful(0)

Posted by chenhui at 2019-09-11 02:13 @LSA hello,(like for 1.1.1.1 we have out label Null & 1024 what it means) the different out labels ...
here only show label for loopback ip not for local route b/w router...how we check label for all routes which are in routing table..??
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chenhui
chenhui Admin Created Sep 11, 2019 06:17:39 Helpful(0) Helpful(0)

Posted by LSA at 2019-09-11 05:15 the different out labels are distributed by the different routers,) but label are distributed only ...
I'm not sure what you mean by multiple in #5.
For the introduction of FEC, you can refer to the post I ever published, here is the link https://forum.huawei.com/enterprise/en/what-is-fec-in-mpls/thread/531223-863
2.2.2.2 NULL/3 indicates the LSP which generates from the router itself to the 2.2.2.2, of course there isn't an upstream peer.
By default, the router only distribute label for the host routes, if you want to distribute labels for other routes, you should add command lsp-trigger all.
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LSA
LSA Created Sep 11, 2019 06:47:36 Helpful(0) Helpful(0)

Posted by chenhui at 2019-09-11 06:17 I'm not sure what you mean by multiple in #5.For the introduction of FEC, you can refer to the pos ...
Thanks chenhui, I think bydefault LDP are assigning label for all rotues in routing table..& what you measn from host routes ?
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