Solved: MPLS wrong information Label

feroz syed · ‎06-04-2014

Hi

This is my first MPLS lab, I just start learning mpls basic from yesterday, All routers have fully ip reachability and ospf is activated on all routers, now my doubt is if Router 1 want to reach Router 5 loopback interface it should go via R4-->R5. but it has two entry for the route 192.168.5.0. please kindly provide me the information why it has wrong entry about 5.0 route.

R5 label range 500-599 <> R4 label range 400-499 <> R1 label range 100 199 <> R6 label range 600 699

R1#sh mpls ldp bindings 192.168.0.5 32
tib entry: 192.168.0.5/32, rev 18
local binding: tag: 105
remote binding: tsr: 192.168.0.4:0, tag: 401
remote binding: tsr: 192.168.0.6:0, tag: 605 ---->>This the wrong information R1 have in ldp database.

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R5#sh mpls ldp bind
tib entry: 172.16.25.0/24, rev 4
local binding: tag: imp-null
remote binding: tsr: 192.168.0.4:0, tag: 400
tib entry: 172.16.69.0/24, rev 14
local binding: tag: 503
remote binding: tsr: 192.168.0.4:0, tag: 403
tib entry: 192.168.0.1/32, rev 16
local binding: tag: 504
remote binding: tsr: 192.168.0.4:0, tag: 404
tib entry: 192.168.0.4/32, rev 8
local binding: tag: 500
remote binding: tsr: 192.168.0.4:0, tag: imp-null
tib entry: 192.168.0.5/32, rev 6
local binding: tag: imp-null
remote binding: tsr: 192.168.0.4:0, tag: 401
tib entry: 192.168.0.6/32, rev 18
local binding: tag: 505
remote binding: tsr: 192.168.0.4:0, tag: 405
tib entry: 192.168.14.0/24, rev 10
local binding: tag: 501
remote binding: tsr: 192.168.0.4:0, tag: imp-null
tib entry: 192.168.16.0/24, rev 12
local binding: tag: 502
remote binding: tsr: 192.168.0.4:0, tag: 402
tib entry: 192.168.45.0/24, rev 2
local binding: tag: imp-null
remote binding: tsr: 192.168.0.4:0, tag: imp-null
R5#

R1#sh ip cef 192.168.0.5 255.255.255.255
192.168.0.5/32, version 25, epoch 0, cached adjacency 192.168.14.4
0 packets, 0 bytes
tag information set
local tag: 105
fast tag rewrite with Fa0/0, 192.168.14.4, tags imposed: {401}
via 192.168.14.4, FastEthernet0/0, 0 dependencies
next hop 192.168.14.4, FastEthernet0/0
valid cached adjacency
tag rewrite with Fa0/0, 192.168.14.4, tags imposed: {401}
R1#

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R4#sh mpls ldp bind
tib entry: 172.16.25.0/24, rev 8
local binding: tag: 400
remote binding: tsr: 192.168.0.5:0, tag: imp-null
remote binding: tsr: 192.168.0.1:0, tag: 103
tib entry: 172.16.69.0/24, rev 14
local binding: tag: 403
remote binding: tsr: 192.168.0.1:0, tag: 100
remote binding: tsr: 192.168.0.5:0, tag: 503
tib entry: 192.168.0.1/32, rev 16
local binding: tag: 404
remote binding: tsr: 192.168.0.1:0, tag: imp-null
remote binding: tsr: 192.168.0.5:0, tag: 504
tib entry: 192.168.0.4/32, rev 6
local binding: tag: imp-null
remote binding: tsr: 192.168.0.5:0, tag: 500
remote binding: tsr: 192.168.0.1:0, tag: 104
tib entry: 192.168.0.5/32, rev 10
local binding: tag: 401
remote binding: tsr: 192.168.0.5:0, tag: imp-null
remote binding: tsr: 192.168.0.1:0, tag: 105
tib entry: 192.168.0.6/32, rev 18
local binding: tag: 405
remote binding: tsr: 192.168.0.1:0, tag: 101
remote binding: tsr: 192.168.0.5:0, tag: 505
tib entry: 192.168.14.0/24, rev 4
local binding: tag: imp-null
remote binding: tsr: 192.168.0.5:0, tag: 501
remote binding: tsr: 192.168.0.1:0, tag: imp-null
tib entry: 192.168.16.0/24, rev 12
local binding: tag: 402
remote binding: tsr: 192.168.0.1:0, tag: imp-null
remote binding: tsr: 192.168.0.5:0, tag: 502
tib entry: 192.168.45.0/24, rev 5
local binding: tag: imp-null
remote binding: tsr: 192.168.0.5:0, tag: imp-null
remote binding: tsr: 192.168.0.1:0, tag: 102

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R1#sh mpls ldp bi
tib entry: 172.16.25.0/24, rev 14
local binding: tag: 103
remote binding: tsr: 192.168.0.4:0, tag: 400
remote binding: tsr: 192.168.0.6:0, tag: 603
tib entry: 172.16.69.0/24, rev 8
local binding: tag: 100
remote binding: tsr: 192.168.0.6:0, tag: imp-null
remote binding: tsr: 192.168.0.4:0, tag: 403
tib entry: 192.168.0.1/32, rev 5
local binding: tag: imp-null
remote binding: tsr: 192.168.0.6:0, tag: 600
remote binding: tsr: 192.168.0.4:0, tag: 404
tib entry: 192.168.0.4/32, rev 16
local binding: tag: 104
remote binding: tsr: 192.168.0.4:0, tag: imp-null
remote binding: tsr: 192.168.0.6:0, tag: 604
tib entry: 192.168.0.5/32, rev 18
local binding: tag: 105
remote binding: tsr: 192.168.0.4:0, tag: 401
remote binding: tsr: 192.168.0.6:0, tag: 605
tib entry: 192.168.0.6/32, rev 10
local binding: tag: 101
remote binding: tsr: 192.168.0.6:0, tag: imp-null
remote binding: tsr: 192.168.0.4:0, tag: 405
tib entry: 192.168.14.0/24, rev 4
local binding: tag: imp-null
remote binding: tsr: 192.168.0.6:0, tag: 601
remote binding: tsr: 192.168.0.4:0, tag: imp-null
tib entry: 192.168.16.0/24, rev 6
local binding: tag: imp-null
remote binding: tsr: 192.168.0.6:0, tag: imp-null
remote binding: tsr: 192.168.0.4:0, tag: 402
tib entry: 192.168.45.0/24, rev 12
local binding: tag: 102
remote binding: tsr: 192.168.0.4:0, tag: imp-null
remote binding: tsr: 192.168.0.6:0, tag: 602
R1#

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R6#sh mpls ldp bind
tib entry: 172.16.25.0/24, rev 14
local binding: tag: 603
remote binding: tsr: 192.168.0.1:0, tag: 103
tib entry: 172.16.69.0/24, rev 4
local binding: tag: imp-null
remote binding: tsr: 192.168.0.1:0, tag: 100
tib entry: 192.168.0.1/32, rev 8
local binding: tag: 600
remote binding: tsr: 192.168.0.1:0, tag: imp-null
tib entry: 192.168.0.4/32, rev 16
local binding: tag: 604
remote binding: tsr: 192.168.0.1:0, tag: 104
tib entry: 192.168.0.5/32, rev 18
local binding: tag: 605
remote binding: tsr: 192.168.0.1:0, tag: 105
tib entry: 192.168.0.6/32, rev 6
local binding: tag: imp-null
remote binding: tsr: 192.168.0.1:0, tag: 101
tib entry: 192.168.14.0/24, rev 10
local binding: tag: 601
remote binding: tsr: 192.168.0.1:0, tag: imp-null
tib entry: 192.168.16.0/24, rev 2
local binding: tag: imp-null
remote binding: tsr: 192.168.0.1:0, tag: imp-null
tib entry: 192.168.45.0/24, rev 12
local binding: tag: 602
remote binding: tsr: 192.168.0.1:0, tag: 102

Giuseppe Larosa · ‎06-04-2014

Hello,

the show mpls ldp binding shows the label to IP prefixes advertisement of every LDP neighbor either upstream (nearest to the prefix) either downstream (more far from the prefix).

The binding via R6 so is a correct binding but it is not used by local node R1 to reach 192.168.0.5/32.

As the sh ip cef shows there is actually a single best path to the destination that is in the direction of R5.

R1#sh ip cef 192.168.0.5 255.255.255.255
192.168.0.5/32, version 25, epoch 0, cached adjacency 192.168.14.4
0 packets, 0 bytes
tag information set
local tag: 105
fast tag rewrite with Fa0/0, 192.168.14.4, tags imposed: {401}
via 192.168.14.4, FastEthernet0/0, 0 dependencies
next hop 192.168.14.4, FastEthernet0/0
valid cached adjacency
tag rewrite with Fa0/0, 192.168.14.4, tags imposed: {401}
R1#

So you don't need to care about the additional entries in show mpls ldp binding.

Hope to help

Giuseppe

View solution in original post

Giuseppe Larosa · ‎06-04-2014

Hello,

the show mpls ldp binding shows the label to IP prefixes advertisement of every LDP neighbor either upstream (nearest to the prefix) either downstream (more far from the prefix).

The binding via R6 so is a correct binding but it is not used by local node R1 to reach 192.168.0.5/32.

As the sh ip cef shows there is actually a single best path to the destination that is in the direction of R5.

R1#sh ip cef 192.168.0.5 255.255.255.255
192.168.0.5/32, version 25, epoch 0, cached adjacency 192.168.14.4
0 packets, 0 bytes
tag information set
local tag: 105
fast tag rewrite with Fa0/0, 192.168.14.4, tags imposed: {401}
via 192.168.14.4, FastEthernet0/0, 0 dependencies
next hop 192.168.14.4, FastEthernet0/0
valid cached adjacency
tag rewrite with Fa0/0, 192.168.14.4, tags imposed: {401}
R1#

So you don't need to care about the additional entries in show mpls ldp binding.

Hope to help

Giuseppe