monitoring mpls on cisco ios

8/14/2019 Monitoring MPLS on Cisco IOS

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2004 Cisco Systems, Inc. All rights reserved.

Monitoring MPLS on CiscoIOS Platforms

5-1


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2004 Cisco Systems, Inc. All rights reserved. 5-2

Outline

Overview

Monitoring MPLS

Monitoring LDP

Monitoring Label Switching

Debugging MPLS and LDP

Lesson Summary


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show mpls ldp parameters

Router#

Displays LDP parameters on the local router.

MPLS Monitoring Commands

show mpls interfaces

Router#

Displays MPLS status on individual interfaces.

show mpls ldp discovery

Router#

Displays all discovered LDP neighbors.


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MPLS Monitoring Commands:

show mpls ldp parameters

Protocol version: 1

Downstream label pool: min label: 16; max label:

100000

[Configured: min label: 1000; max label: 1999]

Session hold time: 180 sec; keep alive interval: 60sec

Discovery hello: holdtime: 15 sec; interval: 5 sec

Discovery targeted hello: holdtime: 180 sec; interval:

5 sec

Downstream on Demand max hop count: 255TDP for targeted sessions

LDP initial/maximum backoff: 15/120 sec

LDP loop detection: off

Router#show mpls ldp parameters


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show mpls interfaces

Router#show mpls interfaces [interface] [detail]

Interface Serial0/0:IP labeling enabled (ldp)

LSP Tunnel labeling enabled

Tag Frame Relay Transport tagging not enabled

Tagging operational

Fast Switching Vectors:

IP to MPLS Fast Switching Vector

MPLS Turbo Vector

MTU = 1500

Interface Serial0/3:

IP labeling enabled (ldp)

LSP Tunnel labeling not enabled

Tag Frame Relay Transport tagging not enabled

Tagging operationalFast Switching Vectors:

IP to MPLS Fast Feature Switching Vector

MPLS Feature Vector

MTU = 1500

Router#show mpls interfaces [interface] [detail]




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Router#show mpls ldp discoveryLocal LDP Identifier:

192.168.3.102:0

Discovery Sources:

Interfaces:

Serial1/0.1(ldp): xmit/recv

LDP Id: 192.168.3.101:0

Serial1/0.2(ldp): xmit/recv

LDP Id: 192.168.3.100:0



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show mpls ldp neighbor

Router#

Displays individual LDP neighbors.

LDP Monitoring Commands

show mpls ldp neighbor detail

Router#

Displays more details about LDP neighbors.

show mpls ldp bindings

Router#

Displays label information base (LIB). show mpls ldp bindings [network{mask| length} [longer-prefixes]]

[local-label label [-label]} [remote-label label[- label] [neighboraddress] [local]


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LDP Monitoring Commands:


Router#show mpls ldp neighbor detail

Peer LDP Ident: 192.168.3.100:0; Local LDP Ident 192.168.3.102:0

TCP connection: 192.168.3.100.646 192.168.3.102.11000

State: Oper; Msgs sent/rcvd: 3117/3112; Downstream;

Last TIB rev sent2

Up time: 2w4d; UID: 4; Peer Id 0;

LDP discovery sources:Serial0/0; Src IP addr: 130.0.0.2

holdtime: 15000 ms, hello interval: 5000 ms

Addresses bound to peer LDP Ident:

192.168.3.10 192.168.3.14 192.168.3.100

Peer holdtime: 180000 ms; KA interval: 60000 ms; Peerstate: estab


State: Oper;


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Router#show mpls ldp bindings

10.102.0.0/16, rev 29

local binding: label: 26

remote binding: lsr: 172.27.32.29:0, label: 26

10.211.0.7/32, rev 32local binding: label: 27


10.220.0.7/32, rev 33

local binding: label: 28


LDP Monitoring Commands:




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show mpls forwarding-table

Router#

Displays contents of LFIB.

Monitoring Label Switching

show ip cef detail

Router#

Displays label or labels attached to a packet duringlabel imposition on edge LSR.


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Monitoring Label Switching:

show mpls forwarding-table

Router#show mpls forwarding-table ? A.B.C.D Destination prefix

detail Detailed information

interface Match outgoing interface

labels Match label values

lsp-tunnel LSP Tunnel idnext-hop Match next hop neighbor

vrf Show entries for a VPN

Routing/Forwarding instance

| Output modifiers

show mpls forwarding-table ?


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show mpls forwarding-table detail

Router#show mpls forwarding-table detail

Local Outgoing Prefix Bytes tag Outgoing Next Hoptag tag or VC or Tunnel Id switched interface

70 Pop tag 192.168.3.3/32 0 Se0/0 point2point

MAC/Encaps=4/4, MTU=1504, Tag Stack{}

0F008847

No output feature configured

Per-packet load-sharing71 Pop tag 192.168.3.4/32 0 Se0/0 point2point

MAC/Encaps=4/4, MTU=1504, Tag Stack{}

0F008847

No output feature configured

Per-packet load-sharing

show mpls forwarding-table detail


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show ip cef detail

Router#show ip cef 192.168.20.0 detail192.168.20.0/24, version 23, cached adjacency to Serial1/0.2

0 packets, 0 bytes

tag information set

local tag: 33

tag rewrite with Se1/0.2, point2point, tags imposed: {32}

via 192.168.3.10, Serial1/0.2, 0 dependenciesnext hop 192.168.3.10, Serial1/0.2

valid adjacency

tag rewrite with Se1/0.2, point2point, tags imposed: {32}

show ip cef 192.168.20.0 detail


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debug mpls ldp ...

Router#

Debugs TDP adjacencies, session establishment,and label bindings exchange.

Debugging MPLS and LDP

debug mpls lfib

Router#

Debugs LFIB events: label creations, removals,rewrite, and so on.

debug mpls packets [ interface ]Router#

Debugs labeled packets switched by the router.


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Summary

The show mpls interfaces command will show only

those interfaces that have had mpls enabled. Use the showmpls ldp bindings command to display

the LIB table.

Use the showmpls forwarding-table command todisplay the LFIB table.

Use the debug mpls packetscommand with carebecause it causes fast and distributed switching to

be disabled.


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2004 Cisco Systems, Inc. All rights reserved. 5-16 2004 Cisco Systems, Inc. All rights reserved.

Troubleshooting MPLS onCisco IOS Platforms

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Outline

Overview

What are Common Frame-Mode MPLS Issues? Solving LDP Session Startup Issues

Solving Label Allocation Issues

Solving Label Distribution Issues

Solving Packet Labeling Issues

Solving Intermittent MPLS Failures After Interface

Failure

Solving Packet Propagation Issues

Lesson Summary


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Symptoms of Common Frame-Mode MPLSIssues

The LDP session does not start.

Labels are not allocated. Labels are not distributed.

Packets are not labeled, although the labels have

been distributed. MPLS intermittently breaks after an interface

failure.

Large packets are not propagated across thenetwork.


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LDP Session Startup Issues

Symptom

LDP neighbors are not discovered. The show mpls ldp discovery command does

not display expected LDP neighbors.

DiagnosisMPLS is not enabled on the adjacent router.

Verification

Verify with the show mpls interface command onthe adjacent router.


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LDP Session Startup Issues (Cont.)

Symptom

LDP neighbors are not discovered. Diagnosis

There is a label distribution protocol mismatch

TDP on one end, LDP on the other end. Verification

Verify with the show mpls interface detail

command on both routers.


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Symptom

LDP neighbors are not discovered. Diagnosis

Packet filter drops LDP neighbor discovery

packets. Verification

Verify access list presence with the show ip

interface command.Verify access list contents with the show access-

list command.


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Symptom

LDP neighbors are discovered; the LDP sessionis not established.

The show mpls ldp neighbor command does notdisplay a neighbor in operational state.

Diagnosis

The connectivity between loopback interfaces isbroken; the LDP session is usually establishedbetween loopback interfaces of adjacent LSRs.

Verification

Verify connectivity with the extended pingcommand.


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Label Allocation Issues

Symptom

Labels are not allocated for local routes. The show mpls forwarding-table command does

not display any labels.

Diagnosis

CEF is not enabled.

Verification

Verify with the show ip cef command.


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Intermittent MPLS Failures After InterfaceFailure

Symptom

The overall MPLS connectivity in a routerintermittently breaks after an interface failure.

Diagnosis

The IP address of a physical interface is used forthe LDP (or TDP) identifier. Configure a loopbackinterface on the router.

Verification

Verify the local LDP identifier with the show mplsldp neighbors command.


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Packet Propagation Issues

Symptom

Large packets are not propagated across the network.

Use of the extended ping command with varying packetsizes fails for packet sizes close to 1500

In some cases, MPLS might work, but MPLS VPN will fail.

DiagnosisThere are label MTU issues or switches that do not support

jumbo frames in the forwarding path.

Verification

Issue the traceroute command through the forwarding path;identify all LAN segments in the path.

Verify the label MTU setting on routers attached to LANsegments.

Check for low-end switches in the transit path.


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Summary

Some common frame-mode issues are as follows: LDP sessiondoes not start, labels are not allocated or distributed, and MPLS

intermittently breaks after an interface failure. One LDP session startup issue is when LSP neighbors are not

discovered.

A label allocation issue is one where the labels are not allocated

for local routes. Labels may be allocated, but not distributed correctly.

Ensure that there are no conflicts between CEF and any otherconfigured features; otherwise, packets might not be labeled.

Use loopback IP addresses, not a configured interface IPaddress, to avoid MPLS connectivity to intermittently breakdown.

Large packets are not propagated across the network.

monitoring mpls on cisco ios

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