Tracing LDP Operations
Problem
You want to check that LDP is properly exchanging messages with its neighbors.
Solution
Set up a tracing file to capture information about the exchange of LDP protocol packets:
[edit protocols ldp] aviva@RouterG# set traceoptions file ldp-log aviva@RouterG# set traceoptions flag packets
Discussion
One tool for troubleshooting LDP operation is the JUNOS tracing facility. If an LDP session that was operating properly suddenly stops working, you can trace the routers LDP packet exchanges with its neighbors to help track down the source of the problem. This recipe sets up an LDP-specific tracing file named ldp-log that captures all LDP packet exchanges with neighboring routers.
Use the show log command to see the file contents:
aviva@RouterG> show log ldp-log Oct 5 19:25:46 Incredible-Hulk clear-log[15758]: logfile cleared Oct 5 19:25:48 LDP sent UDP PDU 10.0.0.1 -> 224.0.0.2 (t1-4/0/0.0) Oct 5 19:25:48 ver 1, pkt len 42, PDU len 38, ID 192.168.19.1:0 Oct 5 19:25:48 Msg Hello (0x100), len 28, ID 396082 Oct 5 19:25:48 TLV HelloParms (0x400), len 4 Oct 5 19:25:48 TLV XportAddr (0x401), len 4 Oct 5 19:25:48 TLV ConfSeq (0x402), len 4 Oct 5 19:25:49 LDP rcvd UDP PDU 10.0.0.2 -> 224.0.0.2 (t1-4/0/0.0) Oct 5 19:25:49 ver 1, pkt len 42, PDU len 38, ID 192.168.17.1:0 Oct 5 19:25:49 Msg Hello (0x100), len 28, ID 397238 Oct 5 19:25:49 TLV HelloParms (0x400), len 4 Oct 5 19:25:49 TLV XportAddr (0x401), len 4 Oct 5 19:25:49 TLV ConfSeq (0x402), len 4 Oct 5 19:25:52 LDP sent UDP PDU 10.0.0.1 -> 224.0.0.2 (t1-4/0/0.0) Oct 5 19:25:52 ver 1, pkt len 42, PDU len 38, ID 192.168.19.1:0 Oct 5 19:25:52 Msg Hello (0x100), len 28, ID 396083 Oct 5 19:25:52 TLV HelloParms (0x400), len 4 Oct 5 19:25:52 TLV XportAddr (0x401), len 4 Oct 5 19:25:52 TLV ConfSeq (0x402), len 4 Oct 5 19:25:52 LDP sent TCP PDU 192.168.19.1 -> 192.168.17.1 (none) Oct 5 19:25:52 ver 1, pkt len 18, PDU len 14, ID 192.168.19.1:0 Oct 5 19:25:52 Msg Keepalive (0x201), len 4, ID 396084 Oct 5 19:25:52 LDP rcvd TCP PDU 192.168.17.1 -> 192.168.19.1 (none) Oct 5 19:25:52 ver 1, pkt len 18, PDU len 14, ID 192.168.17.1:0 Oct 5 19:25:52 Msg Keepalive (0x201), len 4, ID 397241 Oct 5 19:25:53 LDP rcvd UDP PDU 10.0.0.2 -> 224.0.0.2 (t1-4/0/0.0) Oct 5 19:25:53 ver 1, pkt len 42, PDU len 38, ID 192.168.17.1:0 Oct 5 19:25:53 Msg Hello (0x100), len 28, ID 397242 Oct 5 19:25:53 TLV HelloParms (0x400), len 4 Oct 5 19:25:53 TLV XportAddr (0x401), len 4 Oct 5 19:25:53 TLV ConfSeq (0x402), len 4
This log shows normal LDP operation. LDP is sending and receiving UDP and TCP messages with its neighboring routers. LDP multicasts UDP Hello messages to 224.0.0.2 to discover its neighbors. The log output shows that LDP is sending UDP hellos out the connection to the local subnet (10.0.0.1) and receiving hellos from the other end of the connection (10.0.0.2). LDP establishes TCP connections to exchange label and FEC information and sends periodic keepalive messages (every 10 seconds, by default) to its neighbors to keep the TCP session established. The logfile also shows that LDP is sending and receiving TCP keepalives from 192.168.17.1, the neighboring LDP router. All the entries in this logfile are what you would expect to see when an LDP session is operating properly.
When debugging LDP, you can set one or more of the following trace flags to capture LDP-related information:
[edit protocols ldp] aviva@RouterG# set traceoptions flag ? Possible completions: address Trace address packets all Trace everything binding Trace label binding state error Trace errored packets event Trace LDP state machine events general Trace general events initialization Trace initialization packets label Trace label packets normal Trace normal events notification Trace notification packets packets Trace all LDP packets path Trace label path state periodic Trace periodic (hello and keepalive) packets policy Trace policy processing route Trace routing information state Trace state transitions task Trace routing protocol task processing timer Trace routing protocol timer processing
See Also
Recipe 5.10
Router Configuration and File Management
- Introduction
- Configuring the Router for the First Time
- Configuring the Router from the CLI
- Getting Exclusive Access to Configure the Router
- Displaying the Commands to Recreate a Configuration
- Including Comments in the Configuration
- Checking the Syntax of the Configuration
- Activating the Router Configuration
- Debugging a Failed Commit
- Exiting Configuration Mode
- Keeping a Record of Configuration Changes
- Determining What Changes You Have Made to the Configuration
- Configuring the Router by Copying a File from a Server
- Configuring the Router by Copying Text from a Terminal Window
- Backing Up the Routers Configuration
- Scheduling the Activation of a Configuration
- Provisionally Activating a Configuration
- Loading a Previous Router Configuration
- Creating an Emergency Rescue Configuration
- Backing Up Filesystems on M-Series and T-Series Routers
- Backing Up Filesystems on J-Series Routers
- Restoring a Backed-Up Filesystem
- Installing a Different Software Release on M-Series and T-Series Routers
- Installing a Different Software Release on J-Series Routers
- Creating an Emergency Boot Disk
- Gathering Software Version Information
- Gathering Hardware Inventory Information
- Finding Out How Long the Router Has Been Up
- Gathering Information Before Contacting Support
- Managing Routers with Similar Configurations
- Managing Redundant Routing Engines
- Using the Second Routing Engine to Upgrade to a New Software Version
Basic Router Security and Access Control
- Basic Router Security and Access Control
- Introduction
- Allowing Access to the Router
- Controlling Root Authentication
- Logging In to the Routers Console
- Setting the Login Authentication Methods
- Setting Up Login Accounts on the Router
- Changing the Format of Plain-Text Passwords
- Changing the Plain-Text Password Encryption Method
- Creating a Login Account for Remote Authentication
- Creating a Group Login Account
- Customizing Account Privileges
- Creating a Privilege Class that Hides Encrypted Passwords
- Setting Up RADIUS User Authentication
- Setting Up TACACS+ User Authentication
- Restricting Inbound SSH and Telnet Access
- Setting the Source Address for Telnet Connections
- Creating a Login Banner
- Finding Out Who Is Logged In to the Router
- Logging Out of the Router
- Forcibly Logging a User Out
IPSec
- IPSec
- Introduction
- Configuring IPSec
- Configuring IPSec Dynamic SAs
- Creating IPSec Dynamic SAs on J-Series Routers or Routers with AS PICs
- Using Digital Certificates to Create Dynamic IPSec SAs
SNMP
- SNMP
- Introduction
- Configuring SNMP
- Setting Router Information for the MIB-II System Group
- Setting Up SNMP Traps
- Controlling SNMP Access to the Router
- Using a Firewall Filter to Protect SNMP Access
- Controlling Access to Router MIBs
- Extracting Software Inventory Information with SNMP
- Extracting Hardware Inventory Information with SNMP
- Collecting Router Operational Information with SNMP
- Logging SNMP Access to the Router
- Logging Enterprise-Specific Traps
- Using RMON Traps to Monitor the Routers Temperature
- Configuring SNMPv3
- Tracking Router Configuration Changes
- Setting Up SNMPv3 Traps
Logging
- Logging
- Introduction
- Turning On Logging
- Limiting the Messages Collected
- Including the Facility and Severity in Messages
- Changing the Size of a Logging File
- Clearing the Routers Logfiles
- Sending Log Messages to Your Screen
- Sending Logging Messages to a Log Server
- Saving Logging Messages to the Other Routing Engine
- Turning Off Logging
- Turning On Basic Tracing
- Monitoring Interface Traffic
NTP
- NTP
- Introduction
- Setting the Date and Time on the Router Manually
- Setting the Time Zone
- Synchronizing Time When the Router Boots
- Synchronizing Time Periodically
- Authenticating NTP
- Checking NTP Status
Router Interfaces
- Router Interfaces
- Introduction
- Viewing Interface Status
- Viewing Traffic Statistics on an Interface
- Setting an IP Address for the Router
- Setting the Routers Source Address
- Configuring an IPv4 Address on an Interface
- Configuring an IPv6 Address on an Interface
- Configuring an ISO Address on an Interface
- Creating an MPLS Protocol Family on a Logical Interface
- Configuring an Interface Description
- Choosing Primary and Preferred Interface Addresses
- Using the Management Interface
- Finding Out What IP Addresses Are Used on the Router
- Configuring Ethernet Interfaces
- Using VRRP on Ethernet Interfaces
- Connecting to an Ethernet Switch
- Configuring T1 Interfaces
- Performing a Loopback Test on a T1 Interface
- Setting Up a BERT Test on a T1 Interface
- Configuring Frame Relay on a T1 Interface
- Configuring a SONET Interface
- Using APS to Protect Against SONET Circuit Failures
- Configuring an ATM Interface
- Dealing with Nonconfigurable Interfaces
- Configuring Interfaces Before the PICs Are Installed
IP Routing
- IP Routing
- Introduction
- Viewing the Routes in the Routing Table
- Viewing Routes to a Particular Prefix
- Viewing Routes Learned from a Specific Protocol
- Displaying the Routes in the Forwarding Table
- Creating Static Routes
- Blackholing Routes
- Filtering Traffic Using Unicast Reverse-Path Forwarding
- Aggregating Routes
- Load-Balancing Traffic Flows
- Adding Martian Addresses
- Changing Route Preferences to Migrate to Another IGP
- Configuring Routing Protocols to Restart Without Losing Adjacencies
Routing Policy and Firewall Filters
- Routing Policy and Firewall Filters
- Introduction
- Creating a Simple Routing Policy
- Changing a Routes Routing Information
- Filtering Routes by IP Address
- Filtering Long Prefixes
- Filtering Unallocated Prefix Blocks
- Creating a Chain of Routing Policies
- Making Sure a Routing Policy Is Functioning Properly
- Creating a Simple Firewall Filter that Matches Packet Contents
- Creating a Firewall Filter that Negates a Match
- Reordering Firewall Terms
- Filtering Traffic Transiting the Router
- Using a Firewall Filter to Count Traffic on an Interface
- Logging the Traffic on an Interface
- Limiting Traffic on an Interface
- Protecting the Local Routing Engine
- Rate-Limiting Traffic Flow to the Routing Engine
- Using Counters to Determine Whether a Router Is Under Attack
RIP
- RIP
- Introduction
- Configuring RIP
- Having RIP Advertise Its Routes
- Configuring RIP for IPv6
- Enabling RIP Authentication
- Routing RIP Traffic over Faster Interfaces
- Sending Version 1 Update Messages
- Tracing RIP Protocol Traffic
IS-IS
- IS-IS
- Introduction
- Configuring IS-IS
- Viewing the IS-IS Link-State Database
- Viewing Routes Learned by IS-IS
- Configuring IS-IS for IPv6
- Configuring a Level 1Only Router
- Controlling DIS Election
- Enabling IS-IS Authentication
- Redistributing Static Routes into IS-IS
- Leaking IS-IS Level 2 Routes into Level 1
- Adjusting IS-IS Link Costs
- Improving IS-IS Convergence Times
- Moving IS-IS Traffic off a Router
- Disabling IS-IS on an Interface
- Tracing IS-IS Protocol Traffic
OSPF
- Introduction
- Configuring OSPF
- Viewing Routes Learned by OSPF
- Viewing the OSPF Link-State Database
- Configuring OSPF for IPv6
- Configuring a Multiarea OSPF Network
- Setting Up Stub Areas
- Creating a Not-So-Stubby Area
- Summarizing Routes in OSPF
- Enabling OSPF Authentication
- Redistributing Static Routes into OSPF
- Adjusting OSPF Link Costs
- Improving OSPF Convergence Times
- Moving OSPF Traffic off a Router
- Disabling OSPF on an Interface
- Tracing OSPF Protocol Traffic
BGP
- Introduction
- Configuring a BGP Session Between Routers in Two ASs
- Configuring BGP on Routers Within an AS
- Diagnosing TCP Session Problems
- Adjusting the Next-Hop Attribute
- Adjusting Local Preference Values
- Removing Private AS Numbers from the AS Path
- Prepending AS Numbers to the AS Path
- Filtering BGP Routes Based on AS Paths
- Restricting the Number of Routes Advertised to a BGP Peer
- Authenticating BGP Peers
- Setting Up Route Reflectors
- Mitigating Route Instabilities with Route Flap Damping
- Adding a BGP Community to Routes
- Load-Balancing BGP Traffic
- Tracing BGP Protocol Traffic
MPLS
- Introduction
- Configuring LSPs Using LDP as the Signaling Protocol
- Viewing Information and LDP-Signaled LSPs in the Routing Tables
- Verifying that an LDP-Signaled LSP Is Carrying Traffic
- Enabling LDP Authentication
- Tracing LDP Operations
- Setting Up RSVP-Signaled LSPs
- Viewing Information About RSVP-Signaled LSPs in the Routing Tables
- Verifying Packet Labels
- Verifying that the RSVP-Signaled LSP Is Carrying Traffic
- Configuring RSVP Authentication
- Protecting an LSPs Path
- Using Fast Reroute to Reduce Packet Loss Following a Link Failure
- Automatically Allocating Bandwidth
- Prioritizing LSPs
- Allowing IGP Traffic to Use an LSP
- Installing LSPs into the Unicast Routing Table
- Tracing RSVP Operations
VPNs
- Introduction
- Setting Up a Simple Layer 3 VPN
- Viewing the VPN Routing Tables
- Adding a VPN for a Second Customer
IP Multicast
- Introduction
- Configuring PIM-SM
- Manually Establishing a PIM-SM RP
- Using Auto-RP to Dynamically Map RPs
- Setting Up a PIM-SM Bootstrap Router
- Filtering PIM-SM Bootstrap Messages
- Configuring Multiple RPs in a PIM-SM Domain with Anycast RP
- Configuring Multiple RPs in a PIM-SM Domain Anycast PIM
- Limiting the Group Ranges an RP Services
- Viewing Multicast Routes
- Checking the Groups for Which a PIM-SM Router Maintains Join State
- Manually Configuring IGMP
- Using SSM
- Connecting PIM-SM Domains Using MSDP and MBGP
- Configuring PIM-DM
- Tracing PIM Packets
Junos Cookbook (Cookbooks (OReilly))
ISBN: 0596100140
EAN: 2147483647
EAN: 2147483647
Year: 2007
Pages: 290
Pages: 290
Authors: Aviva Garrett
