15.6 Troubleshooting Routing Protocols with the traceoptions Command

15.6 Troubleshooting Routing Protocols with the traceoptions Command

Up until now, we have focused mainly on hardware troubleshooting ”chassis, interface, and component problems. You also need to be able to troubleshoot the routing protocols running on your router effectively. We will focus on three ways to do this ”through show commands, through debug commands, and through the routing table.

You may be familiar with using show commands with other vendor products. You probably also have a good idea of how to troubleshoot routing problems through the use of the routing table (described in Chapter 14). You may not, however, be familiar with the Juniper Networks routers' traceoptions command set, which can be used to monitor protocol traffic.

The traceoptions command set is similar to Cisco Systems' debug command set. Both command toolkits can be used to perform diagnostics related to protocol status and network activity. Both can be CPU- intensive on the router itself because of the power and memory it takes to examine and capture the volume of traffic and tasks flowing through and taking place on today's high-speed routers. Enabling any kind of traceoptions command on a Juniper Networks router can be detrimental to performance and should be used with caution.

While the Cisco Systems' debugging commands are complex enough to warrant a separate command reference, the traceoptions commands are simple yet powerful. Knowing how and when to use traceoptions commands is a key skill in good troubleshooting. Each protocol section in this chapter will discuss how to use them; knowing when to use traceoptions commands is partially based on experience. If you find yourself in a troubleshooting scenario that requires some advanced techniques, try the traceoptions commands. Using the traceoptions command set is a good way to become familiar with how valuable it can be.

Note

A good way to use traceoptions is to set the commonly used traceoptions commands and parameters ahead of time in the configuration and leave them disabled. When you need to run tracing, you simply have to go into your configuration and enable the trace commands needed. This is a great timesaver.

15.6.1 Viewing traceoptions Output

This section will discuss protocol-specific information and how to get it later. Here it specifies what you need to know to retrieve the output gathered by the traceoptions command. There are two ways to see this information: by monitoring it in real-time or by viewing it from a saved file with the show log command.

The monitor command allows you to display the end of either a system log file or a trace file, along with additional entries as they are being added. It can be a very valuable tool during active troubleshooting because you can watch the output and receive immediate feedback on what is happening in the router or network. The syntax of the monitor command is as follows :

 lab@Chicago> monitor (start  stop) list 

The list qualifier prompts the system to provide you with a list of log files from which to select. This list will include not only traceoptions output files, but syslog-produced files as well. To stop the output, enter <ESC>-Q.

The show log command can be used to list log files on the system, view the contents of the log files, or list user logins. The syntax of this command is as follows:

 lab@Chicago> show log [user  username  ] [  filename  ] 

The user qualifier is optional, as is username . If you enter user and do not enter a username , you will see logged information about all users with recent logins. The filename is also optional. If you identify a filename, you will view the contents of that file. The use of no optional qualifiers simply provides a list of all available log files that you can view. Here is an example of the show log output:

 lab@Chicago>  show log user  lab     ttyd0     Thu Apr 4  13:17 still logged in  ted     ttyd0     Tue Apr 2  11:24  13:13      (2+01:49)  

In this example, we see that on Chicago, two users are logged on. We see our session, user lab , and another session, user ted . User ted has been online for 2 days, 1 hour , and 49 minutes. Notice that, because we are still logged in, we do not see an accounting of the amount of time we have been logged in.

15.6.2 Enabling Global traceoptions

For capturing traffic and activity on the Juniper Networks router, you can enable some global parameters for traceoptions , before editing specific parameters for protocols or interfaces. You would do this in the [edit routing-options] configuration mode as shown below:

 [edit routing-options]  lab@Chicago# edit traceoptions file  filename  <replace> <size  size  > <files  number  > <no-stamp> <(world-readable  no-world-readable)> flag  flag  <flag- modifier> <disable> 

Notice that you can specify a particular filename for the trace, such as /var/log/trace-all . Enabling the options at this level is optional, but can be beneficial if you want all routing options tracing to go into a single output file. Table 15-6 describes the parameters you can use with the traceoptions command. This table applies to these parameters regardless of the configuration hierarchy level you are at.

Table 15-6. Configuration Parameters for the traceoptions Command

Parameter	Description
files	Allows you to specify a number of log files that can be created. In other words, if you set files to 5 , the system will create /var/log/rip-trace.0 , then /var/log/rip-trace.1 , and so on, through .5 . When the maximum number of files is reached, the system will overwrite the first file in the series. The default for this parameter is to create one file only. The maximum number that can be set is 1,000 files.
flag	Allows you to flag the particular options you wish to trace. The possible choices are listed in Table 15-7.
no-stamp	An optional parameter that can be used when you do not want to have a timestamp on your traces.
no-world-readable	This allows only the user who created the file to access its contents.
replace	This saves space by replacing a file of the same name that already exists. If you do not specify the replace option, the new tracing will be appended to the file that already exists.
size	This limits the amount of space consumed by the file. You can specify a range from 10KB through the maximum file size supported by your hard disk. To specify KB, use k , as in 400k to represent 400KB. Use m for MB and g for GB. The default size is 1MB. Once a file reaches its limit, it will begin overwriting from the beginning of the trace.

Table 15-7 lists the required and optional flag options you want to trace.

Table 15-7. Required and Optional flag parameters for the traceoptions Command

Options	Description
all	Required; enables all possible tracing operations
detail	Optional; results in more detailed trace information
disable	Optional; turns off the tracing operation preceding the disable flag
general	Required; captures all normal operations and routing table changes (the equivalent of the normal and route trace flags together)
normal	Required; traces all normal operations
policy	Required; captures all instances of policy operations
receive	Optional; logs only packets being received
receive-detail	Optional; logs details of packets being received
route	Required; traces routing table changes
send	Optional; logs only packets being sent
send-detail	Optional; logs details of packets being sent
state	Required; captures state transitions
task	Required; captures interface transactions
timer	Required; traces timer usage

An example of the syntax for a traceoptions command at this level is as follows:

 lab@Chicago# edit traceoptions file  trace-all  replace size  1m  files  4  world-readable flag  receive  

In this example, we have enabled traceoptions at the [edit routing-options] hierarchy. We are directing all output to a file called trace-all , which will replace any file already in existence with that name. We have set the maximum file size at 1MB, limiting the total number of file versions with this name to 4 . We are allowing all users to read this file and are looking at received traffic only.

Now that you have traceoptions enabled globally, let's look at the ways you can use traceoptions with each routing protocol.

15.6.3 Using traceoptions with RIP

Probably the least complex routing protocol you will run in the core is RIP, usually version 2, although Juniper Networks routers also support version 1. Section 15.6.2 described how to set up traceoptions globally. If you prefer, you may specify certain parameters that you want to see on your RIP protocol traffic at the [edit protocols rip] hierarchy. Bear in mind that the more specific you get, the easier it will be to use the file for troubleshooting purposes. More specific logging also takes up less space on the router's hard disk and is less CPU-intensive. Here is how you would enable traceoptions for RIP protocol traffic in configuration mode:

 lab@Chicago# edit protocols rip  [edit protocols rip] lab@Chicago# set traceoptions file  filename  <replace> <size  size  > <files  number  > <no-stamp> lab@Chicago# set traceoptions flag  flag  <  flag-modifier  > <disable> 

The RIP protocol-specific flags can help narrow down the output that you receive. Table 15-8 lists each flag and provides a short description.

The following example shows how to enable the trigger , request , and update flags for RIP:

 [edit protocols rip]  lab@Chicago# set traceoptions file  rip-trace size 400k files 4 no-stamp world-readable lab@Chicago# set flag request update trigger 

Table 15-8. RIP traceoptions Flags

Flag	Description
auth	Captures RIP authentication packets
disable	Turns off the tracing operation of the flag preceding it
error	Captures RIP error packets
expiration	Traces RIP route expiration transaction processing
holddown	Captures RIP hold-down processing
packets	Traces any packets that are RIP-related
request	Captures only RIP informational packets
trigger	Captures any RIP triggered updates
update	Captures all RIP update packets

The following example shows how to disable the trigger flag for the above RIP traceoptions setting:

 [edit protocols rip]  lab@Chicago# set traceoptions lab@Chicago# set flag trigger disable 

15.6.4 Using traceoptions with OSPF

Most large networks are running OSPF in the core. Using the traceoptions command, you can specify certain types of OSPF packets you want to capture. To do this, follow the instructions below to set up specific OSPF parameters within the [edit protocols ospf] hierarchy:

 lab@Chicago# edit protocols ospf  [edit protocols ospf] lab@Chicago# set traceoptions file  filename  <replace> <size  size  > <files  number  > <no-stamp> lab@Chicago# set traceoptions flag flag <  flag-modifier  > <disable> 

Flags allow you to set up some OSPF-specific information that you may want to see. Table 15-9 shows flags that are available for OSPF traceoptions . Alternately, you can enter a partial command for a list of the possible completions you can use as follows:

 lab@chicago# set flag <enter>  Will give you a list of the available flags. 

Table 15-9. OSPF traceoptions Flags

Flags	Description
database-description	Captures all database description packets used when synchronizing the OSPF topological database
lsa-ack	Captures the link-state update acknowledgment packets used when synchronizing the OSPF topological database
lsa-request	Captures the link-state request packets sent from OSPF routers
lsa-update	Shows all link-state update packets on the network
error	Captures only OSPF error packets
flooding	Traces link-state packets that are flooded to all routers
event	Traces OSPF state transitions
hello	Captures the OSPF hello packets sent between neighbors
packets	Traces all OSPF packets on the network
spf	Shows all SPF calculations on the router
packet-dump	Opens and dumps the contents of selected packet types

The following example shows how to run traceoptions in OSPF to capture all OSPF state transitions, as well as all hello packets. The output is being logged to a file called ospf-trace .

 [edit protocols ospf]  lab@Chicago#  set traceoptions file  ospf-trace  lab@Chicago#  set traceoptions flag event hello  

Although some OSPF show commands were discussed in Chapter 8, we wanted to include all of the possible commands here, so that you can use them in your troubleshooting process. To gather information about OSPF databases, processes and routes, you can use show commands. These commands can be used to get a current status of specific OSPF components at a given moment in time. Table 15-10 provides a brief description of each command.

Table 15-10. OSPF show Commands

Command	Description
show ospf database	Provides information about LSA packets from the link-state database. Options include brief , detail , and extensive . You may also choose to show data about only a single named OSPF instance or run the output through an LSA filter.
show ospf interface	Displays the status of all interfaces that are running OSPF. Options include brief , detail , and extensive . You may also view the interfaces connected to a particular OSPF instance and may specify an interface or an interface name using a wildcard.
show ospf log	Provides information on the shortest- path calculations that have been logged. You can view this for one or all routing-instances . The output fields include when the calculation occurred, what type of calculation was run, and how much time has elapsed since the calculation was last run.
show ospf neighbor	Displays neighboring OSPF routers. Options include brief , detail , and extensive . You may also view the neighbors per routing-instance or you may specify one neighbor in particular that you wish to view.
show ospf route	Displays the OSPF routing table entries. Options include detail , abr , asbr , extern , instance instance-name , inter , or intra providing detailed output, routes to area border routers or AS border routers, external routes, routes for a particular routing-instance , inter-area routes, and intra-area routes, respectively.
show ospf statistics	Displays the protocol statistics for OSPF, such as packets in, packets out, and so on.

In this example, we are running a show ospf neighbor command on Chicago. We can see three neighbors, the interface through which we know each neighbor, the state, and the neighbor's router ID. We also see the value of the dead timer and that router's priority value. For more information on the meaning of these OSPF values, please refer to Chapter 8.

 [edit protocols]  lab@Chicago#  run show ospf neighbor   Address         Interface             State      ID              Pri  Dead  10.10.0.130      ae1.0                  Full      10.10.1.1        128   38  10.10.0.138      at-1/2/0.235           Full      10.10.0.2        128   36  10.10.0.134      at-1/2/1.167           Full      10.10.0.3        128   38 

Note that you can use the clear ospf command with the database , neighbors , or statistics qualifiers to clear out some or all of the data in the OSPF databases and routing table. This comes in very handy when troubleshooting, especially when you make a change and need to see the results right away.

15.6.5 Using traceoptions with IS-IS

You can also use the traceoptions command to monitor the behavior of the IS-IS routing protocol. The following example uses the [edit protocols isis] hierarchy:

 lab@Chicago# edit protocols isis  [edit protocols isis] lab@Chicago# set traceoptions file  filename  <replace> <size  size  > <files  number  > <no-stamp> lab@Chicago# set traceoptions flag  flag  <  flag-modifier  > <disable> 

Flags allow you to set up some IS-IS-specific information that you may want to see. Table 15-11 lists flags that are available for traceoptions . To see a list of all possible flags available from the CLI, hit enter after typing set flag to bring up a list of possible completions.

In the following example, you can see that we are going to trace all IS-IS protocol traffic that is being sent. We are logging all traceoptions output to a file called isis-trace .

 [edit protocols isis]  lab@Chicago#  set traceoptions file  isis-trace  lab@Chicago# set traceoptions  flag all send  

In addition to using the traceoptions command for monitoring IS-IS, you can also use the show isis command. While this command can be used alone, you can also add six different qualifiers to gather even more specific information. Table 15-12 lists these qualifiers.

Table 15-11. IS-IS traceoptions Flags

Flags	Description
all	Traces everything
csn	Traces complete sequence number PDUs (CSNP)
error	Shows errored packets
general	Traces all general IS-IS events
hello	Shows all hello packets transmitted
lsp	Traces all LSP packets
lsp-generation	Traces all LSP generation packets
normal	Trace all normal IS-IS events
packets	Captures all IS-IS-related packets
policy	Traces all policy processing
psn	Traces all PSNPs
route	Captures all IS-IS routing-update packets
spf	Captures all SPF calculations performed
state	Captures just state transitions
task	Captures routing-protocol task processing
timer	Traces routing-protocol timer processing

Table 15-12. show isis Command Qualifiers

Qualifier	Description
adjacency	Use with system-ID or as brief or detail output to view all neighboring routers
database	Use with system-ID or as brief , detail , or extensive output to show the entries in the IS-IS link-state database
interface	Use with either brief (default) or detail to show the status of all interfaces running IS-IS
routes	Shows the summary of all IS-IS routes in the routing table
spf	Shows information about SPF calculations that have run
statistics	Shows statistics related to IS-IS, such as packets in, and so on

In this example, we use the show isis route command to view the IS-IS routing table. Notice that it gives us the network prefix, the version of JUNOS running on the router, metrics for the route, and the associated interface through which we connect to this network.

 [edit protocols]  lab@Chicago#  run show isis route  IS-IS routing table        Current version: L1: 38 L2: 55 Prefix             L Version Metric Type Interface    Via  10.10.0.2/32       2      55     10 int  at-1/2/0.235 Montreal  10.10.0.3/32       2      55     10 int  at-1/2/1.167 SanJose 10.10.0.4/32       2      55     20 int  at-1/2/0.235 Montreal                                          at-1/2/1.167 SanJose 10.10.0.160/30     2      55     20 int  at-1/2/0.235 Montreal 10.10.0.164/30     2      55     20 int  at-1/2/1.167 SanJose                                          at-1/2/0.235 Montreal 10.10.0.192/30     2      55     20 int  at-1/2/1.167 SanJose 10.10.0.224/30     2      55     30 int  at-1/2/0.235 Montreal                                          at-1/2/1.167 SanJose 10.10.0.228/30     2      55     30 int  at-1/2/0.235 Montreal                                          at-1/2/1.167 SanJose 10.10.2.132/30     2      55     20 int  at-1/2/0.235 Montreal 17.185.36.224/30   2      55     20 int  at-1/2/1.167 SanJose 192.168.18.4/30    2      55     20 int  at-1/2/1.167 SanJose 

Note that you can use the clear isis command and the same qualifiers to clear out some or all of the data in the IS-IS databases and routing table. This comes in very handy when troubleshooting, especially when you make a change and want to watch the counters and so on.

15.6.6 Using traceoptions with BGP

To enable the monitoring of the BGP on the router, set up BGP-specific flags within the [edit protocols bgp] hierarchy as follows:

 lab@Chicago# edit protocols bgp  [edit protocols bgp] lab@Chicago# set traceoptions file  filename  <replace> <size  size  > <files  number  > <no-stamp> lab@Chicago# set traceoptions flag  flag  <  flag-modifier  > <disable> 

Notice that you may specify an output file of a name of your choosing. You may also instruct the router to replace the current output file, use a specified maximum size for the file, use a certain number of files before overwriting the first one, and indicate that no timestamp should be used. Flags allow you to set up some BGP-specific information that you may want to see. Table 15-13 lists flags that are available for traceoptions . To see a list of all possible flags available from the CLI, hit enter after typing set flag to bring up a list of possible completions.

Table 15-13. BGP traceoptions Flags

Flags	Description
aspath	Traces AS path regular expression operations
damping	Traces route damping operations
keepalive	Captures the BGP keepalive messages
open	Shows the open packets sent between BGP peers when establishing a session
packets	Captures all BGP packets of any type
update	Shows all BGP update packets sent during routing updates on BGP ASs

In the following example, you can see that we are going to trace all BGP protocol traffic that is being received. We are logging all traceoptions output to a file called bgp-trace .

 [edit protocols bgp]  lab@Chicago#  set traceoptions file  bgp-trace  lab@Chicago# set traceoptions  flag all receive  

In addition to using the traceoptions command for monitoring BGP, you can use the show bgp command. While this command can be used alone, you can also add four different qualifiers to gather even more specific information. Table 15-14 lists these qualifiers.

Table 15-14. show bgp Command Qualifiers

Qualifiers	Description
group	Displays information about configured BGP groups
neighbor	Displays information about all BGP peers; you can further specify a particular neighbor by address
next -hop-database	Displays the entries from the internal BGP synchronization database; you can further specify a next-hop router by address or specify that you would like to see the output in brief or detail mode
summary	Shows general BGP information

Notice that in the following example, we provide you with a show bgp summary from Chicago. It gives us a look at the number of groups and peers. It also provides us with a little information about the peering sessions between routers, such as up time and state.

 [edit]  lab@Chicago#  run show bgp summary   Groups: 3 Peers: 4 Down peers: 0  Table    Tot Paths  Act Paths Suppressed    History Damp State    Pending inet.0          0          0          0          0          0          0 inet.2          0          0          0          0          0          0 bgp.l3vpn.0    18         18          0          0          0          0 Peer           AS      InPkt     OutPkt    OutQ   Flaps Last Up/Dwn State#Active/Received/Damped...  10.10.0.2     7500        522        527       0       2     4:20:26 Establ   bgp.l3vpn.0: 0/0/0  10.10.0.3     7500        530        533       0       2     4:23:18 Establ   bgp.l3vpn.0: 9/9/0 10.10.0.4     7500        583        584       0       0     4:50:47 Establ   inet.0: 0/0/0 10.10.0.130   3000        583        592       0       0     4:49:09 Establ   inet.0: 0/0/0   inet.2: 0/0/0  bgp.l3vpn.0: 9/9/0 

Note that you can use the clear bgp command and the same qualifiers to clear out some or all of the data or counters in the BGP routing table and processes. This comes in very handy when troubleshooting, especially when you make a change and want to watch the counters and so on.

15.6.7 Troubleshooting Commands for MPLS and VPNs

Chapter 12 on MPLS has a lot of background and configuration information for this popular new style of routing over Layer 2 virtual private networks (L2VPNs) using MPLS to carry the connection. Juniper Networks routers support traceoptions functionality for advanced MPLS and VPN troubleshooting. As with other protocols, you must first enable traceoptions globally before you set up the tracing of MPLS tunnels. Once global traceoptions are enabled, you can enable certain traceoptions parameters for MPLS as shown below:

 lab@Chicago# edit protocols mpls  [edit protocols mpls] lab@Chicago# set traceoptions file  filename  <replace> <size  size  > <files  number  > <no-stamp> lab@Chicago# set flag  flag  <  flag-modifier  > <disable> 

Again, by setting certain flags, you can selectively enable different elements to trace within the MPLS protocol. Table 15-15 lists the flags that are available for traceoptions . To see a list of all possible flags available from the CLI, hit enter after typing set flag to bring up a list of possible completions.

Table 15-15. MPLS traceoptions Flags

Flags	Description
connection	Captures all activity within CCCs.
connection-detail	Provides a higher level of detail than the connection flag
cspf	Captures calculations performed for CSPF
cspf-link	Captures all links visited during CSPF calculations
cspf-node	Captures all nodes visited during CSPF calculations
error	Traces only MPLS error packets
state	Shows all LSP state transitions

You can also trace information about traffic on an L2VPN by using traceoptions . To do so, use the following syntax:

 lab@Chicago# edit routing-instances  routing-instance-name  protocols l2vpn  [edit routing-instances  routing-instance-name  protocols l2vpn] lab@Chicago# set traceoptions file  filename  <replace> <size  size  > <files  number  > <no-stamp> lab@Chicago# set traceoptions flag  flag  <  flag-modifier  > <disable> 

Flags that you can use for tracing L2VPN information are shown in Table 15-16.

Table 15-16. L2VPN traceoptions Flags

Flags	Description
All	Captures everything
Connections	Captures just events and state changes in the L2VPN
Error	Displays only error packets
Nlri	Captures L2VPN send/receive advertisements from BGP
Route	Displays only the exchange of routing information
Topology	Captures information related to the change of topology due to reconfiguration or advertisements

While traceoptions are important, the additional load they put on the router can sometimes be more than you are willing to use to troubleshoot a problem. This is where show and clear commands come in handy. They are simple tools that can be used to monitor counters, link information, and LSP information in an MPLS or L2VPN environment. Some of the commands you can use when you want to keep it simple are shown in Table 15-17. If you want to see a list quickly of all possible commands to use with show or clear , you can press enter after typing in show l2vpn or clear l2vpn . The system will then display a list of possible completions.

Table 15-17. MPLS and L2VPN show and clear Commands

Commands	Descriptions
show/clear mpls lsp	Shows (or alternately clears) the active, configured LSPs of which this router is a participant; useful when troubleshooting basic communication problems
show connections	Can be used to find information about configured CCCs on the router; a powerful command with a long list of optional parameters
show mpls admin-groups	Displays the administrative groups configured on this router for MPLS
show mpls cspf	Provides a display of statistical information related to CSPF calculations
show mpls interface	Displays information about the interfaces on which MPLS is configured; a very similar command to that on other protocols
show mpls path	Useful if you are using named paths in conjunction with your MPLS configuration; you can display one or all MPLS paths by choosing whether or not to specify a path name
show ted database	Displays a lot of information in brief , detail , or extensive mode about everything known in the TED ”nodes, links, protocols, administrative groups, and so on
show ted link	Shows in brief or detail mode the information for links contained in the TED
show ted protocol	Gives you some information about which protocols, such as IS-IS, are contributing to the TED; protocols will be ranked according to the credibility of their routing information

The following is an example of the show mpls lsp command in use. It shows both ingress (incoming) and egress (outgoing) LSPs, their states, path information, and names . It also shows for the egress LSP, the LabelIn / LabelOut information and summary information at the end.

 [edit]  instruct@Denver#  run show mpls lsp   Ingress LSP: 2 sessions  To              From          State Rt ActivePath       P     LSPname  10.10.0.2       10.10.0.1     Up     0                  *     vpn-dev-mont  10.10.0.3       10.10.0.1     Up     0                  *     uunet-denv-sj Total 2 displayed, Up 2, Down 0  Egress LSP: 2 sessions  To              From          State Rt Style Labelin Labelout LSPname  10.10.0.1       10.10.0.2     Up     0  1 FF       3        - vpn-mont-denv  10.10.0.1     192.168.161.19  Up     0  1 FF       3        - uunet-sj-denv Total 2 displayed, Up 2, Down 0  Transit LSP: 0 sessions   Total 0 displayed, Up 0, Down 0  

The next example shows the show mpls interface command. With this command, we can get a quick summary of all of our MPLS-enabled interfaces, along with their states and the administrative groups to which they belong.

 [edit]  lab@Chicago#  run show mpls interface  Interface        State       Administrative groups  at-1/2/0.235     Up         <none>  at-1/2/1.167     Up         <none> fe-1/0/1.0       Up         <none> fe-1/0/0.0       Up         <none> ae1.0            Up         <none> 

15.6.8 Troubleshooting Commands for Multicast Protocols

There are several different multicast protocols supported by the Juniper Networks routers. In this section, we will discuss commands you can use to troubleshoot each of them. As with other protocols, the traceoptions commands are invaluable in advanced troubleshooting. You can enable specific multicast protocol traceoptions within the [edit routing-options] hierarchy, then set up protocol-specific flags within the [edit protocols multicast protocol] hierarchy. Each of these is discussed below.

15.6.8.1 DVMRP

This section addresses the commands used to turn on the traceoptions capabilities in DVMRP. With an output filename of your choosing, enable traceoptions by using the commands shown below. Then, set up specific output parameters with DVMRP-specific flags.

 lab@Chicago# edit protocols dvmrp  [edit protocols dvmrp] lab@Chicago# set traceoptions file  filename  <replace> <size  size  > <files  number  > <no-stamp> lab@Chicago# set traceoptions flag  flag  <  flag-modifier  > <disable> 

Flags allow you to gather output for some DVMRP-specific information that you may want to see. Table 15-18 lists flags that are available for DVMRP traceoptions .

Table 15-18. DVMRP traceoptions Flags

Flags	Descriptions
all	Traces everything
general	Logs general DVMRP events
graft	Logs DVMRP graft messages
neighbor	Captures the neighbor probe messages
normal	Traces normal events (The default is to capture abnormal or error events only.)
packets	Captures all DVMRP-related packets
poison	Shows only poison-route-reverse packets
policy	Logs any policy processing activity in the router
probe	Traces all probe packets versus the probe packets from neighbors only
prune	Traces all prune messages
report	Captures all DVMRP route report packets
route	Traces all routing updates for DVMRP
state	Displays any DVMRP state transitions
task	Displays protocol task processing
timer	Shows routing-protocol timer processing

The following example sets up a trace for DVMRP prune messages with detailed logging. All traceoptions output is being sent to a file called dvmrp-trace .

 [edit protocols dvmrp]  lab@Chicago#  set traceoptions file  dvmrp-trace  lab@Chicago# set traceoptions  flag prune detail  

Additionally, you can use certain show commands in conjunction with DVMRP for real-time troubleshooting without taking up valuable disk space. Table 15-19 lists these commands.

Table 15-19. DVMRP show Commands

Commands	Descriptions
show dvmrp grafts	Shows any entries in the graft retransmission queue in either brief or detail mode (Normally, this queue should be empty.)
show dvmrp neighbors	Displays some information about DVMRP-enabled neighbors
show dvmrp prefix	Displays the table of known IP prefixes in this protocol instance
show dvmrp prunes	Shows all active and transmitted DVMRP prunes
show dvmrp interfaces	Shows interfaces on which DVMRP is enabled
show multicast tunnels	Displays all multicast tunnels in use for either PIM or DVMRP
show multicast usage	Shows a list of the 10 most active DVMRP or PIM groups

15.6.8.2 MSDP

As with DVMRP, you can enable tracing for MSDP as follows:

 lab@Chicago# edit protocols msdp  [edit protocols msdp] lab@Chicago# set traceoptions file  filename  <replace> <size  size  > <files  number  > <no-stamp> lab@Chicago# set traceoptions flag  flag  <  flag-modifier  > <disable> 

In addition to enabling the tracing for MSDP globally, you can specify tracing for all peers in a group using the [edit protocols msdp group group-name] hierarchy, or for an individual peer using the [edit protocols msdp group group-name peer-address] hierarchy. Setting traceoptions for a group will override anything you set for a peer within that group. You can also add MSDP-specific flags that allow you to gather configurable output from the protocol. The flags used for MSDP are listed in Table 15-20.

The following example shows how to trace all MSDP sa packets. This example logs all traceoptions output to a file called msdp-trace .

 [edit protocols msdp]  lab@Chicago#  set traceoptions file  msdp-trace  lab@Chicago# set traceoptions  flag sa  

Table 15-20. MSDP traceoptions Flags

Flags	Descriptions
keepalive	Traces just the MSDP keepalive packets between peers
packets	Traces all MSDP packets
route	Traces only MSDP routing updates
sa	Traces source-active packets
sa-request	Traces source-active request packets only
sa-response	Traces responses to source-active requests

As you have seen with other protocols, show commands can be helpful in determining statistical information, current status, and cache entries. Table 15-21 lists the commands that are useful in troubleshooting MSDP:

Table 15-21. MSDP Troubleshooting Commands

Commands	Descriptions
clear msdp cache	Clears entries from the MSDP source-active cache
clear msdp statistics	Clears current MSDP statistics
show msdp	Gathers general information about MSDP; options include brief and detail (You can also execute this command for a single peer by specifying the qualifier peer followed by the peer address. Additional options include source-active <group originator source> to get specific information about entries in the sa queue.)
show msdp statistics	Provides information about all MSDP peers, or about a single peer, if you use the qualifier peer followed by the peer address
test msdp	Allows you to find downstream MSDP peers; options include the dependent-peer prefix to show downstream dependent MSDP peers or the rpf-peer originator to find the RPF peer for the identified originator

15.6.8.3 SAP/SDP

If your network is running videoteleconferencing and other multimedia conferences and presentations, you may use SAP/SDP in your network. There are no traceoptions capabilities for SAP/SDP, but you can take a look at the addresses to which the router is listening for multicast announcements by using the following command:

 User1@NewYork> show sap listen [brief  detail] 

The output of this command will show you both the address and the port to which the router is listening.

15.6.8.4 IGMP

IGMP is one of the oldest multicast protocols. It uses join and leave messages to indicate members entering or leaving the multicast group. In that respect, it is like a subscription-based service, sending information only to the members wishing to receive it. Tracing IGMP is similar to that in other protocols.

 lab@Chicago# edit protocols igmp  [edit protocols igmp] lab@Chicago# set traceoptions file  filename  <replace> <size  size  > <files  number  > <no-stamp> lab@Chicago# set traceoptions flag  flag  <  flag-modifier  > <disable> 

IGMP-specific flags for the traceoptions command are provided in Table 15-22. To see a complete list of flags available, press enter after typing set flag , and you will see a list of possible completions for the command.

Table 15-22. IGMP traceoptions Flags

Flags	Descriptions
leave	Traces IGMP group leave messages for IGMPv2 only
mtrace	Captures only mtrace packets
packets	Captures all IGMP packets
query	Show all membership queries to any group type
report	Captures group membership report messages

In the following example, you can see that we are going to trace all IGMP leave packets being sent. All traceoptions output is logged to a file called igmp-trace .

 [edit protocols igmp]  lab@Chicago#  set traceoptions file  igmp-trace  lab@Chicago# set traceoptions  flag leave send  

Table 15-23 lists other helpful commands you can use to troubleshoot IGMP problems.

Table 15-23. IGMP Troubleshooting Commands

Commands	Description
show igmp group	Displays information about all IGMP groups; you can get this output in brief or detail mode and specify a particular group name if you like
show/clear igmp interface	Allows you to show or clear information on one or all interfaces that are running IGMP
show/clear igmp statistics	Allows you to view or clear statistics for one or all IGMP-enabled interfaces

15.6.8.5 PIM

PIM is a popular multicast routing protocol because it is not dependent on a particular unicast protocol, such as IP. Whether you are running PIM-SM or PIM-DM, you can use the following commands to enable tracing:

 lab@Chicago# edit protocols pim  [edit protocols pim] lab@Chicago# set traceoptions file  filename  <replace> <size  size  > <files  number  > <no-stamp> lab@Chicago# set traceoptions flag  flag  <  flag-modifier  > <disable> 

Flags that can be used when tracing PIM output are shown in Table 15-24, along with a brief description of each.

Table 15-24. PIM traceoptions Flags

Flags	Description
assert	Captures assert messages used to discover which of the parallel routers is responsible for forwarding packets on a network
bootstrap	Traces Bootstrap packets sent out by the PIM (PIM-SM only) domain's designated Bootstrap router
cache	Captures packets in the PIM routing cache
graft	Traces both graft and graft-acknowledgment packets
hello	Captures all hello packets sent by the PIM routers to each other join Traces all join messages sent to multicast groups
packets	Traces all PIM packets on the network
prune	Captures prune messages only
register	Traces both register messages sent to the RP when a multicast source first starts communicating with a group and register-stop messages
rp	Captures candidate rp announcements

Here is an example of how to setup traceoptions for capturing all join packets received by a PIM-enabled router. All traceoptions output is logged to a file called pim-trace .

 [edit protocols pim]  lab@Chicago#  set traceoptions file  pim-trace  lab@Chicago# set traceoptions  flag join receive  

Table 15-25 lists additional commands that can be helpful in narrowing down a problem within PIM.

Table 15-25. PIM Troubleshooting Commands

Commands	Descriptions
show pim bootstrap	Shows the status and detail of the Bootstrap router in a PIM-SM domain; no optional qualifiers
show/clear pim join	Displays or clears information about PIM groups; options include brief , detail , and extensive , and you can also specify a range of groups to display by prefix/prefix-length
show pim interfaces	Displays the status of interfaces on which PIM is configured; no optional qualifiers
show pim neighbors	Displays brief or detail information about the status of PIM neighboring routers
show pim rps	Displays the status of PIM RPs; options include brief , detail , or extensive output, and output can be narrowed down to a single group-address
show pim source	Shows the status of the PIM RPF state; options include brief , detail , or extensive output, and output can also be narrowed down to a single range by using source-prefix
show pim wildcard	Displays (*,*.RP) RP join information; no optional parameters
show/clear pim statistics	Allows you to display or clear the statistics for all interfaces running PIM; a single interface can be specified by using interface interface-name
show multicast usage	Shows you a list of the 10 most active DVMRP or PIM groups
show multicast tunnels	Displays all multicast tunnels in use for either PIM or DVMRP