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Solaris route command

The Solaris route command enables manual manipulation of the route table. The syntax of the command is somewhat complicated:

route [-fn] add|delete|get [net|host|default] destination gateway

With keywords add and delete the default for optional [net|host|default] troika is host.

Here are some examples that might help to learn the intricacies of the command: 

• Add a route
  # route add net 128.50.3.0 tuna
   
• Add a default route [host|net] dest. [ gateway]
  # route add default tomato 1
   
• Delete a route
  # route delete net 128.50.3.0 sword-r
  
  
• Lookup and display the route for a destination:
  # route get 128.50.2.0
  
  
• Get routing reports continuously
  # route monitor
  
  
• Flush the routing table:
  # route flush
  
  
• Add the multicast path for 224.0.0.0:
  # route add 224.0.0.0 `uname -n` 0
  
  
• Use the "route add net" command with the -netmask option to make the route command to take the netmask specified on the command line
  
  # route add net 192.168.68.0 128.50.1.250 1 -netmask 255.255.255.192

Note 1: The metric between two machines increases by one each time a new router (gateway) is encountered in the path. RIP automatically chooses the path with the lowest metric. The metric information for a path is kept in the kernel's routing table in cache.

Note 2: When deleting entries from or flushing the routing table, the process in. routed stops listening for RIP broadcasts but continues listening for RDISC advertisements. This freezes the current table. The appropriate process must be manually restarted to have it continue listening for RIP broadcasts.

Specifing default route with /etc/defaultrouter

A default route is a route table entry that allows a host to define default routers to use if no other specific route is available. The default routers must be reliable. There is no need to define every reachable network. All indirectly connected packet destinations go to the default router.

A default router is identified by entries in /etc/defaultrouter.  It contains hostname or IP address entries that correspond to one or more routers. Upon rebooting, this prevents the startup script (/etc/rc2.d/S69inet) from launching the in.routed and in.rdisc dynamic router processes. Default route table entries may also be added by the in.rdisc daemon.

Advantages of default routing are:

• The /etc/defaultrouter file prevents additional routing processes from starting.
  
• A default route is suitable when only one router is used to reach all indirectly connected destinations.
  
• A single default route entry results in a smaller routing table.
  
• Multiple default routers can be identified, which eliminate single points of failures within a network.
  
• A default route can run other routing protocols on the route.

Disadvantages of default routing:

• The default entry is always present, even when the default router is shut down. The host does not learn about other possible paths.
  
• All systems must have the /etc/defaultrouter file configured. This may be a problem on large, evolving networks.
  
• ICMP redirects occur if more than one router is available to a host.

Quiz

Q1. Which command will manipulate the routing table ?

 A: route

 Q2: Command to add a route to server1 via router1:

 A: route add host server1 router1

Q3. Which command will add a route to the network 128.251.0.0 via 128.144.1.254 ?

 A: route add net 128.251.0.0 128.144.1.254

Q4. Which command would delete a route to host server1 via router1 ?

 A: route delete host server1 router1

Q5. Which command will delete the route to the network 128.251.0.0 via 128.144.1.254 ?

 A: route delete net 128.251.0.0 128.144.1.254

Q6. Which command will remove all entries from the routing table ?

 A: route flush

Q7. Which command allows you to monitor the routing requests that are not getting resolved from the routing table ?

 A7: route monitor

Last modified: February 28, 2008