unixdev.net


Switch to SpeakEasy.net DSL

The Modular Manual Browser

Home Page
Manual: (HP-UX-11.11)
Page:
Section:
Apropos / Subsearch:
optional field



 route(1M)							   route(1M)




 NAME
      route - manually manipulate the routing tables

 SYNOPSIS
      /usr/sbin/route [-f] [-n] [-p pmtu] add [net|host] destination
	   [netmask mask] gateway [count]

      /usr/sbin/route [-f] [-n] delete [net|host] destination
	   [netmask mask] gateway [count]

      /usr/sbin/route -f [-n]

 DESCRIPTION
      The route command manipulates the network routing tables manually.
      You must have appropriate privileges.

    Subcommands
      The following subcommands are supported.

	   add		  Add the specified host or network route to the
			  network routing table.  If the route already
			  exists, a message is printed and nothing changes.

	   delete	  Delete the specified host or network route from
			  the network routing table.

    Options and Arguments
      route recognizes the following options and arguments.

	   -f		  Delete all route table entries that specify a
			  remote host for a gateway.  If this is used with
			  one of the subcommands, the entries are deleted
			  before the subcommand is processed.

	   -n		  Print any host and network addresses in Internet
			  dot notation, except for the default network
			  address, which is printed as default.

	   -p pmtu	  Specifies a path maximum transmission unit (MTU)
			  value for a static route.  The minimum value
			  allowed is 68 bytes; the maximum is the MTU of the
			  outgoing interface for this route.  This option
			  can be applied to both host and network routes.

	   net		  The type of destination address.  If this argument
	    or		  is omitted, routes to a particular host are
	   host		  distinguished from those to a network by
			  interpreting the Internet address associated with
			  destination.	If the destination has a local
			  address part of INADDR_ANY(0), the route is
			  assumed to be to a network; otherwise, it is



 Hewlett-Packard Company	    - 1 -   HP-UX Release 11i: November 2000






 route(1M)							   route(1M)




			  treated as a route to a host.

	   destination	  The destination host system where the packets will
			  be routed.  destination can be one of the
			  following:

			       +  A host name (the official name or an
				  alias, see gethostent(3N)).
			       +  A network name (the official name or an
				  alias, see getnetent(3N)).
			       +  An Internet address in dot notation (see
				  inet(3N)).
			       +  The keyword default, which signifies the
				  wildcard gateway route (see routing(7)).

	   netmask
	   mask		  The mask that will be bit-wise ANDed with
			  destination to yield a net address where the
			  packets will be routed.  mask can be specified as
			  a single hexadecimal number with a leading 0x,
			  with a dot-notation Internet address, or with a
			  pseudo-network name listed in the network table
			  (see networks(4)).  The length of the mask, which
			  is the number of contiguous 1's starting from the
			  leftmost bit position of the 32-bit field, can be
			  shorter than the default network mask for the
			  destination address. (see routing(7)).  If the
			  netmask option is not given, mask for the route
			  will be derived from the netmasks associated with
			  the local interfaces. (see ifconfig(1M)).  mask
			  will be defaulted to the longest netmask of those
			  local interfaces that have the same network
			  address.  If there is not any local interface that
			  has the same network address, then mask will be
			  defaulted to the default network mask of
			  destination.

	   gateway	  The gateway through which the destination is
			  reached.  gateway can be one of the following:

			       +  A host name (the official name or an
				  alias, see gethostent(3N)).
			       +  An Internet address in dot notation (see
				  inet(3N)).

	   count	  An integer that indicates whether the gateway is a
			  remote host or the local host.  If the route leads
			  to a destination through a remote gateway, count
			  should be a number greater than 0.  If the route
			  leads to destination and the gateway is the local
			  host, count should be 0.  The default for count is



 Hewlett-Packard Company	    - 2 -   HP-UX Release 11i: November 2000






 route(1M)							   route(1M)




			  zero.	 The result is not defined if count is
			  negative.

    Operation
      All symbolic names specified for a destination or gateway are looked
      up first as a host name using gethostbyname(); if the host name is not
      found, the destination is searched for as a network name using
      getnetbyname().  destination and gateway can be in dot notation (see
      inet(3N)).

      If the -n option is not specified, any host and network addresses are
      displayed symbolically according to the name returned by
      gethostbyaddr() and getnetbyaddr(), respectively, except for the
      default network address (printed as default) and addresses that have
      unknown names.  Addresses with unknown names are printed in Internet
      dot notation (see inet(3N)).

      If the -n option is specified, any host and network addresses are
      printed in Internet dot notation except for the default network
      address which is printed as default.

      If the -f option is specified, route deletes all route table entries
      that specify a remote host for a gateway.	 If it is used with one of
      the subcommands described above, the entries are deleted before the
      subcommand is processed.

      Path MTU Discovery is a technique for discovering the maximum size of
      an IP datagram that can be sent on an internet path without causing
      datagram fragmentation in the intermediate routers.  In essence, a
      source host that utilizes this technique initially sends out datagrams
      up to the the size of the outgoing interface.  The Don't Fragment (DF)
      bit in the IP datagram header is set.  As an intermediate router that
      supports Path MTU Discovery receives a datagram that is too large to
      be forwarded in one piece to the next-hop router and the DF bit is
      set, the router will discard the datagram and send an ICMP Destination
      Unreachable message with a code meaning "fragmentation needed and DF
      set".  The ICMP message will also contain the MTU of the next-hop
      router.  When the source host receives the ICMP message, it reduces
      the path MTU of the route to the MTU in the ICMP message.	 With this
      technique, the host route in the source host for this path will
      contain the proper MTU.

      The -p pmtu option is useful only if you know the network environment
      well enough to enter an appropriate pmtu for a host or network route.
      IP will fragment a datagram to the pmtu specified for the route on the
      local host before sending the datagram out to the remote.	 It will
      avoid fragmentation by routers along the path, if the pmtu specified
      in the route command is correct.

      ping can be used to find the pmtu information for the route to a
      remote host.  The pmtu information in the routing table can be



 Hewlett-Packard Company	    - 3 -   HP-UX Release 11i: November 2000






 route(1M)							   route(1M)




      displayed with the netstat -r command (see netstat(1)).

      The loopback interface (lo0) is automatically configured when the
      system boots with the TCP/IP software. The default IP address and
      netmask of the loopback interface are 127.0.0.1 and 255.0.0.0,
      respectively.

      The 127.0.0.0 loopback route is set up automatically when lo0 is
      configured so that packets for any 127.*.*.* address will loop back to
      the local host. Users cannot add or delete any 127.*.*.* loopback
      routes.

    Output
      add destination: gateway gateway

	   The specified route is being added to the tables.

      delete destination: gateway gateway

	   The specified route is being deleted from the tables.

    Flags
      The values of the count and destination type fields in the route
      command determine the presence of the G and H flags in the netstat -r
      display and thus the route type, as shown in the following table.

	   Count   Destination Type   Flags		Route Type
	   _________________________________________________________________
	    =0	       network	       U      Route to a network directly
					      from the local host
	    >0	       network	       UG     Route to a network through a
					      remote host gateway
	    =0		 host	       UH     Route to a remote host
					      directly from the local host
	    >0		 host	       UGH    Route to a remote host through
					      a remote host gateway
	    =0	       default	       U      Wildcard route directly from
					      the local host
	    >0	       default	       UG     Wildcard route through a
					      remote host gateway
	   _________________________________________________________________

 DIAGNOSTICS
      The following error diagnostics can be displayed:

	   add a route that already exists

      The specified entry is already in the routing table.

	   delete a route that does not exist




 Hewlett-Packard Company	    - 4 -   HP-UX Release 11i: November 2000






 route(1M)							   route(1M)




      The specified route was not in the routing table.

	   cannot update loopback route

      Routes for any 127.*.*.* loopback destination cannot be added or
      deleted.

 WARNINGS
      Reciprocal route commands must be executed on the local host, the
      destination host, and all intermediate hosts if routing is to succeed
      in the cases of virtual circuit connections or bidirectional datagram
      transfers.

      The HP-UX implementation of route does not presently support a change
      subcommand.

 AUTHOR
      route was developed by the University of California, Berkeley.

 FILES
      /etc/networks
      /etc/hosts

 SEE ALSO
      netstat(1), ifconfig(1M), ping(1M), ndd(1M), getsockopt(2), recv(2),
      send(2), gethostent(3N), getnetent(3N), inet(3N), routing(7).




























 Hewlett-Packard Company	    - 5 -   HP-UX Release 11i: November 2000