NAME

routed − network routing daemon

USAGE

/etc/routed [ −s ] [ −q ] [ −t ] [ logfile ]

DESCRIPTION

Routed is started at boot time to manage the network routing tables.  The routing daemon uses a variant of the Xerox NS Routing Information Protocol to maintain up-to-date kernel routing table entries. 

In normal operation, routed listens on number socket 520 (decimal) for routing information packets.  If the host is an internetwork router, it periodically supplies copies of its routing tables to any directly connected hosts and networks. 

When routed is started, it uses the SIOCGIFCONF ioctl to find those directly connected interfaces configured into the system and marked “up” (the software loopback interface is ignored).  If multiple interfaces are present, the host will forward packets between networks.  Routed then transmits a request packet on each interface (using a broadcast packet if the interface supports it) and enters a loop, listening for request and response packets from other hosts. 

When a request packet is received, routed formulates a reply based on the information maintained in its internal tables.  The response packet generated contains a list of known routes, each marked with a “hop count” metric (a count of 16, or greater, is considered “infinite”)  The metric associated with each route returned provides a metric relative to the sender. See route(8C). 

Response packets received by routed are used to update the routing tables if one of the following conditions is satisfied:

(1) No routing table entry exists for the destination network or host, and the metric indicates the destination is “reachable” (i.e., the “hop count” is not infinite). 

(2) The source host of the packet is the same as the router in the existing routing table entry.  That is, updated information is being received from the very internetwork router through which packets for the destination are being routed. 

(3) The existing entry in the routing table has not been updated for some time (defined to be 90 seconds) and the route is as efficient as the current route. 

(4) The new route describes a shorter route to the destination than the one currently stored in the routing tables; to decide this, the metric of the new route is compared against the one stored in the table. 

When an update is applied, routed records the change in its internal tables and generates a response packet to all directly connected hosts and networks.  Routed waits a short period of time (no more than 30 seconds) before modifying the kernel’s routing tables; this allows possible unstable situations to settle. 

In addition to processing incoming packets, routed also checks the routing table entries periodically.  If an entry has not been updated for 3 minutes, the entry’s metric is set to infinity and marked for deletion.  Deletions are delayed an additional 60 seconds to ensure that the invalidation is propagated throughout the internet. 

Hosts acting as internetwork routers supply their routing tables every 30 seconds to all directly connected hosts and networks. 

In addition to the facilities described above, routed supports the notion of “distant” passive and active gateways.  When routed is started up, it reads the file /etc/gateways to find gateways which may not be identified using the SIOGIFCONF ioctl. Gateways specified in this manner should be marked passive if they are not expected to exchange routing information, while gateways marked active should be willing to exchange routing information (i.e., they should have a routed process running on the machine).  Passive gateways are maintained in the routing tables forever and information about them is included in any routing information transmitted.  Active gateways are treated like network interfaces.  Routing information is distributed to the gateway.  If no routing information is received for a period of time, the associated route is deleted. 

The /etc/gateways file is made up of a series of lines, each in the following format:

< net | host > name1 gateway name2 metric value < passive | active >

The net or host keyword indicates if the route is to a network or specific host. 

Name1 is the name of the destination network or host.  This may be a symbolic name located in /etc/networks or /etc/hosts, or an Internet address specified in “dot” notation; see inet(3N). 

Name2 is the name or address of the gateway to which messages should be forwarded. 

Value is a metric indicating the “hop count” to the destination host or network. 

The keyword passive or active indicates if the gateway should be treated as passive or active (as described above). 

OPTIONS

−s forces routed to supply routing information whether it is acting as an internetwork router or not. 

−q is the opposite of the −s option. 

−t prints a list of all packets sent or received, on the standard output. 

In addition, routed will not divorce itself from the controlling terminal, so that interrupts from the keyboard will kill the process.  Logfile is interpreted as the name of a file in which routed’s actions should be logged.  This log will contain information about any changes to the routing tables and a history of recent messages sent and received which are related to the changed route. 

NOTES

The kernel’s routing tables may not correspond to those of routed for short periods of time while processes that are using existing routes exit; the only remedy for this is to place the routing process in the kernel. 

Routed does not currently listen to intelligent interfaces, such as an IMP, or to error protocols, such as ICMP, to gather more information. 

NOTES TO DOMAIN/IX USERS

Routed is normally started on a node at boot time, by executing the run_rc command.  Uncomment the appropriate lines in the /etc/rc file.  You will run the routed daemon only on nodes connected directly to an Ethernet. 

For a node to run routed, it must be correctly configured to run DOMAIN/IX TCP/IP.  See System Administration for DOMAIN/IX bsd4.2 for information on configuring TCP/IP. 

The version of DOMAIN TCP/IP available at SR9.5 includes a slightly different version of routed that supports the new subnet facility.  There are no changes in the way the command appears to the user. 

FILES

/etc/gateways for distant gateways

RELATED INFORMATION

rc(8) run_rc(8) route(8C) “Internet Transport Protocols”, XSIS 028112, Xerox System Integration Standard.