XNSROUTED(8)XNSROUTED(8)NAMEXNSrouted - NS Routing Information Protocol daemon
SYNOPSISXNSrouted [ -s ] [ -q ] [ -t ] [ logfile ]
DESCRIPTIONXNSrouted is invoked at boot time to manage the Xerox NS routing
tables. The NS routing daemon uses the Xerox NS Routing Information
Protocol in maintaining up to date kernel routing table entries.
In normal operation XNSrouted listens for routing information packets.
If the host is connected to multiple NS networks, it periodically sup‐
plies copies of its routing tables to any directly connected hosts and
networks.
When XNSrouted 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, it is assumed the host will forward packets
between networks. XNSrouted 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, XNSrouted 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 ``infi‐
nite''). The metric associated with each route returned provides a
metric relative to the sender.
Response packets received by XNSrouted 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 at least
as cost effective as the current route.
(4) The new route describes a shorter route to the destination than
the one currently stored in the routing tables; the metric of
the new route is compared against the one stored in the table to
decide this.
When an update is applied, XNSrouted 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 to allow possible
unstable situations to settle.
In addition to processing incoming packets, XNSrouted also periodically
checks the routing table entries. If an entry has not been updated for
3 minutes, the entry's metric is set to infinity and marked for dele‐
tion. Deletions are delayed an additional 60 seconds to insure the
invalidation is propagated to other routers.
Hosts acting as internetwork routers gratuitously supply their routing
tables every 30 seconds to all directly connected hosts and networks.
Supplying the -s option forces XNSrouted to supply routing information
whether it is acting as an internetwork router or not. The -q option
is the opposite of the -s option. If the -t option is specified, all
packets sent or received are printed on the standard output. In addi‐
tion, XNSrouted will not divorce itself from the controlling terminal
so that interrupts from the keyboard will kill the process. Any other
argument supplied is interpreted as the name of file in which
XNSrouted's actions should be logged. This log contains information
about any changes to the routing tables and a history of recent mes‐
sages sent and received which are related to the changed route.
SEE ALSO
``Internet Transport Protocols'', XSIS 028112, Xerox System Integration
Standard.
idp(4)4.3 Berkeley Distribution June 24, 1990 XNSROUTED(8)
