HROUTE6D(8) BSD System Manager's Manual HROUTE6D(8)NAME
hroute6d - network routing daemon for IPv6 networks
SYNOPSIS
hroute6d
DESCRIPTION
Hroute6d is invoked at boot time to manage the network routing tables.
The routing daemon is a variant of routing daemon for IPv4 networks and
uses a variant of the Xerox NS Routing Information Protocol in maintain-
ing up to date kernel routing table entries. It reads the configuration
information from a configuration file (see hroute6d.conf(5)).
hroute6d listens on the udp(4) socket for the routing information pack-
ets. If the host is an internetwork router, it periodically supplies
copies of its routing tables to any directly connected hosts and net-
works. The daemon can be administrated by a utility rip6admin(8). Anoth-
er utility rip6query(8) can be used to get all or some routes known by a
RIPng router.
When hroute6d is started, it uses the sysctl(3) to find those directly
connected interfaces configured with IPv6 addresses into the system and
marked ``up'' (the loopback interface is ignored). Hroute6d then trans-
mits a request packet on each interface (using a multicast 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, hroute6d 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.
Response packets received by hroute6d are used to update the routing ta-
bles 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 ex-
isting 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, hroute6d records the change in its internal
tables and updates the kernel routing table. The change is reflected in
the next response packet sent.
In addition to processing incoming packets, hroute6d 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 deletion.
Deletions are delayed an additional 120 seconds to insure the invalida-
tion is propagated throughout the local internet.
Hosts acting as internetwork routers gratuitously supply their routing
tables every 30 (+/- 15) seconds to all directly connected hosts and net-
works. The response is sent to the all router multicast address on at-
tached interfaces. If no response is received on an interface, another
route may be chosen to route around the interface, or the route may be
dropped if no alternative is available.
FILES
/usr/local/v6/etc/hroute6d.conf for configuration file
SEE ALSOrip6admin(8), rip6query(8), routed(8)
KAME March 25, 1997 2