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 maintaining 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 packets. If the host is an internetwork router, it periodically supplies copies of its routing tables to any directly connected hosts and networks. The daemon can be administrated by a utility rip6admin(8). Another 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 transmits 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 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, 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 invalidation 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 networks. The response is sent to the all router multicast address on attached 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 ALSO
rip6admin(8), rip6query(8), routed(8)