HP-UX Reference (11i v1 05/09) - 4 File Formats (vol 8)

g
gated.conf(4) gated.conf(4)
other Any other type of packet. The only valid ones are TRACE_ON and TRACE_OFF both of
which are ignored.
The Hello Protocol
It is really better not to use HELLO unless you have a specific need for it. We plan to drop it some time
around GateD 4.0.
The HELLO protocol is an interior protocol that uses a routing metric based on the length of time it takes a
packet to make the trip between the source and the destination. HELLO packets carry timestamp informa-
tion which allows receivers to compute the shortest delay paths to destinations. The "best" route is the
route with the shortest time delay. The unit of time used in HELLO is milliseconds. If a HELLO update
packet takes less than 100 milliseconds to travel between two routers, a minimum value of 100 is used for
that hop. Thus on networks built of high-speed interfaces HELLO essentially defaults to using hop counts.
As in any routing algorithm, HELLO cannot change routes too rapidly or it would be unstable. To avoid
instabilities, implementations of HELLO build in hysteresis and "hesitate" to change routes until they have
confidence that the change will be lasting.
By default HELLO, like RIP, uses the kernel interface metric set by the ifconfig command to influence
metric added to routes as they are installed in the routing table (metricin). Since the kernel interface
metric is in hops, it must be translated into HELLOs millisecond metric. In order to do that, the following
table is used:
Hops HELLO metric
00
1 100
2 148
3 219
4 325
5 481
6 713
7 1057
8 1567
9 2322
10 3440
11 5097
12 7552
13 11190
14 16579
15 24564
16 30000
HELLO and network masks
HELLO derives the network mask of received networks and hosts from the network mask of the interface
the packet via which the packet was received. If a received network or host is on the same natural network
as the interface over which it was received and that network is subnetted (the specified mask is more
specific than the natural netmask), the subnet mask is applied to the destination. If bits outside the mask
are set, it is assumed to be a host. Otherwise it is assumed to be a subnet.
On point-to-point interfaces, the netmask is applied to the remote address. The netmask on these interfaces
is ignored if it matches the natural network of the remote address or is all ones.
Unlike in previous releases, the zero subnet mask (a network that matches the natural network of the
interface, but has a more specific, or longer, network mask) is ignored. If this is not desirable, a route filter
may be used to reject it.
The Hello Statement
hello yes | no | on | off [ {
broadcast ;
nobroadcast ;
preference preference ;
defaultmetric metric ;
interface interface_list
[nohelloin]|[helloin]
[nohelloout]|[helloout]
[metricin metric]
HP-UX 11i Version 1: September 2005 − 16 − Hewlett-Packard Company Section 4−−85