core gateway
The innermost gateways of the ARPAnet. These
gateways have a total picture of the reacha-
bility to all networks known to the ARPAnet
with EGP. They then redistribute reachabil-
ity information to all those gateways speak-
ing EGP. It is from them your EGP agent
(there is one acting for you somewhere if you
can reach the ARPAnet) finds out it can reach
all the nets on the ARPAnet. Which is then
passed to you via Hello, gated, RIP....
count to infinity
The symptom of a routing problem where
routing information is passed in a circular
manner through multiple gateways. Each gate-
way increments the metric appropriately and
passes it on. As the metric is passed around
the loop, it increments to ever increasing
values til it reaches the maximum for the
routing protocol being used, which typically
denotes a link outage.
hold down
When a router discovers a path in the network
has gone down announcing that that path is
down for a minimum amount of time (usually at
least two minutes). This allows for the pro-
pagation of the routing information across
the network and prevents the formation of
routing loops.
split horizon
When a router (or group of routers working in
consort) accept routing information from mul-
tiple external networks, but do not pass on
information learned from one external network
to any others. This is an attempt to prevent
bogus routes to a network from being propagated
because of gossip or counting to infinity.
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