Summary
275
KEEPALIVE Message
B
GP neighbors use a KEEPALIVE message to confirm that the con-
nection between the neighbors is still active. A BGP speaker sends a KEE-
PALIVE to each peer, usually at an interval of one-third of the agreed hold
time, which is no more than once per second. If an UPDATE message is not
sent during the established hold time, a KEEPALIVE message is sent in its
place. A KEEPALIVE message consists only of a 19-byte header and can be
turned off by setting the hold time to zero.
Summary
T
his chapter focused on BGP terminology and the basics components
of BGP. Let's quickly review what this chapter covered:
Autonomous systems, which are used to identify routers operating in
a common network.
Transit autonomous systems, which are between two autonomous
systems.
7
AS routing loop or looping prefix error
8
Invalid NEXT_HOP prefix
9
Optional attribute error
10
Invalid network field when processing a prefix update
11
Error encountered processing the AS_PATH attribute
T A B L E 7 . 8
Error Subcodes for UPDATE Message Errors (continued)
Code
Number
Type
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