02-21-2009 01:33 AM - edited 03-06-2019 04:09 AM
HELLO
in BGP WHAT IS THE WELL KNOWN AND NOT WELL KNOWN ATTRIBUTS?
IN FACT I REMEBERE..MED-ATOMIC AGGGRAGETOE-AS-PATH -AGGRAEETOR
THANKS
02-21-2009 01:56 AM
Hello Ali,
a well known mandatory attribute is an attribute that every implementation has to support.
BGP next hop, AS path, origin code
an optional attribute is instead an attribute that may be implemented
there are
well-known mandatory
well-known discretionary
optional transitive
optional non transitive
attributes
see
http://www.ietf.org/rfc/rfc1771.txt')">http://www.ietf.org/rfc/rfc1771.txt
section 4.3
Hope to help
Giuseppe
02-21-2009 03:09 AM
hello
the atomic-aggregator is not well known?
can i have ur e-mail?
thanks
02-21-2009 03:16 AM
Hello Ali,
I found a table
Table 2-5. Path Attributes[*]
Attribute Class
ORIGIN Well-known mandatory
AS_PATH Well-known mandatory
NEXT_HOP Well-known mandatory
LOCAL_PREF Well-known discretionary
ATOMIC_AGGREGATE Well-known discretionary
AGGREGATOR Optional transitive
COMMUNITY Optional transitive
MULTI_EXIT_DISC (MED) Optional nontransitive
ORIGINATOR_ID Optional nontransitive
CLUSTER_LIST Optional nontransitive
atomic-aggregate and aggregator are actually two distinct attributes:
ATOMIC_AGGREGATE is a well-known discretionary attribute that is used to alert downstream routers
that a loss of path information has occurred.
When the ATOMIC_AGGREGATE attribute is set, the BGP speaker has the option of also attaching the
AGGREGATOR attribute. This optional transitive attribute provides information about where the
aggregation was performed by including the AS number and the IP address of the router that
originated the aggregate route
both help to provide advice about a BGP route summarization that occurred, the AS path attribute of the summary route is/can be different then that of the component prefixes
Hope to help
Giuseppe
02-21-2009 04:32 AM
Giuseppe,
Just one precision. RFC1771 has been superseded by RFC4271.
Regards
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