Practical Request for BGP Specification and Implementation

1
Practical Request for BGP Specification and
Implementation

• Kenichi Nagami (Intec NetCore / WIDE Project)
• Yasuhiro Ohara (JAIST / WIDE Project)
• Akira Kato (Keio Univ. / WIDE Project)

2
Motivation (BGP incident)

• This incident happened on December, 2007.
• A Latin American ISP sent a prefix with type 0
  attribute.
• Then a Japanese ISP lost many BGP sessions to
  their upstream ISPs.
• This incident happened because of the difference
  in implementations
• Some routers shutdown the BGP session when it
  receives a type 0 attribute
• Others don't just simply pass the attribute to
  the neighbors
• BGP specification (RFC 4271) says For
  well-known attributes, the Transitive bit MUST be
  set to 1. But, this route has well-known and
  non-transitive (Transitive bit 0).

An AS injected a route with type 0 attribute
Different router
All intermediate routers sent the route with type
0 attribute
Some router shutdown the BGP session. Then
Internet connectivity was lost in this ISP.
3
Operators Requirements and Proposal

• Operators Requirements
• Operators do not want to shutdown the BGP session
  unless absolutely necessary for stability of
  connection.
• Proposal
• To avoid shutdown of a BGP session in a
  non-serious error
• We need to define non-serious errors
• We need to define a behavior when it occurs
• logs it, anyway
• ignore the attribute or ignore the prefixes
  associated with it
• operators are happy if a behavior is configurable
  
• The BGP specification needs additional
  clarification
• For example, the BGP specification need to
  clarify or add the UPDATE Message Error Handling
  (Section 6.3) about type 0 attribute.