Dongkee LEE ([email protected]) 1 An Analysis of BGP Multiple Origin AS (MOAS) Conflicts...
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Dongkee LEE ([email protected]) 1 An Analysis of BGP Multiple An Analysis of BGP Multiple Origin AS (MOAS) Conflicts Origin AS (MOAS) Conflicts Xiaoliang Zhao, et al.
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Transcript of Dongkee LEE ([email protected]) 1 An Analysis of BGP Multiple Origin AS (MOAS) Conflicts...
Dongkee LEE ([email protected]) 1
An Analysis of BGP Multiple An Analysis of BGP Multiple Origin AS (MOAS) ConflictsOrigin AS (MOAS) Conflicts
Xiaoliang Zhao, et al.
Dongkee LEE ([email protected]) 2
Overview.Overview.
Motivation Classifications of MOAS conflicts.
Results
Possible explanations for MOAS.
Dongkee LEE ([email protected]) 3
MotivationMotivation
The last AS in an AS path should be the origin of the BGP routes.
Suppose prefix ‘d’ is associated with AS paths, asp1 = (p1, p2, … pn), asp2 = (p1, p2, … pm)If pn != qm :
MOAS conflict occurs.
MOAS could be the result of a ‘fault’ or an ‘attack’. What are the reason for MOAS conflicts and
What are the impacts ?”
Dongkee LEE ([email protected]) 4
Classification of MOASClassification of MOAS
prefix ‘d’, asp1 = (p1, p2, … pn), asp2 = (p1, p2, … pm)
OrigTranAS: pn = qj (j < m)
AS Pn announces itself as the origin AS and as a transit AS.
SplitView: pi = qj (i < n, j < m)
AS Pi announces different routes to different neighbors.
DistinctPaths: pn = qj (for all i in [1..n], j in [1..m] )
There are two totally different routes for the prefix ‘d’.
Dongkee LEE ([email protected]) 5
Results Results
Oregon RouteViews data.
Total Number of MOAS Conflicts.Overall 38225 conflicts were observed over 1279 days.
Duration of MOAS Conflicts.
10177 conflicts
Dongkee LEE ([email protected]) 8
Causes of MOAS conflicts – Causes of MOAS conflicts – (1) (1) Exchange Point Addresses.
Prefix associated with an exchange point is directly reachable from all the ASes, at the exchange point.
30 out of 38225 prefixes.
Multi-homing without BGP.
AS 4128.9/16
AS 11422
AS 226
128.9/16path: 4
Static Route
128.9/16path: 11422, 4
128.9/16path: 226
Dongkee LEE ([email protected]) 9
Causes of MOAS conflicts – Causes of MOAS conflicts – (2) (2) Multi-homing with Private AS Numbers.
AS number Substitution on Egress (ASE).
Anycast addresses. Anycast address is intended to originate from multiple ASes.
Faulty or Malicious Configurations.
AS64512131.79/16
AS X
AS Y
131.79/16path: 64512 131.79/16
path: X
131.79/16path: Y
131.79/16path: 64512
