dokucama

OUTPUT OF BGP TABLE (triplet and parenthesis meaning):
show ip bgp <prefix>
x.x.x.x from y.y.y.y (RID)

• x.x.x.x: next hop to reach the destination
• y.y.y.y IP address of the router's interface who sent the update.
• RID: router-id of the spoke sending the update

Listing all routes and filtering on AS-PATH:

show ip bgp regexp ^$ # test this w/ internal networks

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ASN PREPENDING

ip as-path access-list 1 permit ^$    # this indicates my own local routes
route-map BGP100_SANTANDER_TO_BGP200_FR01_DMZR01_GRE permit 10
 match ip address prefix-list BGP100_SANTANDER_GRE_TO_ALL_SITES
 set as-path prepend 65103 65103 65103 65103 65103 # 

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PATH HUNTING

• Undesired phenomeda. Happens because BGP is, by definition, unaware of the topology
• During convergence, BGP will hunt for another path andn happily advertises these paths to peers even though the path is through the peer itself. External Link