ASpath-tree is a tool to perform IPv6 network operation analysis based on the snapshot of the BGP routing table on IPv6 routers running BGP. Originally ASpath-tree was designed to be used by an IPv6 site involved in the experimentation of the BGP protocol inside the 6Bone network, it now supports a set of features useful within any operational IPv6 network, which makes use of BGP.
The tool currently supports Cisco/Juniper/Zebra routers. Based on a single snapshot of the IPv6 BGP table, ASpath-tree automatically generates a set of html pages providing a graphical view of the routing paths towards the other IPv6 connected domains. Additionally it provides pages for the detection of anomalous route entries announced through BGP (invalid prefixes and unaggregated prefixes), anomalous AS numbers (i.e. reserved or private) in use and a set of summary information such as:
• The number of route entries (valid/total/suppressed/damped/history)
• The number of AS in table (total, originating only, originating/transit, transit only, private and reserved)
• The number of active AS paths
• The number of active BGP neighbours (i.e. announcing routing information)
• An analysis of the network size, in terms of AS distances
• The number of circulating prefixes (total, 6Bone pTLAs, sTLAs, 6to4, others)
Based on repeated snapshots of the IPv6 BGP table at different points in time, ASpath-tree automatically generates html pages reporting on BGP routing stability (last 24 hours) for:
• 6Bone pTLAs
• RIR’s assigned prefixes
ASpath-tree is not a tool that monitors BGP peerings in the way that it does not send any kind of notification when peerings go down or up or when the number of routes received from a given peering is critical (too low or too large). Therefore it cannot be used for continuous operational monitoring of the routing in the network.
On the other hand, ASpath-tree is very useful to check that the routing table of the network matches the routing policy. It helps a lot for network routing engineering. It makes it possible for a network administrator to clearly see what is the routing map and if the announcements are coherent. In this period of IPv6 deployment, while more and more sites are moving to IPv6, network administrators have to check their routing policy frequently to be sure it is optimal.
Examples of implementations in 6NET:
6NET backbone: http://6nettools.dante.net/ASpath-tree/bgp.html (version3.3)
CERN: http://www-ipv6.cern.ch/ASpath-tree-v3_3/htdocs/bgp/bgp.html (version 3.3)
NIIF/HUNGARNET: http://6net.iif.hu/6netaspathtree/ (version 4.2)
JOIN/DFN: http://www.join.uni-muenster.de/bgp/bgp.html (version 4.1)
SWITCH: http://www.switch.ch/network/ipv6/bgp/ (version 3.3)
UNINETT: http://drift.uninett.no/ipv6/bgp/bgp.html (version 4.1)
RENATER: http://supervision-ipv6.renater.fr (for both IPv6 unicast and IPv6 multicast BGP trees)
PSCN: http://www.ipv6.man.poznan.pl/ (version 4.1.)