No single current routing protocol is suitable: an EGP could be used as an IGP, but this would be very inefficient. IGPs are not suitable as EGPs as they don't support the required features.
Experimental. This involves talking to people! Some amount of sniffing network traffic using tcpdump might reveal routing packets going past, but this is unlikely for end-user machines on a switched network.
Many implementations exist, but it is much more educational to implement this kind of thing yourself.
Links. Bellman-Ford is more general than Dijkstra—it will work on networks with negative edge costs—but such kinds of costs are unlikely in real networks. As Dijkstra is faster when it applies, it is usually preferred.
The whois tool sometimes gives the AS for an IP address. If not, try whois -h riswhois.ripe.net <address>
The allocation table of AS numbers tells you which regional registry owns which AS
Combining this with traceroute will allow you to map transits between ASs.
There are many. The simplest being that a router insert routes into the Network that direct traffic to come via itself, thus making it readable as it goes past. Other kinds of attack include denial of service, where a router attracts traffic and then refuses to pass it on.
Multicast routing involves building trees across routers with the root at the source and the leaves at the destinations. These trees change rapidly as hosts join and leave groups. Care must be taken not to create loops. Protocol Independent Routing (PIM) employs normal unicast routing, but in reverse. A multicast packet has a unicast source address: unicast routing tells us where this packet came from, so PIM can forward the packet to the other interfaces.
PIM can run in
or a combination of the two. Other dense mode protocols are RFC1075 (an extension to RIP) and RFC1584 (an extension to OSPF), but these do not scale as well.
In source specific routing the host's request to join a group contains the source's unicast address and routers build a reverse path as the request passes upstream RFC3569
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