Search results
Results from the WOW.Com Content Network
ping is a computer network administration software utility used to test the reachability of a host on an Internet Protocol (IP) network. It is available for virtually all operating systems that have networking capability, including most embedded network administration software.
The routing metric used by RIP counts the number of routers that need to be passed to reach a destination IP network. The hop count 0 denotes a network that is directly connected to the router. 16 hops denote a network that is unreachable, according to the RIP hop limit. [4]
When the UDP mode is used, MTR relies on ICMP port unreachable packets (type 3, code 3) when the destination is reached. MTR also supports IPv6 and works in a similar manner but instead relies on ICMPv6 messages. The tool is often used for network troubleshooting.
Destination unreachable is generated by the host or its inbound gateway [2] to inform the client that the destination is unreachable for some reason. Reasons for this message may include: the physical connection to the host does not exist (distance is infinite); the indicated protocol or port is not active; the data must be fragmented but the ...
A route is considered unreachable if the hop count exceeds the maximum allowed. Route poisoning is a method of quickly forgetting outdated routing information from other router's routing tables by changing its hop count to be unreachable (higher than the maximum number of hops allowed) and sending a routing update.
In other words, a holddown keeps a router from receiving route updates until the network appears to be stable—until either an interface stops changing state (flapping) or a better route is learned. Holddowns are usually implemented with timers. If the router detects that a network is unreachable, the timer is started.
The ability to define network host hierarchies using 'parent' hosts, allowing the detection of and distinction between hosts that are down or unreachable. Contact notifications when service or host problems occur and get resolved (via e-mail, pager, or any user-defined method through plugin system).
Null routes are typically configured with a special route flag; for example, the standard iproute2 command ip route allows to set route types unreachable, blackhole, prohibit which discard packets. Alternatively, a null route can be implemented by forwarding packets to an illegal IP address such as 0.0.0.0 , or the loopback address .