Unicast Routing Table - Fujitsu PSWITCH 2048T User Manual

User's Guide FUJITSU PSWITCH
Each ARP cache entry has an age. The age is the time since the router last
confirmed IP address resolution. If the age of the entry reaches the configured
maximum age (default is 20 seconds), the ARP application will delete or attempt
to update the entry. If the application decides to try to update the entry, it sends
an ARP request and waits for a response. Upon receiving a response, the age is
reset to 0. If the response can not be received, the entry is deleted. Local and static
entries are not aged. Gateway entries are always updated by ARP. Negative entries
will not get aged, but will change to dynamic entries or gateway entries if address
resolution is successful and will be deleted if address resolution fails. Dynamic
entries are not always set to be updated at all times by default, but it is possible to
set them to always update by option setting. When this dynamic update
configuration is invalid, whether this dynamic entry is updated is determined by
whether or not it was used to transfer the data packet since the aging time was last
reset to 0.

3.1.9.8. Unicast Routing Table

This product has a single routing table. This routing table is used for forwarding
unicast IP packets and for response to reverse path forwarding queries from the IP
multicast protocol. This product follows the typical method of the industry, also
called administrative distance, in determining route priorities. The priority ranges
from 1 to 255. The default priority of different types of routes can be set. If there
are multiple routes to the same destination, the routing table selects the route
with the lowest priority value as the optimal route. A route with a priority of 255 is
never selected as an optimal route. The routing table installs only the optimal
route of the forwarding table of the hardware and the routing table of the IP stack.
In the routing table, the upper limit value of the number of installable routes is
fixed and can not exceed this upper limit value. If this limit is exceeded, routing
loops and black holes may occur.
The unicast routing table contains only the routes associated with the routing
interface. The local and default routes of the out-of-band management interface
are not included in this routing table.
Each route have a fixed number of ECMP next hops. For each optimal route, all
ECMP next hops are installed in the hardware forwarding table. This hardware uses
a hash algorithm based on the IP header of the packet to select the next hop for
forwarding. Packets belonging to one stream always hash to the same next hop in
order to avoid transmitting packets to the final destination in random order. Only
one next hop from each ECMP route is installed into the routing table.
In applications such as unicast routing protocols, you can configure the routing
table to notify them when the routing table changes or when the optimal route for
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