31. Dynamic Routing
ROX™ v2.2 User Guide
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RuggedBackbone™ RX5000
31.1.4.8. OSPF Authentication
OSPF authentication is used when it is desirable to prevent unauthorized routers from joining the OSPF
network. By enabling authentication and configuring a shared key on all the routers, only routers which
have the same authentication key will be able to send and receive advertisements within the OSPF
network. Authentication adds a small overhead due to the encryption of messages, so is not to be
preferred on completely private networks with controlled access.
31.1.4.9. RIP Authentication
RIP authentication is used when it is desirable to prevent unauthorized routers from joining the network.
RIP authentication is supported by per-interface configuration or the use of key-chains. Separate key
chains spanning different groups of interfaces and having separate lifespans are possible. By enabling
authentication and configuring a shared key on all the routers, only routers which have the same
authentication key will be able to send and receive advertisements within the RIP network.
31.1.4.10. Administrative Distances
The router may work with different routing protocols at the same time, as well as employing local
interface and statically assigned routes. An administrative distance, (from 0 to 255) is a rating of
the trustworthiness of a routing information source. For a given route, the protocol having the lowest
administrative distance will be chosen. By default the distances for a connected interface is 0 and for a
static route is 1. By default, OSPF will set an administrative distance of 110 and RIP will set a distance
of 120.
31.1.5. OSPF And VRRP Example Network
This network consists of three routers connected in a ring with T1/E1 links. Router 1 and 2 and the
switched network represent a remote site in which the routers supply a redundant gateway to the hosts
via VRRP and the T1/E1 links supply a redundant network connection to the rest of the network.