
3
16 bintec User’s Guide Ethernet
XEY-100BT, Fast Ethernet menu
Brief description of routing
The ➤➤ gateway receives ➤➤ data packets, each of which contains the des-
tination host IP address. On the basis of the entries in the routing table IP ➜
ROUTING, the gateway decides which route to use to forward the data packet to
ensure that it arrives at its destination as quickly and cheaply as possible (with
the fewest possible intermediate stations). The entries in the routing table can
be defined statically or the routing table can be updated constantly by a dynamic
exchange of routing information between several gateways. This exchange is
controlled by a so-called Routing Protocol, e.g. RIP (Routing Information Proto-
col).
RIP (Routing
Information Protocol)
Gateways use ➤➤ RIP to exchange information stored in routing tables by
communicating with each other at regular intervals to mutually supplement and
replace their routing entries. The R Series gateways support both version 1 and
version 2 of RIP, either individually or together.
Gateways can be defined as active or passive gateways: active gateways store
routing entries sent by other gateways and offer their routing entries to the oth-
ers via ➤➤ broadcasts. Passive gateways accept the information from the ac-
tive gateways and store it, but do not pass on their own routing entries. The R
Series gateways provide both variants.
IP accounting This option is for activating or deactivating IP accounting messages for this in-
terface. If IP accounting is activated, accounting messages are generated (and
entered in the biboAdmSyslogTable), which contain detailed information
about the IP-connections of this interface.
Back Route
Verification
This term conceals a simple but very powerful function of the R Series gate-
ways. If Backroute Verification is activated for an interface, incoming data pack-
ets are only accepted over it if outgoing answering packets would be routed
over the same interface. You can therefore prevent packets with fake IP ad-
dresses being accepted – even without filters.
Proxy ARP The ➤➤ Proxy ARP function enables the gateway to answer ➤➤ ARP re-
quests from its own LAN acting for a defined WAN partner. If a host in the LAN
wants to set up a connection to another host in the LAN or to a WAN partner but
doesn’t know its hardware address (MAC address), it sends a so-called ARP re-
quest into the network as a ➤➤ broadcast. If Proxy ARP is activated on the
gateway and the desired target host can be reached e.g. over a host route, the