LevelOne GTL-2881, User Manual

Page: 665 / 706

Chapter 18
| Unicast Routing
Configuring the Routing Information Protocol
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multicasting as normally required by RIPv2. (Using this mode allows older
RIPv2 routers which only receive RIP broadcast messages to receive all of
the information provided by RIPv2, including subnet mask, next hop and
authentication information. (This is the default setting.)
■
Use “Do Not Send” to passively monitor route information advertised by
other routers attached to the network.
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The Receive Version can be specified based on these options:
■
Use “RIPv1” or “RIPv2” if all routers in the local network are based on RIPv1
or RIPv2, respectively.
■
Use “RIPv1 and RIPv2” if some routers in the local network are using RIPv2,
but there are still some older routers using RIPv1. (This is the default
setting.)
■
Use “Do Not Receive” if dynamic entries are not required to be added to the
routing table for an interface. (For example, when only static routes are to
be allowed for a specific interface.)
Protocol Message Authentication
RIPv1 is not a secure protocol. Any device sending protocol messages from UDP
port 520 will be considered a router by its neighbors. Malicious or unwanted
protocol messages can be easily propagated throughout the network if no
authentication is required.
RIPv2 supports authentication using a simple password or MD5 key encryption.
When a router is configured to exchange authentication messages, it will insert the
password into all transmitted protocol packets, and check all received packets to
ensure that they contain the authorized password. If any incoming protocol
messages do not contain the correct password, they are simply dropped.
For authentication to function properly, both the sending and receiving interface
must be configured with the same password or authentication key.
Loopback Prevention
Just as Layer 2 switches use the Spanning Tree Algorithm to prevent loops, routers
also use methods for preventing loops that would cause endless retransmission of
data traffic. When protocol packets are caught in a loop, links will be congested,
and protocol packets may be lost. However, the network will slowly converge to the
new state. RIP supports several methods which can provide faster convergence
when the network topology changes and prevent most loops from occurring.
Parameters
These parameters are displayed:
◆
VLAN ID – Layer 3 VLAN interface. This interface must be configured with an IP
address and have an active link. (Range: 1-4094)