IBM RackSwitch G8000, Application Manual

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RackSwitch G8000: Application Guide
RIPv1
RIP version 1 use broadcast User Datagram Protocol (UDP) data packets for the
regular routing updates. The main disadvantage is that the routing updates do not
carry subnet mask information. Hence, the router cannot determine whether the
route is a subnet route or a host route. It is of limited usage after the introduction of
RIPv2. For more information about RIPv1 and RIPv2, refer to RFC 1058 and RFC
2453.
RIPv2
RIPv2 is the most popular and preferred configuration for most networks. RIPv2
expands the amount of useful information carried in RIP messages and provides a
measure of security. For a detailed explanation of RIPv2, refer to RFC 1723 and
RFC 2453.
RIPv2 improves efficiency by using multicast UDP (address 224.0.0.9) data packets
for regular routing updates. Subnet mask information is provided in the routing
updates. A security option is added for authenticating routing updates, by using a
shared password. N/OS supports using clear password for RIPv2.
RIPv2 in RIPv1 Compatibility Mode
N/OS allows you to configure RIPv2 in RIPv1compatibility mode, for using both
RIPv2 and RIPv1 routers within a network. In this mode, the regular routing updates
use broadcast UDP data packet to allow RIPv1 routers to receive those packets.
With RIPv1 routers as recipients, the routing updates have to carry natural or host
mask. Hence, it is not a recommended configuration for most network topologies.
Note: When using both RIPv1 and RIPv2 within a network, use a single subnet
mask throughout the network.
RIP Features
N/OS provides the following features to support RIPv1 and RIPv2:
Poison
Simple split horizon in RIP scheme omits routes learned from one neighbor in
updates sent to that neighbor. That is the most common configuration used in RIP,
that is setting this Poison to DISABLE. Split horizon with poisoned reverse includes
such routes in updates, but sets their metrics to 16. The disadvantage of using this
feature is the increase of size in the routing updates.
Triggered Updates
Triggered updates are an attempt to speed up convergence. When Triggered
Updates is enabled, whenever a router changes the metric for a route, it sends
update messages almost immediately, without waiting for the regular update
interval. It is recommended to enable Triggered Updates.