HP GbE2c HP GbE2c Ethernet Blade Switch for c-Class BladeSystem Application Gu - Page 94

Routing Information Protocol, Distance vector protocol, Stability, Routing updates, RIPv1 - command reference

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Routing Information Protocol In a routed environment, routers communicate with one another to keep track of available routes. Routers can learn about available routes dynamically, using the Routing Information Protocol (RIP). GbE2c software supports RIP version 1 (RIPv1) and RIP version 2 (RIPv2) for exchanging TCP/IP route information with other routers. NOTE: RIP is available only on the GbE2c Layer 2/3 Ethernet Blade Switch. Distance vector protocol RIP is known as a distance vector protocol. The vector is the network number and next hop, and the distance is the cost associated with the network number. RIP identifies network reachability based on cost, and cost is defined as hop count. One hop is considered to be the distance from one switch to the next which is typically 1. This cost or hop count is known as the metric. When a switch receives a routing update that contains a new or changed destination network entry, the switch adds 1 to the metric value indicated in the update and enters the network in the routing table. The IP address of the sender is used as the next hop. Stability RIP includes a number of other stability features that are common to many routing protocols. For example, RIP implements the split horizon and hold-down mechanisms to prevent incorrect routing information from being propagated. RIP prevents routing loops from continuing indefinitely by implementing a limit on the number of hops allowed in a path from the source to a destination. The maximum number of hops in a path is 15. The network destination network is considered unreachable if increasing the metric value by 1 causes the metric to be 16 (that is infinity). This limits the maximum diameter of a RIP network to less than 16 hops. RIP is often used in stub networks and in small autonomous systems that do not have many redundant paths. Routing updates RIP sends routing-update messages at regular intervals and when the network topology changes. Each router "advertises" routing information by sending a routing information update every 30 seconds. If a router doesn't receive an update from another router for 180 seconds, those routes provided by that router are declared invalid. After another 120 seconds without receiving an update for those routes, the routes are removed from the routing table and respective regular updates. When a router receives a routing update that includes changes to an entry, it updates its routing table to reflect the new route. The metric value for the path is increased by 1, and the sender is indicated as the next hop. RIP routers maintain only the best route (the route with the lowest metric value) to a destination. For more information see The Configuration Menu, Routing Information Protocol Configuration (/cfg/l3/rip) in the HP c-Class GbE2c Ethernet Blade Switch Command Reference 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. GbE2c software supports using clear password for RIPv2. Routing Information Protocol 94

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Routing Information Protocol 94
Routing Information Protocol
In a routed environment, routers communicate with one another to keep track of available routes.
Routers can learn about available routes dynamically, using the Routing Information Protocol (RIP). GbE2c software
supports RIP version 1 (RIPv1) and RIP version 2 (RIPv2) for exchanging TCP/IP route information with other routers.
NOTE:
RIP is available only on the GbE2c Layer 2/3 Ethernet Blade Switch.
Distance vector protocol
RIP is known as a distance vector protocol. The vector is the network number and next hop, and the distance is the
cost associated with the network number. RIP identifies network reachability based on cost, and cost is defined as hop
count. One hop is considered to be the distance from one switch to the next which is typically 1. This cost or hop
count is known as the metric.
When a switch receives a routing update that contains a new or changed destination network entry, the switch adds
1 to the metric value indicated in the update and enters the network in the routing table. The IP address of the sender
is used as the next hop.
Stability
RIP includes a number of other stability features that are common to many routing protocols. For example, RIP
implements the split horizon and hold-down mechanisms to prevent incorrect routing information from being
propagated.
RIP prevents routing loops from continuing indefinitely by implementing a limit on the number of hops allowed in a
path from the source to a destination. The maximum number of hops in a path is 15. The network destination network
is considered unreachable if increasing the metric value by 1 causes the metric to be 16 (that is infinity). This limits
the maximum diameter of a RIP network to less than 16 hops.
RIP is often used in stub networks and in small autonomous systems that do not have many redundant paths.
Routing updates
RIP sends routing-update messages at regular intervals and when the network topology changes. Each router
“advertises” routing information by sending a routing information update every 30 seconds. If a router doesn’t
receive an update from another router for 180 seconds, those routes provided by that router are declared invalid.
After another 120 seconds without receiving an update for those routes, the routes are removed from the routing table
and respective regular updates.
When a router receives a routing update that includes changes to an entry, it updates its routing table to reflect the
new route. The metric value for the path is increased by 1, and the sender is indicated as the next hop. RIP routers
maintain only the best route (the route with the lowest metric value) to a destination.
For more information see The Configuration Menu, Routing Information Protocol Configuration (
/cfg/l3/rip
) in the
HP c-Class GbE2c Ethernet Blade Switch Command Reference 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. GbE2c software supports using clear password for RIPv2.