ROUTING INFORMATION PROTOCOL

Distance Vector IGP◦ Uses split-horizon, poison reverse, count to infinity

◦ UDP port 520 for transport

Two Versions◦ RIPv1

Classful

Updates as broadcast

◦ RIPv2

Classless

Updates as multicast to 224.0.0.9

Broadcast:◦ RIPv1 default◦ RIPv2 optional:

c-if# ip rip v2-broadcast

Multicast:◦ RIPv2 default

Unicast:◦ RIPv1 / RIPv2 optional

c-router# neighbor <address> enable unicast update

c-router# passive-interface <interface> supress normal broadcast/multicast updates

Default Timers:◦ Update timer is 30 Seconds◦ Invalid 180 Seconds◦ Hold down 180 Seconds◦ Flush timer 240 Seconds

The above timers are configurable on Global level aswell as Interface level:◦ c-router# timers basic <update> <invalid> <holddown>

<flush>◦ c-if# ip rip advertise <interval>

RIP supports equal load balancing and maximum 4-paths are allowed.

Best path selection process is based on number ofHop count (it doesn’t mean what bandwidth the pathis using).

Enable the global process◦ c# router rip

Enable the interface process◦ # network <address>

◦ Matches major network only

Verification◦ # show ip protocols

◦ # show ip route rip

◦ # show ip rip database

◦ # debug ip rip

Default processing:◦ Sends version 1 updates

◦ Listen for versions 1 and 2 updates

Modifying the version:◦ c-router# version 1/2

◦ c-if# ip rip receive version

◦ c-if# ip rip send version

Verification:◦ # show ip protocols

RIPv2 is classless but does automatic classfulsummarization by default◦ c-router# no auto-summary

VLSM is supported within the same majornetwork.

Advertisements between major networkboundaries are summarized to classfulboundary◦ Can result in traffic blackholes

Updates received in an interface will not besent back out the same interface.◦ Undesirable on partial mesh NBMA networks.

Enabled by default on all interfaces exceptmain interface in Frame Relay◦ c-if# no ip split-horizon

Verification:◦ # show ip interface

The default feature of RIPv1 is broadcast withthe broadcast address 255.255.255.255.

We have flexibility to configure DirectedBroadcast as per interface level which is bydefault disabled.

Directed RIP Broadcast is possible, but it isnot recommended to configure because theuser sitting in other subnet can also see theip addresses of your active users via justpinging the Directed Broadcast Address whichis a kind of Security Breach.

RIP supports both “clear-text” and “MD5”authentication.

Here Authentication means only that the packetis coming from right neighbor.◦ In MD5, authentication process on the basis of “HASH”.

RIP Authentication is having Five different levelsto enable:◦ Define key chain◦ Define key number◦ Define password (space is also counted)◦ Enable at interface level◦ Apply the key chain

◦ c# key chain <name>

◦ # key <number>

◦ # key-string <PASSWORD>

Enable at interface level:◦ c-if# ip rip authentication mode (text / md5)

◦ c-if# ip rip authentication key-chain <name>

NEED SAME AUTHENTICATION ON R2

Works with RIPv2 only.

Works with Interface level.

At least one subnet must be in the RIP database.

Cannot summarize past the major networkboundary.◦ E.g.:◦ Network_1: 192.168.0.0/24◦ Network_2: 192.168.1.0/24◦ Network_3: 192.168.2.0/24◦ Network_4: 192.168.3.0/24

If we try to summarize the above networks with192.168.0.0/22 RIP don’t allow us.

“OR” need to workaround with “redistribute static”

Distribute-list:◦ Standard access-list

◦ Extended access-list

Source is route source, destination is prefix

◦ Prefix-list

Offset-list◦ Metric of 16 = infinite

Distance◦ 255 = infinite

◦ Can be per prefix and per neighbor

Outbound and Inbound RIP updates can befiltered at any interface or for the entire RIPprocess.

Prefix-list is used to match actual route:◦ E.g.:

ip prefix-list <name> permit 10.10.10.0/24

(means the above entry does not match either10.10.10.0/25 or 10.10.0.0/23 in other words anydifference in address field or subnet mask field, thisprefix-list does not work)

But if we want to match entire range of subnet, we need touse key-words e.g. “le” (less than or equal to) or “ge”(greater than or equal to).◦ E.g.:

ip prefix-list abc 0.0.0.0/0 le 10Means any network with any subnet but mask value must be less than orequal to 10-bits. ip prefix-list abc 0.0.0.0/0 (means default route) ip prefix-list abc 0.0.0.0/0 ge 32 (means all hosts having 32-bit mask) ip prefix-list abc 0.0.0.0/1 ge 8 le 8 (means exact match of 8-bit but

the first bit of network should be 0) ip prefix-list abc 128.0.0.0/2 ge 16 le 16 (means exact match of 16-bit

but the first bit of network should be 128) ip prefix-list abc 192.0.0.0/3 ge 24 le 24 (means exact match of 24-bit

but the first bit of network should be 192) ip prefix-list abc 128.0.0.0/2 le 32 (means anything less than 32-bit

but the first bit of network should be 128)

RIP uses hop-count as Metric◦ 1 hop per interface◦ 16 is infinite

Offset-list to modify metric (added the previousmetric) and could be configuredinbound/outbound to receive/ send the metricvalue.

Offset-list is used to Traffic Engineering (if wehave multiple paths to reach same destination)and Route Filtering.◦ access-list 0 means all routes◦ Could also be configured on per prefix basis

This offset-list could alsoBe configured as “out” on R1To modify the metric of R1 routes.

Default Routing could be configured via twodifferent ways:◦ Normal Default Routing

Under the RIP process via default-informationoriginate command and default route would beadvertised all the interfaces running RIP protocol.

◦ Conditional Default Routing

Use Route-map with prefix-list. This helps to controlwhere we want to send default route.

We configured defaultRouting on R2 under theRouting process and thisDefault information is givenTo all associated routersR1 and R2

R2 is giving defaultroute to R1 only notto R3

RIP Triggered helps to prevent bandwidthusage. RIP will send update only when thereis any change in the topology

Supports suppression of periodic updates.

RIP Triggered is configured on interface level.◦ c-if# ip rip triggered

Updates only accepted from routers on yoursame subnet by default.

Problems with devices running PPP and IPCPaddress negotiation.

Disabled with RIP processing level:◦ c-router# no validate-update-source