RIP and IGRP

.Comparing RIP and IGRP

Feature	RIP	IGRP
Update Timer	30 seconds	90 seconds
Metric	Hop count	Bandwidth/delay (also, reliability, MTU, and load)
Hold-Down Timer	180	280
Flash Updates	Yes	Yes
VLSM	No	No
Infinite-Metric Value	16	4,294,967,295

Configuring RIP and IGRP

Command	Configuration Mode
router rip	Global
router igrp [as number]	Global
router igrp [as number]	Global	enable IGRP for the AS and enter (config-router) mode.
network [net number]	Router subcommand	advertise to other routers that this router has a path to the given network.
passive-interface [default] {interface type interface number}	Router subcommand	don't send routing updates out through the given interface.
maximum-pathsnumber	Router subcommand	keep at most number'''different routes to the same destination in the routing table.
traffic-share {balanced | min}	Router subcommand
traffic-share {balanced | min}	Router subcommand	share traffic between routes, either proportionally or just between those of the minimum metric value.

EXEC Commands

Command	Description
show ip route	Shows the entire routing table, or a subset if parameters are entered.
show ip protocols	Shows routing protocol parameters and current timer values.
debug ip rip	Issues log messages for each RIP update.
debug ip igrp transactions [ip address]	Issues log messages with details of the IGRP updates.
debug ip igrp transactions [ip address]	Issues log messages with details of the IGRP updates.
debug ip igrp events [ip address]	Issues log messages for each IGRP packet.
trace	Sends a series of ICMP echoes with increasing TTL values to verify the current route to a host.

RIP Configuration

router rip

network [network address1] -> Use network number (address w/ normal class address)

network [network address2]

IGRP ConfigurationIGRP Configuration

router igrp [as number] -> Note: All routers should use the same AS number

network [network address1]

network [network address2]

show running-config -> I = address found by IGRP, C = directly connected

Example

I 10.1.4.0 [100/8539] via 10.1.2.14, 00:00:50, Ethernet0

-> The [100/8359] can be broken into two separate parts:

• 100 = administrative distance
• 8539 = metric (function of bandwidth and delay)
• The higher the bandwidth, the lower the metric
• The lower the cumulative delay, the lower the metric

Bandwidth Defaults

LAN Interfaces = default reflects the correct bandwidth

Serial Interfaces = defaults to 1544 kbps (T1 speed)

-> Configure using the bandwidth [kbps] interface command

To migrate from RIP to IGRP (Commands)

• no router rip
• router igrp [as number]
• network [network ID]

Debug/show commands include

• debug ip rip
• show ip route
• debug ip igrp transactions (detailed info on updates)
• debug ip igrp events (summary that states updates received)
• show ip protocol (Update timer, elapsed time since update received)

Additional Notes

- If multiple route exist, router chooses best metric route

- If routes tie, keep the first/pre-existing route

		Command: maximum-paths 1 (default is maximum-paths 4)
		- When RIP places multiple routes, router balances traffic
		Command to use lowest-cost: traffic-share min

variance allows metrics to be considered equal, since IGRP/EIGRP metrics are calculated through formula and often won’t be exactly the same.

Example: metric = 100, variance = 2, If value > (lowest metric * variance), add route

Administrative Distance:In order to compare metrics between different routing protocols, use administrative distance to denote how believable an entire routing protocol is on a single router.

Default Administrative Distances

Route Type	Administrative Distance
Connected	0
Static	1
EIGRP summary route	5
EBGP	20
EIGRP (internal)	90
IGRP	100
OSPF	110
IS-IS	115
RIP	120
EIGRP (external)	170
iBGP (external)	200