RIPv2
Routing Protocols and Concepts – Chapter 7
© 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
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Objectives
 En
cou
nt
e
r
a
n
d

desc
ri
be
th
e
limit
a
ti
o
n
s

o
f RIPv1’
s

© 2007 Cisco Systems, Inc. All rights reserved. Cisco Public
Introduction
Introduction
 Difference between RIPv1 & RIPv2

RIPv1

RIPv1
•A classful distance vector routing protocol
•
Does not support discontiguous subnets
Does

not

support

discontiguous

subnets
•Does not support VLSM
•Does not send subnet mask in routing update
•Routing updates are broadcast
RIPv2
•A classless distance vector routing protocol that is an
enhancement of RIPv1
’
s features
enhancement


loops
– Use of split horizon or split horizon with poison reverse to
also help prevent routing loops.
– Use of triggered updates when there is a change in the
topology for faster convergence.
Maximum hop count of 15 with the hop count of 16 signifying
–
Maximum

hop

count

of

15
,
with

the

hop

count

of

16

signifying

using redistribution.

Routers 1 & 3 contain VLSM
Routers

1

&

3

contain

VLSM

networks
Remember that both the R1 and R3
routers have subnets that are part of
the 172 30 0 0/16 major classful
the

172
.
30
.
0
.
0/16

major

1

Li
m
it
a
ti
ons
 The topology shows that
R2 has a static
R2

has

a

static

summary route to the
192.168.0.0/16 network.
The configuration of this
summar
y
route will be
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y
displayed later in this

subnets
.
–Four of these /24 subnets are
assigned:
–
two to R1
(
172.30.1.0/24 and
(
172.30.2.0/24)
–two to R3 (172.30.100.0/24 and
172.30.110.0/24).
Ithbtt ht h

I
n
th
e
b
o
tt
om c
h
ar
t
, we
h
ave
taken the 172.30.200.0/24
subnet and subnetted it again,

Limitations
 Scenario Continued
S
 VL
S
M
-Recall this is sub netting the
subnet
 Private IP addresses are on
LAN links
 Public IP addresses are used
on WAN links (through an
ISP, or when inside users
dt t id it
nee
d

t
o access ou
t
s
id
e s
it
es,
a public IP address must be
used.)
 Loopback interfaces
-These are virtual interfaces
that can be pinged and

a

physical

interface
.
Like other interfaces, it can be assigned an IP address.
Loopback interfaces are also used by other routing
p
rotocols
,
such as OSPF
,
for different
p
ur
p
oses.
p, , pp
These uses will be discussed in Chapter 11 OSPF.
In a lab environment, loopback interfaces are useful
in creating additional networks without having to add
more physical interfaces on the router
more

physical

interfaces

on


to

demonstrate

multiple

subnets

and

VLSM. Instead, we use loopback interfaces.
RIPv1 Limitations
RIPv1

Limitations
 Route redistribution
Redistribution involves taking the routes from one routing
–
Redistribution

involves

taking

the

routes

from

ti
c
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RIPv1 Limitations
RIPv1

Limitations
 R2(config)#ip route 192.168.0.0 255.255.0.0 Null0
The address space represented by the static summary route
–
The

address

space

represented

by

the

static

summary

route

d
n
u
ll in
te
rf
aces
Stat c outes a d u te aces
R2(config)#ip route 192.168.0.0 255.255.0.0 Null0

a static route must have an active exit interface
a

static

route

must

have

an

active

exit

interface

before it will be installed in the routing table.

Tt thth ttht l h fll
–
T
o
t
es
t
w
h
e
th
er or no
t

th
e
t
opo
l
ogy
h
as
f
u
ll

connectivity, we first verify that both serial
links on R2 are up using the show ip
interface brief
 Ping

unsuccessful

when attempting to ping the 172.30.1.1 on R1.
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RIP 1 Li it ti
RIP
v
1

Li
m
it
a
ti
ons
 RIPv1 – a classful routing protocol
–
Subnet mask
are not sent
in updates
Subnet

mask

are

not

convergence w
ill
no
t

b
e
reached
–RIPv1 on both the R1 and R3 routers will summarize their 172.30.0.0
subnets to the classful major network address of 172 30 0 0 when sending
subnets

to

the

classful

major

network

address

of

172
.
30
.

see
,
R2

installs

both

paths

in

the

routing table.
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RIP 1 Li it ti
RIP
v
1

Li
m
it
a
ti
ons

R2 has two equal cost routes to the
172.30.0.0/16 network.
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RIP 1 Li it ti
RIP
v
1

Li
m
it
a
ti
ons
•
R1 has its own 172 30 0 0 routes:
•
R1

has

its

own

172
.


are only sending the summarized
172.30.0.0 network to R2 in their RIPv1
routing updates.
AltR2lkbtth
•R2 that it is not including the 172.30.0.0 network
in its updates to either R1 or R3.
•Because the split horizon rule is in effect
.
•
R2 learned about 172 30 0 0/16 on both the
•
A
s a resu
lt
,
R2
on
l
y
k
nows a
b
ou
t

th
e
172.30.0.0/16 classful network and is
unaware of any 172.30.0.0 subnets.


Limitations
 Because RIPv1 does not send the
subnet mask in routin
g
u
p
dates, it
R4 is added to
gp
cannot support VLSM.
 R3 router is configured with VLSM
subnets all of which are members
R4

is

added

to

the topology
connected to R3
subnets
,
all

of

which

k

2)
 As we saw with the 172.30.0.0/16
u
p
dates to R2 b
y
R3,
py
–RIPv1 either summarizes the
subnets to the classful boundary
–
or
uses

t
h
e

sub
n
et
m
as
k
o
f
t
h

–
Those subnets do not have the
R4

is

added

to

the topology
connected to R3
Those

subnets

do

not

have

the

same subnet mask as
FastEthernet 0/0.
– R3 will only include those
172 30 0 0 routes in its routing
172
.

y
i
nc
l
u
d
e
172.30.0.0 subnets with a /24
mask. The only one that meets
this condition is 172.30.110.0.
– The other 172.30.0.0 subnets,
172.30.200.16/28 and
172.30.200.32/28, are not
included because the /28 masks
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do not match the /24 mask of the
outgoing interface.
RIP 1 Li it ti
RIP
v
1

Li
m
it
a
ti


its

update
–R1 is not receiving this
192.168.0.0/16 route in its RIP
updates from R2,
 Reason: Classful routing
p
rotocols do not su
pp
ort
p
pp
CIDR routes that are
summarized with a smaller
mask than the classful
bt k
su
b
ne
t
mas
k
–If the 192.168.0.0 static route
were configured with a /24 mask
or
g
reater
,


router

no

longer

depends

upon

the

subnet

mask

of

the

inbound interface or the classful mask when determining the subnet
mask for a route
2nd extension is the addition of next hop address
The Next Hop address is used to identify a better next-hop address - if
one exists - than the address of the sending router.
If the field is set to all zeros (0.0.0.0), the address of the sending router
is the best next
-
hop address

–Even though the router only sends RIPv1 messages, it can
interpret both RIPv1 and RIPv2 messages
interpret

both

RIPv1

and

RIPv2

messages
.
–A RIPv1 router will just ignore the RIPv2 fields in the route
entry.
RIPv1
RIPv2
RIPv1
RIPv2
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Configuring RIPv2
Configuring

RIPv2

Configuring

To verify RIPv2 is

To

verify

RIPv2

is

configured use the
show ip protocols
show

ip

protocols
command
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Comparing RIP v1 and v2
Comparing

RIP

v1

and

Ild
RIP network is broken
Version 1
Version 2
No
.
I

can

not

take version 1
I
can on
l
y sen
d

version 1
Version

1
Version

2
Yes. I can take
version 1 or 2
I can only send
version 2

RIP
v
2

Auto
-
Summary & RIPv2
Auto
Summary

&

RIPv2
 RIPv2 will automatically
summarize routes at major
summarize

routes

at

major

network boundaries and
can also summarize routes
with a subnet mask that is
smaller than the classful
subnet mask
subnet