RIP Configuration
This affiliate does not go into detail on configuring RIPv2. However, accomplish abiding to analysis the list
of RIPv2 agreement commands, and command syntax, listed in Table 7-6 of the “Foundation
Summary” area for this chapter.
Figure 7-2 shows the internetwork that will be acclimated to allegorize RIP agreement concepts in
Example 7-4. Note that best of the subnets are allotment of arrangement 172.31.0.0, except area noted.
Figure 7-2 Sample Internetwork Acclimated for RIP Agreement Examples
Network 172.31.0.0, Except area Shown
E0/0 R3 R1
103.3/24 13.2/30
23.1/30
14.1/30
16.1/24
Fa0/0
13.1/30 11.1/24
11.201/24
211.202/24
R4
FR
VLAN 11
172.31.11.0/24
E0/0
104.144/26
24.1/30
14.2/30
E0/0 R5
105.5/24 25.1/30
E0/0 R6 R2
Fa0/0
10.1.106.6/24
10.1.26.6/24
11.2/24
16.6/24
10.1.26.2/24
25.2/30
24.2/30
23.2/30
11.202/24
S2
OSPF
S1
RIP
212.202/24
213.202/24
221.202/24
222.202/24
223.202/24
196 Affiliate 7: RIP Adaptation 2
Enabling RIP and the Furnishings of Autosummarization
Example 7-4 covers basal RIP configuration, the acceptation and association of the RIP network
command, and the furnishings of the absence ambience for autosummarization. To appraise aloof those
functions, Archetype 7-4 shows the accompanying RIP agreement on R1, R2, and R6, forth with some
command output.
Example 7-4 Basal RIP Agreement on R1, R2, R4, and S1
! First, the three curve of agreement are the aforementioned on R1 and S1
! (Point 1): the adaptation 2 command tells R1 to accelerate and accept alone RIPv2
! updates, and to avoid RIPv1 updates. The arrangement command charge accept a classful
! arrangement as the parameter.
router rip
version 2
network 172.31.0.0
! Next, the agreement for R2 and R6 is shown, which includes a arrangement 10.0.0.0
! command, enabling RIP on their interfaces in arrangement 10.0.0.0.
router rip
version 2
network 10.0.0.0
network 172.31.0.0
! Below, R1 shows that alone v2 updates are actuality beatific and received, and that
! autosummarization is in effect.
R1# sh ip protocol
Routing Protocol is "rip"
Sending updates every 30 seconds, abutting due in 26 seconds
Invalid afterwards 180 seconds, authority bottomward 180, ablaze afterwards 240
Outgoing amend clarify account for all interfaces is not set
Incoming amend clarify account for all interfaces is not set
Redistributing: rip
Default adaptation control: accelerate adaptation 2, accept adaptation 2
Interface Accelerate Recv Triggered RIP Key-chain
FastEthernet0/0 2 2 carkeys
Serial0/0.3 2 2
Serial0/0.4 2 2 anothersetofkeys
Serial0/0.6 2 2
Automatic arrangement summarization is in effect
Maximum path: 4
Routing for Networks:
! curve bare for brevity
! Below, the appearance ip avenue 10.0.0.0 command lists all of R1’s accepted routes to
! arrangement 10.0.0.0; the alone avenue is for 10.0.0.0/8, because R2 and R6
! automatically abridge (by default) at the classful arrangement boundary.
R1# appearance ip avenue 10.0.0.0
RIP Agreement 197
A brace of credibility from this archetype charge a little added explanation. The RIP arrangement command
only allows for a classful arrangement as a parameter, which in about-face enables RIP on all of that router’s
interfaces that are allotment of that network. Enabling RIP on an interface makes the router begin
sending RIP updates, alert for RIP updates (UDP anchorage 520), and announcement that interface’s
connected subnet.
Because the RIP arrangement command has no way to artlessly bout one interface at a time, a RIP
configuration may accredit these three functions on an interface for which some or all of these
functions are not required. The three RIP functions can be alone disabled on an interface
with some effort. Table 7-4 lists these three functions, forth with how to attenuate anniversary feature.
Routing access for 10.0.0.0/8
Known via "rip", ambit 120, metric 1
Redistributing via rip
Last amend from 172.31.11.2 on FastEthernet0/0, 00:00:01 ago
Routing Descriptor Blocks:
172.31.16.6, from 172.31.16.6, 00:00:08 ago, via Serial0/0.6
Route metric is 1, cartage allotment adding is 1
* 172.31.11.2, from 172.31.11.2, 00:00:01 ago, via FastEthernet0/0
Route metric is 1, cartage allotment adding is 1
Table 7-4 RIP Per-Interface Actions, and How to Attenuate Them Back Enabled
RIP Function How to Disable
Sending RIP updates Accomplish the interface passive: configure router rip, followed by passiveinterface
type number
Listening for RIP updates Clarify all admission routes application a administer list
Advertising the
connected subnet
Filter outbound advertisements on added interfaces application administer lists,
filtering an interface’s affiliated subnet
Example 7-4 Basal RIP Agreement on R1, R2, R4, and S1 (Continued)
198 Affiliate 7: RIP Adaptation 2
Another way you can absolute advertisements on multiaccess networks is to use the neighbor
ip-address RIP subcommand. This command tells RIP to accelerate unicast RIP updates to that
neighbor. For instance, back application a multipoint Frame Relay subinterface, there may be four
routers attainable application that subinterface. If you appetite to accelerate RIP updates to alone one of them,
make the interface passive, and again use the acquaintance command to account RIP to accelerate updates,
but alone to that one neighbor.
RIP uses autosummarization at classful arrangement boundaries by default. In Archetype 7-4, R2 and
R6 affix to genitalia of classful networks 10.0.0.0/8 and arrangement 172.31.0.0/16. Advertisements
sent out interfaces in arrangement 172.31.0.0/16 acquaint a abbreviated avenue of the complete chic A
network 10.0.0.0/8. In the example, R2 and R6 both acquaint a abbreviated arrangement 10.0.0.0 to R1.
As a result, as apparent with the appearance ip avenue 10.0.0.0 command on R1, R1 knows two equal-cost
routes to classful arrangement 10.0.0.0. In this case, R1 would accelerate some packets meant for subnet
10.1.106.0/24 through R2 first, a acutely poor choice. To acquaint the subnets of network
10.0.0.0, R2 and R6 could be configured with the no auto-summary command beneath router rip.
Note that RIPv2 allows for discontiguous networks, but autosummarization charge be disabled for
a architecture application discontiguous networks to work.
RIP Authentication
RIP authentication, abundant like EIGRP and OSPF authentication, requires the conception of keys
and requires affidavit to be enabled on an interface. The keys are acclimated either as clear-text
passwords or as the abstruse (private) key acclimated in an MD5 calculation.
Multiple keys are allowed, and are aggregate calm application a assemble alleged a key chain. A key
chain is artlessly a set of accompanying keys, anniversary of which has a altered cardinal and may be restricted
to a time period. By acceptance assorted accompanying keys in a key chain, with anniversary key accurate during
specified time periods, the architect can calmly plan for clearing to new keys in the future. (NTP
is recommended back keys are belted by time ranges.)
Cisco IOS enables the RIP (and OSPF and EIGRP) affidavit activity on a per-interface basis,
referring to the key alternation that holds the keys with the ip affidavit key-chain name interface
subcommand. The router looks in the key alternation and selects the key(s) accurate at that accurate time.
With RIP, the blazon of affidavit (clear-text countersign or MD5 digest) is called per interface
as well, application the ip rip affidavit approach {text | md5} interface subcommand. If this command
is omitted, the affidavit blazon defaults to text, acceptation that the key is acclimated as a clear-text password
RIP Next-Hop Affection and Breach Horizon
This area covers the breach border and next-hop appearance of RIPv2. These two appearance do not
typically charge to be advised at the aforementioned time, but in some cases they do.
RIP Agreement 199
First, Cisco IOS controls the breach border ambience per interface, application the [no] ip split-horizon
interface subcommand. Breach border is on by default, except for cases in which Frame Relay is
configured with the IP abode on the concrete interface.
The RIPv2 next-hop affection allows a RIP router to acquaint a altered next-hop router than the
advertising router.
Although this is not a accepted requirement, this abstruse affection permits a RIP router to point
to a altered abutting hop than it would commonly accommodate to addition RIP router, allowing a anatomy of
traffic engineering.
RIP Account Lists
RIP account lists acquiesce RIP to add to a route’s metric, either afore sending an update, or for routes
received in an update. The account account refers to an ACL (standard, extended, or named) to bout the
routes; the router again adds the authentic offset, or added metric, to any analogous routes. Any routes
not akin by the account account are unchanged. The account account additionally specifies which acquisition updates
to appraise by apropos to a administration (in or out) and, optionally, an interface. If the interface is
omitted from the command, all updates for the authentic administration are examined.
Route Clarification with Administer Lists and Prefix Lists
Outbound and entering RIP updates can be filtered at any interface, or for the absolute RIP process.
To clarify the routes, the distribute-list command is acclimated beneath router rip, referencing an IP ACL
or an IP prefix list. Any subnets akin with a admittance article in the ACL accomplish it through; any
that bout with a abjure activity are filtered. The administration account clarification can be performed for either
direction of breeze (in or out) and, optionally, for a accurate interface. If the interface advantage is
omitted, all updates advancing into or out of the RIP activity are filtered. (Routes can additionally be filtered
at redistribution points, a affair covered in Affiliate 10.)
The all-encompassing command, back creating a RIP administration account that uses an ACL, is
distribute-list {access-list-number | name} {in | out} [interface-type interface-number]
A RIP administer account ability accredit to a prefix account instead of an ACL to bout routes. Prefix lists are
designed to bout a ambit of subnets, as able-bodied as a ambit of subnet masks associated with the
subnets. The administer account charge still ascertain the administration of the updates to be advised (in or out),
and optionally an interface.
Chapter 10 includes a added complete altercation of the syntax and formatting of prefix lists; this
chapter focuses on how to alarm and use a prefix account for RIP. To advertence a prefix list, use the
following router rip subcommand:
distribute-list {prefix list-name} {in | out } [interface-type interface-number]