Upload
baraynavab
View
690
Download
0
Embed Size (px)
Citation preview
Ch.4 – RIPv2
CCNP 1 version 3.0
Rick Graziani
Cabrillo College
Rick Graziani [email protected] 2
Note to instructors
• If you have downloaded this presentation from the Cisco Networking Academy Community FTP Center, this may not be my latest version of this PowerPoint.
• For the latest PowerPoints for all my CCNA, CCNP, and Wireless classes, please go to my web site:
http://www.cabrillo.cc.ca.us/~rgraziani/• The username is cisco and the password is perlman for all of
my materials.
• If you have any questions on any of my materials or the curriculum, please feel free to email me at [email protected] (I really don’t mind helping.) Also, if you run across any typos or errors in my presentations, please let me know.
• I will add “(Updated – date)” next to each presentation on my web site that has been updated since these have been uploaded to the FTP center.
Thanks! Rick
Rick Graziani [email protected] 3
Overview
Rick Graziani [email protected]
Classless Routing Protocols
“The true characteristic of a classless routing protocol is the ability to carry subnet masks in their route advertisements.” Jeff Doyle, Routing TCP/IP
Benefits:
• All-zeros and all-ones subnets
– - Although some vendors, like Cisco, can also handle this with classful routing protocols.
• VLSM
– Can have discontiguous subnets
– Better IP addressing allocation
• CIDR
– More control over route summarization
Rick Graziani [email protected]
Classless Routing Protocols
Classless Routing Protocols:
• RIPv2
• EIGRP
• OSPF
• IS-IS
• BGPv4
Rick Graziani [email protected]
Few RIP facts
• RIP still working on routers and hosts today.
• IP RIP derived from RIP by Xerox for its XNS protocol stack.
• Initially implemented in Berkeley UNIX routed program.
• RIPv1 – Charles Hedrick, RFC 1058, 1988
• RIPv2 – Gary Malkin, RFC 1723, 1994
• RIPng for IPv6 – Gary Malkin, RFC 2080, 1997 (proposed standard), extension to RIPv2 message format.
The Grim Router
Rick Graziani [email protected]
RIP version 1
0 1 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| command (1) | version (1) | must be zero (2) |
+---------------+---------------+-------------------------------+
| address family identifier (2) | must be zero (2) |
+-------------------------------+-------------------------------+
| IP address (4) |
+---------------------------------------------------------------+
| must be zero (4) |
+---------------------------------------------------------------+
| must be zero (4) |
+---------------------------------------------------------------+
| metric (4) |
+---------------------------------------------------------------+
• Classful Routing Protocol, sent over UDP port 520
• Does not include the subnet mask in the routing updates.
• Automatic summarization done at major network boundaries.
• Updates sent as broadcasts unless the neighbor command is uses which sends them as unicasts.
Rick Graziani [email protected]
RIP version 2
0 1 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| command (1) | version (1) | must be zero (2) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Address Family Identifier (2) | Route Tag (2) |
+-------------------------------+-------------------------------+
| IP Address (4) |
+---------------------------------------------------------------+
| Subnet Mask (4) |
+---------------------------------------------------------------+
| Next Hop (4) |
+---------------------------------------------------------------+
| Metric (4) |
+---------------------------------------------------------------+
• Classless Routing Protocol, sent over UDP port 520
• Includes the subnet mask in the routing updates.
• Automatic summarization at major network boundaries can be disabled.
• Updates sent as multicasts unless the neighbor command is uses which sends them as unicasts.
Rick Graziani [email protected] 9
RIP v2 operation
• All of the operational procedures, timers, and stability functions of RIP v1 remain the same in RIP v2, with the exception of the broadcast updates.
• RIP v2 updates use reserved Class D address 224.0.0.9.
Rick Graziani [email protected] 10
Issues addressed by RIP v2
The following four features are the most significant new features added to RIP v2:
• Authentication of the transmitting RIP v2 node to other RIP v2 nodes
• Subnet Masks – RIP v2 allocates a 4-octet field to associate a subnet mask to a destination IP address.
• Next Hop IP addresses – The inclusion of a Next Hop identification field helps make RIP v2 more efficient than RIP v1 by preventing unnecessary hops.
• Multicasting RIP v2 messages – Multicasting is a technique for simultaneously advertising routing information to multiple RIP or RIP v2 devices.
Rick Graziani [email protected] 11
RIP v2 message format
• All the extensions to the original protocol are carried in the unused fields.
• The Address Family Identifier (AFI) field is set to two for IP. The only exception is a request for a full routing table of a router or host, in which case it will be set to zero.
Rick Graziani [email protected] 12
RIP v2 message format
• The Route Tag field provides a way to differentiate between internal and external routes. (Not used by RIP, but can be used by BGP – later.)
• External routes are those that have been redistributed into the RIP v2.• The Next Hop field contains the IP address of a better next hop IP address if one
exists. Next hop on same subnet, that is metrically closer to the destination than the advertising router. (Rather than an IP redirect message)
• Metric indicates how many internetwork hops, between 1 and 15 for a valid route, or 16 for an unreachable route.
Rick Graziani [email protected] 13
Compatibility with RIP v1
RFC 1723 defines a compatibility switch with four settings, which allows versions 1 and 2 to interoperate:
1. RIP v1, in which only RIP v1 messages are transmitted 2. RIP v1 Compatibility, which causes RIP v2 to broadcast its messages
instead of multicast them so that RIP v1 may receive them 3. RIP v2, in which RIP v2 messages are multicast to destination
address 224.0.0.9 4. None, in which no updates are sent
• RFC 1723 recommends that switches be configurable on a per-interface basis. (coming soon)
Rick Graziani [email protected] 14
Classless route lookups
• Classful routing behavior, no ip classless, and classless routing behavior, the ip classless global commands.
• This will be discussed in our presentation on “The Routing Table.” There is a dierence
Rick Graziani [email protected] 15
Classless route lookups
• Route aggregation and supernetting.• A much greater benefit of having a subnet mask associated with each
route is being able to use variable-length subnet masking (VLSM) and to summarize a group of major network addresses with a single aggregate address. – Greater detail in Module 5, EIGRP
Rick Graziani [email protected] 16
Classless routing protocols
• The true defining characteristic of classless routing protocols is the capability to carry subnet masks in their route advertisements.
• “One benefit of having a mask associated with each route is that the all-zeros and all-ones subnets are now available for use.” – Cisco allows the all-zeros and all-ones subnets to be used with
classful routing protocols.
Rick Graziani [email protected] 17
Authentication
• A security concern with any routing protocol is the possibility of a router accepting invalid routing updates.
• The Authentication Type for simple password authentication is two, 0x0002,
• The remaining 16 octets carry an alphanumeric password of up to 16 characters.
• Configuration is coming!
Authentication is supported by modifying what would normally be the first route entry of the RIP message
Rick Graziani [email protected] 18
Authentication
• RFC 1723 describes only simple password authentication • Cisco IOS provides the option of using MD5 authentication instead of
simple password authentication. • Cisco uses the first and last route entry spaces for MD5 authentication
purposes.• MD5 computes a 128-bit hash value from a plain text message of
arbitrary length and a password.
Rick Graziani [email protected] 19
Authentication
Rick Graziani [email protected] 20
MD5 Authentication (FYI) http://www.cisco.com/en/US/tech/tk713/tk507/technologies_tech_note09186a00800b4131.shtml
1 2
3 4
5 6
Rick Graziani [email protected] 21
Limitations of RIPv2
• Slow convergence and the need of holddown timers to reduce the possibility of routing loops.
Note: See CCNA 2 for review if needed.
Rick Graziani [email protected] 22
Limitations of RIPv2
• RIPv2 continues to rely on counting to infinity as a means of resolving certain error conditions within the network.
• Dependent upon holddown timers.• Triggered updates are also helpful.
Note: See CCNA 2 for review if needed.
Rick Graziani [email protected] 23
Limitations of RIPv2
• Perhaps the single greatest limitation that RIPv2 inherited from RIP is that its interpretation of infinity remained at 16.
• Redistributed RIPv2 static cost metrics. (later in redistribution)– The default value of 1 is just like RIP. – This metric remains constant, and can only be changed by the
administrator.– However, the default value can be manually adjusted by the network
administrator.
Rick Graziani [email protected] 24
Basic RIPv2 configuration
Other:For RIP and IGRP, the passive interface command stops the router from
sending updates to a particular neighbor, but the router continues to listen and use routing updates from that neighbor. (More later.)
Router(config-router)# passive-interface interface
Default behavior of version 1 restored: Router(config-router)# no version
Rick Graziani [email protected] 25
Compatibility with RIP v1
NewYork
interface fastethernet0/0
ip address 192.168.50.129 255.255.255.192
ip rip send version 1
ip rip receive version 1
interface fastethernet0/1
ip address 172.25.150.193 255.255.255.240
ip rip send version 1 2
interface fastethernet0/2
ip address 172.25.150.225 225.255.255.240
router rip
version 2
network 172.25.0.0
network 192.168.50.0
• Interface FastEthernet0/0 is configured to send and receive RIP v1 updates.
• FastEthernet0/1 is configured to send both version 1 and 2 updates.
• FastEthernet0/2 has no special configuration and therefore sends and receives version 2 by default.
RIPv2
Rick Graziani [email protected] 26
Discontiguous subnets and classless routing
• RIP v1 always uses automatic summarization.
• The default behavior of RIP v2 is to summarize at network boundaries the same as RIP v1.
router ripversion 2no auto-summary
Rick Graziani [email protected] 27
Configuring authentication
Router(config)#key chain RomeoRouter(config-keychain)#key 1Router(config-keychain-key)#key-string Juliet The password must be the same on both routers (Juliet), but the name of the key
(Romeo) can be different.
Router(config)#interface fastethernet 0/0Router(config-if)#ip rip authentication key-chain RomeoRouter(config-if)#ip rip authentication mode md5
• If the command ip rip authentication mode md5 is not added, the interface will use the default clear text authentication. Although clear text authentication may be necessary to communicate with some RIP v2 implementations, for security concerns use the more secure MD5 authentication whenever possible.
Rick Graziani [email protected] 28
Show commands
Rick Graziani [email protected] 29
show ip rip database
Router# show ip rip database172.19.0.0/16 auto-summary172.19.64.0/24 directly connected, Ethernet0172.19.65.0/24[1] via 172.19.70.36, 00:00:17, Serial1[2] via 172.19.67.38, 00:00:25, Serial0172.19.67.0/24 directly connected, Serial0172.19.67.38/32 directly connected, Serial0172.19.70.0/24 directly connected, Serial1172.19.86.0/24[1] via 172.19.67.38, 00:00:25, Serial0[1] via 172.19.70.36, 00:00:17, Serial1
• The show ip rip database command to check summary address entries in the RIP database.
• These entries will appear in the database if there are only relevant child or specific routes being summarized.
• When the last child route for a summary address becomes invalid, the summary address is also removed from the routing table.
Router#show ip rip database
Rick Graziani [email protected] 30
Show commands
Rick Graziani [email protected] 31
Debug commands
Rick Graziani [email protected] 32
Summary
Rick Graziani [email protected]
RIPv2 Example
Scenario:
• Discontiguous subnets
• VLSM
• CIDR
• Supernet to 207.0.0.0/8
e0
ISP
SantaCruz2SantaCruz1
192.168.4.20/30
172.30.1.0/24
Internet
s0
s0 s0
s1
172.30.100.0/24
e0
192.168.4.24/30
.21
.22
.25
.26
10.0.0.0/8
e0.1
.1.1
Lo0Lo0
172.30.110.0/24172.30.2.0/24 .1
.1
.1
static route to207.0.0.0/8
207.0.0.0/16207.1.0.0/16207.2.0.0/16207.3.0.0/16
etc.
` 172.30.200.16/28
172.30.200.32/28
Lo1
Lo2
With the default auto-summary on ISP, it will load balance for all packets destined for 172.30.0.0/16
Rick Graziani [email protected]
SantaCruz1
router rip
network 172.30.0.0
network 192.168.4.0
version 2
no auto-summary
SantaCruz2
router rip
network 172.30.0.0
network 192.168.4.0
version 2
no auto-summary
ISP
router rip
redistribute static
network 10.0.0.0
network 192.168.4.0
version 2
no auto-summary
ip route 207.0.0.0 255.0.0.0 null0
e0
ISP
SantaCruz2SantaCruz1
192.168.4.20/30
172.30.1.0/24
Internet
s0
s0 s0
s1
172.30.100.0/24
e0
192.168.4.24/30
.21
.22
.25
.26
10.0.0.0/8
e0.1
.1.1
Lo0Lo0
172.30.110.0/24172.30.2.0/24 .1
.1
.1
static route to207.0.0.0/8
207.0.0.0/16207.1.0.0/16207.2.0.0/16207.3.0.0/16
etc.
` 172.30.200.16/28
172.30.200.32/28
Lo1
Lo2
RIPv2 Example
Rick Graziani [email protected]
e0
ISP
SantaCruz2SantaCruz1
192.168.4.20/30
172.30.1.0/24
Internet
s0
s0 s0
s1
172.30.100.0/24
e0
192.168.4.24/30
.21
.22
.25
.26
10.0.0.0/8
e0.1
.1.1
Lo0Lo0
172.30.110.0/24172.30.2.0/24 .1
.1
.1
static route to207.0.0.0/8
207.0.0.0/16207.1.0.0/16207.2.0.0/16207.3.0.0/16
etc.
` 172.30.200.16/28
172.30.200.32/28
Lo1
Lo2
SantaCruz2#show ip route
172.30.0.0/16 is variably subnetted, 6 subnets, 2 masks
C 172.30.200.32/28 is directly connected, Loopback2
C 172.30.200.16/28 is directly connected, Loopback1
R 172.30.2.0/24 [120/2] via 192.168.4.21, 00:00:21, Serial0
R 172.30.1.0/24 [120/2] via 192.168.4.21, 00:00:21, Serial0
C 172.30.100.0/24 is directly connected, Ethernet0
C 172.30.110.0/24 is directly connected, Loopback0
192.168.4.0/30 is subnetted, 2 subnets
R 192.168.4.24 [120/1] via 192.168.4.21, 00:00:21, Serial0
C 192.168.4.20 is directly connected, Serial0
R 10.0.0.0/8 [120/1] via 192.168.4.21, 00:00:21, Serial0
R 207.0.0.0/8 [120/1] via 192.168.4.21, 00:00:21, Serial0
Examining a Routing Table
Supernet, classless routing protcols will route supernets (CIDR)
Rick Graziani [email protected]
RIPv2: Sending and Receiving Updates
ISP#debug ip rip
RIP protocol debugging is on
ISP#01:23:34: RIP: received v2 update from 192.168.4.22 on Serial1
01:23:34: 172.30.100.0/24 -> 0.0.0.0 in 1 hops
01:23:34: 172.30.110.0/24 -> 0.0.0.0 in 1 hops
ISP#
01:23:38: RIP: received v2 update from 192.168.4.26 on Serial0
01:23:38: 172.30.2.0/24 -> 0.0.0.0 in 1 hops
01:23:38: 172.30.1.0/24 -> 0.0.0.0 in 1 hops
ISP#
01:24:31: RIP: sending v2 update to 224.0.0.9 via Ethernet0 (10.0.0.1)
01:24:31: 172.30.2.0/24 -> 0.0.0.0, metric 2, tag 0
01:24:31: 172.30.1.0/24 -> 0.0.0.0, metric 2, tag 0
01:24:31: 172.30.100.0/24 -> 0.0.0.0, metric 2, tag 0
01:24:31: 172.30.110.0/24 -> 0.0.0.0, metric 2, tag 0
01:24:31: 192.168.4.24/30 -> 0.0.0.0, metric 1, tag 0
01:24:31: 192.168.4.20/30 -> 0.0.0.0, metric 1, tag 0
<text omitted>
ISP(config)# line console 0
ISP(config-line)# logging synchronous
multicast
Includes mask
Rick Graziani [email protected]
Adding a default Routes to RIPv2
e0
ISP
SantaCruz2SantaCruz1
192.168.4.20/30
172.30.1.0/24
Internet
s0
s0 s0
s1
172.30.100.0/24
e0
192.168.4.24/30
.21
.22
.25
.26
10.0.0.0/8
e0.1
.1.1
Lo0Lo0
172.30.110.0/24172.30.2.0/24 .1
.1
.1
static route to207.0.0.0/8
207.0.0.0/16207.1.0.0/16207.2.0.0/16207.3.0.0/16
etc.
` 172.30.200.16/28
172.30.200.32/28
Lo1
Lo2
ISP
router rip
redistribute static
network 10.0.0.0
network 192.168.4.0
version 2
no auto-summary
default-information originate
ip route 207.0.0.0 255.0.0.0 null0
ip route 0.0.0.0 0.0.0.0 10.0.0.2 etherenet0
Rick Graziani [email protected]
Other RIPv2 Commands
Router(config-router)# neighbor ip-address
Defines a neighboring router with which to exchange unicast routing information. (RIPv1 or RIPv2)
Router(config-if)# ip rip send|receive version 1 | 2 | 1 2
Configures an interface to send/receive RIP Version 1 and/or Version 2 packets
Router(config-if)# ip summary-address rip ip_address ip_network_mask
Specifies the IP address and network mask that identify the routes to be summarized.
Authentication and other nice configuration commands and examples:
http://www.cisco.com/en/US/products/sw/iosswrel/ps1831/products_configuration_guide_chapter09186a00800d97f7.html
Ch.4 – RIPv2
CCNP 1 version 3.0
Rick Graziani
Cabrillo College