This exercise describes how load balancing activities with the RIP cost equally, consider how the switching process switching and fast-switching. RouterB has two lines to the 10.0.0.0 network. Use debug commands to check the package on the way to the 10.0.0.0 network in case of load balancing on each package (per packet) and to each destination (per destination).
Configuration
RouterA
!
hostname RouterA
!
!
ip subnet-zero
!
!
interface Ethernet0 / 0
ip address 10.0.0.1 255.255.255.0
!
interface Serial0 / 0
ip address 192.168.1.2 255.255.255.0
!
router rip
network 10.0.0.0
network 192.168.1.0
!
ip classless
!
line con 0
line aux 0
line vty 0 4
!
end
RouterB
!
hostname RouterB
!
ip subnet-zero
!
interface FastEthernet0 / 0
ip address 192.168.3.1 255.255.255.0
!
interface Serial0 / 0
ip address 192.168.1.1 255.255.255.0
clockrate 56000
!
interface Serial0 / 1
ip address 192.168.2.1 255.255.255.0
clockrate 56000
!
router rip
network 192.168.1.0
network 192.168.2.0
network 192.168.3.0
!
ip classless
!
line con 0
line aux 0
line vty 0 4
!
end
RouterC
!
hostname RouterC
!
ip subnet-zero
!
!
interface FastEthernet0 / 0
ip address 10.0.0.2 255.255.255.0
!
interface Serial0 / 0
ip address 192.168.2.2 255.255.255.0
!
router rip
network 10.0.0.0
network 192.168.2.0
!
ip classless
!
line con 0
line aux 0
line vty 0 4
!
end
Implementation
1. Initially configured to run RIP on all routers.
RouterA (config) # router rip
RouterA (config-router) # network 192.168.1.0
RouterA (config-router) # network 10.0.0.0
Check the routing table on RouterB, RouterB has two lines to the network 10.0.0.0
RouterB # sh ip route
Gateway of last resort is not set
R 10.0.0.0 / 8 [120 / 1] via 192.168.1.2, 00:00:17, Serial0 / 0
[120 / 1] via 192.168.2.2, 00:00:13, Serial0 / 1
C 192.168.1.0/24 is directly connected, Serial0 / 0
C 192.168.2.0/24 is directly connected, Serial0 / 1
C 192.168.3.0/24 is directly connected, FastEthernet0 / 0
RIP will automatically balance the load on the route costs are equal (both route metric is 1).
There are three criteria for decision-making following the route:
Metric: the routing protocol used to calculate the path metric which is the best path to a remote network. Many routing protocols do not easily share information because the metric of the protocols that are different
AD: If more than one routing protocol running on the router, the value of AD is used to choose which protocol to update routing tables. This value indicates which protocol is the most reliable source.
Prefix length: transition package will use the route when the destination subnet match. It will select the path length prefix match with the largest network address.
2. RouterB to load balance based on each package (per packet) both interface S0 / 0 and S0 / a type of switch used to process switching. Process switching networks require routers need to consider in each packet against the routing table, to select the appropriate line. In contrast, fast switching is only done to see the routing table for the first packet, the router then save the results in a high-speed cache and uses the information in the cache to forward the packet to the destination. Fast switching is the default setting.
To enable process switching on the serial port using the following command
RouterB (congig) # int S0 / 0
RouterB (config-if) # no ip route-cache
RouterB (config) # int S0 / 1
RouterB (config-if) # no ip route-cache
Check off fast switching on the interface using the command show ip interface
RouterB # show ip interface S0 / 0
Serial0 is up, line protocol is up
Internet address is 192.168.1.1 255.255.255.0
Broadcast address is 255255255255
Address determined by non-volatile memory
MTU is 1500 bytes
Helper address is not set
Directed broadcast forwarding is enabled
Outgoing access list is not set
Inbound access list is not set
Proxy ARP is enabled
Security level is default
Split horizon is enabled
ICMP redirects are always sent
ICMP unreachables are always sent
ICMP mask replies are never sent
IP fast switching is disabled
...
3. Because there are two routes to a destination in the routing table, half of the package will be sent on a road, and half the other posts on the road. Debug ip packet command to view IP packet received on a router posts
RouterB # debug ip packet
From the workstation ping 10.0.0.1. View messages appear, send IP packets balance on two lines to stop the debug undebug execute all (or u all).
01:42:24: IP: s = 192.168.3.2 (FastEthernet0 / 0), d = 10.0.0.1 (Serial0 / 0),
g = 192.168.1.2, len 60, forward
01:42:24: IP: s = 10.0.0.1 (Serial0 / 0), d = 192.168.3.2 (FastEthernet0 / 0),
g = 192.168.3.2, len 60, forward
01:42:25: IP: s = 192.168.3.2 (FastEthernet0 / 0), d = 10.0.0.1 (Serial0 / 1),
g = 192.168.2.2, len 60, forward
01:42:26: IP: s = 192.168.3.2 (FastEthernet0 / 0), d = 10.0.0.1 (Serial0 / 0),
g = 192.168.1.2, len 60, forward
01:42:26: IP: s = 192.168.3.1 (local), d = 255 255 255 255 (FastEthernet0 / 0),
len 92, sending broad / multicast
01:42:26: IP: s = 192.168.1.1 (local), d = 255 255 255 255 (Serial0 / 0),
len 72, sending broad / multicast
01:42:26: IP: s = 192.168.2.1 (local), d = 255 255 255 255 (Serial0 / 1),
len 72, sending broad / multicast
01:42:27: IP: s = 192.168.3.2 (FastEthernet0 / 0), d = 10.0.0.1 (Serial0 / 1),
g = 192.168.2.2, len 60, forward
The notice slightly complicated by the ping request, ping relply, RIP updates will appear. To filter the information needed to create access-list on the router. Because only want to see ping request packets to the 10.0.0.0 network, create access-list is as follows:
RouterB (config) # access-list 101 permit icmp 10.0.0.0 0.255.255.255 any
Access-list applied to filter the messages from the debug commands:
RouterB # debug ip packet 101
IP packet debugging is on for access list 101
Repeat the ping command to 10.0.0.1 from the workstation, see the results.
IP: s = 192.168.3.2 (FastEthernet0 / 0), d = 10.0.0.1 (Serial0 / 0), g = 192.168.1.2,
len 60, forward
IP: s = 192.168.3.2 (FastEthernet0 / 0), d = 10.0.0.1 (Serial0 / 1), g = 192.168.2.2,
len 60, forward
IP: s = 192.168.3.2 (FastEthernet0 / 0), d = 10.0.0.1 (Serial0 / 0), g = 192.168.1.2,
len 60, forward
IP: s = 192.168.3.2 (FastEthernet0 / 0), d = 10.0.0.1 (Serial0 / 1), g = 192.168.2.2,
len 60, forward
4. After checking on each packet load balancing, load balancing configuration on each destination as follows. Both of RouterB serial interface mode with fast switching command
RouterB (config-if) # ip route-cache
With fast switching, the appropriate information in the first packet of data stream is saved (cached) so CPU is not processing the next packet in a data stream. Check the fast switching enabled by the command show ip interface. Routing tables consider only once on each landing next to a host of packages and go the same way. Routers need only consider the routing table to another destination network cache expires. Turn on debug ip packet 101 on RouterB, and ping 10.0.0.1 from the workstation. When fast switching enabled, only a notice to appear. Package was sent out interface S0 / 0
RouterB #
IP: s = 192.168.3.2 (FastEthernet0 / 0), d = 10.0.0.1 (Serial0 / 0), g = 192.168.1.2,
len 60, forward
Continue, ping 10.0.0.2, the package will be sent out interface S0 / 1
IP: s = 192.168.3.2 (FastEthernet0 / 0), d = 10.0.0.2 (Serial0 / 1), g = 192.168.2.2,
len 60, forward
5. Try to ping the address 10.0.0.3 and 10.0.0.4 of course there will be no answer, use the command show ip cache to view the content of the route cache. Note that the table cache is available 10.0.0.1 and 10.0.0.2 as well as all IP addresses on network 10.0.0.0, which ping implementation.
RouterB # show ip cache
5 IP routing cache entries, 848 bytes
ADDS 14, 9 invalidates, 0 refcounts
Minimum invalidation interval 2 seconds, maximum interval 5 seconds,
quiet interval 3 seconds, threshold 0 requests
Invalidation rate 0 in last second, 0 in last 3 seconds
Last full cache invalidation occurred 01:40:00 ago
Prefix / Length Age Interface Next Hop
10.0.0.1/32 00:00:15 Serial0 / 0 192.168.1.2
10.0.0.2/32 00:03:19 Serial0 / 1 192.168.2.2
10.0.0.3/32 00:00:57 Serial0 / 0 192.168.1.2
10.0.0.4/32 00:00:43 Serial0 / 1 192.168.2.2
192.168.3.2/32 00:03:37 FastEthernet0 / 0 192.168.3.2
