You are a network engineer for a company, study the exhibit carefully. The company’s network is
running EIGRP and you want to change the path R5 uses to reach 172.30.1.0/24 to R4. How
could you achieve this goal?
A.
Change the bandwidth on the link between R2 and R5 to 70, and change the bandwidth on the
link between R3 and R5 to 70.
B.
Change the bandwidth on the link between R4 and R5 to 110.
C.
Change the bandwidth on the link between R3 and R5 to 70.
D.
Do nothing, the best path to 172.30.1.0/24 from R5 is already through R4.
Explanation:
Here is an example from Cisco on how and why to change the EIGRP bandwidth along with the
verification steps
Change the Bandwidth at R2
Using the bandwidth to influence EIGRP paths is discouraged for two reasons:
Changing the bandwidth can have impact beyond affecting the EIGRP metrics. For example,
quality of service(QoS) also looks at the bandwidth on an interface.
EIGRP throttles to use 50 percent of the configured bandwidth. Lowering the bandwidth can cause
problems like staving EIGRP neighbors from getting hello packets because of the throttling back.
Changing the delay does not impact other protocols nor does it cause EIGRP to throttle back.
Check the EIGRP topology table for R1 before you make any changes.
R1# show ip eigrp topology 10.1.3.0 255.255.255.0
IP-EIGRP (AS 1): topology entry for 10.1.3.0/24
State is Passive, Query origin flag is 1, 1 Successor(s), FD is 2221056
Routing Descriptor Blocks:
10.1.1.2 (Serial0.201), from 10.1.1.2, Send flag is 0x0
Composite metric is (2221056/307200), Route is Internal
Vector metric:
Minimum bandwidth is 1544 Kbit
Total delay is 22000 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1500
Hop count is 2
Check the starting values for the ethernet0 interface on R2.
R2# show interface ethernet0
Ethernet0 is up, line protocol is up
Hardware is Lance, address is 0010.7b3c.6786 (bia 0010.7b3c.6786)
Internet address is 10.1.2.2/24
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec, rely 255/255, load 1/255
Encapsulation ARPA, loopback not set, keepalive set (10 sec)
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:01, output 00:00:02, output hang never
Last clearing of “show interface” counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
1938 packets input, 165094 bytes, 0 no buffer
Received 1919 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
0 input packets with dribble condition detected
1482 packets output, 124222 bytes, 0 underruns
0 output errors, 0 collisions, 18 interface resets0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out
Decrease the bandwidth to see the impact on R1.
R2# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
R2(config)# interface ethernet0
R2(config-if)# bandwidth 5000
R2(config-if)# end
R2#
Confirm the change.
R2# show interface ethernet0
Ethernet0 is up, line protocol is up
Hardware is Lance, address is 0010.7b3c.6786 (bia 0010.7b3c.6786)
Internet address is 10.1.2.2/24
MTU 1500 bytes, BW 5000 Kbit, DLY 1000 usec, rely 255/255, load 1/255
Encapsulation ARPA, loopback not set, keepalive set (10 sec)
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:02, output 00:00:01, output hang never
Last clearing of “show interface” counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
1995 packets input, 169919 bytes, 0 no buffer
Received 1969 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
0 input packets with dribble condition detected
1525 packets output, 127831 bytes, 0 underruns
0 output errors, 0 collisions, 18 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out
Confirm that it also changed in the EIGRP topology table.
R2# show ip eigrp topology 10.1.3.0 255.255.255.0
IP-EIGRP (AS 1): topology entry for 10.1.3.0/24
State is Passive, Query origin flag is 1, 2 Successor(s), FD is 563200
Routing Descriptor Blocks:
10.1.2.4 (Ethernet0), from 10.1.2.4, Send flag is 0x0
Composite metric is (563200/281600), Route is InternalVector metric:
Minimum bandwidth is 5000 Kbit
Total delay is 2000 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1500
Hop count is 1
10.1.2.3 (Ethernet0), from 10.1.2.3, Send flag is 0x0
Composite metric is (563200/281600), Route is Internal
Vector metric:
Minimum bandwidth is 5000 Kbit
Total delay is 2000 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1500
Hop count is 1
Check the impact on the EIGRP topology table for R1.
R1# show ip eigrp topology 10.1.3.0 255.255.255.0
IP-EIGRP (AS 1): topology entry for 10.1.3.0/24
State is Passive, Query origin flag is 1, 1 Successor(s), FD is 2221056
Routing Descriptor Blocks:
10.1.1.2 (Serial0.201), from 10.1.1.2, Send flag is 0x0
Composite metric is (2221056/563200), Route is Internal
Vector metric:
Minimum bandwidth is 1544 Kbit
Total delay is 22000 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1500
Hop count is 2
There is no change, as the Frame Relay connection between R1 and R2 is still the lowest speed
link. You see a change only if you decrease that bandwidth on the ethernet0 interface for R2 to a
value less than 1544.
Decrease the bandwidth on the ethernet0 interface for R2 to 1000.
R2# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
R2(config)# interface ethernet 0
R2(config-if)# bandwidth 1000
R2(config-if)# endR2#
Check the impact on the EIGRP topology table for R1.
R1# show ip eigrp topology 10.1.3.0 255.255.255.0
IP-EIGRP (AS 1): Topology entry for 10.1.3.0/24
State is Passive, Query origin flag is 1, 1 Successor(s), FD is 312320
Routing Descriptor Blocks:
10.1.1.2 (Serial0.201), from 10.1.1.2, Send flag is 0x0
Composite metric is (3123200/2611200), Route is Internal
Vector metric:
Minimum bandwidth is 1000 Kbit
Total delay is 22000 microseconds
Reliability is 255/255
Load is 1/255
Minimum MTU is 1500
Hop count is 2http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a00800c2d96.shtml#change
bandwidthR2