CCNP switching environment troubleshooting Experiment

Lab requirements:
Set up the topology, import the pre-configuration, and troubleshoot the following errors.
1. The link between R1 and SW1 cannot start;
2. SW1 cannot start the trunk link between SW2 and SW3;
3. Problems with etherchannel between SW2 and SW3;
4. The HSRP between SW2 and SW3 cannot be automatically switched;
5. R1 and R2 cannot dynamically obtain the address from DHCP server R3;
6. R1 cannot access the server 5.5.5.5 on the ISP R5 without R2;
7. When the Intranet accesses multiple servers on the ISP, there are too many ARP entries on the gateway R4. Please solve this problem.
Tutorial topology:
650) this. width = 650; "style =" border-bottom: 0px; border-left: 0px; display: block; float: none; margin-left: auto; border-top: 0px; margin-right: auto; border-right: 0px "title =" clip_image002 "border =" 0 "alt =" clip_image002 "height =" 335 "src =" http://www.bkjia.com/uploads/allimg/131227/022PG327-0.jpg "/>Tutorial steps:
1. The link between R1 and SW1 cannot start
Run show run on F0/1 of SW1 and F0/0 of R1 respectively:
R1:
R1 # show run int f0/0
Interface FastEthernet0/0
Ip address dhcp
No ip route-cache
Duplex auto
Speed 10
End
SW1:
Sw1 # show run int f0/1
Interface FastEthernet0/1
Switchport access vlan 10
Switchport mode access
Speed100
End
We can find that the duplex speed of the two ports is different. One is 100 Mb/s and the other is 10 Mb/s, resulting in the failure to establish the link normally.
Solution:
Change the speed of port F0/0 of R1 to automatic or 100 Mb/s.
R1 (config) # int f0/0
R1 (config-if) # speed 100 or r1 (config-if) # speed auto

2. The trunk link between SW1, SW2, and SW3 cannot start.
Show vtp status and show vtp password for SW1, SW2, and SW3 respectively:
SW1:
Sw1 # show vtp st
VTP Version: running VTP1 (VTP2 capable)
Configuration Revision: 0
Maximum VLANs supported locally: 1005
Number of existing VLANs: 9
VTP Operating Mode: Transparent
VTP Domain Name: cisc0
VTP Pruning Mode: Disabled
VTP V2 Mode: Disabled
VTP Traps Generation: Disabled
MD5 digest: 0xC1 0x7B 0xBA 0x68 0x93 0xAF 0xB0 0x4D
Sw1 # show vtp password
VTP Password: cisco
SW2:
Sw2 # show vtp st
VTP Version: 2
Configuration Revision: 0
Maximum VLANs supported locally: 1005
Number of existing VLANs: 9
VTP Operating Mode: Transparent
VTP Domain Name: cisco
VTP Pruning Mode: Disabled
VTP V2 Mode: Disabled
VTP Traps Generation: Disabled
MD5 digest: 0xA6 0x2C 0x47 0x87 0xB0 0xD5 0x5A 0xAD
Sw2 # show vtp password
VTP Password: cisco
SW3:
Sw3 # show vtp st
VTP Version: running VTP1 (VTP2 capable) Configuration Revision: 0
Maximum VLANs supported locally: 1005
Number of existing VLANs: 9
VTP Operating Mode: Transparent
 VTP Domain Name: cisco
VTP Pruning Mode: Disabled
VTP V2 Mode: Disabled
VTP Traps Generation: Disabled
MD5 digest: 0x7F 0xEF 0x7B 0x66 0x28 0x55 0x41 0xAF
Sw3 # show vtp password
The VTP password is not configured.
View the VTP domain names and VTP passwords of the three vswitches respectively. The VTP domain name of SW1 is cisc0, while the VTP domain name of SW2 and SW3 is cisco. The VTP password of SW1 and SW2 is cisco, while that of SW3 is not.
Solution:
Modify the VTP domain name of SW1 and The VTP password of SW3.
SW1 (config) # vtp domain cisco
SW3 (config) # vtp password cisco

3. Problems with etherchannel between SW2 and SW3
Run show run on ports F0/21 and F0/22 of SW3 and SW2:
SW2
Sw2 # show run int f0/22
Interface FastEthernet0/22
Switchport trunk encapsulation dot1q
Switchport trunk native vlan 20
Switchport mode trunk
Channel-group 2 mode on end
Sw2 # show run int f0/21
Interface FastEthernet0/21
Switchport trunk encapsulation dot1q
Switchport trunk native vlan 10
Switchport mode trunk
Channel-group 2 mode on end
SW3
Sw3 # show run int f0/21
Interface FastEthernet0/21
Switchport trunk encapsulation dot1q
Switchport trunk native vlan 10
Switchport mode trunk
Channel-group 1 mode on end
Sw3 # show run int f0/22
Interface FastEthernet0/22
Switchport trunk encapsulation dot1q switchport trunk native vlan 20 switchport mode trunk
Channel-group 1 mode on end
If the Ethernet aggregation link starts trunk, the native vlan must be consistent. Using show run, we can find two different native VLANs exist between the aggregation links.
Solution:
Sw2 (config) # int f0/22
Sw2 (config) # switchport trunk native vlan 10
Sw3 (config) # int f0/22
Sw3 (config) # switchport trunk native vlan 10

4. The HSRP between SW2 and SW3 cannot be automatically switched
Perform show standby and show standby vlan 20 brief for SW2 and SW3 respectively:
Sw3 # show standby
Vlan10-Group 1
State is Active
2 state changes, last state change 00:33:02
Virtual IP address is 172.16.10.254
Active virtual MAC address is already running c07.ac01
Local virtual MAC address is wrongly c07.ac01 (v1 default) Hello time 3 sec, hold time 10 sec
Next hello sent in 2.820 secs
Preemption disabled
Active router is local
Standby router is 172.16.10.3, priority 100 (expires in 8.048 sec) Priority 105 (configured 105)
IP redundancy name is "hsrp-Vl10-1" (default) Vlan20-Group 2
State is Active
2 state changes, last state change 00:34:19
Virtual IP address is 172.16.255.254
Active virtual MAC address is already running c07.ac02
Local virtual MAC address is wrongly c07.ac02 (v1 default) Hello time 3 sec, hold time 10 sec
Next hello sent in 1.708 secs
Preemption disabled
Active router is local
Standby router is 172.16.00003, priority 105 (expires in 7.536 sec) Priority 100 (default 100)
IP redundancy name is "hsrp-Vl20-2" (default)
Sw2 # show standby vlan 20 br
P indicates configured to preempt.
|
Interface Grp Prio P State Active Standby Virtual IP
Vl20 2 100 Active local 172.16.20.3 172.16.255.254
Sw3 # show standby vlan 20 br
P indicates configured to preempt.
|
Interface Grp Prio P State Active Standby Virtual IP
Vl20 2 105 Standby 172.16.20.2 local 172.16.255.254
The HSRP priority of SW3 is 105, which is significantly higher than the 100 priority of SW2. Why is it in standby mode? Through show standby, we can find that SW3's preemption is disabled, so we didn't take the initiative to fight for active mode.
Solution:
Enable preemptible In the SVI interface.
Sw3 (config) # int vlan 10
Sw3 (config-if) # standby 1 preempt
Sw3 (config-if) # int vlan 20
Sw3 (config-if) # standby 2 preempt

5. R1 and R2 cannot obtain the address from the DHCP server.
Through show vlan of SW1 and SW2, we found that DHCP server R3 belongs to VLAN30, while R1 and R2 belong to VLAN10 and VLAN20 respectively, and the three belong to different broadcast domains, therefore, DHCP packets cannot be sent to the DHCP server.
Solution:
Configure DHCP relay in the SVI interface of the gateway.
Sw2 (config-if) # int vlan 10
Sw2 (config-if) # ip helper-address 172.16.30.3 sw2 (config-if) # int vlan 20
Sw2 (config-if) # ip helper-address 172.16.30.3
After the configuration is complete, R1 and R2 get the address:
* Mar 1 04:48:33. 990: % DHCP-6-ADDRESS_ASSIGN: Interface FastEthernet0/0 assigned DHCP
Address 172.16.10.1, mask 255.255.255.0, hostname r1
* Mar 1 00:56:24. 915: % DHCP-6-ADDRESS_ASSIGN: Interface FastEthernet0/0 assigned DHCP
Address 172.16.20.1, mask 255.255.255.0, hostname r2

6. R1 and R2 cannot access the server 5.5.5.5 on ISP R5.
Run the show run command on the gateway R4:
R4 # show run router ospf 1
Log-adjacency-changes
Network 172.16.44.44 0.0.0.0 area 0
!
Ip classless
Ip route 0.0.0.0 0.0.0.0 FastEthernet0/1
!
Access-list 1 permit 172.16.0.0
R4 uses a default route to advertise the subnet to the ISP. To access the ISP, R1 and R2 must advertise the default route to the Intranet, the announcement of default routes is missing in the OSPF routing process of R4. In addition, the Access Control List lacks the anti-masking code and should be added.
Solution:
R4 (config) # router ospf 1
R4 (config-router) # default-information originate r4 (config) # no access-list 1
R4 (config) # access-list 1 permit 172.16.0.0 0.0.255.255
Then run show ip rou:
SW4 # show ip rou
Codes: C-connected, S-static, R-RIP, M-mobile, B-BGP
D-OSPF, EX-VPN external, O-OSPF, IA-OSPF inter area
N1-ospf nssa external type 1, N2-ospf nssa external type 2
E1-OSPF external type 1, E2-OSPF external type 2, E-EGP
I-IS, su-IS summary, L1-IS level-1, L2-IS level-2 ia-IS inter area, *-candidate default, U-per-user static route o-ODR, P-periodic downloaded static route
Gateway of last resort is 172.16.44.44 to network 0.0.0.0
172.16.0.0/24 is subnetted, 6 subnets
C 172.16.44.0 is directly connected, FastEthernet0/4
C 172.16.34.0 is directly connected, FastEthernet0/24
O 172.16.30.0 [110/2] via 172.16.24.2, 00:05:07, FastEthernet0/20
C 172.16.24.0 is directly connected, FastEthernet0/20
O 172.16.20.0 [110/2] via 172.16.34.3, 00:05:07, FastEthernet0/24
[110/2] via 172.16.24.2, 00:05:07, FastEthernet0/20
O 172.16.10.0 [110/2] via 172.16.34.3, 00:05:07, FastEthernet0/24
[110/2] via 172.16.24.2, 00:05:08, FastEthernet0/20
O * E2 0.0.0.0/0 [110/1] via 172.16.44.44, 00:05:08, FastEthernet0/4
The default OSPF route has been advertised to the Intranet. Use R1 and R2 to ping 5.5.5:
R1 # ping 5.5.5
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 MS
R2 # ping 5.5.5
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 MS

7. Too many ARP entries on the gateway R4
Use R1 to ping all the loopback ports on R5, and then show ip arp on R4:
R4 # show ip arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 6.6.6.6 1 0024.14dd.a908 ARPA FastEthernet0/1
Internet 5.5.5 1 0024.14dd.a908 ARPA FastEthernet0/1
Internet 7.7.7.7 1 0024.14dd.a908 ARPA FastEthernet0/1
Internet 8.8.8.8 6 0024.14dd.a908 ARPA FastEthernet0/1
Internet 45.45.45.5 0 0024.14dd.a908 ARPA FastEthernet0/1
Internet 45.45.45.4-0024.14ec.6719 ARPA FastEthernet0/1
Internet 172.16.44.4 0 0012.8077.3200 ARPA FastEthernet0/0
Internet 172.16.44.44-0024.14ec.6718 ARPA FastEthernet0/0
There are too many entries in the ARP table, because the default route uses the Ethernet next hop exit. Because there is no specified next hop, the data sends an ARP packet every time it goes out from the interface, this increases the number of ARP entries in the ARP table.
Solution:
Change the Ethernet hop exit to the next hop address
R4 (config) # no ip route 0.0.0.0 0.0.0.0 FastEthernet0/1
R4 (config) # ip route 0.0.0.0 0.0.0.0 45.45.45.5
Show ip arp again:
R4 # show ip arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 45.45.45.5 0 0024.14dd.a908 ARPA FastEthernet0/1
Internet 45.45.45.4-0024.14ec.6719 ARPA FastEthernet0/1
Internet 172.16.44.4 0 0012.8077.3200 ARPA FastEthernet0/0
Internet 172.16.44.44-0024.14ec.6718 ARPA FastEthernet0/0
The entries in the ARP table are fixed to the preceding entries.

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