Switching issue,

[Bharath Kumar J]

I am using Cisco 2960S as an access switch, and Cisco 3850 is Core switch.

There are two 2960s switch, connected both with trunk. one of the machine connected to 1st 2960S switch and machine is able to obtain the VLAN -10 DHCP info and able to access the internet and other machines.

The issue is when the same machine connected to the second 2960s switch with the same VLAN-10

Machine could able to obtain the DHCP info, but no internet, unable to access other machine, even not able to ping gateway, but at the same time other machine were able to access all with the same VLAN-10

Again machine connect back to the old port (1st switch) it works well.

No issue with machine as i tested in all criteria (new image)

Looks strange issue for me, please help me asap.

[Dennis Mink]

are you sure the machine receives an dhcp IP address on the non funtioning switch? can you do ipconfig -renew and see if it actaully communicates on vlan 10.

can you chech the port and see if its connected to vlan 10 and if the trunk to the 3850 carries vlan 10 as well.

[paul driver]

Hello

This does seem a strange issue - just like to add to what Dennis has mentioned as there cannot be much interms of mis configuration to negate this host from working - 

Make sure the trunk on the offending switch is correct and that the vlan 10 is populated into the vtp database, and the switch has no ip routing enabled.

[Richard Burts]

Can the original poster provide this information:

- identify the port on both 2960 where the PC was connected.

- output on both 2960 of show interface status and show interface trunk

HTH

Rick

[Bharath Kumar J]

Hi All, Thanks for the reply.

Machine is able to obtain the DHCP.

here you can consider VLAN 177

Find the below output for the both switch.

SWITCH 2 2960S

sh inter trunk

Port Mode Encapsulation Status Native vlan
Gi0/1 on 802.1q trunking 1
Gi0/43 on 802.1q trunking 1

Port Vlans allowed on trunk
Gi0/1 154,162,166,172-178
Gi0/43 1,154,166,172,175,177

Port Vlans allowed and active in management domain
Gi0/1 154,162,166,172,174-178
Gi0/43 1,154,166,172,175,177

Port Vlans in spanning tree forwarding state and not pruned
Gi0/1 154,162,166,172,174-178
Gi0/43 1,154,166,172,175,177

L2-2-TF#sh interfaces gigabitEthernet 0/22
GigabitEthernet0/22 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet, address is 3c0e.23c2.6a16 (bia 3c0e.23c2.6a16)
MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 1000Mb/s, media type is 10/100/1000BaseTX
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 4d19h, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 28
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 26000 bits/sec, 7 packets/sec
5 minute output rate 290000 bits/sec, 60 packets/sec
161273386 packets input, 45295842257 bytes, 0 no buffer
Received 1237331 broadcasts (915820 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 915820 multicast, 0 pause input
0 input packets with dribble condition detected
907271128 packets output, 680285395761 bytes, 0 underruns
0 output errors, 0 collisions, 1 interface resets
201 unknown protocol drops
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 pause output
0 output buffer failures, 0 output buffers swapped out

SWITCH 01

sh interfaces gigabitEthernet 0/26
GigabitEthernet0/26 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet, address is c414.3ca6.189a (bia c414.3ca6.189a)
MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 1000Mb/s, media type is 10/100/1000BaseTX
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 1y23w, 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: 476
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 7000 bits/sec, 5 packets/sec
72220206 packets input, 12084103123 bytes, 0 no buffer
Received 2548130 broadcasts (1949266 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 1949266 multicast, 0 pause input
0 input packets with dribble condition detected
152482127 packets output, 137585330722 bytes, 0 underruns
0 output errors, 0 collisions, 1 interface resets
1641 unknown protocol drops
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 pause output
0 output buffer failures, 0 output buffers swapped out
L2-1-TF#sh inter trun
L2-1-TF#sh inter trunk

Port Mode Encapsulation Status Native vlan
Gi0/1 on 802.1q trunking 1
Gi0/48 on 802.1q trunking 1

Port Vlans allowed on trunk
Gi0/1 1-4094
Gi0/48 153,156,166,172,176-177

Port Vlans allowed and active in management domain
Gi0/1 1,10,151-156,161-163,166-167,170-172,174-178
Gi0/48 153,156,166,172,176-177

Port Vlans in spanning tree forwarding state and not pruned
Gi0/1 1,10,151-156,161-163,166-167,170-172,174-178
Gi0/48 153,156,166,172,176-177

[JunaidM]

Hi Dear,

Please follow the below steps for your troubleshooting/verification to point the issue at right. Hope it will work..!!

1- Check the physical cable. If it's fine then proceed next.
2- Check that that ports on switch 2 have same configurations (Access vlan configs) as to switch 1 and are fine.
3- Check that vlan X exists to the switch.
4- Check that on trunk interface Vlan 10 or target vlan is learning/forwarding.
5- Assign the IP from the same range to the switch where its given to DHCP POOL. (Check IF possible)
6- Check that GATEWAY exist on the switch.
-GATEWAY will be the IP address assigned in "default-router" of the DHCP POOL.
7- You can check by changing the trunk interface to another port. (for testing)
8- Verify by pinging to stop by stop, this will help you understand the exact route issue or you can use "traceroute".
9- When machine is connected to the switch check the machine configurations if that are same when connected to switch 1 or not.
10- You can also use "ipconfig/release" then "ipconfig/renew" in your machine CLI.

Guide: To find the issue just use the 7 Layers(Verify node-to-node) and then you will be at your successful destination.

Please rate the helpful posts.

Regards,