New Switch cant Talk to Old Switch

[sysad43]

Im stumped. I have a new 2960-x. Im trying to connect it to an existing 3650 switch which is working just fine. If I leave the default configuration loaded on the 2960-x with no changes, and simply plug it into a unconfigured port on the 3650, such that they have a native vlan1 trunk between them, it all links up fine, but I cant send packets from new switch to old switch and thus the network. Switches are connected with cat6 ethernet cable from 1/0/1 to 1/0/1. Full duplex gigabit.

Show CDP neighbors on both ends shows each others info

show span shows span ports FWD
show int vlan1 shows interface is up

show interface gi1/0/1 on either switch shows packets outgoing from 3650-2960, but no packets the other direction

If i do wireshark on the 2960 I can see all sorts of network traffic, so packets are being sent from the network to 3650, to 2960. 

If I ping the gateway, show arp shows incomplete arp. wireshark shows no answer to arp packets.

What am I missing?

[balaji.bandi]

Trying to Figure out what is the issue here ?

Do you have devices connected on both the switches ? what port they are connected on respected switches.

what is the IP address configured on the device. Do you SVI configured on the VLAN1 interface ?

can you post port the switch configuration if possile ?

[sysad43]

Thanks for assisting. I will go and get the switch config, however the ports are setup with no config. Just blank interface. Thus they have negotiated a vlan1 trunk.

I have devices on both switches and I have tried both leaving a access port (with laptop plugged in to 1/0/25 on the 2960) with no config and also with a preferred vlan103 and then either manually setting my laptop to an IP that is valid for either vlan1 or vlan103 (like 10.5.103.13/24).

I have tried with both a SVI and without (default). When the SVI for vlan103 is configured, and my laptop is in a access port with the same subnet, I can talk to the switch via its management IP. Just not from the next hop switch (the 3650). Nor can I ping from the 2960 to the 3650 or anywhere else on the network. It looks like the switch just doesnt actually fwd the packets to the trunk.

[balaji.bandi]

Can you do basic setup on new switch :

like below setup :

config t

!

vtp mode transparent

!

vlan 1, 103

!

interface  gi 1/0/1

switchport mode trunk

!

end

OLD Switch :

interface  gi 1/0/1

switchport mode trunk

!

New switch connect device with VLAN1 IP address range and test.

[Georg Pauwen]

Hello,

hard to say what is going on. Can you post the full configs of both switches, and indicate which ports are connected ? Also,do you have VTP configured on one or both switches ?

[sysad43]

Here is the config from the new 2960-x. Port 1 is the uplink to 3650

Building configuration...

Current configuration : 2379 bytes
!
! Last configuration change at 16:46:59 UTC Mon May 13 2019
!
version 15.2
no service pad
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname Switch
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
switch 1 provision ws-c2960x-48lps-l
!

spanning-tree mode pvst
spanning-tree extend system-id
!

vlan internal allocation policy ascending
!

interface FastEthernet0
no ip address
!
interface GigabitEthernet1/0/1
!
interface GigabitEthernet1/0/2
!
interface GigabitEthernet1/0/3
!
interface GigabitEthernet1/0/4
!
interface GigabitEthernet1/0/5
!
.......................REST ARE SAME
!
interface Vlan1
no ip address
!
ip http server
ip http secure-server
!
!
!
no vstack
!
line con 0
line vty 5 15
!
end

---

Here is the 3650. gig1 is trunk port to the 2960

Building configuration...

Current configuration : 23188 bytes
!
! Last configuration change at 17:08:14 EDT Mon May 13 2019
! NVRAM config last updated at 15:17:19 EDT Fri May 10 2019 by admin
!
version 15.0
no service pad
service timestamps debug datetime msec
service timestamps log datetime msec localtime
no service password-encryption
service compress-config
!
hostname AXSW103B
!
boot-start-marker
boot-end-marker
!
!
vrf definition Mgmt-vrf
!
address-family ipv4
exit-address-family
!
address-family ipv6
exit-address-family
!

no aaa new-model
clock timezone EST -5 0
clock summer-time EDT recurring
switch 1 provision ws-c3650-48tq
!
ip device tracking
!
!
!

!
!
!
!
diagnostic bootup level minimal
spanning-tree mode pvst
spanning-tree extend system-id
!
redundancy
mode sso
!
!
!
class-map match-any non-client-nrt-class
match non-client-nrt
!
policy-map port_child_policy
class non-client-nrt-class
bandwidth remaining ratio 10
!
!
!
!
!
!
interface GigabitEthernet0/0
vrf forwarding Mgmt-vrf
no ip address
shutdown
negotiation auto
!
interface GigabitEthernet1/0/1

!
interface GigabitEthernet1/0/2
switchport access vlan 103
switchport mode access
switchport voice vlan 72
switchport port-security maximum 2
switchport port-security
switchport port-security aging time 2
switchport port-security violation restrict
switchport port-security aging type inactivity
auto qos voip cisco-phone
macro description cisco-phone
spanning-tree portfast
spanning-tree bpduguard enable
!
interface GigabitEthernet1/0/3
switchport access vlan 103
switchport mode access
switchport voice vlan 72
switchport port-security maximum 2
switchport port-security
switchport port-security aging time 2
switchport port-security violation restrict
switchport port-security aging type inactivity
auto qos voip cisco-phone
macro description cisco-phone
spanning-tree portfast
spanning-tree bpduguard enable
!
.....REST ARE SAME
!
interface GigabitEthernet1/0/48
description trunk to 103GBA
switchport access vlan 103
switchport trunk native vlan 103
switchport mode trunk
auto qos trust
macro description cisco-switch
spanning-tree link-type point-to-point
spanning-tree port-priority 240
!
interface TenGigabitEthernet1/1/1
switchport access vlan 103
switchport trunk native vlan 103
switchport mode trunk
auto qos trust
macro description cisco-switch
spanning-tree link-type point-to-point
spanning-tree port-priority 16
!
interface TenGigabitEthernet1/1/2
switchport access vlan 103
switchport trunk native vlan 103
switchport mode trunk
auto qos trust
macro description cisco-switch
spanning-tree link-type point-to-point
!
interface TenGigabitEthernet1/1/3
switchport access vlan 103
switchport trunk native vlan 103
switchport mode trunk
auto qos trust
macro description cisco-switch
spanning-tree link-type point-to-point
!
interface TenGigabitEthernet1/1/4
switchport access vlan 103
switchport trunk native vlan 103
switchport mode trunk
auto qos trust
macro description cisco-switch
spanning-tree link-type point-to-point
!
interface Vlan1
no ip address
!
interface Vlan103
ip address 10.5.103.6 255.255.255.0
!
ip default-gateway 10.5.103.1
ip http server
ip http authentication local
ip http secure-server
!
!

!
ntp server 10.5.3.3
ntp server 10.5.3.4 prefer
wsma agent exec
profile httplistener
profile httpslistener
wsma agent config
profile httplistener
profile httpslistener
wsma agent filesys
profile httplistener
profile httpslistener
wsma agent notify
profile httplistener
profile httpslistener
!
wsma profile listener httplistener
transport http
!
wsma profile listener httpslistener
transport https
ap group default-group
end

---

I also tried doing switchport mode trunk on both sides. At that point more traffic came through with all the vlans, but still only in one direction. From 3650 to 2960. show interface gi1/0/1 on either switch shows no packets being sent from 2960-2650

[balaji.bandi]

have you tried the config as suggested on the above post ?

config t

!

vtp mode transparent

!

vlan 1, 103

!

interface  gi 1/0/1

switchport mode trunk

!

interface GigabitEthernet1/0/2    <<-- connect the device to this port with the IP address configured 10.5.103.X and test it

switchport access vlan 103
switchport mode access

!

end

OLD Switch :

interface  gi 1/0/1

switchport mode trunk

!

[sysad43]

Yes, no change. Devices can talk to each other on the 2960, but not through through the trunk to the 3650. I can only see packets coming from the 3650. The 3650 can not see packets coming from the 2960.

I also did show int trunking, and all looks as expected. Trunking on, interface trunking, all vlans allowed.

[balaji.bandi]

Can you post new config as modified one. along with below outputs.

show interface trunk  < - from bot the switches all outout mentioned

show ip interface brief

show interface gi 1/0/1

show vtp status

show spanning tree root

show ip arp

[sysad43]

Ill get back to you on that. I connected the 2960 to a fresh 3650 and its working as expected, so I think maybe the issue is the config or ios version (3.5.5) on the old 3650. Im going to update and reset it and see what happens first. Thanks for the help.

[sysad43 · Accepted solution]

Upgrading the IOS to Denali and/or reload resolved this.