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2960L SVI issue

AdamW01248
Level 1
Level 1

I have a 24port 2960-L (running the latest IOS) which being passive cooled fits my requirement well.

 

I have configured it with a number of VLANs with a SVI on each and enabled routing.

 

Seemingly at random an SVI stops responding. Unfortunately I was in a hurry to get things working so power cycled the switch which resolved the issue. I'm hopeful next time it occurs (its already happened a number of times) I can get a laptop and console cable to see what's happening. Other than that its working perfectly.

 

Has anyone experienced a similar issue with the 2960-L series? any hints on where to look for issues?

21 Replies 21

Reza Sharifi
Hall of Fame
Hall of Fame

Hi,

What is your license level? "sh ver" should show you that. Also, is "ip routing" enabled?

HTH

I believe all 2960L have the same (I think LAN Lite) and yes I have ip routing in my config.

As I said, its works fine, then just stops so the feature exists and is enabled. The SVI suddenly doesn't respond to ping and doesn't route, when it has happened it wasn't for all VLANs, traffic was routing correctly between 2 other VLANs so whatever it is appears to be isolated to the SVI.

Adam,

Not sure what version of IOS you are running, but you may want to upgrade the IOS to a different version and test again as this maybe a bug.

HTH

Already on the latest MR for this switch, I guess I could try going back a version and see if that helps.

Already on the latest MR for this switch, I guess I could try going back a version and see if that helps.

Exactly, just try a different version. That would take the IOS bug out of the equation.

HTH

Martin L
VIP
VIP

 

you said you have number of VLANs with a SVI on each and enabled routing.  How many? maybe you have too many and switch simply cannot handle traffic. check configs, look at ip routing table. anything pointing to outgoing interface instead of an IP?  make sure there no chance for ARP table to grow exponentially

check SDM settings, not sure what is preferred or default settings for the 2960 switch

check logs and CPU/memory utilization

 

Regards, ML
**Please Rate All Helpful Responses **

Currently 4 SVIs and VLANs, less than 30 devices on the network. I don't think its traffic but I'll keep an eye on the cpu/memory.

 

The 2960L only has the one SDM template I believe.

 

I think at this stage I'm going to have to wait for it to reoccur and check the state as its happening.

s.hellman
Level 1
Level 1

We have similar problems. We have alot of 2960L with different software 15.2(7)E0, E2 and E3, sometimes a switch loses connection on SVI (Vlan1). It is not possible to connect to the switch with Telnet/SSH/Web or Ping. If we connect with console to the switch, it is not possible to telnet or ping anything else. Cant see anything special in the log and the SVI says UP and no STP blocking. If we do a "shutdown" and then a "no shutdown" on interface vlan 1 everything is good again. Traffic through the switch works all the time, it is just not possible to connect to the SVI.

We have a few C1000-switches to with latest software, 15.2(7)E3, and it has happend once on one of them too.

I have not found anything in the bug search tool, that could explain this, but I guess it is a bug.

You also posted this issue in another discussion in the community to which I responded suggesting the possibility of a memory leak as a possible cause of the issue. But in reading the second description of the issue I am noticing the part that says that a shut/no shut will clear the problem. That suggests that the issue is probably not a memory leak (shut/no shut would not affect available memory) but that there is some other issue. Are these SVI addresses hard coded or learned by DHCP? The next time the problem occurs please access the console and post the output of these commands

show ip interface brief

show ip route

show arp

HTH

Rick

Hi Richard, and thanks for the reply. I've been away for a few days and have not been able to reply until now.

We have been serching for simular cases and finally found this two, so I replied to both hoping that we could get a response.

Yes it is a very strange problem, the switch works fine dispite the SVI-problem, I can connect with console without any problem.

I can ping the switch itself but nothing else.

If I do a shudown and no shutdown on interface vlan 1, it's ok again for weeks, months or it maybe never happens again on that switch, but after some time it happens on another switch.

The outputs from the commands:

----------------------------

Drottningatan_22_C2960_193.65>show arp

Protocol Address Age (min) Hardware Addr Type Interface
Internet 192.168.193.1 0 4431.92f8.1faa ARPA Vlan1
Internet 192.168.193.65 - acf5.e605.9240 ARPA Vlan1
Internet 192.168.193.237 7 e063.dad0.aa8b ARPA Vlan1

 

-----------------------------

Drottningatan_22_C2960_193.65>show ip route
Default gateway is 192.168.193.1

Host Gateway Last Use Total Uses Interface
ICMP redirect cache is empty

 

------------------------------

Drottningatan_22_C2960_193.65>show ip inte brief
Interface IP-Address OK? Method Status Protocol
Vlan1 192.168.193.65 YES NVRAM up up
GigabitEthernet0/1 unassigned YES unset down down
GigabitEthernet0/2 unassigned YES unset up up
GigabitEthernet0/3 unassigned YES unset up up
GigabitEthernet0/4 unassigned YES unset up up
GigabitEthernet0/5 unassigned YES unset up up
GigabitEthernet0/6 unassigned YES unset down down
GigabitEthernet0/7 unassigned YES unset down down
GigabitEthernet0/8 unassigned YES unset up up
GigabitEthernet0/9 unassigned YES unset up up
GigabitEthernet0/10 unassigned YES unset down down
GigabitEthernet0/11 unassigned YES unset down down
GigabitEthernet0/12 unassigned YES unset down down
GigabitEthernet0/13 unassigned YES unset up up
GigabitEthernet0/14 unassigned YES unset up up
GigabitEthernet0/15 unassigned YES unset up up
GigabitEthernet0/16 unassigned YES unset up up
GigabitEthernet0/17 unassigned YES unset down down
GigabitEthernet0/18 unassigned YES unset down down
GigabitEthernet0/19 unassigned YES unset down down
GigabitEthernet0/20 unassigned YES unset up up
GigabitEthernet0/21 unassigned YES unset up up
GigabitEthernet0/22 unassigned YES unset up up
GigabitEthernet0/23 unassigned YES unset up up
GigabitEthernet0/24 unassigned YES unset up up
GigabitEthernet0/25 unassigned YES unset down down
GigabitEthernet0/26 unassigned YES unset down down
GigabitEthernet0/27 unassigned YES unset down down
GigabitEthernet0/28 unassigned YES unset down down
Bluetooth0 unassigned YES unset administratively down down

Thanks for the additional information. Is it correct that these outputs were generated while the problem was going on (that you could not ping or telnet or ssh to the switch and that the switch could not ping anything such as 192.168.193.1)? Can you confirm that 4431.92f8.1faa is the correct mac address for your gateway device at 192.168.193.1? 

 

Am I correct in understanding that all of the switch ports are in a single vlan (vlan 1)? And am I correct in understanding that you have not enabled ip routing on this switch?

HTH

Rick

Yes it is from an unresponsive switch, it is not possible to ping, telnet, ssh or http to it, only console.

It cant ping anything other than itself.

Yes 4431.92f8.1faa is default gateway, 192.168.193.1

Vlan 1 is only on the uplink port (Trunk port) the other ports are other Vlans connected to devices.

IP Routing is not enabled.

Devices connected to the switch is possible to communicate to servers, internet etc, so traffic through the switch is uneffected.

Thanks for the information. It is interesting (and probably significant) that layer 2 forwarding continues to work ok and the problem seems to be with layer 3 processing on the switch. The next time you experience these symptoms I would like to add a couple of commands to the ones I requested: show interface status and show interface trunk. I would ask that you execute the commands while the problem is ongoing, then shut/no shut interface vlan 1, and execute the commands again when things are working. Also after the execution of show arp while problem is active, assuming that the gateway 192.168.193.1 is in the arp table please make another attempt to ping that address.

 

What logging level is configured on these switches? The first couple of pages of output from show log during the problem might be helpful.

HTH

Rick

It is not possible to ping the gateway, even that the mac is in the arp-table.

Logging level is 7, debugging, but there is no messages when the problem occur, cant see anything special.

 

While the switch still have the problem:

 

------------------------------------

Drottningatan_22_C2960_193.65>show interface status

 

Port Name Status Vlan Duplex Speed Type
Gi0/1 notconnect 153 auto auto 10/100/1000BaseTX
Gi0/2 notconnect 153 auto auto 10/100/1000BaseTX
Gi0/3 notconnect 153 auto auto 10/100/1000BaseTX
Gi0/4 connected 153 a-full a-1000 10/100/1000BaseTX
Gi0/5 connected 153 a-full a-100 10/100/1000BaseTX
Gi0/6 notconnect 153 auto auto 10/100/1000BaseTX
Gi0/7 notconnect 153 auto auto 10/100/1000BaseTX
Gi0/8 notconnect 153 auto auto 10/100/1000BaseTX
Gi0/9 connected 153 a-full a-1000 10/100/1000BaseTX
Gi0/10 notconnect 153 auto auto 10/100/1000BaseTX
Gi0/11 connected 153 a-full a-1000 10/100/1000BaseTX
Gi0/12 notconnect 153 auto auto 10/100/1000BaseTX
Gi0/13 connected 153 a-full a-1000 10/100/1000BaseTX
Gi0/14 notconnect 153 auto auto 10/100/1000BaseTX
Gi0/15 connected 153 a-full a-1000 10/100/1000BaseTX
Gi0/16 connected 153 a-full a-1000 10/100/1000BaseTX
Gi0/17 notconnect 153 auto auto 10/100/1000BaseTX
Gi0/18 notconnect 153 auto auto 10/100/1000BaseTX
Gi0/19 notconnect 153 auto auto 10/100/1000BaseTX
Gi0/20 connected 163 a-half a-100 10/100/1000BaseTX
Gi0/21 connected 163 a-full a-100 10/100/1000BaseTX
Gi0/22 connected 163 a-full a-100 10/100/1000BaseTX
Gi0/23 connected 2206 a-full a-100 10/100/1000BaseTX
Gi0/24 Radiolink Linkarve connected trunk a-full a-1000 10/100/1000BaseTX
Gi0/25 notconnect 1 auto auto Not Present
Gi0/26 notconnect 1 auto auto Not Present
Gi0/27 notconnect 1 auto auto Not Present
Gi0/28 notconnect 1 auto auto Not Present

 

------------------------------------

Drottningatan_22_C2960_193.65>show interface trunk

 

Port Mode Encapsulation Status Native vlan
Gi0/24 on 802.1q trunking 1

Port Vlans allowed on trunk
Gi0/24 1-4094

Port Vlans allowed and active in management domain
Gi0/24 1,153,163,2206

Port Vlans in spanning tree forwarding state and not pruned
Gi0/24 1,153,163,2206

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