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Arshad Khan
Beginner

Sudden Ping Drop from Default Gateway in VLAN

Hi,

We have a Layer3 Switch 3560 and we have configure multiple VLANs along with SVI on it. We have then cascade layer2 Switches (Cisco 2960) with 3560 by Trunk links. Now we are facing problem on one VLAN that users are in specific VLAN sudden get ping drop from their default gateway (SVI on Cisco 3560) and this problem is not come with all users in that VLAN as just few users in a single time face this problem. When we unplug the systems for few second and reconnect then problem get resolved for few minutes till hours.

Kindly guide me to resolved this.

 

Regards,

Arshad

10 REPLIES 10
Cisco Freak
Enthusiast

Hi Arshad,

This problem doesn't sound like a switch issue.

This looks more like a PC issue. Can you please try to do a wireshark capture while you are facing the issue.

CF

I have run the wireshark but did not something fruitful.

paul driver
VIP Expert

Hello

" VLAN sudden get ping drop from their default gateway"

Can these clients ping other clients on the same vlan at time of outage or don't that have any access whatsoever?

I guess they receive their addressing from DHCP - Do these clients have a ip address at the time of this drop?

Is it the same clients each time on the same vlan?

Do other clients on this vlan work as normal when this is occurring?

res
Paul


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Kind Regards
Paul

Hi Paul,

Since from problematic days, Sometimes users on the same VLAN ping each other while few of them getting response from gateway and few dont getting response from gateway.

Sometimes, Few of them getting response from gateway but cant able to ping each other and after sometimes they are getting ping each other.

Yes they are getting IP address successfully from DHCP in outage time. 

 

 

Arshad,

While you are having the issue, can you please try to clear the ARP table of your machine and try pinging again.

'netsh interface ipv4 delete arpcache' will clear all the ARP entries from cache.

Also can you please check if there is any HSRP state change happening when you are facing the issue.

 

CF

I have cleared the arp cache on Switches as pinging work fine till some times and then issue arise again. 

Did you try clearing the ARP cache in the machines which has got the problem?

Also, any HSRP state change?

 

CF

We are not running any redundancy protocol like HSRP on distribution level in our environment.

 

 

I have also clean the arp cache on users systems by using "'netsh interface ipv4 delete arpcache" but in vain. Now i have perform the below steps and operation is working fine since last 20 hours approx.

 

1- Change the First Casade Switch Cisco 2960.

2- Remove EtherChannel and Change the Backbone port on Cisco 3560 and Cisco 2960.

3- Connect both switches with single backbone Gig Port.

4- IOS Version on previous Cisco 2960 switch was IOS 12.2(50)SE3 and the IOS Version on newly installed switch is IOS 12.2(50)SE5

Can you please add the Etherchannel configuration back, so that we can test if it was etherchannle problem or the 2960 switch issue.

CF