12-12-2016 10:33 PM - edited 03-08-2019 08:32 AM
with this sample network design that include the 2 x 2960 switches as access and 1 x 3850 for intervlan with SVI routing between more than 40 VLANs , we have issue with Server connected to left 2960 Switch with PC connected to right Switch both these device in same VLAN (50) , and trunk there and allow in trunk , the problem appear recently and the problem is
1- ping not stable after some packet we get replay just 8 or 10 after that not reachable !
i try to decrease the arp time aging lower than Mac address table aging to avoid the Unicast flooding
in switch 3850 we see the LED lighting quickly and rapidly
I look around the interface and INPUT ,OUTPUT ,Drop ,broadcast , in some interface in 2960 switch in have some of Packets and 3850 doesn't
Is that seem that we have a Loop in Network , and from where start to investigate ?
thank you for help
12-13-2016 02:19 AM
I dont think you have a loop in that topology but you can check with show spanning-tree detail | inc ieee|occurr|from|is exec and see if there are constant changes at switch level but your topology doesn't show a looped setup
can you post the interface where the server is connected to ..show interface x/x
can you post the interface where the pc is connected to ..show interface x/x
1- ping not stable after some packet we get replay just 8 or 10 after that not reachable !
do you see this issue if running a ping from the 3850 too or just from the server to pc ?
12-13-2016 10:43 AM
Actually this is the samples for our network that problem happens
Thank you for replying and help after i analysis the traffics cominng to core switch we notice there's a loop on switch #31 there's port down stream that make this issues and effect almost network
It's clear and easy to find it on access layer by looking to LED interface lights but in core distribution very hard as the problem happen in different VLAN and building
Just remove the cable from switch port everything back to normal
Thank you again
12-14-2016 08:04 AM
hi
whats that cable connected to , it should only cause a loop if its connecting to another switch ? or maybe a faulty nic on a device
12-14-2016 12:09 PM
Hello
Given that network I am interested just as Mark is how a loop has occurred!
Can you elaborate please?
res
Paul
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