Access switch cannot ping its own PC

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Oct 25th, 2009
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Has anyone seen a scenario where and edge switch can reach its core (default gateway) but cannot ping the PC connected locally to that switch. While core switch can ping this PC but edge cannot.





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PC is in VLAN 167, for VLAN 167 core is the HSRP active router and root switch , SW3 is the standby HSRP router and

alternate switch. Edge is configured with vlan 101 as management vlan for this vlan active HSRP router is core and standy is SW3, root switch is core and SW3 is alternate


From core and SW3 I can ping PC but when I try to ping PC from the edge it doesnt ping.

Have tried all the options but cannot find the root cause of the issue, edge has been configured with default gateway that gives L3 connectivity all the way to core. There is an etherchannel between SW3 and Core.

Please suggest if I am missing something...I have tried debugging on Core while having ping running on edge and I dont see any hits coming on core which is very strange. I dont have any VTP prunning or vlan blocking on trunks..

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Lucien Avramov Mon, 10/26/2009 - 00:10
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From switch, do a show ip route x.x.x.x where x.x.x.x is the ip of the pc.

Another thing: source your ping on the core from the subnet the PC is on, and your ping will probably fail, that may mean that your edge does not have a route to this subnet of the core/pc.

oqureshi Mon, 10/26/2009 - 00:17
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If i do extended ping from core using the subnet of PC means I am using the same vlan as PC ..and ping wouldnt fail as edge as route to core and it can reach core without any issues...also PC has the route to core and I can reach core from PC as well but not edge...its one of the simplest and strange thing I have noticied in my career cant figure out this weird behaviour..

Lucien Avramov Mon, 10/26/2009 - 00:19
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routing is like rocket science: not that complicated.

Your initial explanation is then confusing, can you try to be more clear on your initial problem.

Please provide your subnetting for your devices as well as interfaces / vlans.

oqureshi Mon, 10/26/2009 - 00:37
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I will try to put in simple words...edge can ping its default gateway which is root and HSRP active for management vlan defined on edge switch.

PC which is part of some other vlan for which same core switch is root and hsrp active..PC is connected to edge switch...Both PC and edge switch can ping their respective gateway (Core) but cannot ping each other...Core switch can reach both edge switch and PC..


Between SW and Core there is etherchannel with mode on.

oqureshi Mon, 10/26/2009 - 00:46
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Found one clue...the moment i disable on etherchannel partner ping starts working from edge

1 Po1(SU) - Te9/1(P) Te9/2(P)

I have two ports in this channel...probably when channel is on switch is considering this traffic as being looped


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