HSRP Problem ............. Very Strange Problem .............

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Jul 4th, 2008
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Dear Sir,

We have 2 Core sw each with 2 MSFC on Sup Cards i.e MSFC no 101 , 102 , 103 , 104. ---- 101 and 102 MSFCs are on CORE 1 ---- 103 and 104 MSFCs are on CORE 2.

Total no of Vlan on Network : 60

Odd No of Vlans are Active on Core 1 MSFCs

Even no of Vlans are Avtive on Core 2 MSFCs.

Now Since today I face the problem :

I can not ping or communicate some of Servers from my PC. My PC is with static Address. Even I can not Ping Out Side Campus Netowrk.

In this case If I will ping all my MSFCs and Core aswell as HSRP ip address of my local vlan than it working.

Again I will turn off my PC for one day than the same problem occurs........

In my Management PC ( also with static IP ) I can not ping perticularly 2 Switch IP. But orhers are working OK. When I ping menagement IPs i can ping gateway but i can not ping hsrp IPs.

Its very confusing for me.

I can understand only that its due to some IP cache. How can I troubleshoot and solve this problem I cant find it.

And ya as i take this pc on DHCP its working ok all are pinging well...

Pls help me soon .............

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Dipesh Patel Fri, 07/04/2008 - 17:47
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Today I can not access MSFC 103 on telnet but I can ping it properly. Now when I will take it on telnet using other MSFC than its working.

Giuseppe Larosa Sat, 07/05/2008 - 04:34
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Hello Patel,

verify that at L2 the interswitch trunks carry all the vlans.

On the two msfc shells do a sh standby brief and check if for all the groups in all the vlans there is communication between the two routers: if you find a standby unknown somewhere this could be a sign of a partitioned vlan.

If your PC is in vlan4 it has to go through the gateway to reach ip addresses on other vlans.

The PC can store info in its ARP table for IP addresses in the same subnet or the results of DNS queries in its DNS table.

What is the default gateway for your PC in vlan4 ?

take care that if all the vty lines are busy you are not accepted on telnet by a device even if you can ping it.

hope to help


Dipesh Patel Sat, 07/05/2008 - 07:11
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Dear Giuseppe,

Thanks for replying ....

Ya, sh standby brief output is working fine all vlan are distributed perfecty and trunk are also fine.

Today whole day the same problem exists. All Static PCs are isolated. When I ping from the mSFCs or from PCs if i ping all msfcs than PC again come in NEtwork.

My PC is in Vlan 4. Gate way is standby IP of HSRP: 10.x.x.35 .

When I can not ping perticular PC it also happen that in the same vlan other pc can ping that PC. So its completely misbehavoiour by Device.

Now what's the xsolution I cant understand.

Dipesh Patel Sat, 07/05/2008 - 07:13
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Dear Giuseppe,

At Present I rebooted both the core one by one and removed one MSFCs from both the Core.

Now on Monday will see weather it may the same problem or resolved.....

Pls help me to solve this problem ..... Device rebooting is not the solution.


Giuseppe Larosa Sun, 07/06/2008 - 02:36
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Hello Patel,

so you had two MSFCs and two supervisor on each chassis as in your picture.

This type of redundancy has to be managed : SRM (Single Router Mode) or DRM (Dual Router Mode) strategies are possible.

I guess you were using DRM because you expect that all MSFCs are taking part in networking and HSRP groups.

However, some years ago Cisco recommended us to change the strategy to SRM on devices like yours.

In SRM only one MSFC in each chassis is really active and the other one is not reachable from outside.

With only one MSFC in each chassis you might expect a normal behaviuor.

Feel free to keep us informed in the forum

hope to help


Dipesh Patel Sun, 07/06/2008 - 07:06
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Dear Sir,

We have two MSFCs in each one but at at time only one is active on each side other one is remain in standby mode.

And Problem I have discussed in above discussion yet I have not get any solution.

I am giving temporary solution by pinging PCs from MSFCs or Pinging MSFCs from Host PCs.


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