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Packets Drop/Loss Constantly when ping a different switch

Have a peculiar problem. When any machine tried to ping to a different VLAN (Subnet), pings dropped on the switch but reaches the destination. We do not have any ACL in place on the switches either.

 

If we ping to the switch directly (where we are connected)... ping works fine with 0 loss.

|------------------------------------------------------------------------------------------|
| | Host - Loss % | Sent | Recv | Best | Avrg | Wrst | Last |
|------------------------------------------------|------|------|------|------|------|------|
| 192.168.2.X - 0 | 597 | 597 | 0 | 6 | 125 | 20 |
|________________________________________________|______|______|______|______|______|______|

 

If we try to ping to another switch on a different VLAN, ping drops between 20-30% however the ping will still reach the destination with zero losses.. it affects any VLAN on different switches.

|------------------------------------------------------------------------------------------|
| | Host - Loss % | Sent | Recv | Best | Avrg | Wrst | Last |
|------------------------------------------------|------|------|------|------|------|------|
| 192.168.2.X - 21 | 306 | 244 | 0 | 6 | 35 | 6 |
| 192.168.1.X - 0 | 550 | 550 | 0 | 4 | 81 | 0 |
|________________________________________________|______|______|______|______|______|______|

It is as if, once the hops starts jumping around VLANs, the packet loss will occur on the switch. We have tested on different VLANs, switches - all of the 10 switches we have demonstrated the same behaviour. 

 

Switch to Switch ping via IOS is fine between switches though...

 

What could be the problem?

Everyone's tags (4)
5 REPLIES 5
VIP Expert

Re: Packets Drop/Loss Constantly when ping a different switch

How are these switches connected together? You may be encountering some sort of loop in your network.  Also, take a look at your static and default routes/gateways on the switches and make sure they configured correctly. Can you post a diagram of your network?

HTH

Re: Packets Drop/Loss Constantly when ping a different switch

Thank you for the response. I also did consider on the loop thingy, but unable to find where the cause is. We do not have alot of static / default routes. only 1 - and that is to pass traffic to the firewall if is 0.0.0.0

 

The connectivity to the switch is pretty straight forward

Core Switch connects to all the switches with Etherchannel.

Core Switch is the root of STP.

 

 

VIP Expert

Re: Packets Drop/Loss Constantly when ping a different switch

I see that your access switches have uplinks to both core switches. For testing, on one of the switches, can you disconnect one of the uplinks and run the same test? Aso, if one core switch is root the other one should be backup root and all access switches should, in fact, see the cores as root and backup. Can you check STP on some of the access switches to make sure that is actually the case?

HTH

Re: Packets Drop/Loss Constantly when ping a different switch

yup, i have checked on all the switches and ensure that they see the root as the core.

Also, i tear one of the switch out from etherchannel yet it is still demonstrating similar behavior of packet losses.

 

Core Switch

Switch is in pvst mode
Root bridge for: VLAN0001, VLAN0010, VLAN0020, VLAN0030, VLAN0040
VLAN0101-VLAN0103, VLAN0105-VLAN0109, VLAN0210, VLAN0300-VLAN0301
VLAN0303-VLAN0304
EtherChannel misconfig guard is enabled
Extended system ID is enabled
Portfast Default is enabled
PortFast BPDU Guard Default is disabled
Portfast BPDU Filter Default is disabled
Loopguard Default is disabled
UplinkFast is disabled
BackboneFast is disabled
Configured Pathcost method used is short

Name Blocking Listening Learning Forwarding STP Active
---------------------- -------- --------- -------- ---------- ----------
VLAN0001 0 0 0 13 13
VLAN0010 0 0 0 31 31
VLAN0020 0 0 0 13 13
VLAN0030 0 0 0 13 13
VLAN0040 0 0 0 14 14
VLAN0101 0 0 0 13 13
VLAN0102 0 0 0 13 13
VLAN0103 0 0 0 15 15
VLAN0105 0 0 0 14 14
VLAN0106 0 0 0 15 15
VLAN0107 0 0 0 14 14
VLAN0108 0 0 0 14 14
VLAN0109 0 0 0 14 14
VLAN0210 0 0 0 13 13
VLAN0300 0 0 0 16 16
VLAN0301 0 0 0 18 18
VLAN0302 0 0 0 18 18
VLAN0303 0 0 0 15 15
VLAN0304 0 0 0 13 13
---------------------- -------- --------- -------- ---------- ----------
19 vlans 0 0 0 289 289

 

 

One of the access switches

Switch is in pvst mode
Root bridge for: none
EtherChannel misconfig guard is enabled
Extended system ID is enabled
Portfast Default is disabled
PortFast BPDU Guard Default is disabled
Portfast BPDU Filter Default is disabled
Loopguard Default is disabled
UplinkFast is disabled
BackboneFast is disabled
Configured Pathcost method used is short

Name Blocking Listening Learning Forwarding STP Active
---------------------- -------- --------- -------- ---------- ----------
VLAN0001 0 0 0 1 1
VLAN0010 0 0 0 2 2
VLAN0020 0 0 0 1 1
VLAN0030 0 0 0 1 1
---------------------- -------- --------- -------- ---------- ----------
4 vlans 0 0 0 5 5

Re: Packets Drop/Loss Constantly when ping a different switch

anyone ??? 

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