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Contributor
nisse
Posts: 14
Registered: ‎07-18-2012
0

Problem with ping from a switch to another (properly simle case)

Okey, I'll attach a picture for you to get a better overview.

 

If I try to ping from the BNT-switch to EX4200, it fails and reverse, if I try to ping from EX4200 to BNT-switches it also fails.

But, when I ping any of the cisco-switches from the BNT-switch it pass. And afterwords that, I can ping between BNT>Juniper and vice verca.

After a couple of minutes it goes back where I started, no ping response.

 

Do you have any suggestions?

 

 

Trusted Contributor
Stac Polaidh
Posts: 90
Registered: ‎01-24-2012
0

Re: Problem with ping from a switch to another (properly simle case)

Hi,

 

Maybe this is caused by VTP pruning, can you disable vtp pruning on the cisco switches.

Search for troubleshoot-l2-connectivity-issue-vtp-pruning for an interesting blog.

Pier
Network and telephony support engineer
JNCIA-FWV, CCNP Voice, CCNA
Contributor
nisse
Posts: 14
Registered: ‎07-18-2012
0

Re: Problem with ping from a switch to another (properly simle case)

Thanks for your answare, non of the cisco-switches have VTP Pruning enabled, they are in "mode transparent".

 

Any other suggestions?

I have no idea...

Contributor
nisse
Posts: 14
Registered: ‎07-18-2012
0

Re: Problem with ping from a switch to another (properly simle case)

After little more testing i got this.

It doesn't matter if I ping another switch in the network, sometimes it works and sometimes not.

 

If I check the apr table on the switches, both have correct entries.

And if I clear the arp entries on the BNT switch I can ping the Juniper Switch.

I have no idea why it behaves like this?

 

Here are the entrys when I can't ping:


>> Address Resolution Protocol# vlan 4

Total number of arp entries : 2
IP address Flags MAC address VLAN Port
--------------- ----- ----------------- ------ ----
10.10.10.1 28:c0:da:2f:fa:40 4 TRK65
10.10.10.10 P 34:40:b5:3b:28:1f 4

>> Address Resolution Protocol# dump

Total number of arp entries : 9
IP address Flags MAC address VLAN Age Port
--------------- ----- ----------------- ------ --- ----
10.10.10.1 28:c0:da:2f:fa:40 4 256 TRK65
10.10.10.10 P 34:40:b5:3b:28:1f 4
10.99.98.210 5c:f3:fc:ef:59:6b 4095 264 1:15
10.99.98.211 P 34:40:b5:3b:28:00 4095
10.99.98.252 5c:f3:fc:ef:59:6b 4095 0 1:15
192.168.46.1 28:c0:da:2f:fa:40 209 53 TRK65
192.168.46.10 P 34:40:b5:3b:28:1f 209

2 ARP entries used by stacking were not displayed!


Here are the entries when I can ping (after I cleared the arp on the BNT switch):

>> Address Resolution Protocol# dump

Total number of arp entries : 8
IP address Flags MAC address VLAN Age Port
--------------- ----- ----------------- ------ --- ----
10.10.10.1 28:c0:da:2f:fa:40 4 7 TRK65
10.10.10.10 P 34:40:b5:3b:28:1f 4
10.99.98.210 5c:f3:fc:ef:59:6b 4095 10 1:15
10.99.98.211 P 34:40:b5:3b:28:00 4095
10.99.98.252 5c:f3:fc:ef:59:6b 4095 0 1:15
192.168.46.10 P 34:40:b5:3b:28:1f 209

2 ARP entries used by stacking were not displayed!

>> Address Resolution Protocol# vlan 4

Total number of arp entries : 2
IP address Flags MAC address VLAN Port
--------------- ----- ----------------- ------ ----
10.10.10.1 28:c0:da:2f:fa:40 4 TRK65
10.10.10.10 P 34:40:b5:3b:28:1f 4

Contributor
nisse
Posts: 14
Registered: ‎07-18-2012
0

Re: Problem with ping from a switch to another (properly simle case)

Here I ping the Juniper-swtich from the BNT-switch:

 

10.10.10.1: #1 timed out.
10.10.10.1: #2 timed out.
10.10.10.1: #3 timed out.
10.10.10.1: #4 timed out.
10.10.10.1: #5 timed out.
10.10.10.1: #6 timed out.
10.10.10.1: #7 timed out.
10.10.10.1: #8 timed out.
10.10.10.1: #9 timed out. 
10.10.10.1: #10 ok, RTT 5 msec. <---- Here I clear the ARP on the BNT switch. 
10.10.10.1: #11 ok, RTT 1 msec.
10.10.10.1: #12 ok, RTT 6 msec.
10.10.10.1: #13 ok, RTT 1 msec.
10.10.10.1: #14 ok, RTT 3 msec.
10.10.10.1: #15 ok, RTT 1 msec.
10.10.10.1: #16 ok, RTT 2 msec.

 

When the new arp entry enters the table, it's exactly the same as before.

Super Contributor
achadha
Posts: 130
Registered: ‎09-27-2011
0

Re: Problem with ping from a switch to another (properly simle case)

Hi,

 

If the links mentioned in the diagram are L2, then could you dump the ethernet switching table and arp table from both the switches?

clearing the ARP table would mean re-ARPing for the IP. This would also mean that the corresponding MAC addresses will be re-learned.. just trying to explore this part of the equation as well.

 

Thanks,

ankit

Contributor
jackycheung
Posts: 52
Registered: ‎02-02-2010
0

Re: Problem with ping from a switch to another (properly simle case)

The symptom looks the BNT-switch don't send mac updates to ex4200? So that packet can't pass through after mac-aging-time expired?

 

Can you tried below tests to confirm it:

1) Check the ethernet-switching table when can't ping through to see where any mac learn from BNT-switch.

2) Change the mac-aging time of BNT-switch interface to see where the connection stay longer.

 

If this is the case you may need to check your BTN-switch.

JNCIP-SP/ENT/SEC
Contributor
nisse
Posts: 14
Registered: ‎07-18-2012
0

Re: Problem with ping from a switch to another (properly simle case)

Thank you for your answers! 

 

Here is the output from the switches, didn't copy all entries.

Little messy but I'll hope you get it.

 

When it doesn't work:

Juniper

# run show arp
MAC Address Address Name Interface Flags
00:1a:a2:6b:dc:c2 10.10.10.3 10.10.10.3 vlan.4 none
00:11:bb:24:1b:c0 10.10.10.4 10.10.10.4 vlan.4 none
00:12:80:c2:69:40 10.10.10.5 10.10.10.5 vlan.4 none
00:1b:53:78:10:c3 10.10.10.7 10.10.10.7 vlan.4 none
34:40:b5:3b:28:1f 10.10.10.10 10.10.10.10 vlan.4 none <----BNTswitch

 

# run show ethernet-switching table
Ethernet-switching table: 40 entries, 17 learned
VLAN MAC address Type Age Interfaces
LABB-MGMT * Flood - All-members
LABB-MGMT 28:c0:da:2f:fa:40 Static - Router
LABB-MGMT 34:40:b5:3b:28:1f Learn 2:10 ae0.0 <----BNTswitch

 

BNT
ARP Entry # IP Address MAC Address VLAN Source Port Flags Age
1 10.10.10.1 28:c0:da:2f:fa:40                   4               TRNK65               5  <---EX4200 ARP on vlan 4


FDB Entry # MAC Address VLAN Source Port Trunk    State   Permanent

1 28:c0:da:2f:fa:40                4                              65      TRUNK <---EX4200 Mac on vlan 4
9 28:c0:da:2f:fa:40                 100                         65       TRUNK
10 28:c0:da:2f:fa:40               209                         65       TRUNK


When it work:

Juniper

ARP
MAC Address Address Name Interface Flags
00:1a:a2:6b:dc:c2 10.10.10.3 10.10.10.3 vlan.4 none
00:11:bb:24:1b:c0 10.10.10.4 10.10.10.4 vlan.4 none
00:12:80:c2:69:40 10.10.10.5 10.10.10.5 vlan.4 none
00:1b:53:78:10:c3 10.10.10.7 10.10.10.7 vlan.4 none
34:40:b5:3b:28:1f 10.10.10.10 10.10.10.10 vlan.4 none <----BNTswitch

 

Ethernet-switching table: 40 entries, 17 learned
VLAN MAC address Type Age Interfaces
LABB-MGMT * Flood - All-members
LABB-MGMT 28:c0:da:2f:fa:40 Static - Router
LABB-MGMT 34:40:b5:3b:28:1f Learn 0 ae0.0 <----BNTswitch

 

BNT

Entry # MAC Address VLAN Source Port Trunk State Permanent
1 28:c0:da:2f:fa:40          4                    65           TRUNK <---EX4200 ARP on vlan 4
8 28:c0:da:2f:fa:40          3                    65           TRUNK
10 28:c0:da:2f:fa:40     100                  65           TRUNK
12 28:c0:da:2f:fa:40     209                  65           TRUNK

 

Entry # IP Address MAC Address VLAN Source Port Flags Age
1 10.10.10.1 28:c0:da:2f:fa:40           4             TRNK65        155 <---EX4200 Mac on vlan 4

 

Contributor
nisse
Posts: 14
Registered: ‎07-18-2012
0

Re: Problem with ping from a switch to another (properly simle case)

Now I noticed one other thing.

 

If i run a Ping from BNT--> Juniper EX4200, it doesn't work.

 

But the second I start a ping from Juniper-EX4200 to a Cisco-swtich, the ping from BNT-->Juniper-EX4200 starting to work.

 

The Juniper-EX4200(VC) is the "core-swtich" and cisco/BNT is connected directly to them.

Contributor
RiGloe
Posts: 26
Registered: ‎12-02-2009
0

Re: Problem with ping from a switch to another (properly simle case)

HI,

 

all that sounds very odd.

 

It might be helpful if you would mention which software versions you are running.

 

It might also be helpful if you'd paste the full configuration of the switch and check the cabling wether it really is the way of your original picture.

 

do you run STP or a variant thereof?

 

lastly, it might be helpful if you could sniff the interfaces of the EX Switch and tell us what you see on the interfaces when you do various things: http://kb.juniper.net/InfoCenter/index?page=content&id=KB23420&cat=JUNOS&actp=LIST&smlogin=true

 

 

Also, regarding the BNT, do you have the Management IP on a physical interface or vlan interface?  can you change whatever you have? does it make a difference?

 

Do you already run any SNMP-aware Application against the switches (cacti for example)?

 

 

 -R

 

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