Unable to ping between 2 directly connected switches

marvin-thomas · ‎06-19-2011

I'm setting up a lab and I'm having problems with one of the vlans. I've got 2 3550 switches connected via 2 trunk links(fastethernet0/1 & 0/11 on each switch). There are vlan interfaces that are pingable between the 2 switches but the problem is with vlan 20. Here ae the relevant parts of the config:

Switch 1

!

interface Vlan20

ip address 10.2.2.2 255.255.255.0

end

interface FastEthernet0/1

switchport trunk encapsulation dot1q

switchport mode trunk

channel-protocol lacp

end

!

interface FastEthernet0/11

switchport trunk encapsulation dot1q

switchport mode trunk

channel-protocol lacp

end

3550_SWITCH#sh cdp neighbors

Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge

S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone,

D - Remote, C - CVTA, M - Two-port Mac Relay

Device ID Local Intrfce Holdtme Capability Platform Port ID

2950SW Fas 0/24 120 S I WS-C2950- Fas 0/2

3550_SWITCH2 Fas 0/11 159 R S I WS-C3550- Fas 0/11

3550_SWITCH2 Fas 0/1 158 R S I WS-C3550- Fas 0/1

3550_SWITCH#sh int trunk

Port Mode Encapsulation Status Native vlan

Fa0/1 on 802.1q trunking 1

Fa0/11 on 802.1q trunking 1

Fa0/24 on 802.1q trunking 1

Port Vlans allowed on trunk

Fa0/1 1-4094

Fa0/11 1-4094

Fa0/24 1-4094

Port Vlans allowed and active in management domain

Fa0/1 1,10,20,200

Fa0/11 1,10,20,200

Fa0/24 1,10,20,200

Port Vlans in spanning tree forwarding state and not pruned

Fa0/1 1,10,20,200

Fa0/11 1

Fa0/24 1,10,20,200

Switch 2

!

interface Vlan20

ip address 10.2.2.1 255.255.255.0

end

!

interface FastEthernet0/1

switchport trunk encapsulation dot1q

switchport mode trunk

channel-protocol lacp

end

!

interface FastEthernet0/11

switchport trunk encapsulation dot1q

switchport mode trunk

channel-protocol lacp

end

3550_SWITCH2#sh cdp neighbors

Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge

S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone

Device ID Local Intrfce Holdtme Capability Platform Port ID

2950SW Fas 0/24 135 S I WS-C2950- Fas 0/1

3550_SWITCH Fas 0/11 148 R S I WS-C3550- Fas 0/11

3550_SWITCH Fas 0/1 143 R S I WS-C3550- Fas 0/1

R4 Fas 0/23 171 R 1750 Fas 0

3550_SWITCH2#sh int trunk

Port Mode Encapsulation Status Native vlan

Fa0/1 on 802.1q trunking 1

Fa0/11 on 802.1q trunking 1

Fa0/24 on 802.1q trunking 1

Port Vlans allowed on trunk

Fa0/1 1-4094

Fa0/11 1-4094

Fa0/24 1-4094

Port Vlans allowed and active in management domain

Fa0/1 1,10,20,200

Fa0/11 1,10,20,200

Fa0/24 1,10,20,200

Port Vlans in spanning tree forwarding state and not pruned

Fa0/1 10,20,200

Fa0/11 10,20,200

Fa0/24 1,10,20,200

The thing thats concerning me is that it looks like there are vlans being pruned on the trunk links between the switches. I've tried to allow all vlans on each link but its not having any impact. Any suggestions are appreciated.

cadet alain · ‎06-19-2011

Hi,

on SW1 can you do a sh spann vlan 20

Regards.

Alain.

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marvin-thomas · ‎06-19-2011

3550_SWITCH#sh span vlan 20

VLAN0020

Spanning tree enabled protocol ieee

Root ID Priority 32788

Address 000d.bce4.b200

Cost 19

Port 1 (FastEthernet0/1)

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32788 (priority 32768 sys-id-ext 20)

Address 000f.8fb2.eb00

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type

------------------- ---- --- --------- -------- --------------------------------

Fa0/1 Root FWD 19 128.1 P2p

Fa0/11 Altn BLK 19 128.11 P2p

Fa0/24 Desg FWD 19 128.24 P2p

cadet alain · ‎06-19-2011

Hi,

So you got your answer as there is no port-channel, spanning-tree must block a port and it blocked f0/11 on this switch.

This is a normal behaviourthat doesn't affect connectivity between the 2 switches..

Regards.

Alain

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marvin-thomas · ‎06-19-2011

That doesn't seem to be the problem. Now there is a port channel:

3550_SWITCH#sh spanning-tree vlan 20

VLAN0020

Spanning tree enabled protocol ieee

Root ID Priority 32788

Address 000d.bce4.b200

Cost 12

Port 65 (Port-channel12)

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32788 (priority 32768 sys-id-ext 20)

Address 000f.8fb2.eb00

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Aging Time 300 sec

Interface Role Sts Cost Prio.Nbr Type

------------------- ---- --- --------- -------- --------------------------------

Fa0/24 Desg FWD 100 128.24 P2p

Po12 Root FWD 12 128.65 P2p

Pings still fail:

3550_SWITCH#ping 10.2.2.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 10.2.2.1, timeout is 2 seconds:

.....

Success rate is 0 percent (0/5)

cadet alain · ‎06-19-2011

Can you do debug arp while pinging

Regards.

Alain.

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rsimoni · ‎06-19-2011

Hi Marvin,

do some L1 troubeshooting.

Ie shut down fa0/ on both sides and see if you can ping; if not try to shut fa0/11 instead.

Also remove portchannel and lacp from ports and see if can ping.

During all the tests always check both mac and arp tables to see if IP is arped and correct mac address is learned on the ports.

Riccardo

marvin-thomas · ‎06-19-2011

Thanks Riccardo and Alain. I tried your suggestions and I'm still not able to ping the other switches vlan 20 interface. Something I should re iterate is that there are other vlan interfaces on the same switch that I can ping and they are going over the same trunk. Its only vlan 20 that's the problem. Vlans 10 and 200 aren't experiencing the same problem.

3550_SWITCH#sh arp

Protocol Address Age (min) Hardware Addr Type Interface

Internet 10.2.2.2 - 000f.8fb2.eb00 ARPA Vlan20

Internet 10.2.1.1 - 000f.8fb2.eb00 ARPA Vlan10

Internet 10.2.2.1 9 000d.bce4.b200 ARPA Vlan20

Internet 10.2.1.2 9 000d.bce4.b200 ARPA Vlan10

Internet 192.168.0.112 0 0016.41e1.8382 ARPA Vlan1

Internet 192.168.0.9 235 001a.6dbf.9f00 ARPA Vlan1

Internet 192.168.0.19 - 000f.8fb2.eb00 ARPA Vlan1

Internet 192.168.1.129 - 000f.8fb2.eb00 ARPA Vlan200

Internet 192.168.1.130 9 000d.bce4.b200 ARPA Vlan200

Internet 10.2.1.254 - 0000.0c07.ac0a ARPA Vlan10

The mac address for vlan 20 is the correct mac address.

Richard Burts · ‎06-19-2011

Marvin

It is interesting that the ARP table has the MAC for the other switch interface, and that you say that it is the correct MAC. So my suggestion for the next step in troubleshooting this is to see if the MAC 000d.bce4.b200 is in the switch MAC address forwarding table and if so what interface is it associated with?

HTH

Rick

HTH

Rick

marvin-thomas · ‎06-19-2011

To me everything looks as I would expect:

3550_SWITCH#sh adjacency 10.2.2.1 detail

Protocol Interface Address

IP Vlan20 10.2.2.1(7)

0 packets, 0 bytes

epoch 0

sourced in sev-epoch 0

Encap length 14

000DBCE4B200000F8FB2EB000800

L2 destination address byte offset 0

L2 destination address byte length 6

Link-type after encap: ip

ARP

3550_SWITCH#sh ip cef 10.2.2.1 detail

10.2.2.1/32, epoch 0, flags attached

Adj source: IP adj out of Vlan20, addr 10.2.2.1 037B15A0

Dependent covered prefix type adjfib cover 10.2.2.0/24

attached to Vlan20

And I just tried a reload of both switches(for the second time)

Reza Sharifi · ‎06-19-2011

Try creating vlan 20 (layer-2) on both switches and test again

"vlan 20"

name vlan-20-test"

If not, remove the ports from the portchannell and just use one port and test

marvin-thomas · ‎06-19-2011

I don't know. Here's what I did. Took the IP off vlan 20, and created vlan 40. I assigned the IP's I was using on vlan 20 to vlan 40 and it works. Vlan.dat file corrupt in some way? Would be interested to hear others thoughts. Thanks again for the responses from everyone.

CSCO11151677 · ‎06-20-2011

Marvin

Could you please confirm whether you have configured any access port into that vlan ? if you not, the vlan won't come up & unable to ping.

please confirm whether the interface is up in both switches.

I don't think so port channel issue as STP will block only one interface not both so it should work with one interface.

Thanks

Vignesh