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VLANs Missing when passing trhough 2 switches...

CiscoSlicster
Level 1
Level 1

Hello,

Maybe someone can help me figure out the issue I'm having?  We have 2 x 3750 switches stacked, one of which is our Default-Gateway or what we call the CORE(SwitchA) and the other is just a stack(SwitchB) without routing that is connected with a Trunk/Etherchannel to the CORE.  We have 3 of our 6 VLANs passing though the Trunk to SwitchB which works fine but attached to SwitchB are some Cisco BladeCenter switches in "Client-Mode". The BladeCenterSwitch does not receive the 3 VLANs from SwitchA even though SwitchB has them however, all the VLANs configured on SwitchB do seem to be available.  I've provided a disagram of the configuration and attached the configurations.  Hopefully someone can help me out because I'm stuck.  Thanks.Diagram.JPG

13 Replies 13

Partha Dasgupta
Cisco Employee
Cisco Employee

Hi,

can we run the following command in swich B

- no ip routing

-no system mtu routing 1500

and verify

Regards

Partha

I had already ran "no ip routing" on SwitchB as you'll see in the configuration files I provided, there is no "ip routing".  As for the "no system mtu routing 1500", I ran it but when I do a "show run" it still shows up.

1. Are we able to reach  SVI ip address of Vlan 11 and 116 of switch A from Switch B.

2. If  step 1 is yes,  are we able to get the arp enteries of the SVI ip address of switch A in the Blade Server when we try to ping them.

3. If Step 1 is no, are we able to get the arp enteries for SVI ip address of Switch A in Switch B.

Regards

Partha

I am able to reach the SVI ip addresses of SwitchA from SwitchB and I do see the arp entries of the SVI entries on SwitchB although they show up as VLAN116 when 172.19.1.0/24 is supposed to be VLAN11.  The BladeCenterSwitch doesn't see any of the ARP entries except for 172.16.1.30 but it is able to ping any of them.

Switch B

Sending 5, 100-byte ICMP Echos to 192.168.116.21, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/8 ms

Protocol  Address          Age (min)  Hardware Addr   Type   Interface

Internet  192.168.116.21        143   0027.0c90.6944  ARPA   Vlan116

Internet  192.168.116.22          -   04fe.7f75.96c3  ARPA   Vlan116

Internet  172.16.0.152          216   001a.64de.1484  ARPA   Vlan1

Internet  172.19.1.254           16   0027.0c90.6944  ARPA   Vlan116**supposed to be VLAN11

Internet  172.16.3.249          186   0027.0c90.6940  ARPA   Vlan1

Internet  172.16.3.236           19   0027.0c90.6940  ARPA   Vlan1

Internet  172.16.213.28           -   04fe.7f75.96c0  ARPA   Vlan1

Internet  172.16.5.54             0   2892.4a23.3e17  ARPA   Vlan1

Internet  192.168.1.254           -   04fe.7f75.96c1  ARPA   Vlan40

Internet  172.19.1.1             17   0027.0c90.6944  ARPA   Vlan116**supposed to be VLAN11

Internet  172.16.0.120          134   0021.5e43.524c  ARPA   Vlan1

Internet  172.16.1.112            0   000c.29ba.d8ef  ARPA   Vlan1

Internet  172.16.0.100            -   04fe.7f75.96c0  ARPA   Vlan1

Internet  172.16.1.100            0   0050.5688.452c  ARPA   Vlan1

BladeCenterSwitch


Sending 5, 100-byte ICMP Echos to 172.19.1.1, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/9 ms

Protocol  Address          Age (min)  Hardware Addr   Type   Interface

Internet  172.16.0.152            -   0024.c341.39b7  ARPA   FastEthernet0

Internet  127.0.20.20             -   0000.0000.0000  ARPA   Virtual1

Internet  172.16.5.54           106   001a.64de.1485  ARPA   FastEthernet0

Internet  192.168.1.253           -   0024.c341.39c1  ARPA   Vlan40**this VLAN is from SwitchB and is seen

Internet  172.16.1.30           212   001a.64de.1485  ARPA   FastEthernet0

Internet  172.16.1.112          212   001a.64de.1485  ARPA   FastEthernet0

Internet  172.16.1.100          213   001a.64de.1485  ARPA   FastEthernet0

It looks like vlan information is getting correclty progagate in arp table.

1. Verify if the arp table in switch A is displaying the correct vlan against the ip address.

2. Clear the arp table and verify whether we are  relearning the arp information correclty . If yes , verify the status

3. If step 1 fails we try to reload the switch B if possible and verify

Regards

Partha

-

correction:

It looks like vlan information is not  getting correclty progagated in arp table of switch B

1. Verify if the arp table in switch A is displaying the correct vlan against the ip address.

2. Clear the arp table and verify whether we are  relearning the arp information correclty . If yes , verify the status

3. If step 1 fails we try to reload the switch B if possible and verify

Regards

Partha

1.  I do see all the arp entries with the correct VLANs on SwitchA

2.  I cleared the arp and here is what I see now, they are all correct but I don't see any from VLAN 11 now.

Protocol  Address          Age (min)  Hardware Addr   Type   Interface

Internet  192.168.116.21          1   0027.0c90.6944  ARPA   Vlan116

Internet  192.168.116.22          -   04fe.7f75.96c3  ARPA   Vlan116

Internet  172.16.213.28           -   04fe.7f75.96c0  ARPA   Vlan1

Internet  172.16.5.54             0   2892.4a23.3e17  ARPA   Vlan1

Internet  192.168.1.254           -   04fe.7f75.96c1  ARPA   Vlan40

Internet  172.16.1.112            0   000c.29ba.d8ef  ARPA   Vlan1

Internet  172.16.0.100            -   04fe.7f75.96c0  ARPA   Vlan1

Internet  172.16.1.100            0   0050.5688.452c  ARPA   Vlan1

I just did another test...

On SwitchB, I added "int vlan 11" with an ip of 172.19.1.252

On BladeCenterSwitch, I added "int vlan 11" with an ip of 172.19.1.253

From SwitchB, I can ping anything in VLAN11 except for 172.19.1.253

From BladeCenterSwitch, I can ping anything in VLAN11 including 172.19.1.252 but cannot ping itself(172.19.1.253)

1. Try to ping vlan 11 SVI ip of switch A from Switch B and verify what is the arp enteries status ?

2. Are we able to get vlan 116 SVI ip  from Blade server

Regards

Partha

1. Works and ARP entry shows up correct with VLAN11

2. Ping works

hi ,

r  we still facing the issue?

Use VTP or create the VLANs in bladecenter switch. The command is

vlan 11

name Voice

etc.

I ended up going through the entire configuration of each switch.  I cleaned up all the old invalid configuration, setup all BladeCenter switches to be identical and then retried passing the VLANs.  At first it didn't seem to work because whenever I added a IP to a VLAN interface on a BladeCenter switch, I was unable to reach the device but when I tried adding the VLAN to a VMWARE host that was connected to a BladeCenter switch it worked.  I looked up the settings on my IBM BladeCenter Management at it turns out that I had to ENABLED the option "External management over all ports".  In other words, the VLANs may have been working this whole time except that I was never able to get any of the VLAN interfaces to work from the BladeCenter switches because of the Management option that was DISABLED.  Anyhow it was a weird one but it's fixed now and it gave me a reason to do an overhaul/cleanup of my configurations.

Thanks for your help.

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