asked on

Why can't I see tagged packets for VLAN6 on a C2950 trunked port - ESX 4.0.0

Hi folks,

I have a C2950 switch, using VLAN100 as mgmt VLAN. I have a server running ESX 4.0.0 on Fa0/12 with trunking enabled. There are 3 VLANs configured on this switch (let's say 5, 6 and 100, not counting 1) - VTP mode is passive, it's all manual.

interface FastEthernet0/12
switchport mode trunk
spanning-tree portfast trunk
end

interface vlan 100
ip address 1.2.3.4 255.255.255.0
no cdp enable
no shut
exit

Now I can ping and see traffic on 2 out of the 3 VLANs. Can someone tell me why I can't ping a VM on the 3rd (VLAN6)? The ESX PortGroup for VLAN6 was added after initial config of the vSwitch.

This has to be simple, surely?

sh arp only displays IP+MAC for addresses learned on VLAN100. How do I debug/watch the ARP traffic on the other VLANs to see if ESX is tagging VLAN6 packets correctly?

Can someone tell me why "sh arp" shows all IP addresses from VLAN100 (mgmt VLAN) but nothing from any other active VLANs on the switch?

Many thanks - this has been a head scratcher for me for more than a day now. Too much coffee.

--Engerd.

Paul Solovyovsky

Is the vswitch setup with "ip hash"? Are all port groups configured on the vswitch to match the VLANs?

engerd

ASKER

Not ip hash. Yes to the matching VLAN numbers in Portgroups.

Only a single FastEthernet interface, so didn't think ip hash was relevant.

--Engerd

engerd

ASKER

I've just put a vswif1 interface in the same VLAN6 portgroup, and can't ping that either (or ssh to it). I can ssh fine to the vswif0 in VLAN100.

rfc1180

on the switch, please output:

show interface trunk
show vlan
show interface status

Billy

engerd

ASKER

I've removed irrelevant lines ...

sw9#sh int status

Port Name Status Vlan Duplex Speed Type
[EDITED]
Fa0/12 connected trunk a-full a-100 10/100BaseTX
Fa0/13 connected 100 a-full a-100 10/100BaseTX
Fa0/14 connected trunk a-full a-100 10/100BaseTX
[EDITED]
Gi0/1 connected trunk a-full a-1000 10/100/1000BaseTX
Gi0/2 connected 100 full 1000 10/100/1000BaseTX
sw9#
sw9#sh int trunk
Port Mode Encapsulation Status Native vlan
Fa0/12 on 802.1q trunking 1
Fa0/14 on 802.1q trunking 1
Fa0/21 on 802.1q trunking 1
Gi0/1 on 802.1q trunking 1

Port Vlans allowed on trunk
Fa0/12 1-4094
Fa0/14 1-4094
Fa0/21 1-4094
Gi0/1 1-4094

Port Vlans allowed and active in management domain
Fa0/12 1,3,6,50,100
Fa0/14 1,3,6,50,100
Fa0/21 1,3,6,50,100
Gi0/1 1,3,6,50,100

Port Vlans in spanning tree forwarding state and not pruned
Fa0/12 1,3,6,50,100
Fa0/14 1,3,6,50,100
Fa0/21 1,3,6,50,100
Gi0/1 1,3,6,50,100
sw9#
sw9#sh vlan brief

VLAN Name Status Ports
---- -------------------------------- --------- -------------------------------
1 default active
3 VLAN3 active
6 VLAN6 active
50 VLAN50 active
100 VLAN100 active Fa0/1, Fa0/2, Fa0/3, Fa0/4, Fa0/5, Fa0/6, Fa0/7, Fa0/8, Fa0/9, Fa0/10, Fa0/11, Fa0/13, Fa0/15, Fa0/16, Fa0/17, Fa0/18, Fa0/19, Fa0/20, Fa0/22
Fa0/23, Fa0/24, Gi0/2
1002 fddi-default act/unsup
1003 token-ring-default act/unsup
1004 fddinet-default act/unsup
1005 trnet-default act/unsup
sw9#

Hope this helps

bgoering

Try something like this on your Cisco to set up trunking (assuming 1 is your native untagged VLAN). If 100 is your untagged change the native number to 100

interface FastEthernet0/12
switchport trunk encapsulation dot1q
switchport trunk native vlan 1
switchport trunk allowed vlan 5,6,100
switchport mode trunk
spanning-tree portfast trunk
end

Good Luck

rfc1180

what vlan are you trying to ping from?
trunking looks solid, so I would think the issue is on the ESX side of things, or you are trying to ping from a vlan other than vlan 6, if so, do you have a router that is handling the inter-vlan routing?

Billy

engerd

ASKER

Hi Billy,

I have a 3550 on Gi0/1. On the 3550 I have:

int vlan 6
ip address 10.100.21.254 255.255.255.0
end

When I attempt a ping from the 3550 I get (with debug arp enabled) there are no ARP responses coming back from the 2950:

sw6# ping 10.100.21.99

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.100.21.99, timeout is 2 seconds:

054118: Sep 9 00:04:37: IP ARP: sent req src 10.100.21.254 0013.7f95.ffff ,
dst 10.100.21.99 0000.0000.0000 Vlan6.
054119: Sep 9 00:04:39: IP ARP: sent req src 10.100.21.254 0013.7f95.ffff ,
dst 10.100.21.99 0000.0000.0000 Vlan6
054122: Sep 9 00:04:41: IP ARP: sent req src 10.100.21.254 0013.7f95.ffff ,
dst 10.100.21.99 0000.0000.0000 Vlan6
054124: Sep 9 00:04:43: IP ARP: sent req src 10.100.21.254 0013.7f95.ffff ,
dst 10.100.21.99 0000.0000.0000 Vlan6.
054125: Sep 9 00:04:45: IP ARP: sent req src 10.100.21.254 0013.7f95.ffff ,
dst 10.100.21.99 0000.0000.0000 Vlan6

Success rate is 0 percent (0/5)
sw6#

sw6#sh spanning-tree vlan 6

VLAN0006
Spanning tree enabled protocol rstp
Root ID Priority 32774
Address 0013.7f95.ffff
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32774 (priority 32768 sys-id-ext 6)
Address 0013.7f95.ffff
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300

Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Fa0/3 Desg FWD 19 128.3 P2p
Fa0/10 Desg FWD 19 128.10 P2p
Fa0/12 Desg FWD 19 128.12 P2p
Gi0/1 Desg FWD 4 128.49 P2p
Po1 Desg FWD 12 128.65 P2p
Po2 Desg FWD 12 128.66 P2p

sw6#

most interesting nugget I think, is a sh arp on the 2950:

sw9#sh arp
Protocol Address Age (min) Hardware Addr Type Interface
Internet 10.100.21.99 3 0013.7f95.ffff ARPA Vlan100
Internet 10.100.20.100 218 0013.7f95.ffff ARPA Vlan100
Internet 10.100.0.45 0 0050.5641.ffff ARPA Vlan100
Internet 10.100.0.43 - 0013.1a39.ffff ARPA Vlan100
Internet 10.100.0.38 155 001c.b078.ffff ARPA Vlan100
Internet 10.100.0.60 224 0005.1e35.ffff ARPA Vlan100
Internet 10.100.0.14 1 0090.27fc.ffff ARPA Vlan100
Internet 10.100.0.25 1 0011.85b8.ffff ARPA Vlan100
Internet 10.100.0.20 95 0013.7f95.ffff ARPA Vlan100
Internet 10.100.0.18 4 0015.c5dc.ffff ARPA Vlan100
Internet 10.100.0.17 219 0015.c5dc.ffff ARPA Vlan100
Internet 10.100.21.254 95 001c.b078.ffff ARPA Vlan100
Internet 10.100.0.167 0 000c.2941.ffff ARPA Vlan100
sw9#

I've obfuscated with "ffff" as this is all probably useless as it's all internal, but I'm nervous about dumping too much on EE.
Why are the 10.100.21.254 entries marked in VLAN100? I know it's only a layer 2 switch, but it does have capacity for 250+ VLANs.

Thanks.

engerd

ASKER

Here's a snippet from the vSphere client on the ESX host showing the VLAN config. Teaming is default (original port). There is no port-channel on the switch.

Thanks.

ESX-VLAN.jpg

engerd

ASKER

VLANs 3, 50 and 100 are all reachable on the C2950 ... only VLAN6 is broken.

I have VMs with interfaces in both VLAN3 and VLAN6. Only VLAN3 works.

Both the C2950 and C3550 are running rapid-pvst. STP looks identical for VLAN3 and VLAN6.

This thing has got me beat for now - I've been looking at it too long.

LARGE virtual beer to the guy/gal who nails this.

Thanks.

bgoering

where do your two vmnics plug in? both on the 2950? If so I expect a port channel config would be in order.

engerd

ASKER

Yes, and yes.

I tried with just one vmnic. Makes no difference. I'm keeping it sim;e until I get VLAN3 operational! I tried creating a new vSwitch1, no change - same behaviour. Removed it and put it back the way it is in the diagram.

Paul Solovyovsky

vswitch0 has two interfaces. If they are trunked they need to be configured with ip hash.

bgoering

Ok, but now I am even more confused - is it VLAN3 that isn't working? Or VLAN5? or both?

Only thing I have to try yet tonight (past my bedtime!) is to take of the spanning tree portfast trunk - not sure how that works with an ESX uplink...I haven't ever used it - and once it converges there would be little chance of a loop into a vswitch..

Good luck

Paul Solovyovsky

Take a look at these KBs, they usually resolve most of the customer issues I have related with trunking.

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1004048
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1001938
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1004074
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1003806
http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1004127

rfc1180

>Why are the 10.100.21.254 entries marked in VLAN100?
this is normal for a layer 2 switch with a layer 3 management interface
cause your layer 3 interface is vlan100 (management)

can you post information from the 3550?

show interface trunk
show ip int bri
show interface status
show mac

on the 2950:
show mac-address-table dynamic | inc 0013.7f95.ffff

Thanks
Billy

bgoering

Also - if you keep both vmnics set up a port channel for them!

engerd

ASKER

vswitch0 has two interfaces, not trunked, default config. I see IDENTICAL behaviour if I remove a sinle vmnic from vswitch0, so it isn't related to the dual NIC config.

It is VLAN6 that doesn't work.

3550 config detail for Billy:

sw6#sh int trunk

Port Mode Encapsulation Status Native vlan
Gi0/1 on 802.1q trunking 1
Po1 on 802.1q trunking 1
Po2 on 802.1q trunking 1

Port Vlans allowed on trunk
Gi0/1 1-4094
Po1 1-4094
Po2 1-4094

Port Vlans allowed and active in management domain
Gi0/1 1-7,13-14,50,56,100
Po1 1-7,13-14,50,56,100
Po2 1-7,13-14,50,56,100

Port Vlans in spanning tree forwarding state and not pruned
Gi0/1 1-7,13-14,50,56,100
Po1 1-7,13-14,50,56,100
Po2 1-7,13-14,50,56,100
sw6#

sw6#sh ip int bri
Interface IP-Address OK? Method Status Protocol
Vlan1 unassigned YES manual up up
Vlan3 10.100.20.254 YES NVRAM up up
Vlan6 10.100.21.254 YES manual up up
Vlan50 82.70.123.28 YES NVRAM up up
Vlan100 10.100.0.20 YES manual up up
FastEthernet0/1 unassigned YES unset up up
FastEthernet0/2 unassigned YES unset up up
FastEthernet0/3 unassigned YES unset up up
[DELETED]
FastEthernet0/23 unassigned YES unset up up
FastEthernet0/24 unassigned YES unset down down
GigabitEthernet0/1 unassigned YES unset up up
GigabitEthernet0/2 unassigned YES unset down down
Port-channel1 unassigned YES unset up up
Port-channel2 unassigned YES unset up up
Loopback0 1.1.1.1 YES manual up up
sw6#

sw6#sh int stat
Vlan1
Switching path Pkts In Chars In Pkts Out Chars Out
Processor 254451 21412087 0 0
Route cache 0 0 0 0
Total 254451 21412087 0 0
Vlan3
Switching path Pkts In Chars In Pkts Out Chars Out
Processor 464086 58241248 95811 9306567
Route cache 90 6120 0 0
Total 464176 58247368 95811 9306567
Vlan6
Switching path Pkts In Chars In Pkts Out Chars Out
Processor 12178 2055937 79 4964
Route cache 0 0 0 0
Total 12178 2055937 79 4964
Vlan50
Switching path Pkts In Chars In Pkts Out Chars Out
Processor 93971 6279743 287 18900
Route cache 0 0 0 0
Total 93971 6279743 287 18900
Vlan100
Switching path Pkts In Chars In Pkts Out Chars Out
Processor 373025 49366260 9702 602298
Route cache 762 51816 0 0
Total 373787 49418076 9702 602298
FastEthernet0/1
Switching path Pkts In Chars In Pkts Out Chars Out
Processor 0 0 2092014 146050869
Route cache 0 0 0 0
Total 0 0 2092014 146050869
[DELETED]
FastEthernet0/47
Switching path Pkts In Chars In Pkts Out Chars Out
Processor 0 0 0 0
Route cache 0 0 0 0
Total 0 0 0 0
FastEthernet0/48
Switching path Pkts In Chars In Pkts Out Chars Out
Processor 0 0 0 0
Route cache 0 0 0 0
Total 0 0 0 0
GigabitEthernet0/1
Switching path Pkts In Chars In Pkts Out Chars Out
Processor 0 0 17170643 1119569929
Route cache 0 0 0 0
Total 0 0 17170643 1119569929
GigabitEthernet0/2
Switching path Pkts In Chars In Pkts Out Chars Out
Processor 0 0 0 0
Route cache 0 0 0 0
Total 0 0 0 0
Port-channel1
Switching path Pkts In Chars In Pkts Out Chars Out
Processor 0 0 12029000 763070740
Route cache 0 0 0 0
Total 0 0 12029000 763070740
Port-channel2
Switching path Pkts In Chars In Pkts Out Chars Out
Processor 0 0 846872 54006640
Route cache 0 0 0 0
Total 0 0 846872 54006640
Loopback0
Switching path Pkts In Chars In Pkts Out Chars Out
Processor 0 0 0 0
Route cache 0 0 0 0
Total 0 0 0 0
sw6#

NB: Portchannels are NOT related to the ISL between the 3550 and the 2950, or the ESX interfaces on the 2950.

sw6#sh mac-add
Mac Address Table
-------------------------------------------

Vlan Mac Address Type Ports
---- ----------- -------- -----
All 0013.7f95.de00 STATIC CPU
All 0013.7f95.de01 STATIC CPU
All 0013.7f95.de02 STATIC CPU
All 0013.7f95.de03 STATIC CPU
All 0013.7f95.de04 STATIC CPU
All 0013.7f95.de05 STATIC CPU
All 0013.7f95.de06 STATIC CPU
All 0013.7f95.de07 STATIC CPU
All 0013.7f95.de08 STATIC CPU
All 0013.7f95.de09 STATIC CPU
All 0013.7f95.de0a STATIC CPU
All 0013.7f95.de0b STATIC CPU
All 0013.7f95.de0c STATIC CPU
All 0013.7f95.de0d STATIC CPU
All 0013.7f95.de0e STATIC CPU
All 0013.7f95.de0f STATIC CPU
All 0013.7f95.de10 STATIC CPU
All 0013.7f95.de11 STATIC CPU
All 0013.7f95.de12 STATIC CPU
All 0013.7f95.de13 STATIC CPU
All 0013.7f95.de14 STATIC CPU
All 0013.7f95.de15 STATIC CPU
All 0013.7f95.de16 STATIC CPU
All 0013.7f95.de17 STATIC CPU
All 0013.7f95.de18 STATIC CPU
All 0013.7f95.de19 STATIC CPU
All 0013.7f95.de1a STATIC CPU
All 0013.7f95.de1b STATIC CPU
All 0013.7f95.de1c STATIC CPU
All 0013.7f95.de1d STATIC CPU
All 0013.7f95.de1e STATIC CPU
All 0013.7f95.de1f STATIC CPU
All 0013.7f95.de20 STATIC CPU
All 0013.7f95.de21 STATIC CPU
All 0013.7f95.de22 STATIC CPU
All 0013.7f95.de23 STATIC CPU
All 0013.7f95.de24 STATIC CPU
All 0013.7f95.de25 STATIC CPU
All 0013.7f95.de26 STATIC CPU
All 0013.7f95.de27 STATIC CPU
All 0013.7f95.de28 STATIC CPU
All 0013.7f95.de29 STATIC CPU
All 0013.7f95.de2a STATIC CPU
All 0013.7f95.de2b STATIC CPU
All 0013.7f95.de2c STATIC CPU
All 0013.7f95.de2d STATIC CPU
All 0013.7f95.de2e STATIC CPU
All 0013.7f95.de2f STATIC CPU
All 0013.7f95.de30 STATIC CPU
All 0013.7f95.de31 STATIC CPU
All 0013.7f95.de32 STATIC CPU
All 0100.0c00.0000 STATIC CPU
All 0100.0ccc.cccc STATIC CPU
All 0100.0ccc.cccd STATIC CPU
All 0100.0ccd.cdce STATIC CPU
All 0180.c200.0000 STATIC CPU
All 0180.c200.0001 STATIC CPU
All 0180.c200.0002 STATIC CPU
All 0180.c200.0003 STATIC CPU
All 0180.c200.0004 STATIC CPU
All 0180.c200.0005 STATIC CPU
All 0180.c200.0006 STATIC CPU
All 0180.c200.0007 STATIC CPU
All 0180.c200.0008 STATIC CPU
All 0180.c200.0009 STATIC CPU
All 0180.c200.000a STATIC CPU
All 0180.c200.000b STATIC CPU
All 0180.c200.000c STATIC CPU
All 0180.c200.000d STATIC CPU
All 0180.c200.000e STATIC CPU
All 0180.c200.000f STATIC CPU
All 0180.c200.0010 STATIC CPU
1 000a.f4d8.c680 DYNAMIC Po1
1 000a.f4d8.c6ad DYNAMIC Po1
1 000a.f4d8.c6b0 DYNAMIC Po1
1 000f.3474.63f6 DYNAMIC Fa0/3
1 0013.1a39.b559 DYNAMIC Gi0/1
1 0013.60e7.ff60 DYNAMIC Po1
1 0013.7f5d.d61e DYNAMIC Po1
1 0015.c5dc.615e DYNAMIC Gi0/1
1 001e.7ae5.5257 DYNAMIC Fa0/12
1 0090.27fc.ab46 DYNAMIC Po2
1 0090.27fc.ab47 DYNAMIC Po2
2 000a.f4d8.c6b0 DYNAMIC Po1
3 0008.0246.757c DYNAMIC Fa0/39
3 000a.f4d8.c6b0 DYNAMIC Po1
3 000c.29c5.ddfa DYNAMIC Gi0/1
3 0010.7504.2560 DYNAMIC Gi0/1
3 0011.0afd.c05c DYNAMIC Fa0/2
3 0011.85b8.65f1 DYNAMIC Fa0/15
3 0019.b986.ca79 DYNAMIC Gi0/1
3 001e.7ae5.5257 DYNAMIC Fa0/12
3 0050.8be2.82f9 DYNAMIC Fa0/10
5 000a.f4d8.c6b0 DYNAMIC Po1
5 000f.3474.63f6 DYNAMIC Fa0/3
5 0013.7f5d.d61e DYNAMIC Po1
5 0050.8be2.82f9 DYNAMIC Fa0/10
5 0090.27fc.ab46 DYNAMIC Po2
7 000a.f4d8.c6b0 DYNAMIC Po1
7 000f.3474.63f6 DYNAMIC Fa0/3
7 0013.7f5d.d61e DYNAMIC Po1
7 0023.3199.ed38 DYNAMIC Po1
7 0050.8be2.82f9 DYNAMIC Fa0/10
7 0090.27fc.ab46 DYNAMIC Po2
13 000a.f4d8.c6b0 DYNAMIC Po1
50 000c.29bd.cd2f DYNAMIC Gi0/1
50 001e.7ae5.5257 DYNAMIC Fa0/12
56 0008.0246.757c DYNAMIC Fa0/39
56 0012.0138.3fc2 DYNAMIC Fa0/6
56 0013.1a1f.5a59 DYNAMIC Fa0/1
100 000c.2941.4e91 DYNAMIC Gi0/1
100 0013.1a39.b540 DYNAMIC Gi0/1
100 0024.e855.cb56 DYNAMIC Gi0/1
100 0050.5641.6f6c DYNAMIC Gi0/1
100 0050.8be2.82f9 DYNAMIC Fa0/10
100 0090.27fc.ab46 DYNAMIC Po2
100 0800.1b43.d9e7 DYNAMIC Gi0/1
100 0800.1b43.ffffDYNAMIC Gi0/1
6 0090.27fc.fff DYNAMIC Po2
Total Mac Addresses for this criterion: 119
sw6#

engerd

ASKER

sw9#sh mac-add dynam | inc 0013.7f95
1 0013.7f95.ffff DYNAMIC Gi0/1
100 0013.7f95.eeee DYNAMIC Gi0/1
100 0013.7f95.ffff DYNAMIC Gi0/1
3 0013.7f95.ffff DYNAMIC Gi0/1
50 0013.7f95.ffff DYNAMIC Gi0/1
sw9#

There are two entries learnt in VLAN6 on the 2950, which relate to the two NICs on the ESX server.

Vlan Mac Address Type Ports
---- ----------- -------- -----
[DELETED]
6 000c.2937.abcd DYNAMIC Fa0/12
6 000c.29c5.abce DYNAMIC Fa0/12
Total Mac Addresses for this criterion: 34
sw9#

ASKER CERTIFIED SOLUTION

rfc1180

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engerd

ASKER

Much appreciated Billy - you'll get a share of the points for getting this far.

I came to the same conclusions, as I'm no IOS slouch either.

I'm also a VCP, and can't see anything wrong with ESX, and have rebuilt it twice. Sigh.

Is there some way I can confirm the 802.1q TAGs using the 2950 at ingres on Fa0/12 abd Fa0/14?

Perhaps a SPAN port to Wireshark? Will I see the frames+tags? Dunno.

Thanks.

bgoering

Yes, with Wireshark and a span port you will be able to see 802.1Q tags.

Just for kicks - could you run a test and see what happens. What I have in mind is your second vmnic remove from the Team and use to create a vSwitch1. Plug into a port on the 2950 that is not trunking, simply a switchport access VLAN 6, create your portgroup and see if you can get traffic that way.

That will at least confirm if vlan 6 is passing properly between to two cisco switches.

engerd

ASKER

Right.

Simplification is king. Spurred on by bgoering's request, I put a laptop on C2950 Fa0/15 in VLAN 6.

I then I proceeded to ping all the VMs on the ESX server, so the trunking config on there was ALWAYS good.

So ... I tried to ping the IP address (10.100.21.96) of the laptop fron the C3550 vlan 6 SVI interface. Nothing!

So - it is a problem between the C3550 and the C2950 UNIQUE to VLAN 6. The others all work just fine.

I have examined the configs on both switches with NOTHING unique to VLAN 6 that hasn't also been done to VLAN 100, VLAN 3 etc. etc.

Heeeeelp! Doin' my head in this is.

rfc1180

Can you please post the configs of the 3550 and 2950, please try to limit what you remove; you can remove passwords and change the last octet of public IP addresses. Thanks

bgoering

Yes, what rfc1180 said :)

The more we have to go on the better

engerd

ASKER

Thanks guys ... configs (obfuscated) now uploaded.

I don't understand why VLANs other than VLAN 6 operate fine, yet VLAN6 will not pass ARP information between the two switches. That seems to be the key.

The C3550 is the command switch in a 3 switch cluster. VLAN100 is the Mgmt VLAN.
sw9-config
sw6-config

bgoering

I am on Blackberry so maybe I missed something looking at config, but looking at link port on 3550 is not a trunk port. If that isn't it what ports on each switch links them?

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bgoering

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engerd

ASKER

Right.

This is where I eat humble pie, as does the person that inserted a Dell PowerConnect 5324 into the link between C2950-Gi0/1 and C3550-Gi0/1.

I went and verified the connectivity in my diagram by visiting the physical switches and tracing the patch panel connections. I was spurred on to do this by noticing that the root of the STP for VLAN6 was different on the C2950 and the C3550. Odd? You bet, as they weren't directly connected and the PC5324 in between knew nothing about VLAN6. *THAT* is what was different between VLAN6 and the other VLANs that were working just fine. The PC5324 had those statically configured and so passed BPDU's and related STP traffic.

This was sooooo hard to find, as the Dell switches are clunky, uninformative and don't run CDP (obviously) so stay below the radar when debugging.

Many apologies for leading you on a merry dance, and I will award 250 to rfc1180 and bgoering for sticking with me this far.

Now, to seek out and destroy the individual that did not update the diagram when they patched in the PC5324 ... grrrrr.

Thanks.

engerd

ASKER

Solved this myself, as I was responsible for the mis-direction!

Dell Powerconnect and Cisco do NOT combine well in the same STP scope.

Apologies.

bgoering

LOL - that is why I was having trouble deducing which ports had them patched together - the comment on the one port led me to assume it was the DTP port linking the two. :)