CentOS bridge not recognizing external Designated Root

I have a core Foundry switch connected (through a dot1Q vlan trunk) to a linux (Centos5) server on eth0. The linux box's eth1 is connected (through a dot1Q vlan trunk) to a Cisco 2960. Note that I do have 2 more interfaces on the linux box, one more "outside" and another "inside", which I plan to turn up once I can get STP working properly.
The Foundry is set to be the STP Designated Root (DR) using a Priority of 12000. The Foundry and the Cisco both agree, but the linux server insists that it is the DR. I do have ebtables and iptables installed. One thing I noticed is that when I restart networking, the server does show the Foundry as the DR for approximately 20 seconds, then falls back to itself as the DR. I think this coincides with the server transitioning its ports from LEARN to FWD. Another interesting note is that i do have another box, same linux kernel, same distribution connected to the same Foundry and it _does_ recognize the Foundry as the DR.

Can anyone shed some light on this situation?

##Foundry output:
FES9604 Switch#show span vlan 950

VLAN 950 BPDU cam_index is 0 and the DMA master Are(HEX) 0 D STP instance owned by VLAN 950

Global STP (IEEE 802.1D) Parameters:

VLAN Root Root Root Prio Max He- Ho- Fwd Last Chg Bridge ID ID Cost Port rity Age llo ld dly Chang cnt Address
Hex sec sec sec sec sec
950 2ee0000480e6a03c 20095100 2ee0 20 2 1 15 935 16 000480e6fcd0

Port STP Parameters:

Port Prio Path State Fwd Design Designated Designated Num rity Cost Trans Cost Root Bridge
Hex
1 80 19 FORWARDING 6 20095 2ee0000480e6a03c 2ee0000480e6fcd0 2 80 0 DISABLED 0 0 0000000000000000 0000000000000000 100 80 19 FORWARDING 1 20076 2ee0000480e6a03c 80000090f2b2490a

##Cisco output:
##Cisco is in pvst mode

as01-vlanfw01#show spanning-tree vlan 950

VLAN0950
Spanning tree enabled protocol ieee

 Root ID    Priority    12000                                                  
            Address     0004.80e6.a03c                                         
            Cost        4                                                      
            Port        25 (GigabitEthernet0/1)                                

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

Bridge ID Priority 33718 (priority 32768 sys-id-ext 950)
Address 0022.913f.e700
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300

Interface           Role Sts Cost      Prio.Nbr Type                            ------------------- ---- --- --------- -------- --------------------------------
Gi0/1               Root FWD 4         128.25   P2p                             Gi0/2               Altn BLK 19        128.26   P2p

##Centos output:
[root@vlan-fw-02 ]# cat /etc/issue
CentOS release 5 (Final)
Kernel \r on an \m

[root@vlan-fw-02 ]# ebtables-save
# Generated by ebtables-save v1.0 on Tue Oct 7 19:37:59 PDT 2003 *broute
:BROUTING ACCEPT
-A BROUTING -p 802_1Q --vlan-id 950 -j DROP

*nat
:PREROUTING ACCEPT
:OUTPUT ACCEPT
:POSTROUTING ACCEPT

*filter
:INPUT ACCEPT
:FORWARD ACCEPT
:OUTPUT ACCEPT

[root@vlan-fw-02 ]# iptables-save
# Generated by iptables-save v1.3.5 on Tue Oct 7 19:38:22 2003
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [14116:1889409]
:RH-Firewall-1-INPUT - [0:0]
-A INPUT -j RH-Firewall-1-INPUT -A FORWARD -j RH-Firewall-1-INPUT -A RH-Firewall-1-INPUT -i lo -j ACCEPT -A RH-Firewall-1-INPUT -p icmp -m icmp --icmp-type any -j ACCEPT -A RH-Firewall-1-INPUT -p esp -j ACCEPT -A RH-Firewall-1-INPUT -p ah -j ACCEPT -A RH-Firewall-1-INPUT -d 224.0.0.251 -p udp -m udp --dport 5353 -j ACCEPT -A RH-Firewall-1-INPUT -p udp -m udp --dport 631 -j ACCEPT -A RH-Firewall-1-INPUT -p tcp -m tcp --dport 631 -j ACCEPT -A RH-Firewall-1-INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT -A RH-Firewall-1-INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT -A RH-Firewall-1-INPUT -j REJECT --reject-with icmp-host-prohibited COMMIT # Completed on Tue Oct 7 19:38:22 2003

[root@vlan-fw-02 ]# brctl show

bridge name     bridge id               STP enabled     interfaces
br0.950         8000.00065b8bce3e       yes             eth3.950
                                                       eth2.950
                                                       eth1.950
                                                       eth0.950

br0 8000.00065b8bce3e yes eth0
eth1

[root@vlan-fw-02 ]# brctl showstp br0.950
br0.950
bridge id 8000.00065b8bce3e
designated root 8000.00065b8bce3e

root port                 0                    path cost                  0
max age                  19.99                 bridge max age            19.99
hello time                1.99                 bridge hello time          1.99
forward delay            14.99                 bridge forward delay      14.99
ageing time             299.95
hello timer               0.83                 tcn timer                  0.00
topology change timer     0.00                 gc timer                   0.08

flags

eth3.950 (4)

port id                8004                    state                  disabled
designated root        8000.00065b8bce3e       path cost                100
designated bridge      8000.00065b8bce3e       message age timer          0.00
designated port        8004                    forward delay timer        0.00
designated cost           0                    hold timer                 0.00

flags

eth2.950 (3)

port id                8003                    state                  disabled
designated root        8000.00065b8bce3e       path cost                100
designated bridge      8000.00065b8bce3e       message age timer          0.00
designated port        8003                    forward delay timer        0.00
designated cost           0                    hold timer                 0.00

flags

eth1.950 (2)

port id                8002                    state                forwarding
designated root        8000.00065b8bce3e       path cost                100
designated bridge      8000.00065b8bce3e       message age timer          0.00
designated port        8002                    forward delay timer        0.00
designated cost           0                    hold timer                 0.00

flags

eth0.950 (1)

port id                8001                    state                forwarding
designated root        8000.00065b8bce3e       path cost                 19
designated bridge      8000.00065b8bce3e       message age timer          0.00
designated port        8001                    forward delay timer        0.00
designated cost           0                    hold timer                 0.00

flags

TIA,
Chris Hunt

For Posterity's sake: apparently the problem stems from the fact that Net:Bridge's STP implementation is not currently compliant with with 802.1W. Until that code is available I've removed the linux boxes from participating in STP and will not be bringing up their secondary interfaces.

-Chris Hunt