Hi Experts
Please forgive rather long winded email but need direction here.....
*topology*
R1 f0/0 > f0/1 CAT 1 (vlan 12)
R2 f0/0 > f0/2 CAT 1 (vlan 12)
*issue*
01:50:21: %SW_MATM-4-MACFLAP_NOTIF: Host 001c.f691.a0f8 in vlan 12 is
flapping between port Po13 and port Po12
01:50:21: %SW_MATM-4-MACFLAP_NOTIF: Host 001c.58a7.d388 in vlan 12 is
flapping between port Po14 and port Po12
these flapps continue across all ether channels....
*R1#show ip arp *
Internet 150.100.12.1 - 001c.58a7.d388 ARPA FastEthernet0/0
Internet 150.100.12.2 0 Incomplete ARPA
*R2#show ip arp*
Protocol Address Age (min) Hardware Addr Type Interface
Internet 150.100.12.1 0 001c.58a7.d388 ARPA FastEthernet0/0
Internet 150.100.12.2 - 001c.f691.a0f8 ARPA FastEthernet0/0
one end of either router's arp is always incomplete
checked all ends, encaps is arpa with full-duplex 100mb/s
*CAT1*
access-list 100 permit icmp any any
access-list 100 permit ospf any any
mac access-list extended MAC
*permit mac any any 0x0806 0x0000 <<< permitted arp*
*permit mac any any 0xAAAA 0x0000 * *<<< **permitted **stp for
dot1q trunks*
mac access-map LAB2-26 10
match mac address MAC
action forward
mac access-map LAB2-26 20
match ip address 100
action forward
mac access-map LAB2-26 30
action drop
vlan filter LAB2-26 vlan-list 12
looking further into spanning-tree....
*Cat3550-1#show spanning-tree vlan 12*
VLAN0012
Spanning tree enabled protocol ieee
Root ID Priority 32780
Address 0016.c8cf.8d80
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32780 (priority 32768 sys-id-ext 12)
Address 0016.c8cf.8d80
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- --------
--------------------------------
Gi0/1 Desg FWD 4 128.1 P2p
Fa0/1 Desg FWD 19 128.3 P2p
Fa0/2 Desg FWD 19 128.4 P2p
Po12 Desg FWD 12 128.144 P2p
Po13 Desg FWD 12 128.152 P2p
Po14 Desg FWD 12 128.160 P2p
*Cat3560-2#show spanning-tree vlan 12*
VLAN0012
Spanning tree enabled protocol ieee
Root ID Priority 32780
Address 0016.c8bc.1100
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32780 (priority 32768 sys-id-ext 12)
Address 0016.c8bc.1100
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- --------
--------------------------------
Gi0/1 Desg FWD 4 128.1 P2p
Po12 Desg FWD 12 128.144 P2p
Po23 Desg FWD 12 128.232 P2p
Po24 Desg FWD 12 128.240 P2p
*cat1*
VLAN0012 32780 0016.c8cf.8d80 0 2 20 15
*cat2*
VLAN0012 32780 0016.c8bc.1100 0 2 20 15
*so both switches think there the root for vlan 12*
resolved by issuing
*Cat3550-1(config)#spanning-tree vlan 12 root primary*
but why does the election not agree when cat2 bridge id is lower (priority
is default) obviously cat 2 tries to become the root by right, but then why
does cat1?
*Bridge ID's*
*
*
*cat 1 vlan 12*
0016.c8cf.8d80
*
*
*cat 2 vlan 12*
0016.c8bc.1100 *<<<<---- should be the winner & IS when no mac
access-list/vlan filter is applied*
looking further into vlan 12
*---------------WITH MAC ACCESS-LIST & ROOT PRIORITY PRIMARY SET ON
CAT1-----------------*
*debugging whilst this is happening*
05:25:34: STP: VLAN0012 heard root 32780-0016.c8cf.8d80 on Po12
05:25:34: STP(12) port Po12 supersedes 19
*Cat3550-1#show spanning-tree vlan 12*
VLAN0012
Spanning tree enabled protocol ieee
Root ID Priority 24588
Address 0016.c8cf.8d80
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 24588 (priority 24576 sys-id-ext 12)
Address 0016.c8cf.8d80
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- --------
--------------------------------
Gi0/1 Desg FWD 4 128.1 P2p
Fa0/1 Desg FWD 19 128.3 P2p
Fa0/2 Desg FWD 19 128.4 P2p
*Po12 Desg FWD 12 128.144 P2p *
Po13 Desg FWD 12 128.152 P2p
*Cat3560-2#show spanning-tree vlan 12*
VLAN0012
Spanning tree enabled protocol ieee
Root ID Priority 24588
Address 0016.c8cf.8d80
Cost 4
Port 1 (GigabitEthernet0/1)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32780 (priority 32768 sys-id-ext 12)
Address 0016.c8bc.1100
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 4 128.1 P2p
*Po12 Altn BLK 12 128.144 P2p *
Po23 Desg FWD 12 128.232 P2p
Po24 Desg FWD 12 128.240 P2p
*-------------------------------WITHOUT MAC ACCESS-LIST & WITHOUT **ROOT
PRIORITY PRIMARY SET ON CAT1-**------------*
*Cat3550-1#show spanning-tree vlan 12*
VLAN0012
Spanning tree enabled protocol ieee
Root ID Priority 32780
Address 0016.c8bc.1100
Cost 4
Port 1 (GigabitEthernet0/1)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32780 (priority 32768 sys-id-ext 12)
Address 0016.c8cf.8d80
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 15
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- --------
--------------------------------
Gi0/1 Root FWD 4 128.1 P2p
Fa0/1 Desg FWD 19 128.3 P2p
Fa0/2 Desg FWD 19 128.4 P2p
*Po12 Altn BLK 12 128.144 P2p *
Po13 Desg FWD 12 128.152 P2p
Po14 Desg FWD 12 128.160 P2p
*Cat3560-2#show spanning-tree vlan 12*
VLAN0012
Spanning tree enabled protocol ieee
Root ID Priority 32780
Address 0016.c8bc.1100
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32780 (priority 32768 sys-id-ext 12)
Address 0016.c8bc.1100
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 15
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- --------
--------------------------------
Gi0/1 Desg FWD 4 128.1 P2p
*Po12 Desg FWD 12 128.144 P2p *
Po23 Desg FWD 12 128.232 P2p
Po24 Desg FWD 12 128.240 P2p
*+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*
*debugging on CAT2 whilst mac access-list is applied to CAT1 & NO
**spanning-tree
vlan 12 root primary*
05:25:34: STP: VLAN0012 heard root 32780-0016.c8cf.8d80 on Po12
05:25:34: STP(12) port Po12 supersedes 19
here's my thinking....
cat1 says my cost is 12 for vlan 12 via Po12 ; cat2 relays this message
saying 12 supersedes 19 but then where does it get cost of 19 from?
*+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*
*
*
what gives i'm confused.com , I know I can resolve the above by running
root primary for vlan 12 on CAT1 but need to understand why this default
behaviour as this lab task clearly asks that I implement this mac
access-list, would this happen in the IE lab ?
Tony
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