环路防护的验证.doc

环路防护的验证
1. 先在SW3上启用bpdufilter，使用S2950收不到BPDU，形成环路。
sw3#sh run int g1/0/11
interface GigabitEthernet1/0/11
spanning-tree bpdufilter enable

s2950#sh span vlan 1

VLAN0001
Spanning tree enabled protocol rstp
Root ID Priority 4097
Address 0019.e70e.c400
Cost 19
Port 10 (FastEthernet0/10)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)
Address 000c.ce0e.3840
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300

Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/1 Desg FWD 19 128.1 Edge P2p
Fa0/2 Desg FWD 19 128.2 Edge P2p

Fa0/10 Root FWD 19 128.10 P2p
Fa0/12 Desg BLK 19 128.12 P2p

s2950#sh span vlan 1

Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/1 Desg FWD 19 128.1 Edge P2p
Fa0/2 Desg FWD 19 128.2 Edge P2p
Fa0/10 Root FWD 19 128.10 P2p
Fa0/12 Desg LRN 19 128.12 P2p

s2950#sh span vlan 1

Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/1 Desg FWD 19 128.1 Edge P2p
Fa0/2 Desg FWD 19 128.2 Edge P2p
Fa0/10 Root FWD 19 128.10 P2p
Fa0/12 Desg FWD 19 128.12 P2p

→ 二层环路，广播风暴

2. 接下来，在S2950上启用guard loop
s2950#sh run int f0/12
interface FastEthernet0/12
spanning-tree guard loop
10:26:17: %SPANTREE-2-LOOPGUARD_BLOCK: Loop guard blocking port FastEthernet0/12 on VLAN0001.

s2950#sh span vlan 1
VLAN0001

Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- -------- --------------------------------
Fa0/1 Desg FWD 19 128.1 Edge P2p
Fa0/2 Desg FWD 19 128.2 Edge P2p
Fa0/10 Root FWD 19 128.10 P2p
Fa0/12 Desg BKN*19 128.12 P2p *LOOP_Inc

s2950#sh span inconsistentports

Name Interface Inconsistency
-------------------- ---------------------- ------------------
VLAN0001 FastEthernet0/12 Loop Inconsistent
VLAN0002 FastEthernet0/12 Loop Inconsistent
VLAN0003 FastEthernet0/12 Loop Inconsistent
VLAN0004 FastEthernet0/12 Loop Inconsisten