Diagram for HSRP test plan
Test objective and test procedures
Both 1841 routers were configured HSRPv2 for redundancy. Vlan 10 is tested in this test plan to demonstrate the failover time when a link failed between router and switch.
Catalyst 3750 switches were stacked together as a single entity, two links were connected to different 1841 routers, vlan 10 was elected to test HSRP performance.
A pc was connected to the stacked 3750, and was assigned a vlan 10 member, the pc ping to both loopback interfaces of the routers.
A link between the router and switch would be removed, the recovery time would be timed and recorded. Test would be performed with RSTP enabled and with RSTP/STP disabled.
HSRP configuration in vlan 10 of both routers
FHRP-1# ! interface FastEthernet0/1.10 encapsulation dot1Q 10 ip address 192.168.10.1 255.255.255.0 ip router isis standby version 2 standby 10 ip 192.168.10.3 standby 10 timers msec 500 msec 1500 standby 10 priority 110 standby 10 preempt standby 10 track 1 decrement 20 end track 1 interface FastEthernet0/1 line-protocol router isis net 49.0001.0000.0000.0001.00 is-type level-1
FHRP-2# ! interface FastEthernet0/1.10 encapsulation dot1Q 10 ip address 192.168.10.2 255.255.255.0 ip router isis standby version 2 standby 10 ip 192.168.10.3 standby 10 timers msec 500 msec 1500 standby 10 preempt end router isis net 49.0001.0000.0000.0002.00 is-type level-1
HSRP when all is normal
HSRP with RSTP enabled, link between router and switch removed
If default STP was used the downtime would be longer than this.
HSRP with RSTP enabled, link reinstated
Switch#sh spanning vlan 10
VLAN0010
Spanning tree enabled protocol rstp
Root ID Priority 32778
Address 0013.c3f1.8d00
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32778 (priority 32768 sys-id-ext 10)
Address 0013.c3f1.8d00
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Fa1/0/1 Desg FWD 19 128.3 P2p
Fa1/0/5 Desg FWD 19 128.7 P2p
Fa2/0/1 Desg BLK 19 128.57 P2p
Switch#sh spanning vlan 10
VLAN0010
Spanning tree enabled protocol rstp
Root ID Priority 32778
Address 0013.c3f1.8d00
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32778 (priority 32768 sys-id-ext 10)
Address 0013.c3f1.8d00
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Fa1/0/1 Desg FWD 19 128.3 P2p
Fa1/0/5 Desg FWD 19 128.7 P2p
Fa2/0/1 Desg LRN 19 128.57 P2p
Switch#
*Mar 1 14:22:15.144: %SW_MATM-4-MACFLAP_NOTIF: Host 0000.0c9f.f00a in vlan 10 is flapping between port Fa2/0/1 and port Fa1/0/1
Switch#
*Mar 1 14:22:20.001: %SW_MATM-4-MACFLAP_NOTIF: Host 0000.0c9f.f00a in vlan 10 is flapping between port Fa1/0/1 and port Fa2/0/1
Switch#sh spanning vlan 10
VLAN0010
Spanning tree enabled protocol rstp
Root ID Priority 32778
Address 0013.c3f1.8d00
This bridge is the root
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32778 (priority 32768 sys-id-ext 10)
Address 0013.c3f1.8d00
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Fa1/0/1 Desg FWD 19 128.3 P2p
Fa1/0/5 Desg FWD 19 128.7 P2p
Fa2/0/1 Desg FWD 19 128.57 P2p
Switch#
While the RSTP state was transiting from blocking to learning and from learning to forwarding no data was sent and received this increased the downtime of the supposedly fast HSRP. Fortunately forward delay has no effect on RSTP so when the RSTP state changed to forwarding the data resumed forwarding immediately.
Disable spanning tree on the tested vlan
Issue no spanning-tree vlan 10 to disable spanning tree from vlan 10, since there is no layer 2 loop disabling spanning tree will not be a problem.
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