I believe I am missing something obvious. I am using GNS3 to lab out having two paths to a CORE network. See picture. The configuration works as I imagined, I can ping from each Switch every other Switch within VLAN212. I can also ping the loopbacks of the CORE switch from the other switches in the VLAN212 domain. Spanning tree has put SW-C f/15 in block mode which is good since this group of switches is a Layer 2 loop. The issue is, if I remove any of the links in the loop, the topology cannot recover. I thought Spanning Tree would only take 30 seconds to recalculate, but something else is preventing each switch to ping each other...Even in the localized VLAN 212. What I mean is if I remove the link from SW-A --> SW-C. I can no longer ping from SW-C any of the switches or even the CORE switch.
Perhaps I am going about this the wrong way. If there is a better way to get a secondary path to a group of non-stackable switches let me know. I am trying to get away from the fact that these non-stackable switches are daisy chained, with only 1 switch having a path to the core.
Any, I appreciate your help. Thank you!
Picture.
Spanning Tree output SW-C with link intact:
SW-C#show spanning-tree brief
VLAN212
Spanning tree enabled protocol ieee
Root ID Priority 32768
Address c801.2308.0001
Cost 19
Port 55 (FastEthernet1/14)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32768
Address c802.2308.0000
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Designated
Name Port ID Prio Cost Sts Cost Bridge ID Port ID
-------------------- ------- ---- ----- --- ----- -------------------- -------
FastEthernet1/14 128.55 128 19 FWD 0 32768 c801.2308.0001 128.56
FastEthernet1/15 128.56 128 19 FWD 19 32768 c802.2308.0000 128.56
SW-C#ping 1.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 20/45/84 ms
REmove link from SW-A to SW-C
SW-C#show spanning-tree bri
VLAN212
Spanning tree enabled protocol ieee
Root ID Priority 32768
Address c801.2308.0001
Cost 19
Port 55 (FastEthernet1/14)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32768
Address c802.2308.0000
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300
Interface Designated
Name Port ID Prio Cost Sts Cost Bridge ID Port ID
-------------------- ------- ---- ----- --- ----- -------------------- -------
FastEthernet1/14 128.55 128 19 FWD 0 32768 c801.2308.0001 128.56
FastEthernet1/15 128.56 128 19 FWD 19 32768 c802.2308.0000 128.56
SW-C#
*Mar 1 00:09:52.311: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 10.0.0.11 (Vla n212) is down: holding time expired
SW-C#
*Mar 1 00:09:55.903: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 10.0.0.2 (Vlan 212) is down: holding time expired
SW-C#ping 1.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
ADDING SW RUNNING_CONFIGS
CORE
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname CORE
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 15
no ip icmp rate-limit unreachable
ip cef
!
!
!
!
no ip domain lookup
!
!
!
!
!
ip tcp synwait-time 5
!
!
interface Loopback0
ip address 1.1.1.1 255.255.255.0
!
interface Loopback1
ip address 2.2.2.2 255.255.255.0
!
interface Loopback2
ip address 3.3.3.3 255.255.255.0
!
interface FastEthernet0/0
no ip address
shutdown
duplex auto
speed auto
!
interface FastEthernet0/1
no ip address
shutdown
duplex auto
speed auto
!
interface FastEthernet1/0
!
interface FastEthernet1/1
switchport access vlan 295
!
interface FastEthernet1/2
switchport access vlan 296
!
interface FastEthernet1/3
!
interface FastEthernet1/4
!
interface FastEthernet1/5
!
interface FastEthernet1/6
!
interface FastEthernet1/7
!
interface FastEthernet1/8
!
interface FastEthernet1/9
!
interface FastEthernet1/10
!
interface FastEthernet1/11
!
interface FastEthernet1/12
!
interface FastEthernet1/13
!
interface FastEthernet1/14
!
interface FastEthernet1/15
!
interface Vlan1
no ip address
!
interface Vlan295
ip address 172.16.0.1 255.255.255.0
ip summary-address eigrp 1 0.0.0.0 0.0.0.0
!
interface Vlan296
ip address 172.16.1.1 255.255.255.0
ip summary-address eigrp 1 0.0.0.0 0.0.0.0
!
router eigrp 1
network 172.16.0.0 0.0.0.255
network 172.16.1.0 0.0.0.255
no auto-summary
!
ip forward-protocol nd
!
no ip http server
no ip http secure-server
!
!
control-plane
!
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
line vty 0 4
login
!
!
end
SW-A
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname SW-A
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 15
no ip icmp rate-limit unreachable
ip cef
!
!
!
!
no ip domain lookup
!
!
!
!
!
ip tcp synwait-time 5
!
!
interface FastEthernet0/0
no ip address
shutdown
duplex auto
speed auto
!
interface FastEthernet0/1
no ip address
shutdown
duplex auto
speed auto
!
interface FastEthernet1/0
!
interface FastEthernet1/1
switchport access vlan 295
!
interface FastEthernet1/2
!
interface FastEthernet1/3
!
interface FastEthernet1/4
!
interface FastEthernet1/5
!
interface FastEthernet1/6
!
interface FastEthernet1/7
!
interface FastEthernet1/8
!
interface FastEthernet1/9
!
interface FastEthernet1/10
!
interface FastEthernet1/11
!
interface FastEthernet1/12
!
interface FastEthernet1/13
!
interface FastEthernet1/14
switchport access vlan 212
!
interface FastEthernet1/15
switchport access vlan 212
!
interface Vlan1
no ip address
!
interface Vlan212
ip address 10.0.0.1 255.255.255.0
!
interface Vlan295
ip address 172.16.0.2 255.255.255.0
!
router eigrp 1
network 0.0.0.0
no auto-summary
!
ip forward-protocol nd
!
no ip http server
no ip http secure-server
!
!
control-plane
!
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
line vty 0 4
login
!
!
end
SW-B
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname SW-B
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 15
no ip icmp rate-limit unreachable
ip cef
!
!
!
!
no ip domain lookup
!
!
!
!
!
ip tcp synwait-time 5
!
!
interface FastEthernet0/0
no ip address
shutdown
duplex auto
speed auto
!
interface FastEthernet0/1
no ip address
shutdown
duplex auto
speed auto
!
interface FastEthernet1/0
!
interface FastEthernet1/1
switchport access vlan 296
!
interface FastEthernet1/2
!
interface FastEthernet1/3
!
interface FastEthernet1/4
!
interface FastEthernet1/5
!
interface FastEthernet1/6
!
interface FastEthernet1/7
!
interface FastEthernet1/8
!
interface FastEthernet1/9
!
interface FastEthernet1/10
!
interface FastEthernet1/11
!
interface FastEthernet1/12
!
interface FastEthernet1/13
!
interface FastEthernet1/14
switchport access vlan 212
!
interface FastEthernet1/15
switchport access vlan 212
!
interface Vlan1
no ip address
!
interface Vlan212
ip address 10.0.0.2 255.255.255.0
!
interface Vlan296
ip address 172.16.1.2 255.255.255.0
!
router eigrp 1
network 0.0.0.0
no auto-summary
!
ip forward-protocol nd
!
no ip http server
no ip http secure-server
!
mac-address-table static c809.094c.0000 interface FastEthernet1/14 vlan 1
!
control-plane
!
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
line vty 0 4
login
!
!
end
SW-C
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname SW-C
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 15
no ip icmp rate-limit unreachable
ip cef
!
!
!
!
no ip domain lookup
!
!
!
!
!
ip tcp synwait-time 5
!
!
interface FastEthernet0/0
no ip address
shutdown
duplex auto
speed auto
!
interface FastEthernet0/1
no ip address
shutdown
duplex auto
speed auto
!
interface FastEthernet1/0
!
interface FastEthernet1/1
!
interface FastEthernet1/2
!
interface FastEthernet1/3
!
interface FastEthernet1/4
!
interface FastEthernet1/5
!
interface FastEthernet1/6
!
interface FastEthernet1/7
!
interface FastEthernet1/8
!
interface FastEthernet1/9
!
interface FastEthernet1/10
!
interface FastEthernet1/11
!
interface FastEthernet1/12
!
interface FastEthernet1/13
!
interface FastEthernet1/14
switchport access vlan 212
!
interface FastEthernet1/15
switchport access vlan 212
!
interface Vlan1
no ip address
!
interface Vlan212
ip address 10.0.0.10 255.255.255.0
!
router eigrp 1
network 0.0.0.0
no auto-summary
!
ip forward-protocol nd
!
no ip http server
no ip http secure-server
!
mac-address-table static c80a.094c.0000 interface FastEthernet1/15 vlan 212
!
control-plane
!
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
line vty 0 4
login
!
!
end
SW-D
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname SW-D
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
memory-size iomem 15
no ip icmp rate-limit unreachable
ip cef
!
!
!
!
no ip domain lookup
!
!
!
!
!
ip tcp synwait-time 5
!
!
interface FastEthernet0/0
no ip address
shutdown
duplex auto
speed auto
!
interface FastEthernet0/1
no ip address
shutdown
duplex auto
speed auto
!
interface FastEthernet1/0
!
interface FastEthernet1/1
!
interface FastEthernet1/2
!
interface FastEthernet1/3
!
interface FastEthernet1/4
!
interface FastEthernet1/5
!
interface FastEthernet1/6
!
interface FastEthernet1/7
!
interface FastEthernet1/8
!
interface FastEthernet1/9
!
interface FastEthernet1/10
!
interface FastEthernet1/11
!
interface FastEthernet1/12
!
interface FastEthernet1/13
!
interface FastEthernet1/14
switchport access vlan 212
!
interface FastEthernet1/15
switchport access vlan 212
!
interface Vlan1
no ip address
!
interface Vlan212
ip address 10.0.0.11 255.255.255.0
!
router eigrp 1
network 0.0.0.0
no auto-summary
!
ip forward-protocol nd
!
no ip http server
no ip http secure-server
!
!
control-plane
!
!
line con 0
exec-timeout 0 0
privilege level 15
logging synchronous
line aux 0
exec-timeout 0 0
privilege level 15
logging synchronous
line vty 0 4
login
!
!
end
HERE IS AN EXAMPLE OF REMOVE THE LINK BETWEEN SW C and B, and then readding the link.
SW-C#ping 1.1.1.1 repeat 100000
Type escape sequence to abort.
Sending 100000, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!........
*Mar 1 00:32:23.183: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 10.0.0.2 (Vlan212) is down: holding time expired................!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
*Mar 1 00:32:55.739: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 10.0.0.2 (Vlan212) is up: new adjacency!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!..........................................
.........................................................
For some reason it never recovers....