Failure Points
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Sequence of Events
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ENCS chassis hardware failure:
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Power down
-
Power cycle
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Reboot
Cisco Enterprise NFVIS software failure
Cisco ISRv software failure
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Stop (shutdown)
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Reboot
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Crash
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Error
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HSRP on ENCS2 detects the reachability failure to ENCS1, and triggers the failover. LAN virtual IP becomes active on ENCS2.
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WAN-IP1 on ENCS1 becomes unreachable, and all the routes converge towards WAN-IP2 on ENCS2. WAN-IP2 is the only IP for branch
connectivity.
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All the WAN to LAN, and LAN to WAN traffic will now flow through ENCS2.
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The PBR/PFR configuration will now select the LAN port as the preferred path instead of the transit link for the traffic
heading to LAN.
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ISRv1 (Active) Before the Failure
ISRv1# show platform software vnic-if interface-mapping
-------------------------------------------------------------
Interface Name Driver Name Mac Addr
-------------------------------------------------------------
GigabitEthernet5 i40evf 5254.003a.1020 (LAN-SRIOV-2)
GigabitEthernet4 virtio 5254.0053.e392 (service-net)
GigabitEthernet3 i40evf 5254.00c4.b925 (LAN-SRIOV-1)
GigabitEthernet2 igbvf 5254.00d2.cc9a (GE0-0-SRIOV-1)
GigabitEthernet1 virtio 5254.00d2.1b1c (int-mgmt-net)
-------------------------------------------------------------
ISRv1# show standby brief
P indicates configured to preempt.
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Interface Grp Pri P State Active Standby Virtual IP
Gi4 25 105 P Active local 192.0.2.1 192.0.2.222
#
ISRv2 (Standby) Before the Failure
ISRv2#show platform software vnic-if interface-mapping
-------------------------------------------------------------
Interface Name Driver Name Mac Addr
-------------------------------------------------------------
GigabitEthernet5 i40evf 5254.00cc.ce9f (LAN-SRIOV-2)
GigabitEthernet4 virtio 5254.00e7.523f (Service-net)
GigabitEthernet3 i40evf 5254.0055.ee45 (LAN-SRIOV-1)
GigabitEthernet2 igbvf 5254.00a3.d443 (GE0-0-SRIOV-1)
GigabitEthernet1 virtio 5254.0048.e84c (int-mgmt-net)
-------------------------------------------------------------
ISRv2#show standby brief
P indicates configured to preempt.
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Interface Grp Pri P State Active Standby Virtual IP
Gi4 25 100 P Standby 192.0.2.20 local 192.0.2.222
ISRv2 After the Failure
ISRv1 becomes unreachable. ISRv2: The HSRP failover occurs, and the state changes from Standby to Active. The virtual IP (LAN
side default gateway) becomes active on ENCS2 ISRv2.
ISRv2# show standby brief
P indicates configured to preempt.
|
Interface Grp Pri P State Active Standby Virtual IP
Gi4 25 100 P Active local unknown 192.0.2.222
ISRv2# show logging
*Dec 13 21:22:17.138: %HSRP-5-STATECHANGE: GigabitEthernet4 Grp 25 state Speak -> Standby
*Dec 13 21:22:32.385: %HSRP-5-STATECHANGE: GigabitEthernet4 Grp 25 state Standby -> Active
Failure Points
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Sequence of Events
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WAN Net1 failure (WAN SRIOV VF connected to ISRv1)
WAN Phy link failure
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ISRv1 HSRP on ENCS1 detects the WAN connection failure. It reduces the LAN-HSRP priority. This failure is detected when the
interface goes down due to VF going down or track object going down.
-
WAN-IP1 becomes unreachable, and all the routes converge towards WAN-IP2 on ENCS2. WAN-IP2 is the only IP for branch connectivity.
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HSRP on ENCS2 becomes higher priority in the group, and takes over the active role. LAN-virtual IP becomes active on ENCS2.
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The PBR/PFR configuration will now select the LAN port as the preferred path instead of the transit link for the traffic destined
to LAN.
-
All the WAN to LAN, and LAN to WAN traffic will now flow through ENCS2.
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ISRv1 After the Failure
ISRv1 becomes standby.
ISRv1# show ip interface brief
Interface IP-Address OK? Method Status Protocol
GigabitEthernet1 192.0.2.1 YES NVRAM up up
GigabitEthernet2 192.0.2.2 YES NVRAM down down
GigabitEthernet3 unassigned YES NVRAM administratively down down
GigabitEthernet4 192.0.2.3 YES NVRAM up up
GigabitEthernet5 unassigned YES NVRAM up up
ISRv1# show standby brief
P indicates configured to preempt.
|
Interface Grp Pri P State Active Standby Virtual IP
Gi4 25 85 P Standby 192.0.2.22 local 192.0.2.222
ISRv1#
ISRv1#show logg
*Dec 14 03:41:52.307: %TRACK-6-STATE: 2 interface Gi2 line-protocol Up -> Down
*Dec 14 03:42:37.744: %HSRP-5-STATECHANGE: GigabitEthernet4 Grp 25 state Active -> Speak
*Dec 14 03:42:43.663: %HSRP-5-STATECHANGE: GigabitEthernet4 Grp 25 state Speak -> Standby
ISRv1#
ISRv1#show track
Track 1
IP SLA 1 reachability
Reachability is Down
1405 changes, last change 00:03:08
Latest operation return code: Timeout
Tracked by:
HSRP GigabitEthernet4 25
ISRv2 After the Failure
ISRv2# show standby brief
P indicates configured to preempt.
|
Interface Grp Pri P State Active Standby Virtual IP
Gi4 25 100 P Active local 192.0.2.3 192.0.2.222
Failure Points
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Sequence of Events
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LAN Phy link failure
LAN connectivity failure
SC Net failure (ISRv service-net down)
VNFs (Cisco ASAv, Cisco vWAAS, and Windows/Linux)
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Power down
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Power cycle
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Crash/reboot
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ISRv1 HSRP on ENCS1 detects the LAN connection failure, and shut down the HSRP group. This failure is detected when the interface
goes down due to the track object going down.
-
EEM script on ISRv1 withdraws the routes (for example, delete EIGRP networks). All the branch traffic routes will now converge
towards WAN-IP2 on ENCS2. WAN-IP2 is the only IP for branch connectivity.
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HSRP on ENCS-2 becomes active in the group. LAN virtual IP becomes active on ENCS2.
-
On ISRv2, the PBR/PFR configuration will now select the LAN port as the preferred path, instead of the transit link for the
traffic destined to LAN.
-
All the WAN to LAN and LAN to WAN traffic will now flow through ENCS2.
|
ISRv1 After the Failure
ISRv1# show track
Track 7
IP SLA 7 reachability
Reachability is Down
7 changes, last change 00:01:40
Latest operation return code: Timeout
Tracked by:
HSRP GigabitEthernet3 25
EEM 2450904616
EEM 2450905656
ISRv1#
ISRv1# show ip eigrp topo
EIGRP-IPv4 Topology Table for AS(10)/ID(53.53.53.51)
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
r - reply Status, s - sia Status
P 19.19.19.0/24, 1 successors, FD is 3328
via 38.38.38.38 (3328/3072), GigabitEthernet2
P 9.9.9.0/24, 1 successors, FD is 3328
via 38.38.38.38 (3328/3072), GigabitEthernet2
P 25.25.25.0/24, 0 successors, FD is Infinity
via 38.38.38.38 (3840/3584), GigabitEthernet2
P 27.27.27.0/24, 1 successors, FD is 3328
via 38.38.38.38 (3328/3072), GigabitEthernet2
P 38.38.38.0/24, 1 successors, FD is 2816
via Connected, GigabitEthernet2
P 29.29.29.0/24, 1 successors, FD is 3072
via 38.38.38.38 (3072/2816), GigabitEthernet2
P 33.33.33.0/24, 1 successors, FD is 3840
via 38.38.38.38 (3840/3584), GigabitEthernet2
P 8.8.8.0/24, 1 successors, FD is 3584
via 38.38.38.38 (3584/3328), GigabitEthernet2
P 53.53.53.0/24, 1 successors, FD is 2816
via Connected, GigabitEthernet4
ISRv2 After the Failure
ISRv2# show standby brief
P indicates configured to preempt.
|
Interface Grp Pri P State Active Standby Virtual IP
Gi3 25 100 P Active local unknown 192.0.2.222
Failure Points
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Sequence of Events
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WAN Net2 failure (WAN SRIOV VF connected to ISRv2 is down)
|
-
ISRv2 on ENCS2 detects the WAN connection failure. This failure is detected when the interface goes down due to VF going down
or the track object going down.
-
WAN-IP2 becomes unreachable, and all the routes converge towards WAN-IP1 on ENCS1. WAN-IP1 is the only IP for branch connectivity.
-
All the WAN to LAN and LAN to WAN traffic will now flow through ENCS1.
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Transit link between ENCS1 and ENCS2 fails
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ISRv2 on ENCS2 detects the link going down due to VF going down or connection failure. The connection failure is detected
by the track object. Then, ENCS2 WAN-IP2 link with EEM script is shut down.
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WAN-IP2 becomes unreachable, and all the routes converge towards WAN-IP1 on ENCS1. WAN-IP1 is the only IP for branch connectivity.
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All the WAN to LAN and LAN to WAN traffic will now flow through ENCS1.
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