Hi all,
I've been working on changing the IGP for my company. We want to move from EIGRP to OSFP.
The IT-equipments are from differents Cisco Family's products, we have Nexus 7k, 5k, Metro Ethernet 3600s, Cisco 2900 and Cisco 2800.
I've configuring the OSPF process on all platforms and estableshing adyacencies over the same Links where EIGRP is actually running.
All OSPF adjacencies have been configured on the backbone area announcing only the subnets for adjacencies and a loopback address for RID.
I've been checking the Routing table on some of the Nexus at the HQ and I found that routes for loopback addresses from branch sites are flapping even when OSPF adjacencies are in FULL state.
That is causing that communication to the remote branches loopback be unstable. I think that something in the OSPF configuration is missing and causing that the SPF algorithm has been executing more than usual.
I leave here some output of the OSPF configuration, if you need additional info, let me know
NX5548UP-DIST-02
router ospf 20
router-id 172.16.250.19
area 0.0.0.0 authentication message-digest
log-adjacency-changes
auto-cost reference-bandwidth 10000 Mbps
ME3600-BR-01#sh run | be router os
router ospf 20
router-id 172.16.250.16
log-adjacency-changes
auto-cost reference-bandwidth 10000
area 0 authentication message-digest
passive-interface default
no passive-interface GigabitEthernet0/5
no passive-interface GigabitEthernet0/8
no passive-interface TenGigabitEthernet0/1
network 172.16.250.16 0.0.0.0 area 0
network 192.168.100.184 0.0.0.3 area 0
network 192.168.101.172 0.0.0.3 area 0
network 192.168.101.224 0.0.0.3 area 0
!
NX5548UP-DIST-02# show ip ospf
Routing Process 20 with ID 172.16.250.19 VRF default
Stateful High Availability enabled
Graceful-restart is configured
Grace period: 60 state: Inactive
Last graceful restart exit status: None
Supports only single TOS(TOS0) routes
Supports opaque LSA
Administrative distance 110
Reference Bandwidth is 10000 Mbps
SPF throttling delay time of 200.000 msecs,
SPF throttling hold time of 1000.000 msecs,
SPF throttling maximum wait time of 5000.000 msecs
LSA throttling start time of 0.000 msecs,
LSA throttling hold interval of 5000.000 msecs,
LSA throttling maximum wait time of 5000.000 msecs
Minimum LSA arrival 1000.000 msec
LSA group pacing timer 10 secs
Maximum paths to destination 8
Number of external LSAs 0, checksum sum 0
Number of opaque AS LSAs 0, checksum sum 0
Number of areas is 1, 1 normal, 0 stub, 0 nssa
Number of active areas is 1, 1 normal, 0 stub, 0 nssa
Area BACKBONE(0.0.0.0)
Area has existed for 6w6d
Interfaces in this area: 5 Active interfaces: 4
Passive interfaces: 0 Loopback interfaces: 0
Message-digest authentication
SPF calculation has run 302712 times
Last SPF ran for 0.005798s
Area ranges are
Number of LSAs: 126, checksum sum 0x3a4a6b
ME3600-BR-01#SHOW IP OSpf
Routing Process "ospf 20" with ID 172.16.250.16
Start time: 2y51w, Time elapsed: 7w0d
Supports only single TOS(TOS0) routes
Supports opaque LSA
Supports Link-local Signaling (LLS)
Supports area transit capability
Router is not originating router-LSAs with maximum metric
Initial SPF schedule delay 5000 msecs
Minimum hold time between two consecutive SPFs 10000 msecs
Maximum wait time between two consecutive SPFs 10000 msecs
Incremental-SPF disabled
Minimum LSA interval 5 secs
Minimum LSA arrival 1000 msecs
LSA group pacing timer 240 secs
Interface flood pacing timer 33 msecs
Retransmission pacing timer 66 msecs
Number of external LSA 0. Checksum Sum 0x000000
Number of opaque AS LSA 0. Checksum Sum 0x000000
Number of DCbitless external and opaque AS LSA 0
Number of DoNotAge external and opaque AS LSA 0
Number of areas in this router is 1. 1 normal 0 stub 0 nssa
Number of areas transit capable is 0
External flood list length 0
IETF NSF helper support enabled
Cisco NSF helper support enabled
Reference bandwidth unit is 10000 mbps
Area BACKBONE(0)
Number of interfaces in this area is 4 (1 loopback)
Area has message digest authentication
SPF algorithm last executed 00:00:04.569 ago
SPF algorithm executed 82880 times
Area ranges are
Number of LSA 126. Checksum Sum 0x3A40EF
Number of opaque link LSA 0. Checksum Sum 0x000000
Number of DCbitless LSA 45
Number of indication LSA 0
Number of DoNotAge LSA 0
Flood list length 0