OSPF - what happens when graceful restart occurs
9271
Created On 03/23/19 15:10 PM - Last Modified 03/25/19 10:42 AM
Question
What happens if an OSPF graceful restart is triggered on a firewall in the BDR role
Environment
-OSPF
-BDR role
Answer
Restarting the routing service will trigger a graceful restart:
>debug routing restart >debug software restart routed
105 16:13:06.398383 192.168.10.3 224.0.0.5 OSPF 106 LS Update Frame 105: 106 bytes on wire (848 bits), 106 bytes captured (848 bits) Ethernet II, Src: Vmware_9b:75:1b (00:50:56:9b:75:1b), Dst: IPv4mcast_05 (01:00:5e:00:00:05) Internet Protocol Version 4, Src: 192.168.10.3, Dst: 224.0.0.5 Open Shortest Path First OSPF Header Version: 2 Message Type: LS Update (4) Packet Length: 72 Source OSPF Router: 192.168.10.3 Area ID: 0.0.0.5 Checksum: 0x76be [correct] Auth Type: Null (0) Auth Data (none): 0000000000000000 LS Update Packet Number of LSAs: 1 LSA-type 9 (Opaque LSA, Link-local scope), len 44 .000 0000 0000 0000 = LS Age (seconds): 0 0... .... .... .... = Do Not Age Flag: 0 Options: 0x02, (E) External Routing 0... .... = DN: Not set .0.. .... = O: Not set ..0. .... = (DC) Demand Circuits: Not supported ...0 .... = (L) LLS Data block: Not Present .... 0... = (N) NSSA: Not supported .... .0.. = (MC) Multicast: Not capable .... ..1. = (E) External Routing: Capable .... ...0 = (MT) Multi-Topology Routing: No LS Type: Opaque LSA, Link-local scope (9) Link State ID Opaque Type: grace-LSA (3) Link State ID Opaque ID: 0 Advertising Router: 192.168.10.3 Sequence Number: 0x80000001 Checksum: 0xa12e Length: 44 Grace Period: 120 seconds. <<<<<<<<<<<<<<<<<<<<<< TLV Type: grace-LSA Grace Period (1) TLV Length: 4 Grace Period: 120 seconds Restart Reason: Unknown (0) Restart IP: 192.168.10.3
There are two possible outcomes:
1. if the process is able to complete the reload within the allotted grace time (120 seconds), the Firewall's role as a BDR is maintained.
2. if the process takes longer than 120 seconds, the firewall will take the new role as a DROTHER
246 16:14:36.368084 192.168.10.3 224.0.0.5 OSPF 86 Hello Packet Frame 246: 86 bytes on wire (688 bits), 86 bytes captured (688 bits) Ethernet II, Src: Vmware_9b:75:1b (00:50:56:9b:75:1b), Dst: IPv4mcast_05 (01:00:5e:00:00:05) Internet Protocol Version 4, Src: 192.168.10.3, Dst: 224.0.0.5 Open Shortest Path First OSPF Header OSPF Hello Packet Network Mask: 255.255.255.0 Hello Interval [sec]: 10 Options: 0x02, (E) External Routing 0... .... = DN: Not set .0.. .... = O: Not set ..0. .... = (DC) Demand Circuits: Not supported ...0 .... = (L) LLS Data block: Not Present .... 0... = (N) NSSA: Not supported .... .0.. = (MC) Multicast: Not capable .... ..1. = (E) External Routing: Capable .... ...0 = (MT) Multi-Topology Routing: No Router Priority: 1 Router Dead Interval [sec]: 40 Designated Router: 192.168.10.1 Backup Designated Router: 192.168.10.2. <<<<<<<<<<<<< changed from 192.168.10.3 Active Neighbor: 192.168.10.1 Active Neighbor: 192.168.10.2