Reference Guide

By default, FTOS implements an enhanced flooding procedure which dynamically and intelligently detects when to
optimize flooding. Wherever possible, the OSPF task attempts to reduce flooding overhead by selectively flooding on a
subset of the interfaces between two routers.
Enabling RFC-2328 Compliant OSPF Flooding
To enable OSPF flooding, use the following command.
When you enable this command, it configures FTOS to flood LSAs on all interfaces.
• Enable RFC 2328 flooding.
ROUTER OSPF mode
flood-2328
To confirm RFC 2328 flooding behavior, use the debug ip ospf packet command. The following example shows
no change in the updated packets (shown in bold).
ACKs 2 (shown in bold) is printed only for ACK packets.
Example of Viewing the Debug Log for Flooding Behavior
00:10:41 : OSPF(1000:00):
Rcv. v:2 t:5(LSAck) l:64 Acks 2 rid:2.2.2.2
aid:1500 chk:0xdbee aut:0 auk: keyid:0 from:Vl 1000
LSType:Type-5 AS External id:160.1.1.0 adv:6.1.0.0 seq:0x8000000c
LSType:Type-5 AS External id:160.1.2.0 adv:6.1.0.0 seq:0x8000000c
00:10:41 : OSPF(1000:00):
Rcv. v:2 t:5(LSAck) l:64 Acks 2 rid:2.2.2.2
aid:1500 chk:0xdbee aut:0 auk: keyid:0 from:Vl 100
LSType:Type-5 AS External id:160.1.1.0 adv:6.1.0.0 seq:0x8000000c
LSType:Type-5 AS External id:160.1.2.0 adv:6.1.0.0 seq:0x8000000c
00:10:41 : OSPF(1000:00):
Rcv. v:2 t:4(LSUpd) l:100 rid:6.1.0.0
aid:0 chk:0xccbd aut:0 auk: keyid:0 from:Gi 10/21
Number of LSA:2
LSType:Type-5 AS External(5) Age:1 Seq:0x8000000c id:170.1.1.0 Adv:6.1.0.0
Netmask:255.255.255.0 fwd:0.0.0.0 E2, tos:0 metric:0
LSType:Type-5 AS External(5) Age:1 Seq:0x8000000c id:170.1.2.0 Adv:6.1.0.0
Netmask:255.255.255.0 fwd:0.0.0.0 E2, tos:0 metric:0
To confirm that you enabled RFC-2328–compliant OSPF flooding, use the show ip ospf command.
Example of Verifying that RFC-2328–Compliant OSPF Flooding is Enabled
FTOS#show ip ospf
Routing Process ospf 1 with ID 2.2.2.2
Supports only single TOS (TOS0) routes
It is an Autonomous System Boundary Router
It is Flooding according to RFC 2328
SPF schedule delay 5 secs, Hold time between two SPFs 10 secs
Number of area in this router is 1, normal 0 stub 0 nssa 1
--More--
OSPF ACK Packing
The OSPF ACK packing feature bundles multiple LS acknowledgements in a single packet, significantly reducing the
number of ACK packets transmitted when the number of LSAs increases.
This feature also enhances network utilization and reduces the number of small ACK packets sent to a neighboring
router. OSPF ACK packing is enabled by default and non-configurable.
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