I was watching INE’s EIGRP videos and it put an idea in my head about how it might be possible to use FPM to prevent the EIGRP reply from making it back and therefore forcing things into a SIA state. Since I was bored today (terrible weather out) I did that very thing!
Here is the config I used to break stuff
Step 1: Load the IP.phdf
CSR01(config)#do copy ftp://10.10.2.11/ip.phdf flash: Destination filename [ip.phdf]? CSR01(config)#load protocol flash:ip.phdf
Step 2: Make a FPM class-map that matches the query reply
class-map type access-control match-all CM_EIGRP_REPLY match start l3-start offset 21 size 1 eq 4 match field IP protocol eq 88
Step 3: Make a FPM policy-map and drop the traffic then apply it to the relevant interface(s)
policy-map type access-control PM_DROP_EIGRP_REPLY class CM_EIGRP_REPLY drop interface g2.103 service-policy type access-control input PM_DROP_EIGRP_REPLY
Now if we kill my 126.96.36.199/32 route the reply will be filtered so SIA will be forced!
R02(config-subif)#do sh ip eigrp top 188.8.131.52/32 EIGRP-IPv4 VR(LAB) Topology Entry for AS(123)/ID(172.16.1.85) for 184.108.40.206/32 State is Passive, Query origin flag is 1, 1 Successor(s), FD is 163840 Descriptor Blocks: 0.0.0.0 (Loopback0), from Connected, Send flag is 0x0 Composite metric is (163840/0), route is Internal Vector metric: Minimum bandwidth is 8000000 Kbit Total delay is 1250000 picoseconds Reliability is 255/255 Load is 1/255 Minimum MTU is 1514 Hop count is 0 Originating router is 172.16.1.85 R02(config-subif)# int g0/1.102 R02(config-subif)#shut R02(config-subif)# *Apr 25 23:24:33.902: %DUAL-5-NBRCHANGE: EIGRP-IPv4 123: Neighbor 10.0.2.254 (GigabitEthernet0/1.102) is down: interface down CSR01#sh ip eigrp topology 220.127.116.11/32 EIGRP-IPv4 VR(LAB) Topology Entry for AS(123)/ID(172.16.1.74) for 18.104.22.168/32 State is Active, Query origin flag is 1, 0 Successor(s), FD is 1392640, RIB is 10880 Waiting for 1 replies Descriptor Blocks: 10.0.2.2 (GigabitEthernet2.102), from 10.0.2.2, Send flag is 0x0 Composite metric is (Infinity/Infinity), route is Internal Vector metric: Minimum bandwidth is 4294967295 Kbit Total delay is 281474976710655 picoseconds Reliability is 255/255 Load is 1/255 Minimum MTU is 1500 Hop count is 255 Originating router is 172.16.1.85