I was testing mutual redistribution between EIGRP and OSPF, under eigrp process without
"default-metric" statement, mutual redistribution doesnt work.
router eigrp 1
redistribute ospf 4
network 192.168.1.20 0.0.0.3
default-metric 100000 1000 255 1 1500
router ospf 4
redistribute eigrp 1 subnets
network 10.10.10.1 0.0.0.0 area 0
Is "default-metric" statement a must.
your understanding is correct for EIGRP to be able to import routes from another dynamic routing protocol a seed metric has to be set with default metric command.
This is actually one of first checks in troubleshooting redistribution into EIGRP.
the reason is that EIGRP composite metric cannot be compared to the metric of the source protocol, the seed metric provides values for bandwidth, delay and other parameters.
OSPF is a special case it has default seed metrics.
Hope to help