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'Connected subnets' doesn't redistribute a network. Why ?

I am getting redistribution EIGRP->ISIS just fine. However, I noticed the following. Can someone clarify:

RouterB(EIGRP 100)

s0:152.1.1.1/24

LO:1.1.1.1/24

connected V.35 to

S0/0:152.1.1.2/24

RouterA

e0/0:3.3.3.4/24

LO:4.4.4.4/24

(running ISIS and EIGRP 100)

connected to

ROuterC

e0/0:3.3.3.3/24

Lo0:2.2.2.2/24

(running ISIS)

Please find attached RouterA,B,C and respective show ip routes.

Then on RouterA, I redistribute EIGRP->ISIS. I do:

!

router isis

net 47.0002.0010.0100.1001.00

area-password pass

redistribute eigrp 100 metric 10 level-1-2

!

Then on routerC, I am able to see all related EIGRP advertised networks distributed

into ISIS - OK as shown in the 'ip route#1' pasted below, which is showing the route 152.1.0.0/16.

I notice that if I try to add the following onto the router isis configuration above:

'redistribute connected' then the router 152.1.0.0/16 is no longer redistributed into ISIS on RouterC. Can someone explain why ? Isn't the 'redistribute connected' a configuration to allow me see all related routes from the respective AS even if they were not advertised through the 'network' command ? Interesting, because the '152.1.0.0' network is advertised on the router EIGRP 100 in my RouterB.

'ip route#1

RouterC#show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is 3.3.3.4 to network 0.0.0.0

1.0.0.0/24 is subnetted, 1 subnets

i L1 1.1.1.0 [115/20] via 3.3.3.4, Ethernet0/0

i L1 152.1.0.0/16 [115/20] via 3.3.3.4, Ethernet0/0

2.0.0.0/24 is subnetted, 1 subnets

C 2.2.2.0 is directly connected, Loopback0

3.0.0.0/24 is subnetted, 1 subnets

C 3.3.3.0 is directly connected, Ethernet0/0

i*L1 0.0.0.0/0 [115/10] via 3.3.3.4, Ethernet0/0

Then with the 'redistribute connected' this the show ip route on RouterC. Note that the '152.1.0.0/16' network is no longer included.

show ip route

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route

Gateway of last resort is 3.3.3.4 to network 0.0.0.0

1.0.0.0/24 is subnetted, 1 subnets

i L1 1.1.1.0 [115/20] via 3.3.3.4, Ethernet0/0

2.0.0.0/24 is subnetted, 1 subnets

C 2.2.2.0 is directly connected, Loopback0

3.0.0.0/24 is subnetted, 1 subnets

C 3.3.3.0 is directly connected, Ethernet0/0

i*L1 0.0.0.0/0 [115/10] via 3.3.3.4, Ethernet0/0

2 REPLIES
Cisco Employee

Re: 'Connected subnets' doesn't redistribute a network. Why ?

You probably didn't specify which level you wanted the connected routes to be distributed in. By default redistributed routes are only injected in L2. This would explain why you are not seeing this route on RouterC since RouterC and RouterA have an L1 adjacency only.

To fix it, either change the redistribute command on RouterA as follow:

redistribute connected level-1

or

change the configuration on both RouterC and RouterA so the adjacency is formed as an L2 or L1/L2 instead of a L1 only.

Hope this helps,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México 
Paseo de la Reforma 222 Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
New Member

Re: 'Connected subnets' doesn't redistribute a network. Why ?

You nailed it. Thanks !

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