Task 4.11 Redist Loop Prevention

The SG says the answer to the question is to add "distance ospf ex 171" to R1 and R2, along with "distance 109" to the rip process on SW1.

Whilst this means that (for example), R5's loopback is now known by both R1 and R2 as a DEX route, the RIP routes from SW1 are messed up:

example:
(R1) D EX 30.2.0.0 [170/2560025856] via 152.1.125.2
(R2) O E2 30.2.0.0 [171/20] via 152.1.123.1

anyone?

Comments

  • Personally I only changed the AD on R1 and R2 for the EIGRP external routes learnt via R5 RIP process:

    router ospf 1
    router-id 150.1.1.1
    log-adjacency-changes
    area 123 virtual-link 150.1.3.3
    redistribute eigrp 10 subnets
    network 150.1.1.1 0.0.0.0 area 0
    network 152.1.123.1 0.0.0.0 area 123
    distance 200 0.0.0.0 255.255.255.255 EIGRP-EXTERNAL

    ip access-list standard EIGRP-EXTERNAL
    permit 54.1.10.0
    permit 150.1.4.0
    permit 152.1.5.0
    permit 152.1.4.0
    permit 150.1.10.0
    permit 152.1.45.4
    permit 152.1.45.0
    permit 212.18.2.0
    permit 212.18.3.0
    permit 212.18.0.0
    permit 212.18.1.0

    Before I redistributed on R1 and R2 I checked which routes I needed to changed the AD on through command:

    show ip route eigrp | inc EX

    and build the access-list from that output.
  • You need to change the RIP distance or SW1 sees the routes learnt from BB3 as OSPF external routes which it uses over the correct RIP routes. if you check the routing table on SW1, the next hop for all the BB3 subnets is R3.
    This is resolved by changing the AD
  • I changed the distance for external EIGRP routes to 109 on R1 and R2. Is this a valid solution?

    router eigrp 10
    redistribute ospf 1 metric 1 1 1 1 1
    network 152.1.125.1 0.0.0.0
    distance eigrp 90 109
    no auto-summary
  • Answer to my previous post. This is definitely wrong. OSPF routes
    are replaced by EIGRP external routes on R1/R2 and the reacheability to OSPF domain is broken.
  • we should add on R1 and R2 :
    distance 110 0.0.0.0 255.255.255.255 FromBB3
    with FromBB3 an access list permitting all subnets advertised by BB3
  • I just set the distance of ALL EX EIGRP ROUTES to 255 in R1 and R2 from one another:

    ip access-list standard DEX
    permit 212.18.0.0 0.0.3.255
    perm 152.1.4.0 0.0.1.255
    perm 152.1.45.0 0.0.0.255
    perm 150.1.4.0 0.0.0.255
    perm 150.1.2.0 0.0.0.255
    perm 150.1.10.0 0.0.0.255
    perm 54.1.10.0 0.0.0.255


    R1
    router ospf 1
    distance 255 150.1.2.2 0.0.0.0 DEX

    R2
    router ospf 1
    distance 255 150.1.1.1 0.0.0.0 DEX

    To me, this sounded more like what the task says "Ensure that EIGRP external routes that are redistributed into OSPF on R1 and R2 do not get redistributed back into EIGRP."

    No need to do anything in SW1.
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