difference between redistribtuions

[Amafsha1]

Hello everyone.  I'm having a difficult time understanding what the difference between the set of commands between these 2 routers.  What's confusing is me how the redistribute command is being used under the router bgp process for DC2 wan router, but is not being used under DC1 router.  I understand that in DC1 wan router, everything is being redistributed into BGP from EIGRP including a default route....but I can't tell if the same is for DC2? 

---

DC2 WAN ROUTER#

router bgp 65425

 !

 address-family ipv4 

      redistribute eigrp 1

!

ip prefix-list eigrp-to-bgp seq 100 permit 0.0.0.0/0

!

route-map eigrp-to-bgp, permit, sequence 100 

Match clauses:

 ip address prefix-lists: eigrp-to-bgp 

Set clauses:

 Policy routing matches: 0 packets, 0 bytes

---

DC1-WAN-ROUTER

router bgp 65425 

! 

address-family ipv4

 redistribute eigrp 1 route-map eigrp-to-bgp 

!

ip prefix-list eigrp-to-bgp seq 100 permit 0.0.0.0/0 

ip prefix-list eigrp-to-bgp seq 320 permit 0.0.0.0/0 le 32 

! 

route-map eigrp-to-bgp, permit, sequence 100 

Match clauses: ip address prefix-lists: eigrp-to-bgp 

Set clauses:

 Policy routing matches: 0 packets, 0 bytes

[Warren Sullivan - Corp]

Hi Amafsha,

I would say that DC2 will redistribute all EIGRP routes and DC1 will only redistribute the 0.0.0.0/0....

[Amafsha1]

do you mean the other way around?

[Francesco Molino · Accepted solution]

Hi 

For DC2, you'll redistribute everything from eigrp to BGP. There's a prefix-list but not used here which means it's useless if not used anywhere else.

For DC1, you'll also redistribute everything based on a route-map calling a prefix.

The first statement of the prefix-list will match the default route. The second statement 0.0.0.0/0 le 32 will match anything. This is the prefix-list command to use when you want to take everything.

The final result of both is the same: redistribute all eigrp prefixes into bgp.

[Amafsha1]

Thank you.  That is correct, the route-map on dc2 is not applied to anything so it is useless I guess.  So in DC2 everything that's learned from EIGRP is being redistrubuted into BGP and that's because of the "redistribute eigrp 1" command under the bgp process correct? 

[Troy Jackson · Accepted solution]

The route map on DC1 is not required but it can be used to filter or change attributes. Based on the configs DC2 looks like it will redistribute all EIGRP learned routes. It also looks like DC1 will redistribute all EIGRP learned routes as well. The only thing I can see not redistributing is the default route. It will need a network statement under the BGP process to work. 

[Francesco Molino]

If the default route is learned within eigrp and installed in the RIB, redistribution will work.

[Amafsha1]

Thank you.  So you're saying that EIGRP is not advertising currently a default route to anything in BGP?

[Francesco Molino]

Nope, I'm saying everything is redistributed from eigrp to bgp.

[Amafsha1]

ok so to summarize to make sure I'm understanding this correctly.  Both of these DC1/2 are both redistrubiting everything from EIGRP to BGP including a default route because default route falls under 0.0.0.0/0 le 32.  So anything that's in the BGP domain will learn everything that EIGRP knows?

[Troy Jackson]

Yes, that is correct. You can verify this by looking at a few show commands like: 

-show ip route <X.X.X.X>

-show ip bgp 

-show ip bgp <X.X.X.X>

-show ip eigrp <X> topology  

[Francesco Molino]

Yes default route falls into 0.0.0.0/0 le 32. This means that first statement of prefix-list is useless here.