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Very confused with BGP?

2020-09-28 17_38_24-S-TEST1 - s-test1 - Remote Desktop Connection.png

 

Using the above topology, I have ebgp running between edge1 and edge2 with isp1 and isp2, and ibgp running between the two edge routers and core routers.  I had this up and working before but I'm studying for the CCNP so I decided to tear it down and redo it for practice.

 

An odd thing, the routing tables on core 1 and 2 have bgp routes for the ISP subnets.  This wasn't the case when I did this before, and it required me to run the "next-hop-self" command on the edge routers so that the core routers could ping the ISP subnets.  According to my study material, these routes shouldn't be in the routing tables on core 1 and core 2.  Core 1 and core 2 should not know what the next hops are without the "next-hop-self" commands on the 2 edge routers.  I'm very confused.

 

The edge and core routers are peering ibgp with loopbacks on the 10.5.5.0/24 net.

 

ISP1:

ISP1#sh run | s bgp
router bgp 65111
 bgp log-neighbor-changes
 no bgp default ipv4-unicast
 neighbor 4.2.2.2 remote-as 65222
 neighbor 172.16.0.2 remote-as 65000
 !
 address-family ipv4
  network 4.2.2.0 mask 255.255.255.252
  network 172.16.1.0 mask 255.255.255.0
  network 172.16.2.0 mask 255.255.255.0
  network 172.16.3.0 mask 255.255.255.0
  network 172.16.4.0 mask 255.255.255.0
  neighbor 4.2.2.2 activate
  neighbor 172.16.0.2 activate
 exit-address-family

ISP1#sh ip ro
Gateway of last resort is not set

      4.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C        4.2.2.0/30 is directly connected, GigabitEthernet2/0
L        4.2.2.1/32 is directly connected, GigabitEthernet2/0
      10.0.0.0/24 is subnetted, 4 subnets
B        10.0.1.0 [20/0] via 4.2.2.2, 00:17:53
B        10.0.2.0 [20/0] via 4.2.2.2, 00:17:53
B        10.0.3.0 [20/0] via 4.2.2.2, 00:17:53
B        10.0.4.0 [20/0] via 4.2.2.2, 00:17:53
      172.16.0.0/16 is variably subnetted, 10 subnets, 3 masks
C        172.16.0.0/30 is directly connected, GigabitEthernet1/0
L        172.16.0.1/32 is directly connected, GigabitEthernet1/0
C        172.16.1.0/24 is directly connected, Loopback1
L        172.16.1.1/32 is directly connected, Loopback1
C        172.16.2.0/24 is directly connected, Loopback2
L        172.16.2.1/32 is directly connected, Loopback2
C        172.16.3.0/24 is directly connected, Loopback3
L        172.16.3.1/32 is directly connected, Loopback3
C        172.16.4.0/24 is directly connected, Loopback4
L        172.16.4.1/32 is directly connected, Loopback4

ISP2:

ISP2#sh run | s bgp
router bgp 65222
 bgp log-neighbor-changes
 no bgp default ipv4-unicast
 neighbor 4.2.2.1 remote-as 65111
 neighbor 10.0.0.2 remote-as 65000
 neighbor 10.0.0.6 remote-as 65000
 !
 address-family ipv4
  network 4.2.2.0 mask 255.255.255.252
  network 10.0.1.0 mask 255.255.255.0
  network 10.0.2.0 mask 255.255.255.0
  network 10.0.3.0 mask 255.255.255.0
  network 10.0.4.0 mask 255.255.255.0
  neighbor 4.2.2.1 activate
  neighbor 10.0.0.2 activate
  neighbor 10.0.0.6 activate
 exit-address-family
ISP2#
ISP2#sh ip ro
Gateway of last resort is not set

      4.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C        4.2.2.0/30 is directly connected, GigabitEthernet3/0
L        4.2.2.2/32 is directly connected, GigabitEthernet3/0
      10.0.0.0/8 is variably subnetted, 12 subnets, 3 masks
C        10.0.0.0/30 is directly connected, GigabitEthernet1/0
L        10.0.0.1/32 is directly connected, GigabitEthernet1/0
C        10.0.0.4/30 is directly connected, GigabitEthernet2/0
L        10.0.0.5/32 is directly connected, GigabitEthernet2/0
C        10.0.1.0/24 is directly connected, Loopback1
L        10.0.1.1/32 is directly connected, Loopback1
C        10.0.2.0/24 is directly connected, Loopback2
L        10.0.2.1/32 is directly connected, Loopback2
C        10.0.3.0/24 is directly connected, Loopback3
L        10.0.3.1/32 is directly connected, Loopback3
C        10.0.4.0/24 is directly connected, Loopback4
L        10.0.4.1/32 is directly connected, Loopback4
      172.16.0.0/24 is subnetted, 4 subnets
B        172.16.1.0 [20/0] via 4.2.2.1, 00:16:11
B        172.16.2.0 [20/0] via 4.2.2.1, 00:16:11
B        172.16.3.0 [20/0] via 4.2.2.1, 00:16:11
B        172.16.4.0 [20/0] via 4.2.2.1, 00:16:11

EDGE1:

EDGE1#sh run | s bgp
router bgp 65000
 bgp log-neighbor-changes
 no bgp default ipv4-unicast
 neighbor AS65000 peer-group
 neighbor AS65000 remote-as 65000
 neighbor AS65000 update-source Loopback1
 neighbor 10.0.0.1 remote-as 65222
 neighbor 10.5.5.2 peer-group AS65000
 neighbor 10.5.5.3 peer-group AS65000
 neighbor 10.5.5.4 peer-group AS65000
 neighbor 172.16.0.1 remote-as 65111
 !
 address-family ipv4
  aggregate-address 192.168.0.0 255.255.0.0
  neighbor 10.0.0.1 activate
  neighbor 10.0.0.1 route-map ISP2-FILTER out
  neighbor 10.5.5.2 activate
  neighbor 10.5.5.3 activate
  neighbor 10.5.5.4 activate
  neighbor 172.16.0.1 activate
  auto-summary
 exit-address-family
EDGE1#
EDGE1#sh ip ro
Gateway of last resort is not set

      4.0.0.0/30 is subnetted, 1 subnets
B        4.2.2.0 [20/0] via 172.16.0.1, 00:18:08
      10.0.0.0/8 is variably subnetted, 11 subnets, 3 masks
C        10.0.0.0/30 is directly connected, GigabitEthernet2/0
L        10.0.0.2/32 is directly connected, GigabitEthernet2/0
B        10.0.1.0/24 [20/0] via 10.0.0.1, 00:17:49
B        10.0.2.0/24 [20/0] via 10.0.0.1, 00:17:49
B        10.0.3.0/24 [20/0] via 10.0.0.1, 00:17:49
B        10.0.4.0/24 [20/0] via 10.0.0.1, 00:17:49
C        10.5.5.0/24 is directly connected, Loopback1
L        10.5.5.1/32 is directly connected, Loopback1
O        10.5.5.2/32 [110/2] via 192.168.0.19, 02:07:34, GigabitEthernet4/0
O        10.5.5.3/32 [110/2] via 192.168.0.2, 02:05:46, GigabitEthernet3/0
O        10.5.5.4/32 [110/3] via 192.168.0.19, 00:19:14, GigabitEthernet4/0
                     [110/3] via 192.168.0.2, 02:03:36, GigabitEthernet3/0
      172.16.0.0/16 is variably subnetted, 6 subnets, 3 masks
C        172.16.0.0/30 is directly connected, GigabitEthernet1/0
L        172.16.0.2/32 is directly connected, GigabitEthernet1/0
B        172.16.1.0/24 [20/0] via 172.16.0.1, 00:44:35
B        172.16.2.0/24 [20/0] via 172.16.0.1, 00:44:35
B        172.16.3.0/24 [20/0] via 172.16.0.1, 00:44:35
B        172.16.4.0/24 [20/0] via 172.16.0.1, 00:44:35
      192.168.0.0/24 is variably subnetted, 6 subnets, 3 masks
C        192.168.0.0/30 is directly connected, GigabitEthernet3/0
L        192.168.0.1/32 is directly connected, GigabitEthernet3/0
O        192.168.0.4/30 [110/2] via 192.168.0.2, 00:23:45, GigabitEthernet3/0
O        192.168.0.8/30 [110/2] via 192.168.0.19, 00:19:14, GigabitEthernet4/0
C        192.168.0.16/29 is directly connected, GigabitEthernet4/0
L        192.168.0.18/32 is directly connected, GigabitEthernet4/0
O     192.168.1.0/24 [110/2] via 192.168.0.2, 02:05:46, GigabitEthernet3/0
O     192.168.2.0/24 [110/3] via 192.168.0.19, 00:19:14, GigabitEthernet4/0
                     [110/3] via 192.168.0.2, 02:03:36, GigabitEthernet3/0

EDGE2:

EDGE2#sh run | s bgp
router bgp 65000
 bgp log-neighbor-changes
 no bgp default ipv4-unicast
 neighbor AS65000 peer-group
 neighbor AS65000 remote-as 65000
 neighbor AS65000 update-source Loopback1
 neighbor 10.0.0.5 remote-as 65222
 neighbor 10.5.5.1 peer-group AS65000
 neighbor 10.5.5.3 peer-group AS65000
 neighbor 10.5.5.4 peer-group AS65000
 !
 address-family ipv4
  aggregate-address 192.168.0.0 255.255.0.0
  neighbor 10.0.0.5 activate
  neighbor 10.5.5.1 activate
  neighbor 10.5.5.3 activate
  neighbor 10.5.5.4 activate
  auto-summary
 exit-address-family
EDGE2#
EDGE2#sh ip ro
Gateway of last resort is not set

      4.0.0.0/30 is subnetted, 1 subnets
B        4.2.2.0 [20/0] via 10.0.0.5, 00:20:16
      10.0.0.0/8 is variably subnetted, 11 subnets, 3 masks
C        10.0.0.4/30 is directly connected, GigabitEthernet1/0
L        10.0.0.6/32 is directly connected, GigabitEthernet1/0
B        10.0.1.0/24 [20/0] via 10.0.0.5, 00:20:16
B        10.0.2.0/24 [20/0] via 10.0.0.5, 00:20:16
B        10.0.3.0/24 [20/0] via 10.0.0.5, 00:20:16
B        10.0.4.0/24 [20/0] via 10.0.0.5, 00:20:16
C        10.5.5.0/24 is directly connected, Loopback1
O        10.5.5.1/32 [110/2] via 192.168.0.18, 02:04:56, GigabitEthernet2/0
L        10.5.5.2/32 is directly connected, Loopback1
O        10.5.5.3/32 [110/3] via 192.168.0.18, 02:02:59, GigabitEthernet2/0
                     [110/3] via 192.168.0.10, 00:21:42, GigabitEthernet3/0
O        10.5.5.4/32 [110/2] via 192.168.0.10, 00:21:42, GigabitEthernet3/0
      172.16.0.0/24 is subnetted, 4 subnets
B        172.16.1.0 [20/0] via 10.0.0.5, 00:20:16
B        172.16.2.0 [20/0] via 10.0.0.5, 00:20:16
B        172.16.3.0 [20/0] via 10.0.0.5, 00:20:16
B        172.16.4.0 [20/0] via 10.0.0.5, 00:20:16
      192.168.0.0/24 is variably subnetted, 6 subnets, 3 masks
O        192.168.0.0/30 [110/2] via 192.168.0.18, 02:03:09, GigabitEthernet2/0
O        192.168.0.4/30 [110/2] via 192.168.0.10, 00:21:42, GigabitEthernet3/0
C        192.168.0.8/30 is directly connected, GigabitEthernet3/0
L        192.168.0.9/32 is directly connected, GigabitEthernet3/0
C        192.168.0.16/29 is directly connected, GigabitEthernet2/0
L        192.168.0.19/32 is directly connected, GigabitEthernet2/0
O     192.168.1.0/24 [110/3] via 192.168.0.18, 02:02:59, GigabitEthernet2/0
                     [110/3] via 192.168.0.10, 00:21:42, GigabitEthernet3/0
O     192.168.2.0/24 [110/2] via 192.168.0.10, 00:21:42, GigabitEthernet3/0

CORE1:

CORE1#sh run | s bgp
router bgp 65000
 bgp log-neighbor-changes
 no bgp default ipv4-unicast
 neighbor AS65000 peer-group
 neighbor AS65000 remote-as 65000
 neighbor AS65000 update-source Loopback1
 neighbor 10.5.5.1 peer-group AS65000
 neighbor 10.5.5.2 peer-group AS65000
 neighbor 10.5.5.4 peer-group AS65000
 !
 address-family ipv4
  neighbor 10.5.5.1 activate
  neighbor 10.5.5.2 activate
  neighbor 10.5.5.4 activate
 exit-address-family
CORE1#
CORE1#sh ip ro
Gateway of last resort is 192.168.0.17 to network 0.0.0.0

S*    0.0.0.0/0 [1/0] via 192.168.0.17
      4.0.0.0/30 is subnetted, 1 subnets
B        4.2.2.0 [200/0] via 172.16.0.1, 00:10:45
      10.0.0.0/8 is variably subnetted, 9 subnets, 2 masks
B        10.0.1.0/24 [200/0] via 10.0.0.1, 00:10:45
B        10.0.2.0/24 [200/0] via 10.0.0.1, 00:10:45
B        10.0.3.0/24 [200/0] via 10.0.0.1, 00:10:45
B        10.0.4.0/24 [200/0] via 10.0.0.1, 00:10:45
C        10.5.5.0/24 is directly connected, Loopback1
O        10.5.5.1/32 [110/2] via 192.168.0.1, 01:46:23, GigabitEthernet1/0
O        10.5.5.2/32 [110/3] via 192.168.0.6, 00:24:14, GigabitEthernet2/0
                     [110/3] via 192.168.0.1, 01:46:23, GigabitEthernet1/0
L        10.5.5.3/32 is directly connected, Loopback1
O        10.5.5.4/32 [110/2] via 192.168.0.6, 01:44:12, GigabitEthernet2/0
      172.16.0.0/24 is subnetted, 4 subnets
B        172.16.1.0 [200/0] via 172.16.0.1, 00:10:45
B        172.16.2.0 [200/0] via 172.16.0.1, 00:10:45
B        172.16.3.0 [200/0] via 172.16.0.1, 00:10:45
B        172.16.4.0 [200/0] via 172.16.0.1, 00:10:45
      192.168.0.0/24 is variably subnetted, 6 subnets, 3 masks
C        192.168.0.0/30 is directly connected, GigabitEthernet1/0
L        192.168.0.2/32 is directly connected, GigabitEthernet1/0
C        192.168.0.4/30 is directly connected, GigabitEthernet2/0
L        192.168.0.5/32 is directly connected, GigabitEthernet2/0
O        192.168.0.8/30 [110/2] via 192.168.0.6, 00:42:46, GigabitEthernet2/0
O        192.168.0.16/29 [110/2] via 192.168.0.1, 00:42:46, GigabitEthernet1/0
      192.168.1.0/24 is variably subnetted, 2 subnets, 2 masks
C        192.168.1.0/24 is directly connected, GigabitEthernet3/0
L        192.168.1.1/32 is directly connected, GigabitEthernet3/0
O     192.168.2.0/24 [110/2] via 192.168.0.6, 01:44:12, GigabitEthernet2/0

CORE2:

CORE2#sh run | s bgp
router bgp 65000
 bgp log-neighbor-changes
 no bgp default ipv4-unicast
 neighbor AS65000 peer-group
 neighbor AS65000 remote-as 65000
 neighbor AS65000 update-source Loopback1
 neighbor 10.5.5.1 peer-group AS65000
 neighbor 10.5.5.2 peer-group AS65000
 neighbor 10.5.5.3 peer-group AS65000
 !
 address-family ipv4
  neighbor 10.5.5.1 activate
  neighbor 10.5.5.2 activate
  neighbor 10.5.5.3 activate
 exit-address-family
CORE2#
CORE2#sh ip ro
Gateway of last resort is 192.168.0.17 to network 0.0.0.0

S*    0.0.0.0/0 [1/0] via 192.168.0.17
      4.0.0.0/30 is subnetted, 1 subnets
B        4.2.2.0 [200/0] via 172.16.0.1, 00:11:39
      10.0.0.0/8 is variably subnetted, 9 subnets, 2 masks
B        10.0.1.0/24 [200/0] via 10.0.0.1, 00:11:39
B        10.0.2.0/24 [200/0] via 10.0.0.1, 00:11:39
B        10.0.3.0/24 [200/0] via 10.0.0.1, 00:11:39
B        10.0.4.0/24 [200/0] via 10.0.0.1, 00:11:39
C        10.5.5.0/24 is directly connected, Loopback1
O        10.5.5.1/32 [110/3] via 192.168.0.9, 00:25:04, GigabitEthernet1/0
                     [110/3] via 192.168.0.5, 01:38:03, GigabitEthernet2/0
O        10.5.5.2/32 [110/2] via 192.168.0.9, 00:25:04, GigabitEthernet1/0
O        10.5.5.3/32 [110/2] via 192.168.0.5, 01:38:03, GigabitEthernet2/0
L        10.5.5.4/32 is directly connected, Loopback1
      172.16.0.0/24 is subnetted, 4 subnets
B        172.16.1.0 [200/0] via 172.16.0.1, 00:11:39
B        172.16.2.0 [200/0] via 172.16.0.1, 00:11:39
B        172.16.3.0 [200/0] via 172.16.0.1, 00:11:39
B        172.16.4.0 [200/0] via 172.16.0.1, 00:11:39
      192.168.0.0/24 is variably subnetted, 6 subnets, 3 masks
O        192.168.0.0/30 [110/2] via 192.168.0.5, 01:38:03, GigabitEthernet2/0
C        192.168.0.4/30 is directly connected, GigabitEthernet2/0
L        192.168.0.6/32 is directly connected, GigabitEthernet2/0
C        192.168.0.8/30 is directly connected, GigabitEthernet1/0
L        192.168.0.10/32 is directly connected, GigabitEthernet1/0
O        192.168.0.16/29 [110/2] via 192.168.0.9, 00:25:04, GigabitEthernet1/0
O     192.168.1.0/24 [110/2] via 192.168.0.5, 01:38:03, GigabitEthernet2/0
      192.168.2.0/24 is variably subnetted, 2 subnets, 2 masks
C        192.168.2.0/24 is directly connected, GigabitEthernet3/0
L        192.168.2.1/32 is directly connected, GigabitEthernet3/0

Also I'm not sure why the aggregate address command isn't advertising the 192.168.0.0/24 network to the ISP?

 

Any guidance would be appreciated.  Note that ISP networks in the routing tables have an admin distance of 200...it almost seems like it's converting those to iBGP without the need for the "next-hop-self" command?

1 Accepted Solution

Accepted Solutions

Yes, because if you don't have a specific route to next hop for iBGP route then you will use default route and your default route actually allows you to reach routers that have a route to these next hop that you don't know how to reach directly on core 1 and 2.

 

Just try, remove default route, by doing and trying different approaches you will learn a lot and understand how this works.

View solution in original post

13 Replies 13

The aggrate will make new route depend on if the original route is appear or not.

This new route will be handle as you config netwrok command under bgp BUT the different is the path, this new route have path for all original route.

kubn2
Level 1
Level 1

Ok first things first in the config on ISP1 and ISP2 i see you defined them as a neighbors but on the graph I don't see 4.2.2. network that should connect them.

 

According to my study material, these routes shouldn't be in the routing tables on core 1 and core 2.  Core 1 and core 2 should not know what the next hops are without the "next-hop-self" commands on the 2 edge routers. 

Why? Edge1 and Edge2 have eBGP peering with isps and eBGP routes by default are advertised to iBGP peers

 

In regards to no route to 192.168. network you don't have it in ISP because BGP doesn't know this network. You should add BGP network statement on Core1 and Core 2 to allow BGP to redistribute this network. If you don't want to do this you should perform redistribution from ospf and connected to BGP on Edge 1 and Edge 2.

Ok first things first in the config on ISP1 and ISP2 i see you defined them as a neighbors but on the graph I don't see 4.2.2. network that should connect them.

 

Yeah old screen shot from when I first built the topology.  I hadded the 4.2.2.2 link later.  Sorry

 

Why? Edge1 and Edge2 have eBGP peering with isps and eBGP routes by default are advertised to iBGP peers

 

I built this by following a CCNP ITProTV video.  In the video, he had to add the "next-hop-self" command, and so did I the first time I configured this.  It's the same exact topology as what is in the video.  In the video, he had routes in the RIB, but none of them were in the routing table.  They weren't in the routing table because they weren't considered the "best routes".  The reason was because of the way BGP replicates the next hop values.  

 

BGP only cares about AS to AS communication.  When it publishes an eBGP route it basically says "You can get to this route through this other AS by going to this next hop" which is an IP in another autonomous system.  In the video for example, the Core2 router didn't have a way to get to 172.16.0.1...so the routes were advertised and in the RIB, but they didn't make it into the routing table because the "next hop" wasn't reachable from Core2.

 

He fixed this by using the "next-hop-self" command....and I definitely had to do the same thing the first time I configured this before I tore it down and decided to do it again....so I'm curious why I didn't have to this time.  

Ok and that is true BUT you know how to reach these next hops in other networks. You can reach team because you have static default route towards Edge1 or Edge2:

 

S*    0.0.0.0/0 [1/0] via 192.168.0.17

and due to ospf you know how to reach your default route:

O        192.168.0.16/29 [110/2] via 192.168.0.9, 00:25:04, GigabitEthernet1/0

So if core1 want to go to for example to 172.16.2.0 he will want to forward packet to 172.16.0.1 but he doesn't have a destination for that so he will forward it using default gateway so towards 192.168.0.17 and Core1 know how to reach it thanks to OSPF he knows that he should use G1/0 and 192.168.0.9 to reach his default gateway. Now you are on Edge2 and this device in RIB have all the routes how to reach all the ISP subnets with next hops that are also reachable for him so thats why it's working.

 

If you want these BGP routes to disappear from Cores just remove default route.

 

P.S You don't have to solve this issue by adding next-hop you can also just put network statement in BGP for up links so: network 172.16.0.0 mask 255.255.255.0 or redistribute connected on Edges because after that Cores will know from BGP what is the next hop for 172.16.0.1.

Hello
 the routing tables on core 1 and 2 have bgp routes for the ISP subnets.  This wasn't the case when I did this before  Core 1 and core 2 should not know what the next hops are without the "next-hop-self" commands on the 2 edge routers.  I'm very confused.
without the need for the "next-hop-self" command?

Not sure how you had the configuration previous however the below should negate the isp prefixes from the ibgp peers and set edge 1 as the preference egress path for the ibgp rtrs via a conditional default routes from either edge rtr
Lastly you will need to advertised the ibgp subnets to the isps for NLRI.

 

Edge1
access-list 10 permit 172.16.1.0 0.0.0.255
route-map con-default
match ip address xxx

router bgp 65000
bgp default local-preference 200
neighbor AS65000 default-originate route-map con-default


Edge2
access-list 10 permit 10.0.1.0 0.0.0.255
route-map con-default
match ip address xxx

router bgp 65000
bgp default local-preference 100
neighbor AS65000 default-originate route-map con-default

 

core1/2
ip prefix-list noebgp  permit 0.0.0.0/0
route-map default
match ip address prefix-list noebgp

router bgp 65000
neighbor AS6500 route-map default in


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Kind Regards
Paul

There is HSRP between edge 1 and edge 2 of 192.168.0.17 with a track object as well.  I'm not trying to make traffic always take one path, it's just for redundancy. 

 

I'm more curious why I needed the "next-hop-self" command the first time, and why the guy needed to do it in the video, and now I don't.  I basically built the config while watching the video and it's bothering me that it's not the same as what's in the video nor is it the same as how I had to do it the first time.  

If you want these BGP routes to disappear from Cores just remove default route.

 

This is confusing to me.  You're saying the routes are showing in BGP with an admin distance of 200 (iBGP) because Core1 and Core2 have default routes to 192.168.0.17?

Yes, because if you don't have a specific route to next hop for iBGP route then you will use default route and your default route actually allows you to reach routers that have a route to these next hop that you don't know how to reach directly on core 1 and 2.

 

Just try, remove default route, by doing and trying different approaches you will learn a lot and understand how this works.

.....

I thought I read somewhere that the aggregate-address command would advertise the route itself.  So it doesn't and I still need a network statement?

So why isn't the below working?

 

Edge1:

 

Edge1#sh run | s bgp
router bgp 65000
 bgp log-neighbor-changes
 no bgp default ipv4-unicast
 neighbor AS65000 peer-group
 neighbor AS65000 remote-as 65000
 neighbor AS65000 update-source Loopback1
 neighbor 10.0.0.1 remote-as 65222
 neighbor 10.5.5.2 peer-group AS65000
 neighbor 10.5.5.3 peer-group AS65000
 neighbor 10.5.5.4 peer-group AS65000
 neighbor 172.16.0.1 remote-as 65111
 !
 address-family ipv4
  network 192.168.0.0 mask 255.255.0.0
  aggregate-address 192.168.0.0 255.255.0.0
  neighbor 10.0.0.1 activate
  neighbor 10.5.5.2 activate
  neighbor 10.5.5.3 activate
  neighbor 10.5.5.4 activate
  neighbor 172.16.0.1 activate
  auto-summary
 exit-address-family

With this configuration, ISP1 isn't getting any of the 192.168 routes.  

 

ISP1#sh ip bgp     
BGP table version is 9, local router ID is 172.16.4.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, 
              r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter, 
              x best-external, a additional-path, c RIB-compressed, 
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

     Network          Next Hop            Metric LocPrf Weight Path
 *   10.0.1.0/24      172.16.0.2                             0 65000 65222 i
 *>                   4.2.2.2                  0             0 65222 i
 *   10.0.2.0/24      172.16.0.2                             0 65000 65222 i
 *>                   4.2.2.2                  0             0 65222 i
 *   10.0.3.0/24      172.16.0.2                             0 65000 65222 i
 *>                   4.2.2.2                  0             0 65222 i
 *   10.0.4.0/24      172.16.0.2                             0 65000 65222 i
 *>                   4.2.2.2                  0             0 65222 i
 *>  172.16.1.0/24    0.0.0.0                  0         32768 i
 *>  172.16.2.0/24    0.0.0.0                  0         32768 i
 *>  172.16.3.0/24    0.0.0.0                  0         32768 i
 *>  172.16.4.0/24    0.0.0.0                  0         32768 i

 

 

 

If I just do "network 192.168.0.0" and don't include a mask on Edge 1, then ISP1 suddenly gets routes?

 

EDGE1#sh run | s bgp
router bgp 65000
 bgp log-neighbor-changes
 no bgp default ipv4-unicast
 neighbor AS65000 peer-group
 neighbor AS65000 remote-as 65000
 neighbor AS65000 update-source Loopback1
 neighbor 10.0.0.1 remote-as 65222
 neighbor 10.5.5.2 peer-group AS65000
 neighbor 10.5.5.3 peer-group AS65000
 neighbor 10.5.5.4 peer-group AS65000
 neighbor 172.16.0.1 remote-as 65111
 !
 address-family ipv4
  network 192.168.0.0
  aggregate-address 192.168.0.0 255.255.0.0
  neighbor 10.0.0.1 activate
  neighbor 10.5.5.2 activate
  neighbor 10.5.5.3 activate
  neighbor 10.5.5.4 activate
  neighbor 172.16.0.1 activate
  auto-summary
 exit-address-family
ISP1#sh ip bgp
BGP table version is 11, local router ID is 172.16.4.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, 
              r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter, 
              x best-external, a additional-path, c RIB-compressed, 
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

     Network          Next Hop            Metric LocPrf Weight Path
 *   10.0.1.0/24      172.16.0.2                             0 65000 65222 i
 *>                   4.2.2.2                  0             0 65222 i
 *   10.0.2.0/24      172.16.0.2                             0 65000 65222 i
 *>                   4.2.2.2                  0             0 65222 i
 *   10.0.3.0/24      172.16.0.2                             0 65000 65222 i
 *>                   4.2.2.2                  0             0 65222 i
 *   10.0.4.0/24      172.16.0.2                             0 65000 65222 i
 *>                   4.2.2.2                  0             0 65222 i
 *>  172.16.1.0/24    0.0.0.0                  0         32768 i
 *>  172.16.2.0/24    0.0.0.0                  0         32768 i
 *>  172.16.3.0/24    0.0.0.0                  0         32768 i
 *>  172.16.4.0/24    0.0.0.0                  0         32768 i
 *   192.168.0.0      4.2.2.2                                0 65222 65000 i
 *>                   172.16.0.2               0             0 65000 i
 *   192.168.0.0/16   4.2.2.2                                0 65222 65000 i
 *>                   172.16.0.2               0             0 65000 i

So why does defining the mask in the network statement stop the routes from showing up on ISP1?

I'll start a new topic for the aggregate address things.  Thanks to all who replied.  

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