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New Member

BGP with different AS in GNS3

Good day all,

I have a topology where im trying to configure a bgp with different AS number as per attached.

The problem now is, i can see the S_1 network in K_1 routing table, but i could not ping the S_1 router.

I've been checking in the past hour and could not find the issue.

Im thinking im missing somthing here.

Ignore S_2 and K_2 since i havent got S_1 and K_1 to work yet

Forgot to mention that this is testing using GNS3

K_1 routing table

K_1#sh 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 not set

     10.0.0.0/8 is variably subnetted, 5 subnets, 3 masks

C       10.20.1.0/30 is directly connected, FastEthernet0/0

B       10.8.40.0/24 [20/0] via 10.20.1.1, 00:02:49

C       10.8.53.0/24 is directly connected, FastEthernet0/1

B       10.8.100.40/32 [20/0] via 10.20.1.1, 00:02:49

C       10.8.100.53/32 is directly connected, Loopback0

K_1#

S_1 Routing Table

S_1#sh 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 not set

     10.0.0.0/8 is variably subnetted, 5 subnets, 3 masks

C       10.10.1.0/30 is directly connected, FastEthernet0/0

C       10.8.40.0/24 is directly connected, FastEthernet0/1

B       10.8.53.0/24 [20/0] via 10.10.1.1, 00:04:11

C       10.8.100.40/32 is directly connected, Loopback0

B       10.8.100.53/32 [20/0] via 10.10.1.1, 00:01:41

S_1#

S_1#ping  10.8.100.53 so lo0

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 10.8.100.53, timeout is 2 seconds:

Packet sent with a source address of 10.8.100.40

...

Success rate is 0 percent (0/3)

S_1#ping  10.8.100.53

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 10.8.100.53, timeout is 2 seconds:

.....

Success rate is 0 percent (0/5)

S_1#

Routing Table VRF TEST in PE_1

PE_1#sh ip route vrf TEST

Routing Table: TEST

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 not set

     10.0.0.0/8 is variably subnetted, 5 subnets, 3 masks

C       10.10.1.0/30 is directly connected, FastEthernet0/0

B       10.8.40.0/24 [20/0] via 10.10.1.2, 00:48:02

B       10.8.53.0/24 [200/0] via 10.2.2.1, 00:37:49

B       10.8.100.40/32 [20/0] via 10.10.1.2, 00:48:02

B       10.8.100.53/32 [200/0] via 10.2.2.1, 00:35:18

PE_1#

Routing Table VRF TEST in PE_2

PE_2#sh ip route VRF TEST

Routing Table: TEST

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 not set

     10.0.0.0/8 is variably subnetted, 5 subnets, 3 masks

C       10.20.1.0/30 is directly connected, FastEthernet0/0

B       10.8.40.0/24 [200/0] via 10.2.2.2, 00:48:47

B       10.8.53.0/24 [20/0] via 10.20.1.2, 00:38:49

B       10.8.100.40/32 [200/0] via 10.2.2.2, 00:48:47

B       10.8.100.53/32 [20/0] via 10.20.1.2, 00:36:14

PE_2#

1 ACCEPTED SOLUTION

Accepted Solutions
New Member

Re: BGP with different AS in GNS3

Each PE router won't understand the MPLS VPNV4 labels coming in from the other.

Edit: In case that wasn't clear you need 'mpls ip' on your Serial interfaces

6 REPLIES
Purple

BGP with different AS

Hi,

when you ping 10.8.100.53 from S_1 the source IP will be 10.10.1.2(subnet 10.10.1.0/30) but K_1 hasn't got this subnet in its routing table so it can't reply.

Regards

Alain

Don't forget to rate helpful posts.

Don't forget to rate helpful posts.
New Member

BGP with different AS

Hi Alain,

Thank you for the reply,

i did what you mention, using a source from LAN interface of S_1, i still could not get the reply from K_1

S_1#ping 10.8.100.53 so lo0

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 10.8.100.53, timeout is 2 seconds:

Packet sent with a source address of 10.8.100.40

.....

Success rate is 0 percent (0/5)

S_1#ping 10.8.100.53 so fa0/1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 10.8.100.53, timeout is 2 seconds:

Packet sent with a source address of 10.8.40.2

.....

Success rate is 0 percent (0/5)

S_1#

Purple

BGP with different AS in GNS3

Hi,

Can you enable the following debugs on both routers:

-debug ip icmp

-debug ip packet detail 100

-debug arp

before that configure ACL 100: access-list 100 permit icmp any any

and do this:

no service timestamp debug

Post the results.

Regards

Alain

Don't forget to rate helpful posts.

Don't forget to rate helpful posts.
New Member

Re: BGP with different AS in GNS3

Each PE router won't understand the MPLS VPNV4 labels coming in from the other.

Edit: In case that wasn't clear you need 'mpls ip' on your Serial interfaces

New Member

Re: BGP with different AS in GNS3

Dear Jamie,

thats it. I've configured both serial interface with mpls ip and both K_1 ans S_1 now reachable. Thank you so much.

K_1#sh 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 10.20.1.1 to network 0.0.0.0

     10.0.0.0/8 is variably subnetted, 5 subnets, 3 masks

C       10.20.1.0/30 is directly connected, FastEthernet0/0

B       10.8.40.0/24 [20/0] via 10.20.1.1, 00:00:50

C       10.8.53.0/24 is directly connected, FastEthernet0/1

B       10.8.100.40/32 [20/0] via 10.20.1.1, 00:00:50

C       10.8.100.53/32 is directly connected, Loopback0

S*   0.0.0.0/0 [1/0] via 10.20.1.1

K_1#ping 10.8.100.40 so lo0

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 10.8.100.40, timeout is 2 seconds:

Packet sent with a source address of 10.8.100.53

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 28/87/128 ms

K_1#

New Member

BGP with different AS in GNS3

Hi,

there you need i-BGP reachability through IGP protocols or static routing between the same AS (K_1 and S_1)

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