BGP Config help needed

Unanswered Question
Oct 14th, 2007

I attached a diagram of a network I'm working with. It is an eWan connection and connecting to the ISP currently works but my BGP may be a little messed up.

ISP Assigned me 20.10.10.0\24

I need to make sure my outbound and inbound traffic is load-shared as much as possible but I dont know if my current config will work.

I'm running OSPF as an IGP and BGP out to the ISP. The ISP is advertising about 120,000+ BGP routes to R1 & R2.

I know I need to create some route-maps but not sure how to properly set them up.

R1:

Int vlan 123

description "Connect to ISP"

ip address 15.10.10.133 255.255.255.248

int g1/1

description "connection to ISP"

switchport access vlan 123

switchport mode access

int vlan 300

description "ISP Assigned IP Block"

ip address 20.10.10.1 255.255.255.0

int g1/20

description "connection between R1 & R2"

switchport trunk encap dot1q

switchport mode trunk

Int g1/21

description "Connection to R3"

switchport trunk encap dot1q

switchport mode trunk

Router ospf 10

network 20.10.10.0 0.0.0.255 area 0

Router BGP 100

no synchronization

neighbor 15.10.10.129 remote-as 200

neighbor 20.10.10.4 remote-as 100

no auto-summary

______________________________________

R2:

Int vlan 123

description "Connect to ISP"

ip address 15.10.10.141 255.255.255.248

int g1/1

description "connection to ISP"

switchport access vlan 123

switchport mode access

int vlan 300

description "ISP Assigned IP Block"

ip address 20.10.10.4 255.255.255.0

int g1/20

description "connection between R2 & R1"

switchport trunk encap dot1q

switchport mode trunk

Int g1/21

description "Connection to R3"

switchport trunk encap dot1q

switchport mode trunk

Router ospf 10

network 20.10.10.0 0.0.0.255 area 0

Router BGP 100

no synchronization

neighbor 15.10.10.137 remote-as 200

neighbor 20.10.10.1 remote-as 100

no auto-summary

_____________________________________

R3:

Int Vlan 300

ip address 20.10.10.2\24

Int g1/1

description "Connection to R1"

switchport trunk encap dot1q

switchport mode trunk

Int g1/2

description "Connection to R2"

switchport trunk encap dot1q

switchport mode trunk

Router OSPF 10

network 20.10.10.0 0.0.0.255 area 0

Attachment: 
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htarra Fri, 10/19/2007 - 06:59

Another way to specify OSPF routes to be imported into BGP is by using route redistribution. The default is for all routing redistribution to be disabled. I didn't find anything that stood out as being misconfigured at this point. can you send the following to me:

sh ip bgp nei ISP advertise

sh ip bgp nei ISP routes

http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a008009425c.shtml#t1

gaurav_thapar79 Fri, 10/19/2007 - 11:01

Hi,

You are nowhere redistributing routes in the posted configuration. How have you seen the received routes and are redistrbuted in OSPF.

Please share the exact config alongwith problem statement.

darrenj Mon, 10/22/2007 - 09:08

I wouldn't go redistributing 120,000 BGP routes into OSPF, thats going to be a world of pain for your OSPF routers :-(

Why don't you redistribute default routes from both R1 and R2 into the OSPF domain as External Type 1 routes? This way, each internal OSPF router will use the 'closest' router (R1 or R2) for external routes. If you advertise you internal routes to your ISP identically on both R1 and R2, you can 'hope' that the ISP will utilise both links for inbound traffic to your AS, but it depends on there set-up.

Hope this helps

Dazzler

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