BGP HELP

[Lajuwo]

Dear all, 

Presently we have 2 ISP configured on a router with bgp and failover.

Now, we plan to add another ISP on a new router with bgp configured.

I need help on how to do this since my ASN can only be on a router at once.

Also, we need to introduce access router, all customers interface with the router directly.

The core router only do the bgp pairing. 

I need help on this configuration setup.

Thank you all.

[Deepak Kumar]

Hi,

Share your network diagram and current configuration for better suggestions. 

I need help on how to do this since my ASN can only be on a router at once.

 If all you need to do is to appear as multiple different ASes to your BGP peers, the local-as feature could be a solution.

https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/13761-39.html

Regards,

Deepak Kumar

[Lajuwo]

Thank you Deepak Kumar,

See attached the topology also find bellow my present configuration.

router bgp 37--- bgp log-neighbor-changes neighbor 197.2.1.1 remote-as 29465 neighbor 197.2.1.1 description PEERING WITH M
neighbor 197.2.2.1 ebgp-multihop 10 neighbor 197.2.2.1 timers 10 30 neighbor 197.2.2.1 remote-as 37148 neighbor 197.2.2.1 description PEERING WITH G neighbor 197.2.2.1 ebgp-multihop 10 neighbor 197.2.2.1 timers 30 90 ! address-family ipv4 bgp dampening network 41.2.6.0 mask 255.255.240.0 network 41.2.6.0 mask 255.255.255.0 network 41.2.6.0 mask 255.255.255.0 network 41.2.6.0 mask 255.255.255.0 network 41.2.6.0 mask 255.255.255.0 network 41.2.6.0 mask 255.255.255.0 network 41.2.6.0 mask 255.255.255.0 network 41.2.6.0 mask 255.255.255.0 network 41.2.6.0 mask 255.255.255.0 network 41.2.6.0 mask 255.255.255.0 network 41.2.6.0 mask 255.255.255.0 network 41.2.6.0 mask 255.255.255.0 network 41.2.6.0 mask 255.255.255.0 network 41.2.6.0 mask 255.255.255.0 network 41.2.6.0 mask 255.255.255.0 network 41.2.6.0 mask 255.255.255.0 network 41.2.6.0 mask 255.255.255.0 network 197.2.1.1
network 197.2.2.1 redistribute static neighbor 197.2.1.1 activate neighbor 197.2.1.1 next-hop-self neighbor 197.2.1.1 soft-reconfiguration inbound neighbor 197.210.179.213 route-map M out neighbor 197.2.2.1 activate neighbor 197.2.2.1 next-hop-self neighbor 197.2.2.1 soft-reconfiguration inbound neighbor 197.2.2.1 route-map G out 

[paul driver]

Hello

@Lajuwo 
Parts of that configuration isnt correct, Is this is a lab simulation?

You have multiple duplicate network statements( possibly typos?) and non existent neighbors.
Can you confirm what are the roue-maps doing?

[paul driver]

Hello

That seems a more viable readout than the previous one you posted?
I do see however you have two default static routes with no preference to either and your redistributing them into bgp not so sure why you doing that as you have network statements in bgp advertsing your internal subnets?

Can you confirm what routes are you receiving from either ISP?

I see you are as-path pre-pending on specific routes for ISP return traffic but no preference given for egress traffic, ( hence the default static routes)

I dont see any thing to negate/filter possible transient traffic between either ISP for favoring your own rtr as a better path to take.

Lastly you have soft-reconfiguration inbound enabled which isn't really required on newer software these days, BGP has the route refresh capability which is a fair better option and less resource intensive on your wan rtr(s) for bgp prefix refresh

[paul driver]

Hello

---

@Lajuwo wrote:

Dear all, 

Presently we have 2 ISP configured on a router with bgp and failover.

Now, we plan to add another ISP on a new router with bgp configured.

I need help on how to do this since my ASN can only be on a router at once.

---

These are two separate ISP's correct? - Adding an additional router will then not be a problem so would having the same ASN on two routers, Naturally however you need to make sure you dont become a transit path for each ISP which i assume you are already doing?.

The addressing will still be the same and would the local ASN you use , You would then IBGP between your local wan rtrs and depending on what routes you are receiving from your isp's you could utilize BGP Path Attributes for egress/ingress routing preference, 

Also, we need to introduce access router, all customers interface with the router directly.

---

Not so sure what you mean by this, can you elaborate?

[Lajuwo]

Thank you Paul,

Also, we need to introduce access router, all customers interface with the router directly.

Not so sure what you mean by this, can you elaborate?

What I want to do here is to

1. We have our core router for bgp pearing alone

2. Have another router for the access. We create all sub interface and all Van for our end users. This router will be directly connected to the core. 

Thank you

[paul driver]

Hello

Okay, You have various options.

One option could be that between your lan core and your wan rtrs (that are running bgp), you could have static routes pointing internally towards your lan and redistribute these statics in to bgp or just advertise a summary of those routes into bgp, the dual lan interfaces of each wan rtr could then provide a virtual gateway via hrsp or vrrp for the connected core default route. 

Another option is you could introduce an IGP like OSPF ( no need for statics) between you wan rtrs and lan core and redistribute your internal ospf routes into bgp whilst at the same time advertise a default route for either wan rtr into ospf for the lan core resiliency?