Originating Default route

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Jun 3rd, 2008
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Hi I'm not sure how to do this so was looking for someone to give some advice.

What I'm trying to do is I have a BGP peering and there are some routes that need to go over my internet connection. So what he is asking me to do is for me to originate a defualt route and advertise it over the BGP connection. The router that is doing the peering on my side is rt4. I think of doing this:

Please see attached

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wgranada1 Tue, 06/03/2008 - 11:22
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I was looking on my RT4 and noticed that there is a Gateway of last resort that is

configured which points to the internet

should I advertise that over BGP instead

of what I did above?

Edison Ortiz Tue, 06/03/2008 - 11:36
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Please see


on how to advertise a default-route in BGP.

The attached file isn't advertising a default route but it's just advertising a host device in BGP.




wgranada1 Tue, 06/03/2008 - 11:57
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Sorry I guess I not a very good explainer what I wanted to do is I have a BGP peer and I'm advertising certain subnets to him via prefix-list and route-maps what I was trying to do is the distant end has maybe 1 or 2 servers that needs to use my internet services

Can I just make up an IP address put a static route pointing to the internet and advertise that made up IP address over BGP so whatever server on his side needs to hit the internet he can point it to that made up IP address and that will take it to the internet? Is that doable?

wgranada1 Tue, 06/03/2008 - 12:15
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ok I looked this over again and I think I got it going to try it out and see what happens.

Thank you in advance

sdoremus33 Thu, 06/05/2008 - 08:50
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Hi I dont know if you remember me from SG IOC but here is a tip as Edison mentioned

Advertising a Default Route Using BGP

Perform this task to advertise a default route to BGP peers. The default route is locally originated. A default route can be useful to simplify configuration or to prevent the router from using too many system resources. If the router is peered with an Internet service provider (ISP), the ISP will carry full routing tables, so configuring a default route into the ISP network saves resources at the local router.


1. enable

2. configure terminal

3. ip prefix-list list-name [seq seq-value] {deny network/length | permit network/length} [ge ge-value] [le le-value]

4. route-map map-tag [permit | deny] [sequence-number]

5. match ip address {access-list-number [access-list-number... | access-list-name...] | access-list-name [access-list-number... | access-list-name] | prefix-list prefix-list-name [prefix-list-name...]}

6. exit

7. router bgp autonomous-system-number

8. neighbor {ip-address | peer-group-name} default-originate [route-map map-name]

9. end

sdoremus33 Thu, 06/05/2008 - 08:56
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Also in BGPtheir are three origin types which are carried within the BGP message

I = --> Via static default route

E = --> Via network statement originating

Incomplete = --> Via redistribution form another RP


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