Re: [swinog] BGP hint required

2007-06-07 Diskussionsfäden Fredy Kuenzler

Michael Horn schrieb:

Now, BGP mechanism prevents AS-pathes like

^[Transit-AS]_8302$

in my case

^13030_8302$

if I'm AS8302 myself.

I know there is some tweak to prevent this default behaviour. Could
anyone give a hint for Foundry and Cisco gear?


you may want to use the "allowas-in" statement in the neighbor 
configuration (at least on cisco)


  allowas-in Accept as-path with my AS present in it

-> neighbor 1.2.3.4 allowas-in


Thanks Michael and Ueli, who pointed me to the same command. This in 
fact fixes the issue, at least on Cisco.


No I have to find the similar command on Foundry.

Best regards,
Fredy
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Re: [swinog] BGP hint required

2007-06-07 Diskussionsfäden Andre Oppermann

Fredy Kuenzler wrote:
I'm building the CDN for Zattoo and as it's some sort of 'anycast' 
infrastructure (refer to the presentation @ SwiNOG #14), I have several 
geographically dispersed network islands, not connected via a layer-2 link.


Each network island propagates one or more /24 networks, using AS8302.

Now, BGP mechanism prevents AS-pathes like

^[Transit-AS]_8302$

in my case

^13030_8302$

if I'm AS8302 myself.

I know there is some tweak to prevent this default behaviour. Could 
anyone give a hint for Foundry and Cisco gear?


Ah, here it is.  It may work with some tweaks.

http://www.cisco.com/en/US/products/ps6350/products_configuration_guide_chapter09186a008045565b.html
http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a00800949cd.shtml

--
Andre

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Re: [swinog] BGP hint required

2007-06-07 Diskussionsfäden Andre Oppermann

Fredy Kuenzler wrote:
I'm building the CDN for Zattoo and as it's some sort of 'anycast' 
infrastructure (refer to the presentation @ SwiNOG #14), I have several 
geographically dispersed network islands, not connected via a layer-2 link.


Each network island propagates one or more /24 networks, using AS8302.

Now, BGP mechanism prevents AS-pathes like

^[Transit-AS]_8302$

in my case

^13030_8302$

if I'm AS8302 myself.

I know there is some tweak to prevent this default behaviour. Could 
anyone give a hint for Foundry and Cisco gear?


Normally BGP speakers MUST not be able to disable loop prevention.
You're probably thinking of "no bgp enforce-first-as" but that's not
relevant here.  There was another hack related to network transitions
and have two ASs configured at the same time.  Though I don't know if
this is good enough either.

As an alternative you can have a static route for your entire anycast
netblock to one of your upstreams.  That fixes the immediate issues
but doesn't provide load balancing or failover.

--
Andre

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Re: [swinog] BGP hint required

2007-06-07 Diskussionsfäden Michael Horn

Hi Fredy,

On Thu, 7 Jun 2007, Fredy Kuenzler wrote:

I'm building the CDN for Zattoo and as it's some sort of 'anycast' 
infrastructure (refer to the presentation @ SwiNOG #14), I have several 
geographically dispersed network islands, not connected via a layer-2 link.


Each network island propagates one or more /24 networks, using AS8302.

Now, BGP mechanism prevents AS-pathes like

^[Transit-AS]_8302$

in my case

^13030_8302$

if I'm AS8302 myself.

I know there is some tweak to prevent this default behaviour. Could anyone 
give a hint for Foundry and Cisco gear?


you may want to use the "allowas-in" statement in the neighbor 
configuration (at least on cisco)


  allowas-in Accept as-path with my AS present in it

-> neighbor 1.2.3.4 allowas-in

Kind regards,
Michael

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+
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[swinog] BGP hint required

2007-06-07 Diskussionsfäden Fredy Kuenzler
I'm building the CDN for Zattoo and as it's some sort of 'anycast' 
infrastructure (refer to the presentation @ SwiNOG #14), I have several 
geographically dispersed network islands, not connected via a layer-2 link.


Each network island propagates one or more /24 networks, using AS8302.

Now, BGP mechanism prevents AS-pathes like

^[Transit-AS]_8302$

in my case

^13030_8302$

if I'm AS8302 myself.

I know there is some tweak to prevent this default behaviour. Could 
anyone give a hint for Foundry and Cisco gear?


Thanks,
Fredy
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