[j-nsp] Help: Learning routes from same ASN, cisco vs juniper

[David Miller]

On 9/10/2013 1:28 PM, OBrien, Will wrote:
> I've found an interesting issue and I wanted to get some thoughts before talking to JTAC about it.
> 
> 
> I have a few of MX480s.  In the past, I've advertised a dedicated /24 from my lab to my providers upstream.
> That /24 was never learned by my primary MX.
> 
> The issue comes down to either the MX or the Cisco filtering routes that are from the same ASN.  It's been a couple of years since I ran across this and I can't remember who was at fault.
> 
> 
> This behavior is biting my with regard to my DR site.
> 
> 
> At my DR, I have a SRX with say ASN 1234. It's advertising a /24.
> 
> At my primary site, I also use ASN1234. I do not receive the /24 via BGP.
> 
> So, either the Cisco (7600 I think) isn't advertising the route to me because it's from my ASN - OR - The MX is filtering it because it's from my ASN and coming in on a eBGP link.
> 
> 
> If it's the MX, I'm certain I can write an import filter, but I'm having an issue hunting down syntax on that.
> If it's the Cisco, then I can yell at the provider to have them open a TAC case. 
> 
> 
> 
> Like I said, I ran across this a few years ago, but can't remember who was at fault. I could build a multi-hop neighbor relationship to get around this, but surely there's a simpler solution...

In Juniper:

https://www.juniper.net/techpubs/en_US/junos/topics/reference/configuration-statement/loops-edit-protocols-bgp-family.html

protocols {
    bgp {
        neighbor 10.2.3.4 {
            family inet {
                unicast {
                    loops 1;
                }
            }
        }
    }
}

-set-

set protocols bgp neighbor 10.2.3.4 family inet unicast loops 1

^^ Will allow AS in path 1 time (can be set higher).

-DMM

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