[j-nsp] Route Reflecting & Next-Hop Self

[Dan Armstrong]

I had that thought too - but for some reason this condition matches all 
external routes... even those learned by other ebgp routers... so this 
effectively sucks all traffic towards the rr server too..



Sean Clarke wrote:
>
> Hi Dan
>
> You may want to use the "external" keyword in your policy. This way 
> you only set nhs to the external bgp routes, not ones learned via iBGP.
>
> i.e.
>
> policy-options {
>    policy-statement nhs {
>        from {
>            protocol bgp;
>             external;
>        }
>        then {
>            next-hop self;
>            accept;
>        }
>    }
> }
>
> cheers
> Sean
>
>
> Dan Armstrong wrote:
>> I'm new to JunOS, coming from IOS - and I'm having a heck of a time 
>> wrapping my brain around something that should be fairly simple...
>>
>>
>> eg:
>>
>> If I am a route-reflector server.  I also have eBGP sessions.  My 
>> ebgp session's next hop is in 'other people's' address space, so I 
>> don't carry it in my IGP, so I use next-hop self...  Seems fairly 
>> normal and common right?
>>
>>
>> In IOS, if I set next-hop self in a neighbor relationship with an 
>> RR-Client, it sets the next-hop to itself for routes learned from 
>> local eBGP sessions, but leaves the next-hop unchanged for routes 
>> that it's passing on from other fellow route-reflectors...
>>
>> The *problem* is that in JunOS, if I set next-hop self on a neighbor 
>> relationship with an RR-Client, it sets the next-hop to itself all 
>> the time, even on routes it's passing on from other fellow 
>> route-reflectors, effectively sucking all traffic into the route 
>> reflector and totally defeating the purpose of route reflecting.
>>
>> Now, of course we can policy-statement our way out of this - with big 
>> messy kludgey stuff, but it seems to me that there has to be a fairly 
>> simple and elegant way to do this, since it's pretty common, no?
>>
>>
>> (My current kludge is to set an import policy on my eBGP sessions 
>> that tag each route with a community called "HERE", have an export 
>> policy towards all my iBGP neighbors to set next-hop self if the 
>> route is tagged with the community "HERE", then strip it off - so 
>> that the community "HERE" never leaves any box.)
>>
>>
>>
>>
>>
>>
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>>
>
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