A hotly debated topic among BGP nerds.... I honestly don't know how
I feel about it either way.
Many people think that because the IPs that you often use between
yourself and a transit provider belong to your transit provider, they
have no business being in your IGP.... "My IGP is for MY address
space". At the end of the day I don't think it really matters, but
you know how passionate some people can be.
Amos Rosenboim wrote:
Hello Dan,
You can also work around all of this by simply adding the inter-AS
prefix into your IGP by adding this interface as a passive interface
for the IGP.
This will eliminate the need for next hop self in the first place.
This seems simpler to me, am I missing any reason not to use this?
Regards
Amos Rosenboim
[EMAIL PROTECTED] <mailto:[EMAIL PROTECTED]>
On Sep 6, 2008, at 12:46 AM, Dan Armstrong wrote:
EUREKA you're a genius!
Thanks... That works perfectly.
And thanks to all who replied!
Kevin Hodle wrote:
Hi Dan,
Instead of 'from external' you need 'from route-type external', like so:
term external-nexthopself {
from {
protocol bgp;
route-type external;
}
then {
next-hop self;
accept;
}
}
HTH,
Kevin
On Fri, Sep 5, 2008 at 9:26 AM, Dan Armstrong <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> wrote:
I was trying to make a generic policy statement that I could deploy
across all our boxes... this is not possible if we name ebgp peers
specifically, and if we change transit providers - we have to keep
track of changing policy statements as well... kind of messy.
Chuck Anderson wrote:
On Thu, Sep 04, 2008 at 10:08:45PM -0400, Dan Armstrong wrote:
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.
That's just the way it is in JunOS--not much policy-related
behavior is hard-coded into JunOS like it might be in other
vendors. This gives you the most flexibility in writing policy to
do exactly what you want.
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.)
That is one recommended method. The other is to match the eBGP
neighbor and only apply next-hop self to routes from your eBGP peers.
e.g. in your IBGP export policy (from the JNCIP study guide):
term 3 {
from {
protocol bgp;
neighbor [ 172.16.0.14 172.16.0.18 ];
}
then {
next-hop self;
}
}
where 172.16.0.14 and 17.16.0.18 are eBGP peer addresses.
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