From: dusth@comcast.net
Date: Fri Sep 02 2005 - 00:03:09 GMT-3
Hi Andy, Thanks for the clarification. I got it now.
Dustin
-------------- Original message --------------
> Dustin,
>
> Conditional route advertisement is on a per neighbor basis for existing
> prefixes in the BGP table. IOW, the prefix already exists... the
> question is should the router advertise it? Yes, if the non-exist-map
> is false. No if the non-exist-map is true.
>
> Route injection, on the other hand, allows you to ADD more specific
> routes to the BGP table. It must be a more specific route though and
> from a defined source.
>
> See guidelines from before, specifically:
>
> "The inject-map defines the prefixes that will be created and installed
> into the routing table. Injected prefixes are installed in the local BGP
>
> RIB. A valid parent route must exist; Only prefixes that are equal to or
>
> more specific than the aggregate route (existing prefix) can be
> injected."
>
>
> They offer similar results, not the same. I sounds like you understand
> it, because as you pointed out they are quite different.
>
> Hence, look for wording that might lead you one way or another.
>
> Injection example:
>
> Rx and Ry are eBGP neighbors.
> When Rx advertises prefix a.b.0.0 /16 have Ry source the more specific
> route a.b.1.0 /25.
>
> Advertise-map example:
>
> Rx and Ry are eBGP neighbors.
> Have Ry advertis prefix x.y.1.0 /24. Ensure Rx advertises z.x.2.0/16 if
> x.y.1.0 /24 is no longer advertised by Ry.
>
> HTH,
>
> Andy
>
> -----Original Message-----
> From: dusth@comcast.net [mailto:dusth@comcast.net]
> Sent: Thursday, September 01, 2005 4:00 PM
> To: Edwards, Andrew M; ccielab@groupstudy.com
> Subject: RE: bgp inject-map vs. neighbor advertise-map
>
>
> Hi Edwards,
>
> Yes, you are right. However, I do not know when to use b/t
> and the .
> These two commands offer same result besides advertise-map
> populates to specific neighbor vs. bgp inject-map populate into BGP
> routing table or using bgp inject-map with route-map apply to neighbor
> to limit only certain segment(s) pass to the neighbor.
>
> Any advise when to use the other other than depend on the
> question in the test??
>
> Thanks,
> Dustin
>
>
> -------------- Original message --------------
>
> > Dustin,
> >
> > The advertise-map simply provides "tweaked logic" on
> which routes to
> > advertise. Such as when a non-exist-map is true, do
> NOT advertise the
> > exist-map. Obviously, when the non-exist-map is false,
> the exist-map is
> > then advertised.
> >
> >
> > Inject-map however has a more specific function of
> allowing you to
> > inject "more specific" prefixes into the BGP table
> with the following
> > usage guidelines from CCO.
> >
> >
> > "Inject-map
> >
> > Usage Guidelines
> > The bgp inject-map command is used to configure
> conditional route
> > injection. Conditional Route Injection allows you to
> originate a more
> > specific prefix into a BGP routing table without a
> corresponding match.
> > Two route maps (exist-map and inj! ec! t-map) are
> configured in global
> > configuration mode and then specified with the bgp
> inject-map command in
> > address family or router configuration mode.
> >
> > The exist-map specifies the prefix that the BGP
> speaker will track. This
> > route map must contain a match ip address prefix-list
> command statement
> > to specify the aggregate prefix and a match ip
> route-source prefix-list
> > command statement to specify the route source.
> >
> > The inject-map defines the prefixes that will be
> created and installed
> > into the routing table. Injected prefixes are
> installed in the local BGP
> > RIB. A valid parent route must exist; Only prefixes
> that are equal to or
> > more specific than the aggregate route (existing
> prefix) can be
> > injected.
> >
> > The copy-attributes keyword is used to optionally
> configure the injected
> > prefix to inherit the same attributes as the aggregate
> route. If th! is!
> > keyword is not entered, the injected prefix will use
> the default
> > attributes for locally originated routes. "
> >
> > HTH,
> >
> > andy
> > -----Original Message-----
> > From: dusth@comcast.net [mailto:dusth@comcast.net]
> > Sent: Thursday, September 01, 2005 3:06 PM
> > To: ccielab@groupstudy.com
> > Subject: bgp inject-map vs. neighbor advertise-map
> >
> >
> > Hi group,
> > I need some of your BGP knowledge shed me in the light
> on the similarity
> > and differences and when to use which option b/t these
> two commands
> > inject-map vs. neighbor advertise-map>.
> > Besides, has extra option to advertise
> > segment(s) to peer if the condition is not exist or
> > exist vs. has only option to
> > advertise segments(s) to peer only if the condition
> exist, whatelse or
> > when I! s! hould use over the other.
> >
> > Thanks in advance.
> > Dustin
> >
> >
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