From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Wed Sep 29 2004 - 12:31:07 GMT-3
Correct :)
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
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> -----Original Message-----
> From: Edwards, Andrew M [mailto:andrew.m.edwards@boeing.com]
> Sent: Wednesday, September 29, 2004 10:29 AM
> To: Brian McGahan; James
> Cc: Matt; ccielab@groupstudy.com
> Subject: RE: Ccie R&S lab 3 questions for the list....
>
> And so I would conclude the route-map sequence 20 is NOT required if
> only ONE specific route (222.22.2.0) is required to be dampened.
>
> 8)
>
>
> -----Original Message-----
> From: Brian McGahan [mailto:bmcgahan@internetworkexpert.com]
> Sent: Tuesday, September 28, 2004 3:44 PM
> To: James; Edwards, Andrew M
> Cc: Matt; ccielab@groupstudy.com
> Subject: RE: Ccie R&S lab 3 questions for the list....
>
>
> Yes, route-maps have an implicit deny at the end of them like
> access-lists, but that doesn't relate to BGP dampening.
>
> When BGP dampening is configured with the route-map option, only
> sequences that have the "set dampening" option configured will have
> dampening applied. Sequences that do not have this option will not
have
> default dampening parameters applied, regardless if the sequence says
> permit or deny.
>
> For example, look at the output when dampening is configured
> without a route-map:
>
> router bgp 200
> bgp dampening
>
> Rack4R1#show ip bgp dampening parameters
> dampening 15 750 2000 60 (DEFAULT)
> Half-life time : 15 mins Decay Time : 2320 secs
> Max suppress penalty: 12000 Max suppress time: 60 mins
> Suppress penalty : 2000 Reuse penalty : 750
>
> The "show ip bgp dampening parameters" output dictates the
> default dampening options for all prefixes. Now look at what happens
> when a route-map is applied:
>
> router bgp 200
> bgp dampening route-map DAMPENING
> !
> ip prefix-list 222.22.2.0 seq 5 permit 222.22.2.0/24
> !
> route-map DAMPENING permit 10
> match ip address prefix-list 222.22.2.0
> set dampening 15 750 2000 60
> !
> route-map DAMPENING permit 20
>
> Rack4R1#show ip bgp dampening parameters
> dampening 15 750 2000 60 (route-map DAMPENING 10)
> Half-life time : 15 mins Decay Time : 2320 secs
> Max suppress penalty: 12000 Max suppress time: 60 mins
> Suppress penalty : 2000 Reuse penalty : 750
>
> Note that the "show ip bgp dampening parameters" only lists the
> parameters defined in sequence 10 of route-map DAMPENING. Even though
> sequence 20 is explicit permit, there are no dampening parameters
> defined, hence no other routes besides 222.22.2.0/24 will be dampened.
>
>
>
> HTH,
>
> Brian McGahan, CCIE #8593
> bmcgahan@internetworkexpert.com
>
> Internetwork Expert, Inc.
> http://www.InternetworkExpert.com
> Toll Free: 877-224-8987 x 705
> Outside US: 775-826-4344 x 705
> 24/7 Support: http://forum.internetworkexpert.com
> Live Chat: http://www.internetworkexpert.com/chat/
>
>
> > -----Original Message-----
> > From: James [mailto:james@towardex.com]
> > Sent: Tuesday, September 28, 2004 3:49 PM
> > To: Edwards, Andrew M
> > Cc: Brian McGahan; Matt; ccielab@groupstudy.com
> > Subject: Re: Ccie R&S lab 3 questions for the list....
> >
> > On Tue, Sep 28, 2004 at 01:39:33PM -0700, Edwards, Andrew M wrote:
> > > Then, if I were only asked to dampen ONE route, and I match it
with
> the
> > > first sequence of the route-map, I wouldn't need an additional
> sequence
> > > because I have no other routes I want to dampen... True?
> >
> > Correct. route-maps are implicit deny.
> >
> > -J
> >
> > >
> > >
> > > -----Original Message-----
> > > From: Brian McGahan [mailto:bmcgahan@internetworkexpert.com]
> > > Sent: Tuesday, September 28, 2004 11:53 AM
> > > To: Matt; ccielab@groupstudy.com
> > > Subject: RE: Ccie R&S lab 3 questions for the list....
> > >
> > >
> > > Matt,
> > >
> > > Dampening is applied on the router itself not on a specific
> > > peering. This is why it doesn't relate to what it advertised.
When
> you
> > > call your route-map you need to call it like this:
> > >
> > > router bgp 1
> > > bgp dampening route-map DAMPEN
> > >
> > > If you then want to filter what is advertised to a specific peer
>
> > > create another route-map for that purpose and apply it to the
peer.
> > >
> > >
> > > HTH,
> > >
> > > Brian McGahan, CCIE #8593
> > > bmcgahan@internetworkexpert.com
> > >
> > > Internetwork Expert, Inc.
> > > http://www.InternetworkExpert.com
> > > Toll Free: 877-224-8987 x 705
> > > Outside US: 775-826-4344 x 705
> > > 24/7 Support: http://forum.internetworkexpert.com
> > > Live Chat: http://www.internetworkexpert.com/chat/
> > >
> > >
> > > > -----Original Message-----
> > > > From: Matt [mailto:matt_ccie_2004@yahoo.com]
> > > > Sent: Tuesday, September 28, 2004 1:41 PM
> > > > To: Brian McGahan
> > > > Subject: RE: Ccie R&S lab 3 questions for the list....
> > > >
> > > > Actually, maybe I am missing something here.
> > > >
> > > > R1 is advertising 3 /32 routes to R3:
> > > >
> > > > R3#sh ip bgp
> > > > BGP table version is 4, local router ID is 1.1.1.2
> > > > Status codes: s suppressed, d damped, h history, *
> > > > valid, > best, i - internal,
> > > > r RIB-failure, S Stale
> > > > Origin codes: i - IGP, e - EGP, ? - incomplete
> > > >
> > > > Network Next Hop Metric LocPrf
> > > > Weight Path
> > > > *> 1.1.1.1/32 10.1.1.1 0
> > > > 0 1 i
> > > > *> 2.2.2.2/32 10.1.1.1 0
> > > > 0 1 i
> > > > *> 3.3.3.3/32 10.1.1.1 0
> > > > 0 1 i
> > > > R3#
> > > >
> > > > now when i add the following route-map to that
> > > > peering:
> > > > route-map dampen permit 10
> > > > match ip address prefix-list Dampen
> > > > set dampening 2 15 15 2
> > > >
> > > > ip prefix-list Dampen seq 5 permit 1.1.1.1/32
> > > >
> > > > R3(config)#router bgp 2
> > > > R3(config-router)#neigh 10.1.1.1 route-map dampen in
> > > > % "dampen" used as BGP inbound route-map, set
> > > > dampening not supported
> > > > R3(config-router)#^Z
> > > > R3#
> > > > 01:44:11: %SYS-5-CONFIG_I: Configured from console by console
> > > > R3#
> > > > R3#clear ip bgp * s
> > > > R3#sh ip bgp
> > > > BGP table version is 6, local router ID is 1.1.1.2
> > > > Status codes: s suppressed, d damped, h history, *
> > > > valid, > best, i - internal,
> > > > r RIB-failure, S Stale
> > > > Origin codes: i - IGP, e - EGP, ? - incomplete
> > > >
> > > > Network Next Hop Metric LocPrf
> > > > Weight Path
> > > > *> 1.1.1.1/32 10.1.1.1 0
> > > > 0 1 i
> > > > R3#
> > > >
> > > > it gives me an error, yet it only allows the route specified by
> > > > the prefix list since I do not have a permit 20 statement.
> > > >
> > > > thoughts? (didn't want to spam the whole list with
> > > > this)
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > --- Brian McGahan <bmcgahan@internetworkexpert.com>
> > > > wrote:
> > > >
> > > > > Actually this second route-map statement will not
> accomplish
> > > > > anything, because the routes will not be dampened unless
> > > > > specific dampening parameters are applied to them. This is
> > > > > not to say that the
> > > > > routes will or will not be used or advertised,
> > > > > simply that they will not
> > > > > be dampened regardless whether the second route-map
> > > > > sequence is there or
> > > > > not.
> > > > >
> > > > >
> > > > > HTH,
> > > > >
> > > > > Brian McGahan, CCIE #8593 bmcgahan@internetworkexpert.com
> > > > >
> > > > > Internetwork Expert, Inc. http://www.InternetworkExpert.com
> > > > > Toll Free: 877-224-8987 x 705
> > > > > Outside US: 775-826-4344 x 705
> > > > > 24/7 Support: http://forum.internetworkexpert.com
> > > > > Live Chat: http://www.internetworkexpert.com/chat/
> > > > >
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: nobody@groupstudy.com
> > > > > [mailto:nobody@groupstudy.com] On Behalf
> > > > > Of
> > > > > > Matt
> > > > > > Sent: Tuesday, September 28, 2004 11:02 AM
> > > > > > To: Edwards, Andrew M; ccielab@groupstudy.com
> > > > > > Subject: Re: Ccie R&S lab 3 questions for the
> > > > > list....
> > > > > >
> > > > > > regarding the second permit statement in the
> > > > > dampening
> > > > > > route-map...that statement is there to permit
> > > > > anything
> > > > > > else not specified in the first statement.
> > > > > Without
> > > > > > it, the rest will be denied.
> > > > > >
> > > > > > -matt
> > > > > >
> > > > > > --- "Edwards, Andrew M"
> > > > > <andrew.m.edwards@boeing.com>
> > > > > > wrote:
> > > > > >
> > > > > > > For those of you familiar with the lab, I'd
> > > > > > > appreciate any feedback.
> > > > > > > Especially on bgp dampening because I think I
> > > > > really
> > > > > > > need to get the
> > > > > > > purpose of the second route-map permit sequence.
> > > > > > > Re: requirement to not accept routes from any
> > > > > other
> > > > > > > EIGRP routers on
> > > > > > > VLAN 1 that may be added in the future
> > > > > > > The author used a distribute list with the
> > > > > gateway
> > > > > > > statement to allow
> > > > > > > only R2 to provide updates to R3 on this VLAN.
> > > > > > > I used a different method and wanted to run it
> > > > > by
> > > > > > > the groupstudy.
> > > > > > > I used the distance command such that there were
> > > > > two
> > > > > > > entries in the
> > > > > > > following order:
> > > > > > > 1. distance 90 172.16.0.1 0.0.0.0
> > > > > > > 2. distance 255 172.16.0.0 0.0.255.255
> > > > > > >
> > > > > > > With this configuration, R3 became adjacent to
> > > > > > > another router (I used
> > > > > > > the 3550 switch to test) on the VLAN, but DID
> > > > > NOT
> > > > > > > take any routing
> > > > > > > updates from it.
> > > > > > > Would this have also met the requiremet from the
> > > > > > > lab? Curious...
> > > > > > > re: bgp dampening
> > > > > > > I noticed that there were 2 route map sequences
> > > > > in
> > > > > > > the solution.
> > > > > > >
> > > > > > > I am not sure what the purpose is to the final
> > > > > > > route-map sequence
> > > > > > > "permit 20". Can someone elaborate?
> > > > > > >
> > > > > > > Generally it was this in Lab 3:
> > > > > > >
> > > > > > > bgp dampen route-map dampen
> > > > > > >
> > > > > > > route-map dampen permit 10
> > > > > > > match ip add 3
> > > > > > > set damp x x x x
> > > > > > >
> > > > > > > route-map dampen permit 20
> > > > > > >
> > > > > > > access-list 3 permit ip w.x.y.z 0.0.0.15
> > > > > > >
> > > > > > > re: bgp rib failures
> > > > > > > The author indicates that all the IGP routes
> > > > > should
> > > > > > > be backdoored for
> > > > > > > full points.
> > > > > > >
> > > > > > > If you only backdoor the peered eBGP neighbor
> > > > > > > networks though the routes
> > > > > > > will stop flapping and the other routes will
> > > > > just be
> > > > > > > eBGP instead of
> > > > > > > OSPF.
> > > > > > >
> > > > > > > Is it true, in a lab environment, that we should
> > > > > > > ALWAYS set backdoor
> > > > > > > routes for IGP learned routes over EGP routes?
> > > > > > >
> > > > > > > Andy
> > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
>
This archive was generated by hypermail 2.1.4 : Fri Oct 01 2004 - 15:00:51 GMT-3