From: Sergio Jimenez Arguedas (sejimenez@its.co.cr)
Date: Thu May 06 2004 - 23:16:21 GMT-3
Hi Mohamed,
Nobody helped us!!! Don4t worry if I get the answer I will share with you
it!!!
Rgds,
Sergio
----- Original Message -----
From: "Mohamed" <nmohamed@cisco.com>
To: "'Devi Mallampalli'" <Devi.Mallampalli@chubb.com.au>; "'Sergio Jimenez
Arguedas'" <sejimenez@its.co.cr>; <ccielab@groupstudy.com>
Sent: Wednesday, May 05, 2004 8:49 AM
Subject: RE: BGP MED Scenario!!!-2nd try
> Hi Devi,
>
> I checked in my routers,pls chk the config
>
> Down---------SFM---------Side
>
> SFM#sh ip bgp
> BGP table version is 5, local router ID is 219.2.1.1
> Status codes: s suppressed, d damped, h history, * valid, > best, i -
> internal,
> S Stale
> Origin codes: i - IGP, e - EGP, ? - incomplete
>
> Network Next Hop Metric LocPrf Weight Path
> *> 100.100.100.0/24 0.0.0.0 0 32768 i
> *> 200.100.100.0 25.25.25.26 156160 32768 i
> *> 201.100.100.0 25.25.25.26 156160 32768 i
> *> 203.1.1.0 99.99.99.2 0 300 400 ?
> SFM#
> SFM#
> SFM#
> SFM#
> SFM#sh run | b router bgp
> router bgp 100
> no synchronization
> bgp log-neighbor-changes
> network 0.0.0.0
> network 100.100.100.0 mask 255.255.255.0
> network 200.100.100.0
> network 201.100.100.0
> neighbor 25.25.25.26 remote-as 100
> neighbor 25.25.25.26 route-map INT out
> neighbor 99.99.99.2 remote-as 300
> no auto-summary
> !
> ip classless
> no ip http server
> !
> !
> !
> !
> route-map INT permit 10
> set metric-type internal
> !
> !
> !
> dial-peer cor custom
> !
> !
> !
> !
> line con 0
> exec-timeout 35791 0
> line vty 0 4
> no login
> transport input lat pad mop telnet rlogin udptn nasi
> !
> end
>
> SFM#
>
>
> In SFM I give the command set metric-type internal in the route-map to
> Down router and I expect that ? Routes will be converted to IGP as you
> specified,but iam not getting as IGP in Down.Pls clarify!!
>
> Down#sh ip bgp
> BGP table version is 202, local router ID is 201.100.100.100
> Status codes: s suppressed, d damped, h history, * valid, > best, i -
> internal
> Origin codes: i - IGP, e - EGP, ? - incomplete
>
> Network Next Hop Metric LocPrf Weight Path
> *>i100.100.100.0/24 25.25.25.25 0 100 0 i
> *>i200.100.100.0 25.25.25.25 156160 100 0 i
> *>i201.100.100.0 25.25.25.25 156160 100 0 i
> *>i203.1.1.0 99.99.99.2 0 100 0 300 400 ?
> Down#
> Down#
>
>
>
> Thanks
> Mohamed.
>
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Devi Mallampalli
> Sent: Tuesday, May 04, 2004 6:11 PM
> To: Mohamed; Sergio Jimenez Arguedas; ccielab@groupstudy.com
> Subject: RE: BGP MED Scenario!!!-2nd try
>
>
> Hi Mohamed & Sergio ,
>
> Let me see if I can elaborate on what I said earlier. May be any CCIE
> present in the forum can validate my conceptual understanding on BGP
> here.
>
> The command "set metric-type internal" is used with in BGP context where
> you want BGP to "fake" ( just like AS prepend) inbound IGP routes which
> appear as "?" with in "sh ip bgp" output to "i". In otherwords , you
> want BGP to make incoming "incomplete ("?") routes , i.e IGP routes to
> be consider as iBGP routes which can appear as "i" with in "sh ip bgp"
> output.
>
> That makes logical sense if you think about it.
>
> As part of BGP route selection process, "i"(iBGP) routes are preferable
> to "?" routes(incomplete which are redistributed
> routes) and then "?" routes are preferred to "e" (EGP routes which are
> older version of BGP 4.0) routes.
>
> So there are 2 ways to accomplish this task of converting incomplete/?
> routes of IGP in to iBGP/i routes on the AS border router so that those
> routes will be preferred according to the BGP route selection process.
> This is true even though the IGP's route's AD is lesser(90 in case of
> EIGRP) when compared to "i"/iBGP route which is 200. Because BGP table
> unlike Routing table , will picking up most attractive routes in the
> above said order rather based on AD or Prefix length which is the case
> with Routing table.
>
> 1st method of accomplishing this is "set metric-type internal" condition
> under route map and second one being "set origin" attribute. Thus if I
> remember correctly , Sergio original config is correct , i.e. his Route
> map is doing her job and that is why he was seeing IGP routes with "i"
> sign in sh ip bgp output.
>
> Do not worry about Multi homing scenario and I do not think LAB exam
> covers such a kind of complex MED scenarios.
>
> I think as long as we are aware MED's nature ( i.e. it is configured on
> the local AS to influence the external AS) and
> functionality ( i.e. defines which incoming route/interface the
> external AS should take in order to come in to my AS) ,the applicable
> interface ( always on outbound ) and possible scenarios , we are pretty
> much safe in the MED section of the BGP in the exam , I think.
>
> Hope I am making sense here.
>
> Regards
>
> Devi....
>
>
> -----Original Message-----
> From: Mohamed [mailto:nmohamed@cisco.com]
> Sent: Tuesday, 4 May 2004 5:45 PM
> To: Devi Mallampalli; 'Sergio Jimenez Arguedas'; ccielab@groupstudy.com
> Subject: RE: BGP MED Scenario!!!-2nd try
>
>
> Hi Devi,
> Still iam not clear,I know bgp deterministic-med command,to choose the
> router with the best MED. But what does set metric-type internal does is
> the doubt. The explanation given in the cisco site is not that much
> clear.-The cmd (set metric-type internal) in BGP will enable the MED
> values on prefixes advertised to EBGP peer to match the IGP metric of
> the next hop.- It is also confusing when you say "If this command is
> used, multiple BGP speakers in a common autonomous system can advertise
> different MED values" In an AS how can multiple BGP speakers advertise
> diff MED values,when they use the same IGP for calculating the metrics.
>
> Thanks for giving your time, please clarify us more.
>
> Thanks
> Mohamed.
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Devi Mallampalli
> Sent: Tuesday, May 04, 2004 9:49 AM
> To: Sergio Jimenez Arguedas; ccielab@groupstudy.com
> Subject: RE: BGP MED Scenario!!!-2nd try
>
>
> Hi Sergio,
>
> When you originate a BGP route sourced from an IGP , then IGP's metric
> is converted to BGP MED by default. However if the route is local to the
> router the MED is by default "0" when you inject that route in to EBGP.
>
> The cmd (set metric-type internal) in BGP will enable the MED values on
> prefixes advertised to EBGP peer to match the IGP metric of the next
> hop. If this command is used, multiple BGP speakers in a common
> autonomous system can advertise different MED values ( If multihoming
> with multiple ISPs and peering with one ISP at multiple points, use "bgp
> deterministic-med" and enable it on all routers in the AS . And this
> will ensure the comparison of "MED variable" when choosing routes
> advertised by different peers in the same AS)for a particular prefix.
> Also, note that if the IGP metric changes, BGP will readvertise the
> route every 10 minutes.
>
> Hope this helps in terms of what this command does in BGP.
>
> Regards
>
> Devi.
>
>
>
>
>
> -----Original Message-----
> From: Sergio Jimenez Arguedas [mailto:sejimenez@its.co.cr]
> Sent: Tuesday, 4 May 2004 4:45 AM
> To: ccielab@groupstudy.com
> Subject: Fw: BGP MED Scenario!!!-2nd try
>
>
> Hi Devi,
>
> I agree with you, but the doubt is the following:
>
> ___________________________________
> Hi,
>
> Mohamed, I really did it, but WITHOUT the route-map INT SFM Tx the
> prefix to Side with the eigrp metric.
>
> So, I got confused with that cmd (set metric-type internal) in BGP.
> ___________________________________
>
> Thanks for your time!!!
>
>
> Sergio
>
>
> ----- Original Message -----
> From: "Devi Mallampalli" <Devi.Mallampalli@chubb.com.au>
> To: "Mohamed" <nmohamed@cisco.com>; <ccielab@groupstudy.com>
> Sent: Monday, May 03, 2004 7:25 AM
> Subject: RE: BGP MED Scenario!!!-2nd try
>
>
> > Hi Sergio & Mohamed,
> >
> > Let me understand this me being a late comer/listener to this Hi,
> > >
> > > Mohamed, I really did it, but WITHOUT the route-map INT SFM Tx the
> > > prefix to Side with the eigrp metric.
> > >
> > > So, I got confused with that cmd (set metric-type internal) in BGP.
>
> > conversation.
> >
> > Down---------------SFM-----------Side---------Up . In this topology,
> > Down and SFM are running "eigrp" between them and SFM and "side" are
> > running BGP between them. And you are "not" redistributing IGP in to
> > Side from SFM and instead you want to publish the "inbound" IGP
> > networks from Down to SFM in to the "BGP" Process at SFM. And you want
>
> > to EIGRP routes of 200.100.100.0/24 appear at "side" as internal
> > routes with the help of Router-maps & internal metric types.
> >
> > This is the scenario , right ?
> >
> > Honestly speaking with my very limited knowledge of BGP, I did not
> > come across manipulating routes with the help of "metric-type"
> > internal. Indeed I was in impression this kind of "metric-external
> > types" (Type 1 and type 2) feature is more to do with "OSPF" when you
> > want to influence incoming external routes from ASBR.
> >
> > But when you look at your below config & outputs , I kind of agree
> > with Mohamed that the route map is doing what she is suppose to do and
>
> > as result on "side " you are indeed seeing the "inbound" eigrp route
> > as IGP ( "I")
> >
> > 200.100.100.0 99.99.99.1 128512 0 100 I >>>>
> >
> > Am I thinking on right lines here ? Please elaborate the issue if you
> > can.
> >
> > On another note from LAB exam point of view , Determining the BGP
> > filtering policy (what do you want to do or what author wants to
> > achieve) is more critical along with which router or interface to
> > apply the policy on and the configuration part is relatively easier.
> > personally speaking, I try to be little cautious in getting what the
> > policy should be based on the question and more importantly where to
> > apply the BGP's knobs & twiddles ( ex: AS Path prepending is always
> > "out" , "community is always "out" , MED is always "out" , Local
> > Preference is always "In" and Weight is always "out"...etc) as it is
> > very easy to commit a mistake.
> >
> > Regards
> >
> > Devi....
> >
> > -----Original Message-----
> > From: Mohamed [mailto:nmohamed@cisco.com]
> > Sent: Monday, 3 May 2004 7:05 PM
> > To: ccielab@groupstudy.com
> > Subject: RE: BGP MED Scenario!!!-2nd try
> >
> >
> > Hi all,
> >
> > 2nd try, can anyone help on this!!
> >
> > Thanks
> > Mohamed.
> >
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> > Of Sergio Jimenez Arguedas
> > Sent: Friday, April 30, 2004 8:35 PM
> > To: ccielab@groupstudy.com
> > Subject: Fw: BGP MED Scenario!!!
> >
> >
> > Hi Group
> >
> > Is someone able to help us, please?
> >
> >
> > Rgds,
> >
> > Sergio Jiminez A.
> >
> >
> > ----- Original Message -----
> > From: "Mohamed" <nmohamed@cisco.com>
> > To: "'Sergio Jimenez Arguedas'" <sejimenez@its.co.cr>;
> > <ccielab@groupstudy.com>
> > Sent: Friday, April 30, 2004 12:10 AM
> > Subject: RE: BGP MED Scenario!!!
> >
> >
> > > Hi,
> > > Sergio,
> > > Yeah, really I also don't know,hope someone would be able to help
> > > us..
> > >
> > >
> > > Thanks
> > > Mohamed.
> > >
> > >
> > >
> > > -----Original Message-----
> > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
>
> > > Of Sergio Jimenez Arguedas
> > > Sent: Thursday, April 29, 2004 8:27 PM
> > > To: ccielab@groupstudy.com
> > > Subject: Fw: BGP MED Scenario!!!
> > >
> > >
> > >> >
> > > Thanks,
> > > Sergio
> > >
> > >
> > > ----- Original Message -----
> > > From: "Mohamed" <nmohamed@cisco.com>
> > > To: "'Sergio Jimenez Arguedas'" <sejimenez@its.co.cr>;
> > > <ccielab@groupstudy.com>
> > > Sent: Thursday, April 29, 2004 12:56 AM
> > > Subject: RE: BGP MED Scenario!!!
> > >
> > >
> > > > Hi,
> > > > I got your question, sorry I couldnot spare time to do in OSPF!.
> > > >
> > > > SFM#sh ip route eigrp
> > > > 20.0.0.0/24 is subnetted, 1 subnets
> > > > D 20.1.1.0 [90/28416] via 25.25.25.26, 00:01:31,
> > FastEthernet3/6
> > > > 200.100.100.0/24 is variably subnetted, 2 subnets, 2 masks
> > > > D 200.100.100.0/24
> > > > [90/128512] via 25.25.25.26, 00:01:31, FastEthernet3/6
> > > > 201.100.100.0/24 is variably subnetted, 2 subnets, 2 masks
> > > > D 201.100.100.0/24
> > > > [90/128512] via 25.25.25.26, 00:01:31, FastEthernet3/6
> > > >
> > > > Note the metric on eigrp route-128512 for network 200.100.100.0/24
> > > >
> > > > Now -
> > > > SFM#sh run | b router bgp
> > > > router bgp 100
> > > > no synchronization
> > > > bgp log-neighbor-changes
> > > > network 200.100.100.0 <<<<<<<<<<<<<<<<
> > > > network 201.100.100.0 <<<<<<<<<<<<<<<<<
> > > > neighbor 25.25.25.26 remote-as 100
> > > > neighbor 99.99.99.2 remote-as 300
> > > > neighbor 99.99.99.2 route-map INT out
> > > > no auto-summary
> > > >
> > > > So here iam advertising network 200.100.100.0.
> > > >
> > > > Down---------------SFM-----------Side---------Up
> > > >
> > > > From down to sfm router,I run eigrp and down advertise
> > > > 200.100.100.0
> >
> > > > and 201.100.100.0 as eigrp routes to sfm router. I DON'T
> > > > REDISTRIBUTE EIGRP HERE!!!! In SFM. I advertise using network
> > > > command.I set a route-map to Side router. Now see what the
> > > > route-map
> >
> > > > is
> > > >
> > > >
> > > > ip as-path access-list 9 permit .*
> > > > route-map INT permit 10
> > > > match as-path 9
> > > > set metric-type internal
> > > > End
> > > >
> > > >
> > > > So BGP set the metric of the advertised routes 200.100.100.0 and
> > > > 201.100.100.0 to Side as Eigrp metric=128512 . Side#sh ip bgp BGP>
> > > table version is 78, local router ID is 213.1.4.1 Status codes: s
> > > > suppressed, d damped, h history, * valid, > best, i - internal
> > > > Origin codes: i - IGP, e - EGP, ? - incomplete
> > > >
> > > > Network Next Hop Metric LocPrf Weight Path
> > > > *> 200.100.100.0 99.99.99.1 128512 0 100 i
> > > > *> 201.100.100.0 99.99.99.1 128512 0 100 i
> > > > Side#
> > > >
> > > > I think it don't do anyother job than this!!
> > > >
> > > > Thanks
> > > > Mohamed.
> > > >
> > > >
> > > >
> > > > -----Original Message-----
> > > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
> > > > Behalf
> >
> > > > Of Sergio Jimenez Arguedas
> > > > Sent: Wednesday, April 28, 2004 10:08 PM
> > > > To: ccielab@groupstudy.com
> > > > Subject: Fw: BGP MED Scenario!!!
> > > >
> > > >
> > > > Hi Mohamed,
> > > >
> > > >
> > > > I really understand that, but the doubt is the following,
> > > >
> > > > 172.16.0.0------RA-------------RB-------------RC-------------RD
> > > >
> > > >
> > > > Config RB
> > > >
> > > >
> > > > router bgp 1
> > > > netw 172.16.0.0
> > > > neighbor x.x.x.x remote-as 2
> > > >
> > > >
> > > > RBsi
> > > > Tx the prefix if it has a route of 172.16.0.0 in the routing
> > > > table.
> >
> > > > RB Rx the route from RA by ospf, So RB tx the prefix with the IGP
> > > > metric to RC without THE ROUTE-MAP with set metric-type internal.
> > > >
> > > >
> > > > Question: How can I use a route-map with set metric-type internal?
> > > >
> > > >
> > > > Thanks,
> > > >
> > > >
> > > > Sergio
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > ----- Original Message -----
> > > > From: "Mohamed" <nmohamed@cisco.com>
> > > > To: "'Sergio Jimenez Arguedas'" <sejimenez@its.co.cr>;
> > > > <ccielab@groupstudy.com>
> > > > Sent: Wednesday, April 28, 2004 1:20 AM
> > > > Subject: RE: BGP MED Scenario!!!
> > > >
> > > >
> > > > > I tried in my router,
> > > > >
> > > > > A----------B----------C---------D
> > > > >
> > > > > A,B are IBGP,running OSPF.
> > > > > B redistributing OSPF into BGP.
> > > > > C is EBGP of B.
> > > > > D is Ebgp of C
> > > > >
> > > > > Now in C,we get the metrics from B,bcoz C only reset the metric
> > > > > to
> >
> > > > > zero. In D we don't get metric.
> > > > >
> > > > >
> > > > > Now if u put route-map and set metric-type int or even set
> > > > > origin igp,I don't get any mteric in D,bcoz MED is a optional
> > > > > Non-transitive attribute,which never passed to EBGP peers.
> > > > >
> > > > >
> > > > > Thanks
> > > > > Mohamed.
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > -----Original Message-----
> > > > > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
> > > > > Behalf
> > >
> > > > > Of Sergio Jimenez Arguedas
> > > > > Sent: Wednesday, April 28, 2004 2:29 AM
> > > > > To: ccielab@groupstudy.com
> > > > > Subject: BGP MED Scenario!!!
> > > > >
> > > > >
> > > > > Hi Group,
> > > > >
> > > > > I have a question about BGP MED, the scenario is the following:
> > > > >
> > > > >
> > > > >
> > > > > --------------EB GP----------------------R4
> > > > > OSPF |
> > > > > |ibgp
> > > > > NETA
> > > > > ----------R1------------------------------R2------------EBGP----
> > > > > --
> > > > > --
> > > > > --
> > > > > --
> > > > > -----
> > > > > -----R3-------------EBGP-----------------R5
> > > > >
> > > > >
> > > > > R1 Tx NETA to R2 by OSPF and R2 Tx NetA to R3/R4 by EBGP. R3 and
>
> > > > > R4 Rx
> > > >
> > > > > NETA with the IGP (OSPF) metric. When R3 Tx the route R5, R5 Rx
> > > > > the route with the metric 0. I understood it, but I have the
> > > > > following
> > > > > question:
> > > > >
> > > > >
> > > > > If I apply a route-map from R3 to R5 with set metric-type
> > > > > internal.......This would cause BGP routes to carry the internal
>
> > > > > IGP
> > >
> > > > > metric as the BGP MED?
> > > > >
> > > > > R3/R4 carried the IGP metric without a route-map in R2.
> > > > >
> > > > >
> > > > >
> > > > > Could you help me, please?
> > > > >
> > > > >
> > > > > Reference: HALABI Pag_340
> > > > >
> > > > >
> > > > >
> > > > > Rgds,
> > > > >
> > > > >
> > > > > Sergio Jiminez A.
> > > > >
> > > > > ________________________________________________________________
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> > > > > __
> > > > > __
> > > > > _
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