Getting on my soapbox, and thinking about the way the light dawned
for me when I first studied exterior routing, it's terribly difficult
to plan complex BGP configurations without first writing a clear, and
preferably formal, definition of policies.
I like to think of policies as formal statements of the business or
other requirements that define "what problem are you trying to
solve." The basic mechanism for describing interdomain routing is
RPSL:
RFC 2622 Routing Policy Specification Language (RPSL). C. Alaettinoglu, C.
Villamizar, E. Gerich, D. Kessens, D. Meyer, T. Bates, D. Karrenberg,
M. Terpstra. June 1999.
RFC 2650 Using RPSL in Practice. D. Meyer, J. Schmitz, C. Orange, M.
Prior, C. Alaettinoglu. August 1999.
>David,
> I know what the commands are needed and how they work, what I
>didn't understand is why in the fatkid solution they were using the
>"send-community string within AS200 between route reflector(R4) and it
>clients(R2,R3). As well their solution was applying the route-map on
>inbound routing information from AS 300 at R2 and R3, whereas I applied my
>statements outbound to the route reflector(R4) which controls outbound
>traffic flow and information to AS 100. I was simply looking for the logic
>behind the provided solution.
>
>Nigel.
>
>----- Original Message -----
>From: David FAHED <[EMAIL PROTECTED]>
>To: Nigel Taylor <[EMAIL PROTECTED]>
>Cc: CCIE_Lab Group Study <[EMAIL PROTECTED]>; Cisco Group Study
><[EMAIL PROTECTED]>; Bryant Andrews <[EMAIL PROTECTED]>;
><[EMAIL PROTECTED]>
>Sent: Sunday, February 25, 2001 7:49 AM
>Subject: Re: Fatkid - Adv BGP Lab 325
>
>
>> The communities are not propagatedto internal or external BGP neighbors by
>> default. The send-community option is required in order for the assigned
>> community to be sent out.
>> And you need to use the community no-export to avoid the route to be
>> propagated ....
>>
>>
>> Nigel Taylor wrote:
>>
>> > All,
>> > I just got done working through lab 325 - Adv BGP Routing and I was
>=
>> > hoping someone could tell me if I'm missing something or =
>> > misunderstanding the requirements for task (11) eleven. The =
>> > requirements calls for the implementation of communitites attribute to =
>> > dynamically limit the advertisment of an external learned network route
>=
>> > from AS300 to AS100. In doing so I accomplished this with the use of =
>> > applying the following configuration commands. In the fatkid solution =
>> > they make use of the command "send-community" on every bgp peer =
>> > connection. Based on the requirements I don't think this necessary? =
>> > Anyone did this lab and had the same questions or thoughts..
>> >
>> > Nigel.
>> >
>> > R2:
>> > router bgp 200
>> > bgp router-id 190.19.15.145
>> > redistribute eigrp 200 route-map localnet
>> > neighbor 190.19.15.177 remote-as 200
>> > neighbor 190.19.15.177 update-source Loopback0
>> > neighbor 190.19.15.177 send-community
>> > neighbor 190.19.15.177 route-map setcom out
>> > neighbor 210.10.10.5 remote-as 300
>> > neighbor 210.10.10.5 weight 450
>> > no auto-summary
>> > !
>> > ip classless
>> > !
>> > dialer-list 1 protocol ip permit
>> > route-map setcom permit 10
>> > set community no-export
>> >
>> > R3:
>> > router bgp 200
>> > bgp router-id 190.19.15.161
>> > redistribute eigrp 200 route-map localnet
>> > neighbor 190.19.15.177 remote-as 200
>> > neighbor 190.19.15.177 update-source Loopback0
>> > neighbor 190.19.15.177 send-community
>> > neighbor 190.19.15.177 route-map setcom out
>> > neighbor 210.10.10.1 remote-as 300
>> > no auto-summary
>> > !
>> > ip classless
>> > !
>> > dialer-list 1 protocol ip permit
>> > route-map setcom permit 10
>> > set community no-export
>> >
>> > R4:
>> > router bgp 200
>> > bgp router-id 190.19.15.177
>> > bgp log-neighbor-changes
>> > redistribute eigrp 200 route-map localnet
>> > neighbor 190.19.15.145 remote-as 200
>> > neighbor 190.19.15.145 update-source Loopback0
>> > neighbor 190.19.15.145 route-reflector-client
> > > neighbor 190.19.15.161 remote-as 200
>> > neighbor 190.19.15.161 update-source Loopback0
>> > neighbor 190.19.15.161 route-reflector-client
>> > neighbor 192.19.15.1 remote-as 100
>> > neighbor 192.19.15.1 route-map weight250 in
>> > no auto-summary
>> >
>> > R4#sh ip bgp
>> > BGP table version is 25, local router ID is 190.19.15.177
>> > 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
>> > *> 20.1.1.0/24 192.19.15.1 0 250 100 i
>> > *> 22.1.1.0/24 192.19.15.1 0 250 100 i
>> > *> 24.1.1.0/24 192.19.15.1 0 250 100 i
>> > * i190.1.0.0 210.10.10.1 0 100 0 300 i
>> > *>i 210.10.10.5 0 100 0 300 i
>> > *> 190.19.15.0/26 0.0.0.0 0 32768 ?
>> > * i 190.19.15.161 0 100 0 ?
>> > *> 190.19.15.64/26 0.0.0.0 0 32768 ?
>> > * i 190.19.15.145 0 100 0 ?
>> > *> 190.19.15.128/28 190.19.15.66 40537600 32768 ?
>> > * i 190.19.15.161 0 100 0 ?
>> > * i 190.19.15.145 0 100 0 ?
>> > *> 190.19.15.129/32 190.19.15.2 40537600 32768 ?
>> > * i 190.19.15.161 0 100 0 ?
>> > *> 190.19.15.130/32 190.19.15.66 40537600 32768 ?
>> > * i 190.19.15.145 0 100 0 ?
>> > *> 190.19.15.144/28 190.19.15.66 409600 32768 ?
>> > * i 190.19.15.145 0 100 0 ?
>> > Network Next Hop Metric LocPrf Weight Path
>> > *> 190.19.15.160/28 190.19.15.2 409600 32768 ?
>> > * i 190.19.15.161 0 100 0 ?
>> > *> 190.19.15.176/28 0.0.0.0 0 32768 ?
>> > *> 192.19.15.0 0.0.0.0 0 32768 ?
>> > *> 210.10.10.0/30 190.19.15.2 2195456 32768 ?
>> > * i 190.19.15.161 0 100 0 ?
>> > *> 210.10.10.4/30 190.19.15.66 2195456 32768 ?
>> > * i 190.19.15.145 0 100 0 ?
>> > r3_14#
>> >
>> > r4#sh ip bgp 190.1.0.0=20
>> > BGP routing table entry for 190.1.0.0/16, version 2
>> > Paths: (2 available, best #2, table Default-IP-Routing-Table, not =
>> > advertised to EBGP peer)
>> > Advertised to non peer-group peers:
>> > 190.19.15.161=20
>> > 300, (Received from a RR-client)
>> > 210.10.10.1 (metric 2195456) from 190.19.15.161 (190.19.15.161)
>> > Origin IGP, metric 0, localpref 100, valid, internal, synchronized
>> > Community: no-export
>> > 300, (Received from a RR-client)
>> > 210.10.10.5 (metric 2195456) from 190.19.15.145 (190.19.15.145)
>> > Origin IGP, metric 0, localpref 100, valid, internal, =
>> > synchronized, best
> > > Community: no-export
>
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