From: mattclark@hispeed.ch
Date: Thu Jul 06 2006 - 06:19:16 ART
Excellent examples, thankyou both for your time.
matt
>*Note if R1 router is receiving routing information for network
>150.1.2.0/24 from two different sources, let's say EBGP and Eigrp and
>Eigrp was
>offering a more attractive path to Network 150.1.2.0 /24, R1 will accept the
>routing information from EBGP, because it has a lower administrative
>distance (20 versus 90). The "Network backdoor" command is BGP's solution to
>this situation, BGP's "backdoor" command assigns an administrative distance
>of 200 to the Eigrp network that its advertising, in this case 150.1.2.0/24.
>*
>*After entering the "backdoor" command, the router will accept Eigrp's
>advertisement, because Eigrp will have a lower administrative distance (90
>versus 200). *
>
>*Understand that this router is not the originator of network 150.1.2.0 /24,
>but it has to use the "network" command in order to apply the "backdoor"
>keyword to network 150.1.2.0 /24. *
>
>*A "show ip route" command will reveal that Eigrp is the path that this
>router takes to get to network 150.1.2.0 /24. *
>
>
>
> R1(config)#router bgp 200
>
> R1(config-router)#network 150.1.2.0 mask 255.255.255.0 backdoor
>
>
>Narbik Kocharians
>CCIE# 12410 (R&S, SP, Security)
>CCSI# 30832
>Network Learning, Inc. (CCIE class Instructor)
>www.ccbootcamp.com (CCIE Training)
>
>
>On 7/6/06, Mister T <romantic24hrs@gmail.com> wrote:
>>
>> Hi...I took this from McGraw Hill book (I already practiced it), saying :
>>
>> Cisco provides a way to force IGP routes to take precedence over EBGP
>> routes. The concept is called
>> "backdoor links." EBGP routes can be tagged as backdoor routes, which sets
>> the distance of these routes to the
>> same as BGP local or 200. Since the distance is then higher than the IGP
>> route, the backdoor IGP route is preffered.
>>
>> In order to get Router to prefer the IGP learned route, the BGP learned
>> prefix must be tagged as a backdoor route. To tag the network prefix as a
>> backdoor route perform the following on Router:
>> Router(config)#router bgp 300
>> Router(config−router)#network 152.1.1.4 mask 255.255.255.252backdoor
>>
>> mister t
>>
>> On 7/6/06, mattclark@hispeed.ch <mattclark@hispeed.ch> wrote:
>> >
>> > Hi group
>> >
>> > Came across this command and wanted to know a useful example of when to
>> > implement this feature. is a backdoor route just a fancy way of saying a
>> > backup route if you lost routes? the DocCD states that a backdoor
>> network is
>> > treated as a local network, except that it is not advertised.
>> > Any other explanations would be appreciated.
>> >
>> > Matt
>> >
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