Static Route Disappear and BGP advertise

[MrBeginner]

Hi All,

I would like to confuse static route in routing table.When i add static route in routing table i didn't see this route in routing table.In the lab i can see ( #sh ip route) this static route.So let me know when static route can not display in routing table ? I knew if interface is up static will be always in routing table .is it correct ?

I aslo want to know BGP advertisement.I have many branches and one DC.we are peer to ISP router with BGP.if we increase new site one advertise route are added to our DC router that peer to ISP router also.I don't want alot of advertise route to MY DC router.I want only one summarize route ,is can be ? Let me know bgp can advertise ISP router to my DC router that everywhere you want to go come to me ?

[Deepak Kumar]

Hi,

I would like to confuse static route in routing table.When i add static route in routing table i didn't see this route in routing table.In the lab i can see ( #sh ip route) this static route.So let me know when static route can not display in routing table ? I knew if interface is up static will be always in routing table .is it correct ?4

Ans: The static route will only avaiable in the routing table of Interface is UP and next-hop (which is defined in the Static route) is available. As an example, you are configuring a static router as:

IP route 192.168.10.0 255.255.255.0 10.10.10.1 ---> If Router does not know where is 10.10.10.1 then this route will not appear in the routing table.

IP route 192.168.10.0 255.255.255.0 GigabitEthernet0/0 ----> If Interface gig0/0 is up and having a valid IP address.

I aslo want to know BGP advertisement.I have many branches and one DC.we are peer to ISP router with BGP.if we increase new site one advertise route are added to our DC router that peer to ISP router also.I don't want alot of advertise route to MY DC router.I want only one summarize route ,is can be ? Let me know bgp can advertise ISP router to my DC router that everywhere you want to go come to me ?

Ans: Your question is not clear to me. If you want to summaries the BGP route then uses a command under the  BGP configuration as "aggregate-address x.x.x.x x.x.x.x" .Really, we need some more information as a diagram and basic information on the BGP configuration.    

[MrBeginner]

Hi,

IP route 192.168.10.0 255.255.255.0 10.10.10.1 ---> If Router does not know where is 10.10.10.1 then this route will not appear in the routing table.

If Router know where is 10.10.10.1 then this route will appear in the routing table correct ? if the next hop is the tunnel ip ,will it appear in routing table ?

For Eg, ip route 192.168.10.0 255.255.255.0 10.10.10.1 ( let say 10.10.10.1 is local tunnel ip ) ,will appear in routing table,correct ?

For BGP, Please see the below diagram.let me know.I didn't know ISP how to configure.I only configure my CE router BGP peer to ISP router. I want to know or i want to get route advertisement as single route like default route in DC router.is it possible ? ISP router 1 can advertise to my DC router that he is the next hop for every network ?

Eg.

0.0.0.0/0 [1/0] via 1.1.1.1

[Deepak Kumar]

Hi,

If Router know where is 10.10.10.1 then this route will appear in the routing table correct ? if the next hop is the tunnel ip ,will it appear in routing table ?

For Eg, ip route 192.168.10.0 255.255.255.0 10.10.10.1 ( let say 10.10.10.1 is local tunnel ip ) ,will appear in routing table,correct ?

As I am looking your route configuration "IP route 192.168.10.0 255.255.255.0 10.10.10.1" and 10.10.10.1 is the local tunnel IP address is local Tunnel IP then you will get en error message as "%Invalid next hop address (it's this router)"

If 10.10.10.1 belongs to the remote end tunnel IP address then your tunnel interface must be in UP/UP state. 

For BGP, Please see the below diagram.let me know.I didn't know ISP how to configure.I only configure my CE router BGP peer to ISP router. I want to know or i want to get route advertisement as single route like default route in DC router.is it possible ? ISP router 1 can advertise to my DC router that he is the next hop for every network ?

Eg.

0.0.0.0/0 [1/0] via 1.1.1.1

No, you can't & your ISP will not allow you to advertise default route. If you have purchased your own Public IP address space from the Govt or IP address provider then you can advertise only your own address space as suppose you had purchased 1.1.1.0/24 space for your datacenter then you can advertise it.

[MrBeginner]

Hi,

10.10.10.1 is the local tunnel IP address is local Tunnel IP then you will get en error message as "%Invalid next hop address (it's this router)"

==>This is i just want to know weather it is working on cisco routers because somebody typed tunnel ip as next hop router IP on HP router. I always type on cisco router like==>ip route 192.168.10.0 255.255.255.0 tunnel 1<==..When i tested in lab you are right.can not type on cisco router.I don't know why HP router can type.

suppose you had purchased 1.1.1.0/24 space for your data center then you can advertise it

==>this mean we need to purchase special purchase to summarize and advertise one route to our DC router?

[Deepak Kumar]

Hi,

==>this mean we need to purchase special purchase to summarize and advertise one route to our DC router?

I think Here question has changed, Are you configuring your ISP router or CE or PE router? As I was understating that you are configuring CE router and you want to a default route toward to the PE router. 

As now again I have gone through the complete question and got that you are configuring PE router. You want to advertise an only default route from PE to CE then the configuration would be like:

ip prefix-list default-route seq 10 permit 0.0.0.0/0

router bgp xxx
 ...
 neighbor a.b.c.d prefix-list default-route out

[MrBeginner]

hi ,

Sorry for my misunderstanding question. i only configure CE router.I only peer to ISP PE router.i cannot touch ISP router.I only want to know if my DC router want only one advertise route from ISP router ,what should i do ?

All branch sites router is no problem.All branches site peer to ISP router also. I only want to know if DC router want one route only from ISP router to go other sites,How should i do ?

[Deepak Kumar]

Hi,

I only want to know if my DC router want only one advertise route from ISP router ,what should i do ?

Please speak with your ISP team. You can't do anything in this case. Because routes are advertising from PE to CE so your ISP must reconfigure the PE router and advertise only a default route toward your CE router. 

[MrBeginner]

Hi,

Thank for your ans.

 ISP must reconfigure the PE router and advertise only a default route toward your CE router. 

==>This mean ISP can advertise only default route to our DC router ? it is not effect to other network,correct? I didn't know BGP can do or not.So,If it is can ,i want to request ISP to do that.Now ,ISP advertise all branches sites network to My DC router.

[Deepak Kumar]

Hi,

If it is an Internet connection, nothing will affect but you will lose flexibility for traffic engineering. If it is an MPLS connection then Its required BGP routes on your CE router. 

Again, It is better if you will share your CE router configuration with us.

[paul driver]

Hello

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@MrBeginner wrote:
All branch sites router is no problem.All branches site peer to ISP router also. I only want to know if DC router want one route only from ISP router to go other sites,How should i do ?

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A more deterministic way to advertise a default route to specific or individual bgp peers and it doesn't require to have a default route in the route table beforehand would be to use the following command, but use this with caution as it could black hole you traffic if the upstream peer that's advertising these default itself loses connection its isp peer

router bgp xxx
neighbor xxx default-originate

[paul driver]

Hello

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@Deepak Kumar  wrote:

wants only default from ISP

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If thats the case then a simple prefix-list negating any other route other than a default can be appended towards the ISP peer that if the peer is advertsieng a default.

ip prefix-list default permit 0.0.0.0/0
ip prefix-list default permit 0.0.0.0/0 le 32 < not needed but for clarity

router bgp xx
neighbor <-->> prefix-list default in

.

[Deepak Kumar]

Hi,

His question is different because he wants to change this behavior for routes that is receiving from the PE router. And PE router is not in his control.

[paul driver]

Hello

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@Deepak Kumar wrote:

Hi,

His question is different because he wants to change this behavior for routes that is receiving from the PE router. And PE router is not in his control.

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Why can't he just do that by filtering ingress routes advertised by his PE route to his rtr as per example above?

[Deepak Kumar]

Hi,
Yes, We can do it but still not sure that it is having MPLS or Internet connection. If there is an MPLS connection then I don't think that he is receiving the Default route.