basic BGP configuration

[kami sh]

Hi everyone,

I have an ISP that based on ADSL media.I have a ASR 1002 router and a 3560 SW and some Servers.I have a range of IP address /24 but I will take 1024 IP from RIN and want to run BGP between my internet service provider.Now I have 100 online ADSL users.Finally I will get Internet service from another ISP (totally two ISP) and keep redundancy between two ISP.If it is needed I am going to buy a another router like Cisco 7200.

Would you help me about designing new BGP  but still i have not run BGP yet and I want to keep this range of IP address /24 that consumption to ADSL users.

The attached file is my topology diagram.

[Nagendra Kumar Nainar]

Hi Kamish,

Am I assuming right that you have /24 assigned to the servers and need to advertise the same via BGP to ISP?. Are you getting 1024 IP from RIR because the current /24 is private range?.

Can you explain more about the ADSL users?. When you say you have 100 ADSL users connected, do you mean IP connection from 100 users accessing the server?. or a DSLAM terminating the sesions?.

-Nagendra

[kami sh]

Hi Negenda,

Thank you for answering,

the range of IP /24 is public IP that got it from my first ISP.I define /24 IP in my DHCP server that it gets to ADSL users.ISP routed these IPs toward to internet.

1024 IPs i got from ARIN(new).ARIN requseted me to run BGP.

Now I want to run BGP between my router and first ISP and i want to advertise 256 IPs and new 1024 IPs via BGP .

my router and switch and servers and 100 ADSL users assigned by 38.x.x.0 /24 and new IPs are  new Range 74.x.x.x.I want to assigned new IPs to new ADSL users.

if you want another information please inform me.

Thank you

[blau grana]

Hi Kamish,

Do you have your own public AS number? I am not expert in BGP peering but after first ISP gave you /24 of public IP addresses, you have to make some sort of agreement with him before you start this block of IPs advertise via another ISP. 

This is basic BGP config, if you have some questions or further requirements let us know.

router bgp YOUR_AS

neighbor 1.1.1.1 remote-as ISP1_AS

neighbor 2.2.2.2 remote-as ISP2_AS

!

address-family ipv4

  network x.x.x.x mask y.y.y.y

       .

       .

       .

  network x.x.x.x mask y.y.y.y

  aggregate-address 38.0.0.0 255.255.255.0 summary-only

  aggregate-address 74.0.0.0 255.255.255.0 summary-only

  neighbor 1.1.1.1 activate

  neighbor 1.1.1.1 send-community both

  neighbor 1.1.1.1 prefix-list RECEIVE_DEFAULT in

  neighbor 1.1.1.1 prefix-list ADVERTISE_OUR_NET out

  neighbor 1.1.1.1 route-map PREFER_THIS_LINK_FOR_OUTGOING_TRAFFIC in

  neighbor 1.1.1.1 filter-list 1 out

  neighbor 2.2.2.2 activate

  neighbor 2.2.2.2 send-community both

  neighbor 2.2.2.2 prefix-list RECEIVE_DEFAULT in

  neighbor 2.2.2.2 prefix-list ADVERTISE_OUR_NET out

  neighbor 2.2.2.2 route-map PREFER_OTHER_LINK_FOR_INCOMMING_TRAFFIC out

  neighbor 2.2.2.2 filter-list 1 out

exit-address-family

!

ip bgp-community new-format

ip as-path access-list 1 permit ^$

!

ip prefix-list ADVERTISE_OUR_NET seq 5 permit 38.0.0.0/24

ip prefix-list ADVERTISE_OUR_NET seq 10 permit 74.0.0.0/24

!

ip prefix-list RECEIVE_DEFAULT seq 5 permit 0.0.0.0/0

!

route-map PREFER_OTHER_LINK_FOR_INCOMMING_TRAFFIC permit 10

set as-path prepend YOUR_AS YOUR_AS YOUR_AS

!

route-map PREFER_THIS_LINK_FOR_OUTGOING_TRAFFIC permit 10

set local-preference 1000

set weight 1000

Best Regards

Please rate all helpful posts and close solved questions

[kami sh]

HI blau grana

Thank you for sending a configuration.

We have public AS.My first block IP /24 i;v got from first ISP and another block IP that recently i'v Got it from ARIN.

I am goinig to negotiate with 2 ISPs for advertise these IPs but i want to use second ISP for backup only.

Best Regards