BGP between 2 ISP links with auto failover & load balancing

[needtechhelp]

Dear friends, plz help in following scenerio.

My company have 7 locations all over India.We had a link from one ISP.Now, my company want to a link from other ISP which would be act as back up in case of primary goes down & can use in load balancing facility.

My doubts:

1. My doubt is can a BGp router has 2 AS since, in this case , both ISPs would provide me 2 AS.

2. How can I configure load balancing in BGP?

3. How can I configure auto failover ?

PLz guide me

[r.malviya]

Hi Abhi ,

Answers

1) You no need to use 2 AS no .

ISP 1 (AS 100)                ISP 2(AS 200)

            |                                   |

            |                                   |

                       U R (AS 300)

U can't do Ioadbalancing in BGP like other routing protocol do .

Sample config

--------------------

interface Serial 0
ip address 10.10.10.1 255.255.255.0
no ip route-cache
   
interface Serial 1
ip address 20.20.20.1 255.255.255.0
no ip route-cache
  
router bgp 300
neighbor 10.10.10.2 remote-as 100
neighbor 10.10.10.2 route-map UPDATES-1 in

!--- This allows only the networks up to 128.0.0.0.

neighbor 20.20.20.2 remote-as 200
neighbor 20.20.20.2 route-map UPDATES-2 in

!--- This allows anything above the 128.0.0.0 network.

auto-summary
 
route-map UPDATES-1 permit 10
match ip address 1
set weight 100

route-map UPDATES-1 permit 20
match ip address 2
 
route-map UPDATES-2 permit 10
match ip address 1
 
route-map UPDATES-2 permit 20
match ip address 2
set weight 100
 
access-list 1 permit 0.0.0.0  127.255.255.255
access-list 2 deny 0.0.0.0 127.255.255.255
access-list 2 permit any

There are other paramiter as well you can set to influance the incoming & outgoing traffic

like u can set local Pref/weight attribute for outgoing
& AS Path prepand for incoming traffic as well .

Regards

Ritesh 

[needtechhelp]

Ritesh, Thanks for answer.

There is one command in BGp : Maximum-path =

can I use the same for load balancing?

[amigomnemonik]

Load balancing works only if you have 2 peer connections to the same AS number. Filtering prefixes via route maps and attaching them to the neighbour statements seems to be the best option.

Sent from my iPhone

[r.malviya]

How can I configure auto failover ?

Auto failover is always there becasue when u config both off the ISP , So on u r router u can see u are getting the same prefix from 2 different Next-hop(or ISP)

it will use only one as best & next will be ideal ,

when u r primary will down u still have same prefix from other ISP in bgp table

& automatically it will install in routing table .

Regards

Ritesh