We are in the processing of implementing multi-homed BGP using two T1 lines from two different providers, ATT and Cogent on our Cisco 3825. Wanted to add some redundancy to the Cogent line in case Cogent and Level3 have any more peering disputes! 
We have done all the leg work with obtaining our own /24 class C IP block and our own ASN with ARIN. We are at the point of implementing BGP for failover, but I would like to utilize both lines if possible. Here is what I am trying to accomplish:
ISP A and ISP B connect to our Cisco 3825 ISR (512MB memory). We advertise our full class C network out both interfaces. If ISP A's link goes down all traffic will route through ISP B and vice versa - this should be transparent to our internal users browsing the web and outside clients connecting to our servers (web, ftp, email, citrix, vpn, etc).
I know it is almost impossible to get a true 50/50 load balancing when you BGP with two different ISP's, but I do want to utilize both lines equally as much as I can. How can this be accomplished? I have the initial config below to start with:
router BGP XXXXX
no synchronization
network xxx.xxx.xxx.xxx
neighbor xxx.xxx.xxx.xxx remote-as 174
neighbor xxx.xxx.xxx.xxx route-map localonly out
neighbor xxx.xxx.xxx.xxx description Cogent's Peer
neighbor xxx.xxx.xxx.xxx password *************
neighbor xxx.xxx.xxx.xxx remote-as 7132
neighbor xxx.xxx.xxx.xxx route-map localonly out
neighbor xxx.xxx.xxx.xxx description ATT's Peer
neighbor xxx.xxx.xxx.xxx password *************
I have the following questions
1. Is it best to receive full route tables (I have 512MB memory)?
2. Is the "route-map localonly out" command all I need to ensure that our AS will not become a transit AS for Internet traffic?
3. I have read pro's and con's to the "bgp log-neighbor-changes" command. Is this something I should enable?
4. Is the "neighbor xxx.xxx.xxx.xxx soft-reconfiguration inbound" command recommended - what does this command do?
5. I have come across some posts that suggest adding these statements:
ip as-path access-list 10 permit ^$
!
route-map localonly permit 10
match as-path 10
What does this accomplish? Does this need to be included with the "route-map localonly out" command issued within?
6. I want to make sure that both outbound and inbound traffic are "load-sharing" between the two lines. Again I know you cannot achieve a true 50/50 load balance, but I want to utilize both lines and also make sure they act as a failover for each other. How can I best achieve this? Should I enable per-packet or per-destination load sharing? Should IP CEF be enabled for both load sharing methods?
I appreciate any help anyone can offer as I am a little new to BGP.
We have done all the leg work with obtaining our own /24 class C IP block and our own ASN with ARIN. We are at the point of implementing BGP for failover, but I would like to utilize both lines if possible. Here is what I am trying to accomplish:ISP A and ISP B connect to our Cisco 3825 ISR (512MB memory). We advertise our full class C network out both interfaces. If ISP A's link goes down all traffic will route through ISP B and vice versa - this should be transparent to our internal users browsing the web and outside clients connecting to our servers (web, ftp, email, citrix, vpn, etc).
I know it is almost impossible to get a true 50/50 load balancing when you BGP with two different ISP's, but I do want to utilize both lines equally as much as I can. How can this be accomplished? I have the initial config below to start with:
router BGP XXXXX
no synchronization
network xxx.xxx.xxx.xxx
neighbor xxx.xxx.xxx.xxx remote-as 174
neighbor xxx.xxx.xxx.xxx route-map localonly out
neighbor xxx.xxx.xxx.xxx description Cogent's Peer
neighbor xxx.xxx.xxx.xxx password *************
neighbor xxx.xxx.xxx.xxx remote-as 7132
neighbor xxx.xxx.xxx.xxx route-map localonly out
neighbor xxx.xxx.xxx.xxx description ATT's Peer
neighbor xxx.xxx.xxx.xxx password *************
I have the following questions
1. Is it best to receive full route tables (I have 512MB memory)?
2. Is the "route-map localonly out" command all I need to ensure that our AS will not become a transit AS for Internet traffic?
3. I have read pro's and con's to the "bgp log-neighbor-changes" command. Is this something I should enable?
4. Is the "neighbor xxx.xxx.xxx.xxx soft-reconfiguration inbound" command recommended - what does this command do?
5. I have come across some posts that suggest adding these statements:
ip as-path access-list 10 permit ^$
!
route-map localonly permit 10
match as-path 10
What does this accomplish? Does this need to be included with the "route-map localonly out" command issued within?
6. I want to make sure that both outbound and inbound traffic are "load-sharing" between the two lines. Again I know you cannot achieve a true 50/50 load balance, but I want to utilize both lines and also make sure they act as a failover for each other. How can I best achieve this? Should I enable per-packet or per-destination load sharing? Should IP CEF be enabled for both load sharing methods?
I appreciate any help anyone can offer as I am a little new to BGP.
