BGP revisited

[rhltechie]

Hi All,

I popped in a while back to ask about some BGP situations. Things have changed and I am stuck on how to even begin a design. I obviously am very new to the BGP world! This is my situation:

Internet router - || - WAN router - wan cloud - backup internet pe router

My provider has asked that i run BGP between my internet router and my wan router and also between my wan router and their router for my backup internet connection. out in the wan cloud, all of the remote sites are headed back to the main site for internet connection, if something should happen to this host internet connected i would like for them to be able to routed to the backup internet. In the documentation i got from them, i see a command after the bgp commands that says " address-family ipv4" what exactly is this for? also, i was told to run iBGP between my internet route and my wan router and to run eBGP between my wan router and the provider router. can someone give me a nudge in the right direction? or comments on if this is the correct way to go about this.

TIA,

R

[olorunloba]

I really do not understand the diagram.

However, BGP is the dynamic routing protocol you can run on the internet. Because it is dynamic, it can be used to implement primary and secodary links situation. If the BGP session is within routers in the same AS, then it is called iBGP (Internal BGP). If the session is to another AS, then it is called eBGP (extenal BGP).

BGP can be used to advertise routes, aside the normal IPv4 (the common IP address). It can be used to advertise VPNv4 addresses as it is used in MPLS VPN for example. This concept gave rise to the address families in the BGP configuration. The IPv4 address family is the normal address family for our IPv4 configurations. Depending on the IOS, you might or might not see these address families. Note anyway, when BGP is used to advertise multiple protocols this way, is called MP-BGP (Multi Protocol BGP)

The following links should be helpful in understanding BGP and also for sample configuration.

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a00800c95bb.shtml

http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a008009456d.shtml

http://www.cisco.com/en/US/tech/tk365/tk80/tsd_technology_support_sub-protocol_home.html