Advertise Networks via BGP

[johnhesd6]

I have 2 Headend routers at a DataCenter. I have 4 different ISP being installed. I want to make sure everything is redundant.

!. Best practices would be to have IBGP between the two routers and to advitise networks out of both router. so basically both configuration for BGP willl match?

2. Do I need to prepend anything?

thank you 

[Reza Sharifi]

If you prepend your AS, it will effect inbound (incoming) traffic to you. For example, if you want site-A to be the primary and site-B backup, then you prepend your AS on site-B, so site A is always the preferred path.  

HTH

[johnhesd6]

thank you!

These routers will be at the same location I just need to set them up so we are redundant.

I dont think what I can do is set something like this up. Please let me know

Router A
!
router bgp [EBGP]
bgp log-neighbor-changes
network 44.44.44.0 mask 255.255.255.0 set higher Local Pref
network 55.55.55.0 mask 255.255.255.0 set higher Local Pref
network 66.66.66.0 mask 255.255.255.0 prepend this
network 77.77.77.0 mask 255.255.255.0 prepend this
!
neighbor x.x.x.x remote-as [EBGP]
neighbor x.x.x.x remote-as [EBGP]
!
neighbor 10.0.0.2 remote-as [EBGP] L3 switch
neighbor 10.2.2.2 remote-as [IBGP] secondary router

RouterB
router bgp [EBGP]
bgp log-neighbor-changes
network 44.44.44.0 mask 255.255.255.0 prepend this
network 55.55.55.0 mask 255.255.255.0 prepent this
network 66.66.66.0 mask 255.255.255.0 set higher Local Pref
network 77.77.77.0 mask 255.255.255.0 set higher Local Pref
!
neighbor x.x.x.x remote-as [EBGP]
neighbor x.x.x.x remote-as [EBGP]
!
neighbor 10.0.0.1 remote-as [EBGP] L3 switch
neighbor 10.2.2.1remote-as [IBGP] primary router

[Julio E. Moisa]

Hi

You can use higher Local preference and lowest AS-Prepend on the primary router and lowest Local preference and Higher AS-Prepend on the secondary router in order to have symmetric traffic. Also remember to configure each router as next-hop-self for each other.

:-)

[johnhesd6]

I forgot about next-hop-self. "thanks"

As I have it now will that be ok I am trying to split the two routers so it is basically active active.

Note those address spaces are provided by ISP. So I can if ATT goes down I can advitise that ip space out Verizon?

[Julio E. Moisa]

Hi

Yes you can, I recommend use prefix-lists and route-maps, also you can configure fall-over on the peering. 

[johnhesd6]

great that is what I was planning route-maps for prepend and local preference 

Not sure the command fail-over is can you please explain 

[Julio E. Moisa]

Hi 

This command is used to immediately detect when a neighbor is down and deactivate the peering otherwise BGP will wait until the dead time. 

I recommend a scheme active-standby

http://www.cisco.com/c/en/us/td/docs/ios/12_0s/feature/guide/cs_bsfda.html

:-)

[johnhesd6]

@Jon

You are correct I don't need to set Local Pref.

Does anybody have a really good bgp looking glass to use

Active standby ? I will have 4 differnet ISP on two routers all 1 gig connections.

This will be customers coming in via the public ip address provided by the ISP

[Reza Sharifi]

Does anybody have a really good bgp looking glass to use

I use this site to look up prefixes.

They are in CA

https://lg.he.net/

http://bgp.he.net/

HTH

[Jon Marshall]

I may be misunderstanding but you don't set local preference on routes you are advertising, you set it on routes you receive.

Jon

[Reza Sharifi]

Yes, you advertise all routes from both routes.  This way, if one provider goes down, the other one has the same routes. If you want to do active/active than you really don't need to use prepend. Prepend is used mostly for active/stand-by, so one path is longer then the other one.

HTH