BG question

[mustafa.s.raza]

Currently, the client has single site and dual ISP providers running BGP. Now the client is tryinng to implement Geographic diversity for an Internet services via adding an internet circuit at site 2. In the event the internet down at site 1, the users will connect to site2 internet via mpls circuit between two sites. The internet service provider at each site is Verizon. Typically, the BGP is ran between two separate service provider.  What will be your design recommendations or throughts are geographic diversity using BGP, same provider and two sites? Any gains or benifits using two sites and same ISP provider? ANy design guide or white paper  explaining multi hop bgp or geographic diverse internet via bgp?

Thanks

[Marwan ALshawi]

Hi there

It is good to have redundant sites or links so the high availability will be higher

But you need to make sure each site uses the local Internet link and use the other site as a backup

This can be done in different ways and all it depends on you network design

If you have a logical dogram

Describe the network and routing to share here we can help you to get done in the right way

Generally speaking if each site uses the local edge router as a default gateway and each ISP link send you default route so what could do simply increase the weight of the local ISP default route to be the preferred one

But again not sure how those sites communicate is it via igp or another MPLs bgp peer over wan ?!

Sent from Cisco Technical Support iPhone App

[mustafa.s.raza]

Hi

I will send a visio tomorrow. High level overview:

Site 1:main site,internet 10mb Verizon ,10mb MPLS,users 60

Site2: no users, strictly dr site, T1 Internet Verizon, 10mb MPLS , users 0

Currently the client has dual ISP at the main site via two different provider. Provider x will be eliminated and the client will be keeping Verizon only circuit. Site2(dr) only and MPLS bgp between two site and T1 for back up purpose in the event internet connection to the main site failed.

Since the client already invested money in AS number and they will like to keep BGP design via geographic diversity using a second dr site as a backup for the Internet.

I wanted to know how this will be done.

My thought are same as yours, more weight for the ISP at the main site and appropriate bgp configuration at the edge Internet router. if the Internet fails at the main site, the Internet edge router at site2 should detect a failure and the bgp edge router at the DR site should become primary and business as usual. Again there are no users at dr site2.

What your thoughts ?

Note: the client has separate u2 and MPLA routers

Thanks for your help

Sent from Cisco Technical Support iPhone App

[Kishore Chennupati · Accepted solution]

Hi Mustafa,

1.Enable eBGP between your internet edge routers and the ISP. At the primary site edge router increase the local pref of incoming routes. This will ensure that the default route being learned from the ISP is preferred by your AS.

2. Enable iBGP between the Internet edge routers. The local pref will be propagated to this router and this will prefer the default route learned via the primary edge router over its ISP router.

In the event your primary internet should fail then both the sites would switch over to the DR site's internet.

Note:  make sure also to use AS_PATH prepending on the DR site edge router so that you dont have assymetric routing.

If you need more info please ask

HTH,

Kishore

Please rate if helps

[mustafa.s.raza]

Thanks Kishore. I appreciate your help

Sent from Cisco Technical Support iPhone App

[Marwan ALshawi]

the concept suggested by Kishore is correct but not sure how the two edge routers connected to each other

is it L2 link and you can run iBGP between them

or they go over andother MPLS BGP link ? as this effect the choice

[mustafa.s.raza]

MPLS link so that means we will run bgp not ibgp. Correct?

Sent from Cisco Technical Support iPhone App

[Kishore Chennupati]

Hi mustafa,

If you are not going to have a L2 link and would be sending default routes across the MPLS cloud then iBGP won't be necessary and local pref etc wont be needed as well. Just run eBGP with the MPLS ISP

All you need to do is to increase the weight of the incoming routes on the secondary router towards the MPLS ISP to say 40000 or something .

That would ensure that the default route from the primary router is preferred and when this fails then the secondary router will start advertisign its default route learned via its internet ISP. and the pirmary site will start using it.

on your secondary router

  router bgp 65000

  neighbor <  mpls ISP ebgp neighbor ip addres> weight 40000

HTH

Regards

Kishroe

Please rate if helps

[mustafa.s.raza]

MPLs link between sites and separate edge Internet and MPLS router

Sent from Cisco Technical Support iPhone App

[Kishore Chennupati]

One more thing there is small scenario you need to keep in mind.

1. When the primary internet goes down and it starts learnign the default route from the secondary site,

    what happens when the primary internet comes back up again.?

     What happens here is that the primary router learns the defualt route from the secondary router and also the Internet ISP. Since the BGP attributes are not being changed it might not start using the the default route from Internet ISP.

So you need to make some changes here as well. Just put the weight command towards the Internet ISP

router bgp 65000

  neighbor < Internet ISP ebgp neighbor ip addres> weight 40000

This wil ensure that the default route via the Internet ISP is preferred and that will be sent to the secondary router.

and the secondary router will start using the primary internet again and its business as usual

Regards

HTH

Please rate ifhelpful

[mustafa.s.raza]

Kishore

One more question:

If the ISP fails at primary site and the traffic goes to secondary site over the MPLs out to outbound internet, this is good for outbound Internet traffic. What happen for the incoming traffic? What should we so if the web servers are located in Primary and Secondary site which needed to access by clients. Basically I am asking how to switch the incoming traffic to secondary site in the event connection- Internet fails at the main site.

Thanks

Sent from Cisco Technical Support iPhone App

[mustafa.s.raza]

Thanks for your help

Sent from Cisco Technical Support iPhone App

[Marwan ALshawi]

well you can do it in many diffrent way

i think if you share a diagram shows how the logical routing of your client looks like wil be better to direct you to the right path

[mustafa.s.raza]