BGP AS numbers
We're switching to mpls sometime this year so I need to learn some bgp basics. Im labbing it up right now and I want to mimic it as close to our production network as possible, just the routers at least. How does one determine what bgp AS numbers to use? And not the AS number provided by isp used to connect to the mpls cloud but to establish connectivity outside of the cloud with existing p2p links. Screenshot attached is basically what we have now and everything is currently static routes. I'd like to get bgp running before going to mpls. In this video he says "AS in BGP is routers under your control" so does that mean all the routers below should be in the same AS or will there be 4 different AS's?
Comments
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networker050184
Mod Posts: 11,962 Mod
If its just BGP within your organization you can use any of the private AS numbers from 64512 to 65535.
As far as one AS or four AS, that would depend on what you are trying to accomplish. Is there any reason in particular you are using BGP rather than an IGP for your internal connectivity? I'd go with OSPF in this scenario personally. You probably aren't going to need any of the features BGP provides for a simple internal network like you have in your diagram. If you go with BGP there are quite a few design considerations.An expert is a man who has made all the mistakes which can be made. -
phoeneous
Member Posts: 2,333 ■■■■■■■□□□
networker050184 wrote: »If its just BGP within your organization you can use any of the private AS numbers from 64512 to 65535.
As far as one AS or four AS, that would depend on what you are trying to accomplish. Is there any reason in particular you are using BGP rather than an IGP for your internal connectivity? I'd go with OSPF in this scenario personally. You probably aren't going to need any of the features BGP provides for a simple internal network like you have in your diagram. If you go with BGP there are quite a few design considerations.
So all my current p2p links I can just use any igp and then on the interfaces that hit the mpls cloud just use bgp to talk to the pe's? Theres no particular reason why I chose bgp, I just figured I would use the same protocol throughout. They did this at my last job that had about 10 sites on mpls and used bgp internally and for the cloud. -
networker050184
Mod Posts: 11,962 Mod
So all my current p2p links I can just use any igp and then on the interfaces that hit the mpls cloud just use bgp to talk to the pe's? Theres no particular reason why I chose bgp, I just figured I would use the same protocol throughout. They did this at my last job that had about 10 sites on mpls and used bgp internally and for the cloud.
Yep you can set it up that way. Thats basically what they are designed for. IGPs for internal connectivity and BGP for external connectivity. I guess they are both technically internal connectivity in this scenario though.
You could also ask the provider to run OSPF with you instead of BGP. There are many ways to accomplish the same thing. It sounds like you aren't extremely familiar with BGP so I'd stick with what you know if possible.An expert is a man who has made all the mistakes which can be made. -
phoeneous
Member Posts: 2,333 ■■■■■■■□□□
networker050184 wrote: »It sounds like you aren't extremely familiar with BGP so I'd stick with what you know if possible.
Everything I learned about bgp has been from youtube.
Aside from the more complex configs it seems like using bgp to connect to mpls is just a few command lines. We have a vendor that is assisting with the conversion, I just wanted to do as much as possible on my own and leave the more difficult stuff for them. -
chrisone
Member Posts: 2,278 ■■■■■■■■■□
Everything I learned about bgp has been from youtube..
You should probably lean toward something very simple to learn and implement, like EIGRP. OSPF maybe a little more complicated to understand, and BGP, with all due respect, is not up your alley of expertise. If you have the time, I would consider the CCNP to further your routing and switching knowledge. Then branch off into the CCNA SP Operations and CCNP SP Operations, both will give you the knowledge you need with BGP and MPLS at a high level of understanding.
If you have senior engineers on staff i would consult their expertise before implementing such designs. I am sorry if I have given you doubts , but these technologies are not something you can really understand by viewing youtube videos. Youtube should only be used to supplement study materials such as books and labs.Certs: CISSP, EnCE, OSCP, CRTP, eCTHPv2, eCPPT, eCIR, LFCS, CEH, SPLK-1002, SC-200, SC-300, AZ-900, AZ-500, VHL:Advanced+
2023 Cert Goals: SC-100, eCPTX -
phoeneous
Member Posts: 2,333 ■■■■■■■□□□
You should probably lean toward something very simple to learn and implement, like EIGRP. OSPF maybe a little more complicated to understand, and BGP, with all due respect, is not up your alley of expertise. If you have the time, I would consider the CCNP to further your routing and switching knowledge. Then branch off into the CCNA SP Operations and CCNP SP Operations, both will give you the knowledge you need with BGP and MPLS at a high level of understanding.
If you have senior engineers on staff i would consult their expertise before implementing such designs. I am sorry if I have given you doubts , but these technologies are not something you can really understand by viewing youtube videos. Youtube should only be used to supplement study materials such as books and labs.
I'll be the first to admit that a project of this scope is above my knowledge and experience. We don't have any senior engineers, I'm the only IT staff for the company. The vendor that we are working with for this project employs several ccie's.
And NP is coming right after ccna:s and ccna:v. -
networker050184
Mod Posts: 11,962 Mod
Everything I learned about bgp has been from youtube.
Aside from the more complex configs it seems like using bgp to connect to mpls is just a few command lines. We have a vendor that is assisting with the conversion, I just wanted to do as much as possible on my own and leave the more difficult stuff for them.
Hey, you gotta learn somewhere right? It is basically just a few commands in that scenario. The hard part will be figuring out issues if you don't have a complete understanding of what those few lines do. The config is always the easy part.
I'd try to be as involved in what the vendor does as you can. Next time you will have a bit more experience to go with.An expert is a man who has made all the mistakes which can be made. -
phoeneous
Member Posts: 2,333 ■■■■■■■□□□
networker050184 wrote: »Hey, you gotta learn somewhere right?
Having a home lab helps a ton with that! -
phoeneous
Member Posts: 2,333 ■■■■■■■□□□
Bad news, the provider just told me that if I put my routers at the edge than I have to run BGP because they do not support OSPF. Is this common for ISP's? I already configured my routers for OSPF...
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networker050184
Mod Posts: 11,962 Mod
Depends on the provider I guess. Might have to talk to the right person to get an OSPF set up. Might cost you a bit more if they usually don't run it though.An expert is a man who has made all the mistakes which can be made.
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Forsaken_GA
Member Posts: 4,024
Bad news, the provider just told me that if I put my routers at the edge than I have to run BGP because they do not support OSPF. Is this common for ISP's? I already configured my routers for OSPF...
Most providers do not want to run IGP's if they can avoid it. Their routers already have to run BGP for their MPLS backbone, since MP-BGP is how the MPLS information is distributed. And honestly, I would not want to run an IGP with someone elses network, the last thing I want is for them to be able to influence my internal routing in any way. There are very good reasons to keep your internal routing and external routing seperate. OSPF in particular can be very intensive as a PE routing protocol, since it pretty much requires a seperate OSPF process for every customer. -
Panzer919
Member Posts: 462
Bad news, the provider just told me that if I put my routers at the edge than I have to run BGP because they do not support OSPF. Is this common for ISP's? I already configured my routers for OSPF...
You might be able to get someone at the ISP to help you set up your BGP, once you do it for one site you can pretty much create a template for all other sites.Cisco Brat Blog
I think “very senior” gets stuck in there because the last six yahoos that applied for the position couldn’t tell a packet from a Snickers bar.
Luck is where opportunity and proper planning meet
I have not failed. I've just found 10,000 ways that won't work.
Thomas A. Edison -
networker050184
Mod Posts: 11,962 Mod
Forsaken_GA wrote: »Most providers do not want to run IGP's if they can avoid it. Their routers already have to run BGP for their MPLS backbone, since MP-BGP is how the MPLS information is distributed. And honestly, I would not want to run an IGP with someone elses network, the last thing I want is for them to be able to influence my internal routing in any way. There are very good reasons to keep your internal routing and external routing seperate. OSPF in particular can be very intensive as a PE routing protocol, since it pretty much requires a seperate OSPF process for every customer.
If you are setting up a customer with IGP in their VRF it isn't going to influence your internal routing. Not unless you have something configured horribly wrong.
An expert is a man who has made all the mistakes which can be made. -
shodown
Member Posts: 2,271
Forsaken_GA wrote: »Most providers do not want to run IGP's if they can avoid it. Their routers already have to run BGP for their MPLS backbone, since MP-BGP is how the MPLS information is distributed. And honestly, I would not want to run an IGP with someone elses network, the last thing I want is for them to be able to influence my internal routing in any way. There are very good reasons to keep your internal routing and external routing seperate. OSPF in particular can be very intensive as a PE routing protocol, since it pretty much requires a seperate OSPF process for every customer.
This is death, lol. I worked a large enterprise before where the WAN group was its own department and all it took was one of the smaller sub groups to screw up routing and black holed a entire OSPF area in the WAN, after that we only took static routes from the activities and redistributed them into the WAN, A lesson we learned the hardway.Currently Reading
CUCM SRND 9x/10, UCCX SRND 10x, QOS SRND, SIP Trunking Guide, anything contact center related -
Forsaken_GA
Member Posts: 4,024
networker050184 wrote: »If you are setting up a customer with IGP in their VRF it isn't going to influence your internal routing. Not unless you have something configured horribly wrong.
I was speaking from the customers perspective hehe. If I add the provider via OSPF, then changes they make on their end have the potential to influence my internal routing -
networker050184
Mod Posts: 11,962 Mod
Again, if its configured right there is nothing to worry about. Same as with BGP. Not like it just magically configures itself properly.An expert is a man who has made all the mistakes which can be made.
