Configuring BGP

[zaradell]

Good afternoon to you all

I need your help

I´m a noob when it comes to BGP, and i need to configure it in the following topology:

+------+ +------+
| AS1 |------| AS2 |
+------+\ /+------+
| \ / |
| \/ |
| /\ |
| / \ |
| / \ |
+------+ +------+
| AS3 | | AS4 |
+------+ +------+


Basically want I need is the following regarding to AS3:

Regarding the links to AS1 and AS2 what i want is to configure X traffic to go to AS1 and Y traffic to go to AS2; if the link to AS1 goes down, X traffic then goes to AS2 and the same to Y traffic.

And since AS1 and AS2 are the default gateways of AS3, i want to deny all incoming bgp routes from AS1 and AS2.

Basically what I want is to have AS1 and AS2 as default gateways of AS3 (so i don´t need to receive their routes), and send X traffic through one link and Y traffic through another.

Can someone post the configuration block necessary for that?

Any help is much apreciated.

Thkx

 

[unclerico]

My first question is do you really need BGP at all?? Are you looking to have AS1 advertise routes for AS2 and vice versa so that you can route around a link failure?? I am looking at your description and I see a need for PBR and nothing more. Where does AS4 come in to play here??

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[zaradell]

unclerico

Thkx for your reply

The representation that I gave you is not complete: this 2 layers only represent the access and distribution layer of my platform: AS1 and AS2 will connect to the core portion of my network: all the core and distribution layers are configured with BGP; the access layers are configured with EIGRP.

The client wants to migrate all the EIGRP routing to BGP, and establish a single protocol in the network.

So as for AS1 and AS2 they need to advertise AS3 and AS4 routes between them, and then to the core portion of the network.

As for AS4 it´s a replica of AS3: is has the same hosts, and is configured with HSRP. AS3 and AS4 have a link between them, and AS4 only exists as fault tolerance.

Basically i will set the same BGP configurations on AS3 and AS4:

+-------------------+
| CORE |
| |
+-------------------+
| |
| |
| |
+------+ +------+
| AS1 |------| AS2 | Distribution Layer
+------+\ /+------+
| \ / |
| \/ |
| /\ |
| / \ |
| / \ |
+------+ +------+
| AS3 |------| AS4 | Access Layer
+------+ HSRP +------+

 

[zaradell]

Ouh, and these aren´t routers, but multilayer switches.

 

[vipergg]

Normally you would use a protocol like OSPF or EIGRP down into the distribution layer and below and redistribute BGP from the core into one of those protocols .

 

[zaradell]

yes, that´s true...

but this is a specific platform of an ISP network. Even though I´m regarding this as an access layer, this is all part of the ISP "core" network.


I know that design wise, BGP is not the best option: for me what makes sense is to implement ISIS on AS3 and AS4 but I´m not the boss... =)

And since the boss want´s BGP, and I´m not very good at it (I have more experience with IGP protocols), I´m asking for Tek Tips community help...

so...can someone help me with the configuration block for implementing BGP on AS3 and AS4 that:

- block incoming routes from AS1 and AS2;
- create default routes from AS3 and AS4 to AS1 and AS2;
- create route-maps where I send X traffic to AS1 and Y traffic to AS2, while maintaining a fault tolerance between those 2 circuits;

I would apreciate your help on this matter.

 

[zaradell]

Anyone?

 

[unclerico]

i'll work on labbing this up this weekend at some point.

I hate all Uppercase... I don't want my groups to seem angry at me all the time! =)
- ColdFlame (vbscript forum)

 

[zaradell]

unclerico

Thkx

Have you had the chance to lab it up?

 

[unclerico]

i apologize, i've had family matters to tend to. i'll try my best to get it labbed up tonight. can you clear a couple of things up??
- Are all routers involved under the same administrative control??
- If yes, are all of the routers Cisco routers??

I hate all Uppercase... I don't want my groups to seem angry at me all the time! =)
- ColdFlame (vbscript forum)

 

[zaradell]

unclerico

thkx for your attention to this matter


and yes to both your questions: they are Cisco Multilayer Switches and are under the same administrative control.

 

[unclerico]

ok, this should be a relatively simple configuration. i'll take some time tonight and create a replica of your environment that you've drawn.

I hate all Uppercase... I don't want my groups to seem angry at me all the time! =)
- ColdFlame (vbscript forum)

 

[zaradell]

unclerico

Any progress?

 

[unclerico]

you're going to kill me man, i did lab it up last night but i was in such a rush this morning that i forgot to grab the configs. what i am about to post is my attempt to create a bgp configuration on the fly (including a toplogy drawing). now, it's not EXACTLY like yours as i'm sure yours has some different variables than my lab, but hopefully it will give you a push in the right direction. i have only recreated two of the configs; one for R1 and one for R3. R4 is almost a duplicate copy of R3 except for some ip addresses are different and the HSRP setup is a little bit different. R2 is almost a duplicate copy of R1. R5 is essentially a copy of R1 and R2. there are multiple loopback interfaces in each config, i only put those in there to get more routes into the routing table (with the exception of loop0 which is used to source routing updates and establish neighborship in the bgp process). 99% of the time there is more than one way to accomplish something so just note that this is one of the many possibilities. post back with any questions.

http://www.box.net/shared/rf8ejvoc46

I hate all Uppercase... I don't want my groups to seem angry at me all the time! =)
- ColdFlame (vbscript forum)