11-24-2009 02:50 AM - edited 03-06-2019 08:42 AM
Hi Experts,
As of now we have single internet provider to my DC and we have public IP pool (195.34.56.0/24 leased from old provider)
Now we take another internet provider for redundancy and we bought one public IP pool (193.141.24.0/24)
I have two my routers (1841) in hsrp at my DC, both providers have their own routers at perimeter network at my DC.
Both new and Old internet lines are ready to use, now I have to do BGP multihoming on my both hsrp routers and I dont want use IP pool 195.34.56.0 which taking leased from old provider.
At present I have my own two public IP pools those are 193.141.24.0/24 and 193.143.209/20
Experts can someone guide me how I have to proceed with Mutlihoming and what are the steps I have to follow and how to configure and all...
Thanks in advance.
Regards,
Naidu.
Solved! Go to Solution.
11-25-2009 10:11 AM
Hello Naidu,
some safety measures have to be added :
use route filters to decide what you are willing to accept from each provider.
use an as path access-list to be sure you will never act as a transit between the two providers
example:
you want to accept only a default route
ip prefix-list only-default permit 0.0.0.0/0
route-map fromISP1 permit 10
match ip address prefix only-default
route-map fromISP2 permit 10
match ip address prefix only-default
ip as-path access-list 11 permit ^$
route-map toISP1 permit 10
match as-path 11
route-map toISP2 permit 10
match as-path 11
router bgp your.ASN
neigh ISP1.ipaddress route-map fromISP1 in
neigh ISP1.ipaddress route-map toISP1 out
neigh ISP2.ipaddress route-map fromISP2 in
neigh ISP2.ipaddress route-map toISP2 out
It is better to have separated route-maps you may want to make changes in the future
Hope to help
Giuseppe
11-24-2009 05:53 AM
Hello Naidu,
I hope you are well.
if you have your own public IP blocks you are fine
use the following example for BGP multihoming
http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a00800945bf.shtml
Hope to help
Giuseppe
11-25-2009 06:16 AM
Hi Giuseppe,
Thanks for your response.
I too have the same document, what I would like to request you is if you have experienced in BGP multihoming and I want your best suggestions how to go towards success on this.
Can you provide me If you have any kind of templete.
Thanks & Regards,
Naidu.
11-25-2009 10:11 AM
Hello Naidu,
some safety measures have to be added :
use route filters to decide what you are willing to accept from each provider.
use an as path access-list to be sure you will never act as a transit between the two providers
example:
you want to accept only a default route
ip prefix-list only-default permit 0.0.0.0/0
route-map fromISP1 permit 10
match ip address prefix only-default
route-map fromISP2 permit 10
match ip address prefix only-default
ip as-path access-list 11 permit ^$
route-map toISP1 permit 10
match as-path 11
route-map toISP2 permit 10
match as-path 11
router bgp your.ASN
neigh ISP1.ipaddress route-map fromISP1 in
neigh ISP1.ipaddress route-map toISP1 out
neigh ISP2.ipaddress route-map fromISP2 in
neigh ISP2.ipaddress route-map toISP2 out
It is better to have separated route-maps you may want to make changes in the future
Hope to help
Giuseppe
11-26-2009 02:33 AM
Hi Guiseppe,
Nice to see your reply and good explanation .
As of now the BGP multihoming configured and maintain will be by Provider itself.
Yes, I would like to point only default route to provider GW.
say 0.0.0.0 0.0.0.0 197.28.56.1
I hope the ip as-path access-list can configure on my routers, to not accept any other AS from internet; is that right?
I couldn't understand......
you want to accept only a default route
ip prefix-list only-default permit 0.0.0.0/0
You mean shall I accept default route, which means the whole default route from internet?
Please correct me if I am wrong.
Thanks in advance,
Regards,
Naidu.
11-26-2009 03:26 AM
Hello Naidu,
yes the idea is to accept a BGP route 0.0.0.0/0 that is a default route from providers routers
using a default static route is not recommended because your router cannot know when one router has a problem (indirect failure)
your router sends your public IP blocks and you receive a default BGP route
Hope to help
Giuseppe
11-26-2009 06:19 AM
Hi Giuseppe,
Oh....great...!
I have small doubts.
If we accept a default route from providers, will it be not accept like whole internet routing table like that?
If that is not the case, I heard sometimes the whole internet routing table will land on our routers then router get crash like that because of some miss configuration; is that right?
In what situations will be like that happen, what could be the causes to came whole internet routing table to our router?
Is there any specific BGP default route like that? (yes the idea is to accept a BGP route 0.0.0.0/0 that is a default route from providers routers)
Can you please clear me.
Thanks & Regards,
Naidu.
11-26-2009 06:40 AM
Hello Naidu,
the proposed input route filter has the objective to accept only the default route that is a single BGP prefix.
a full routing table is made of 300,000 routes nowdays and cannot be handled by your router.
accepting a default route means accepting only special prefix 0.0.0.0/0 as I wrote so your router shouldn't be overhwhelmed by it.
Hope to help
Giuseppe
04-07-2010 08:11 AM
Hi Giuseppe,
picking up on your point about not adding a default static route but to accept static route from ISP. In multi homed network how would you make it so the one ISP is higher priority and used as default exit point. If the main ISP fails then the default gateway should be to the second ISP?
Thanks
04-07-2010 12:47 PM
Hi,
You can set the your preferences in your neighbor
route-map RouteMAP_Name
match ip address 1
set local-preference 25
set metric 127
set weight 30000
set next-hop 192.92.68.24
set origin igp
!
Any of the parameter above.
http://www.ciscosystems.com/en/US/docs/ios/12_0/np1/configuration/guide/1cbgp.html#wp6018
Thanks,
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide