09-07-2011 10:56 AM - edited 03-04-2019 01:31 PM
Dear Experts,
We have topology as shown in the diagram running with dual MPLS links from two different Service Providers.
Topology :
The sample configuration for the BGP at HQ1 is as shown :
BGP Configuration on TATA CE Router :
router bgp 65510
no synchronization
bgp log-neighbor-changes
network 10.3.1.0 mask 255.255.255.0
network 10.3.2.0 mask 255.255.255.0
network 10.3.3.0 mask 255.255.255.0
network 10.3.4.0 mask 255.255.255.0
network 10.3.5.0 mask 255.255.255.0
neighbor 172.1.30.169 remote-as 2511
no auto-summary
BGP Configuration on Airtel CE Router :
router bgp 65500
no synchronization
bgp log-neighbor-changes
network 10.3.1.0 mask 255.255.255.0
network 10.3.2.0 mask 255.255.255.0
network 10.3.3.0 mask 255.255.255.0
network 10.3.4.0 mask 255.255.255.0
network 10.3.5.0 mask 255.255.255.0
neighbor 172.200.10.33 remote-as 2577
neighbor 172.200.10.33 allowas-in 6
no auto-summary
Can you suggest how Can I configure theese two routers for Load Sharing using BGP?
Can you give the sample configuration for the same according to given one?
Regards,
09-07-2011 11:14 AM
There are plenty of examples in the web with BGP load sharing. In short, you need to add the command maximum-paths on the routers receiving these prefixes so both can be installed.
You need to also keep in mind, to configure BGP equal-cost multipath load sharing, all path attributes must be the same.
The path attributes include weight, local preference, autonomous system path (entire attribute and not just the length), origin code, Multi Exit Discriminator (MED), and Interior Gateway Protocol (IGP) distance.
Here is one example of such configuration:
http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a00800945bf.shtml
08-25-2014 05:17 PM
I think you can only use this command when a single router is connected to two different ISP but on this case there are two routers with each of them connected to their respective ISPs. So, to achieve load balancing, a L3 Core switch will need to be put in place between the two routers and the rest of the network with the core switch acting as the default-gateway for all the end-users devices, which is now the case in this network.
Or...
Just use one router to connect to two different ISP and use the two BGP commands below:
maximum-paths
bgp bestpath as-path multipath-relax
09-07-2011 02:40 PM
hi there
in order to get you BGP to load share over multiple paths you will need to have the BGP attributes same over both paths as sated above by Edison
also using the above command will work if you peering with one BGP AS in your case you are peering with two differnt BGP AS numbers and you need to add the bellow hidden command to get your BGP load sharing working assuming all the above have met:
bgp bestpath as-path multipath-relax
HTH
if helpful Rate
09-07-2011 07:11 PM
Dear Edition / Marwanshawi,
Yes, I understand to do loadsharing using BGP. But that is the case when I can do IBGP between my two CE routers as shown in Topplogy. Both are running different AS no's.
How Can I run iBGP betwen CE Routers with two different AS no's?
Can you give sample config according to the configuration I have shown?
It will be helpful to understand.
Regards,
09-07-2011 08:50 PM
from your topology you have two edge routers in each site with L3 core switches
the load sharing decision has to be made by the core switches not the edge routers
what you can do is run IGP between the Core switches and the edge routers using equal cost multipathing ECMP
and this way the core swithc will load cshare the traffic for remote prefixes on both edge routers per flow
and each edge router learns the relevant prefixes of remote site through directly connected eBGP peer
HTH
09-08-2011 12:29 AM
Dear Marwanshawi,
Thanks,
Yes Thr Load balacning decesion will be taken care by CORE switch. We can run IGP - OSPF using ECMP and load balance but the problem is the BW of both the links are differen - unequall hence need to go with EIGRP but CORE switch switches are Nortel, Cisco and Juniper platforms.So eigrp will not work. hence searching the solution using BGP.
Is it posible using BGP in my case?
Regards,
09-08-2011 03:22 AM
With ospf you can assign the cost manually to make it equal cost
But keep In mind this design might lead to asymmetrical routing
HTH
Sent from Cisco Technical Support iPhone App
09-08-2011 06:00 AM
Hi dipesh,
Can you post the BGP routing table out put,right now which path is using bgp to reach the destination.
pls check which attribute is used to select that link as best path
Message was edited by: SHEHIN PM
09-08-2011 02:53 PM
Shehin
We discussing here how to approach the solution using either bgp/igp not a bgp config issue
Sent from Cisco Technical Support iPhone App
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