+- How2pass.com Forums (https://www.how2pass.com/forum)
+-- Forum: CCNP (https://www.how2pass.com/forum/forum-6.html)
+--- Forum: CCNP ENARSI 300-410 Forum (https://www.how2pass.com/forum/forum-15.html)
+--- Thread: QID:NF76 BGP multipath needed for load sharing over multiple links (/thread-338.html)
QID:NF76 BGP multipath needed for load sharing over multiple links - joshuad31 - 03-25-2010
Hello,
Please refer to the following resources as the answer to this question needs to be reconsidered as multipath not multihop:
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094431.shtml#bgpmpath
BGP Multipath allows installation into the IP routing table of multiple BGP paths to the same destination. These paths are installed in the table together with the best path for load sharing
http://www.cisco.com/en/US/docs/ios/12_2sx/feature/guide/fsxeibmp.html
The BGP Multipath Load Sharing for eBGP and iBGP feature allows you to configure multipath load balancing with both external BGP (eBGP) and internal BGP (iBGP) paths in Border Gateway Protocol (BGP) networks that are configured to use Multiprotocol Label Switching (MPLS) Virtual Private Networks (VPNs). This feature provides improved load balancing deployment and service offering capabilities and is useful for multi-homed autonomous systems and Provider Edge (PE) routers that import both eBGP and iBGP paths from multihomed and stub networks.
22. (QID:NF76) Which BGP option is required when load sharing over multiple equal-bandwidth parallel links from a single CE router to a single ISP router over eBGP?
eBGP Multipath
eBGP Multihop
BGP Synchronization
Public AS numbers
Correct Answer: eBGP Multihop
Re: QID:NF76 BGP multipath needed for load sharing over multiple links - forumsupport - 03-26-2010
You are looking at wrong place. Check below ref:
http://www1.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a00800945bf.shtml#conf1
and this note in Building Scalable Cisco Internetworks (BSCI) v3.0, page 6-46:
"BGP is not designed to perform load balancing; paths are chosen because of policy, not
based on bandwidth. BGP will choose only a single best path. Using the loopback
addresses and the neighbor ebgp-multihop command as shown in this example allows
load balancing, as well as redundancy, across the two paths between the autonomous
systems".
Pay close attention to the requirements given in question:
"multiple equal-bandwidth parallel links from a single CE router to a single ISP router over eBGP".
Re: QID:NF76 BGP multipath needed for load sharing over multiple links - joshuad31 - 03-26-2010
load balancing and load sharing seem like they might be the same thing... but really they are not. The answer is multipath. The quotes you site say "load balancing" which peering off of a loopback interface is a good idea to accomplish "load balancing" my quotes say "load sharing". These are direct quotes from materials on Cisco's website. I am just trying to help you present accurate information. If you want to argue with Cisco then I think it defeats the purpose of presenting answers to the questions.
Re: QID:NF76 BGP multipath needed for load sharing over multiple links - forumsupport - 03-27-2010
I have provided the ref. to support what I believe is correct. You have provided the ref. to support your answer. If you see this question in exam, please choose what you think is correct. That is a better solution to this confusion.
We face this situation too often when users start arguing on ambiguous things. I believe Cisco exam writers put these things deliberately to confuse candidates.
Thank you anyway.