about interdomain multipath routing.
Hi: These days, in the research, the interdomain multipath routing is pretty hot but i doubt its actually use in reality. Does anyone tell me any use of interdomain multipath routing like multipath BGP in the real world? Best, Daniel
We use eBGP multipath where I work. We usually get two or more connections to each provider we have. Using multipath we are able to add hardware redundancy with bandwidth balancing (to an extent) with this method. There are some providers who will only allow multipath eBGP and not even let you run multihop eBGP. Bin Dai wrote:
Hi: These days, in the research, the interdomain multipath routing is pretty hot but i doubt its actually use in reality. Does anyone tell me any use of interdomain multipath routing like multipath BGP in the real world?
Best, Daniel
-- Steve King Network Engineer - Liquid Web, Inc. Cisco Certified Network Associate CompTIA Linux+ Certified Professional CompTIA A+ Certified Professional
On Mon, Nov 9, 2009 at 5:56 PM, Bin Dai <bin.danieldai@gmail.com> wrote:
Hi: These days, in the research, the interdomain multipath routing is pretty hot but i doubt its actually use in reality. Does anyone tell me any use of interdomain multipath routing like multipath BGP in the real world?
I've outlawed the use of multihop eBGP for load-sharing here; when we get multiple links off the same router to a peer or upstream, they are configured with multipath. We've got hundreds of BGP sessions across the network configured with multipath on them. Matt
Best, Daniel
Matthew Petach wrote:
I've outlawed the use of multihop eBGP for load-sharing here; when we get multiple links off the same router to a peer or upstream, they are configured with multipath. We've got hundreds of BGP sessions across the network configured with multipath on them.
Same here for my connections, though some of my customers are stuck with multihop eBGP in certain remote areas, but that's a completely different scenario (single link, but obsolete equipment) and out of my control. I much prefer multipath, especially given that the standard multihop config uses static routing and there are conditions that could cause the flap of the eBGP session during a single link outage. With Multipath, only the effected path goes down, as it should. Jack
Those are very good points Jack. We stopped using multihop for those same reasons. Jack Bates wrote:
Matthew Petach wrote:
I've outlawed the use of multihop eBGP for load-sharing here; when we get multiple links off the same router to a peer or upstream, they are configured with multipath. We've got hundreds of BGP sessions across the network configured with multipath on them.
Same here for my connections, though some of my customers are stuck with multihop eBGP in certain remote areas, but that's a completely different scenario (single link, but obsolete equipment) and out of my control.
I much prefer multipath, especially given that the standard multihop config uses static routing and there are conditions that could cause the flap of the eBGP session during a single link outage. With Multipath, only the effected path goes down, as it should.
Jack
-- Steve King Network Engineer - Liquid Web, Inc. Cisco Certified Network Associate CompTIA Linux+ Certified Professional CompTIA A+ Certified Professional
On Tue, Nov 10, 2009 at 3:50 AM, Matthew Petach <mpetach@netflight.com> wrote:
I've outlawed the use of multihop eBGP for load-sharing here; when we get multiple links off the same router to a peer or upstream, they are configured with multipath. We've got hundreds of BGP sessions across the network configured with multipath on them.
Do you use iBGP multipath as well to load-balance between links on different routers? I know eBGP multipath is fairly common, but I wonder how many are using iBGP multipath as well. I doubt any carriers would support it, so it's probably only useful for load-balancing outbound traffic. The problem with eBGP multipath alone is that you might want to terminate circuits from a given carrier on two different routers for redundancy reasons, but that precludes any load-balancing with eBGP multipath. Obviously your network has to be designed with equal-cost paths for iBGP multipath to be of any value. -Doug
On Tue, Nov 10, 2009 at 1:10 AM, Doug Lane <laned1@gmail.com> wrote:
On Tue, Nov 10, 2009 at 3:50 AM, Matthew Petach <mpetach@netflight.com> wrote:
I've outlawed the use of multihop eBGP for load-sharing here; when we get multiple links off the same router to a peer or upstream, they are configured with multipath. We've got hundreds of BGP sessions across the network configured with multipath on them.
Do you use iBGP multipath as well to load-balance between links on different routers?
Yes.
I know eBGP multipath is fairly common, but I wonder how many are using iBGP multipath as well. I doubt any carriers would support it, so it's probably only useful for load-balancing outbound traffic. The problem with eBGP multipath alone is that you might want to terminate circuits from a given carrier on two different routers for redundancy reasons, but that precludes any load-balancing with eBGP multipath. Obviously your network has to be designed with equal-cost paths for iBGP multipath to be of any value.
-Doug
iBGP with multipath, multiple LSPs to each BGP next-hop...much load balancing across all same-cost internal links to each of the eBGP multihop next-hops. inet.0: 300787 destinations, 2675963 routes (300092 active, 2 holddown, 2086 hidden) Yes...takes up a chunk more memory keeping track of all the different paths, but it does provide more end-to-end load balancing of traffic even on different routers. Matt
We use multipath setups for our EIGRP and iBGP configurations for our internal routing as well. Although for larger networks iBGP multipath might be of use due to memory limitations on a lot of devices. Doug Lane wrote:
On Tue, Nov 10, 2009 at 3:50 AM, Matthew Petach <mpetach@netflight.com> wrote:
I've outlawed the use of multihop eBGP for load-sharing here; when we get multiple links off the same router to a peer or upstream, they are configured with multipath. We've got hundreds of BGP sessions across the network configured with multipath on them.
Do you use iBGP multipath as well to load-balance between links on different routers?
I know eBGP multipath is fairly common, but I wonder how many are using iBGP multipath as well. I doubt any carriers would support it, so it's probably only useful for load-balancing outbound traffic. The problem with eBGP multipath alone is that you might want to terminate circuits from a given carrier on two different routers for redundancy reasons, but that precludes any load-balancing with eBGP multipath. Obviously your network has to be designed with equal-cost paths for iBGP multipath to be of any value.
-Doug
-- Steve King Network Engineer - Liquid Web, Inc. Cisco Certified Network Associate CompTIA Linux+ Certified Professional CompTIA A+ Certified Professional
Bin Dai wrote:
Hi: These days, in the research, the interdomain multipath routing is pretty hot but i doubt its actually use in reality. Does anyone tell me any use of interdomain multipath routing like multipath BGP in the real world?
"BGP multipath" is extremely common and used to load balance multiple links to the same neighbor ASN. As implemented by popular vendors it requires most attributes (like as-path) to be identical. Did you really mean this or something that uses different as-paths in parallel? - Kevin
participants (6)
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Bin Dai -
Doug Lane -
Jack Bates -
Kevin Loch -
Matthew Petach -
Steven King