As I mentioned in the Configuration Flow graph - BGP will only advertise routes present in the active routing table (RIB) by default. One note: unlike in FG3, which distributes into BGP the directly connected loopback 10.10.10.1, I need both Fortigates here to advertise default route 0.0.0.0/0 which they don't have. Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcdīGP settings of both peers are almost identical (except local to each AS number and FG3 peering IP) so I will list just FG1. I create route-map to do so:īGP router identifier 10.10.10.1, local AS number 1680 Usually you do it by prepending your own AS number to the advertised route(s). The next step is to make sure my advertised route 10.10.10.1 is reachable via both ISPs, but is preferred by Internet clients via ISP1. Here we are not trying to prefer specific routes via ISP1 but all routes learned from it, so I will set weight on the neighbor. The other way would be to increase Local Preference of the routes learned from ISP1, but this would require to configure route-map, an additional extra step. Or it can be used by first config route prefix-list to match specific route(s), then setting the weight for these specific matched routes inside config router route-map, which in turn will be applied to the neighbor.
The easiest way to do so is via weight setting, which can be used inside config neighbor to set the weight for ALL routes learned from this neighbor. Prefer ISP1 to reach the Internet, having ISP2 as backup in case of failure. Create prefix list to allow ONLY default route (0.0.0.0/0) and deny everything else.The BGP configuration flow in general is: Also we want to use ISP1 to reach the Internet, and only if it fails to use ISP2. Advertise to both ISPs our internal network of 10.10.10.1, making sure clients on the Internet prefer ISP1 (AS 111) to reach this network.
Limit the learned routes from each ISP to default route only. Task: Configure 2 BGP peerings with different providers, each ISP advertising to us (FG3, AS 1680) both, default and Internet routes. Remotely Triggered Black Hole Routing configurationīGP with two ISPs for multi-homing, each advertising default gateway and full routing table Set up BGP peering between FG3 and FG1 using loopback in FG3 Make sure we can see received routing advertisements before and after any filtering is applied. Secure BGP session between ISP1 and FG3 with one way hash. Limit announced connected routes to 3.3.3.3 only.
Uses route-map, aspath-listįorce FG1 to advertise default route without having one in RIB and without using blackhole routing. Prevent our Fortigate from becoming a transit AS, do not advertise learned via eBGP routes. PDF version of this post: Fortigate BGP cookbook of example configuration and debug commands.pdf"īGP with two ISPs for multi-homing, each advertising default gateway and full routing table.
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