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Forgive me if I'm not using the correct terminology here but I'm on a Juniper MX204 router, call it router A. I'm receiving full table from my ISP. I do a show route, i.e. show route 1.1.1.1 and I get one prefix back.

show route 1.1.1.1

inet.0: 811234 destinations, 811234 routes (811190 active, 44 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

1.1.1.0/24         *[BGP/170] 1d 19:42:09, localpref 100
                      AS path: 7473 6453 13335 I, validation-state: unverified
                    >  to TRANSIT_IP_HERE via xe-0/1/1.0

Cloudflare, and the real network that is prompting this question, is multihomed. As far as I know about how BGP works the router receives all of the routes to 1.1.1.0/24 from the transit provider and selects the 'best' one to put into the FIB (based on a multitude of criteria, AS path length being the main one).

How can I show all of the AS paths for a network recieved from a transit provider, including those that were not chosen by BGP?

What I'm really trying to troubleshoot is a prefix which I'm multihoming. While I'm advertising the prefix to transit A and transit B I have a feeling transit B is filtering upstream. The show route statements only contain transit A but even in 1.1.1.0/24's case it also only shows one (the "best" AS-Path). I'm hopping to a few random internet routers and I want to prove that I'm not even receiving a route at all through transit B's.

  • The command you gave would display the route from ISP-B unless you had rejected it via routing policy (hidden) or the advertisement contained your own ASN and loops is not configured (not the case for your question.) You are correct to think ISP-B is at fault. Check show bgp summary and see if you are getting dramatically fewer routes from them, or only missing a small number. That might help them troubleshoot. – Jeff Wheeler Aug 28 at 21:46
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show route <ip address> all shows you all routes received for a given destination, not just the one installed in your FIB.

However, if you receive routes from a transit provider, you typically receive only one route to that given destination, being the route via their network.

If you are multihomed, show route <ip address> all will show you routes via all upstreams that provided you a route to that network.

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