Understanding Path Discovery Behavior in Multipath Mode

[arpan21020]

I am running the client with the multipath flag using the following command:

./picoquicdemo -M -A ::0/0 -n test 192.168.226.151 4443 hi

As shown in the attached output, the client reports two paths (Path[0] and Path[1]), even though I am only using localhost for testing. Could you please clarify how multiple paths are being established in this setup? Is this expected behaviour when using the -A::0/0 option?

Also, for testing with multipath, if I want to establish 4 separate paths, should I provide multiple client-side IPs or server-side IPs? What is the recommended way to configure this?

[huitema]

The ::0/0 convention is a hack. The client will create paths with the same IP and different ports.The typical configuration is one server IP, several client IP.-- Christian Huitema On May 2, 2025, at 3:32 PM, Arpan Kumar ***@***.***> wrote: I am running the client with the multipath flag using the following command: ./picoquicdemo -M -A ::0/0 -n test 192.168.226.151 4443 hi image.png (view on web) As shown in the attached output, the client reports two paths (Path[0] and Path[1]), even though I am only using localhost for testing. Could you please clarify how multiple paths are being established in this setup? Is this expected behaviour when using the -A::0/0 option? Also, for testing with multipath, if I want to establish 4 separate paths, should I provide multiple client-side IPs or server-side IPs? What is the recommended way to configure this? —Reply to this email directly, view it on GitHub, or unsubscribe.You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[huitema]

Previous answer was sent over email, and is a bit garbled. The actual answers are:

1. The option "-A ::/0" ask picoquic to exercise multipath by using two different port numbers. This is useful for testing the multipath code, but the two paths will share the same IP.

2. If you want to actually test multipath, the client should be configured with multiple IP addresses. In Picoquicdemo, they should be documented using the A option.

The syntax of picoquicdemo options can be shown using picoquicdemo -h. It will show:

  -A "ip/ifindex[,ip/ifindex]"  IP and interface index for multipath alternative
                        path, e.g. "10.0.0.2/3,10.0.0.3/4". This option only
                        affects the behavior of the client.
                        Use -A ::0/0 or -A 0.0.0.0/0 to test multipath with
                        a second path from the same IP and different port.