topic RE: How to use a ping test of upstream device (more than 1 hop away) to change default route in ExtremeSwitching (EXOS/Switch Engine)

How to use a ping test of upstream device (more than 1 hop away) to change default route

Tim_Kimball — Wed, 25 Oct 2017 00:02:00 GMT

Using Summit x690s XOS 22. No dynamic routing protocols. Want to change the default route on the switch if a ping test to an upstream router fails. The upstream router is more than one hop away so cannot use the flow redirect.

RE: How to use a ping test of upstream device (more than 1 hop away) to change default route

Karthik_Mohando — Mon, 06 Nov 2017 18:55:00 GMT

Hi Tim,

Please check if this helps.

configure iproute add [default | ipv4_or_ipv6_network] gateway
{protection [bfd | ping | none]}

Usage Guidelines
For static routes configured with protection type ping, static routes are initially down. Static routes
become "up" for each configured gateway/device IP when a timely ICMP Echo Reply is received from
that IP within the configured ping interval. Static routes transition from up to down when no timely
reply is received for the configured number of missed intervals. Severely delayed ICMP Echo Replies are
ignored if received after the configured interval time elapses, because a new ICMP Echo Request has
already been sent. Static routes with ping protection need not be ECMP routes. Thus when a device is
unresponsive, a different route with a higher cost or shorter prefix length can route packets elsewhere.

This command was first available in ExtremeXOS 22.1.

RE: How to use a ping test of upstream device (more than 1 hop away) to change default route

Tim_Kimball — Tue, 07 Nov 2017 03:10:00 GMT

This only works to test the default gateway IP to see if it is up. We need to test a few hops away.
Thanks

RE: How to use a ping test of upstream device (more than 1 hop away) to change default route

Stephane_Grosj1 — Tue, 07 Nov 2017 03:47:00 GMT

Hi,

I usually do this via a script, executed by a UPM timer. You ping whatever (group of) remote IP(s), add whatever weight for each and do what is needed (change the default, add/remove a PBR, etc).