01-27-2023 02:41 AM - edited 01-27-2023 02:42 AM
Perhaps this is only the case in Packet Tracer and doesn't happen with real devices.
But I was building a simple setup in packet tracer to test static routes and came across something that confuses me.
Here's a screenshot of what I set up:
I set static routes on the first two routers (from left to right) towards the subnets on their right.
On the router on the right I set a floating static route 0.0.0.0 0.0.0.0 with exit interface g0/0/0.
I then initiated traceroute on the left PC with the right PC as target. When TTL was set to 3 the ICMP request reached the router on the right, which decreased TTL to zero, dropped the packet and created a ICMP type 11 message (time exceeded) and packaged it in an IP packet with destination address of the left PC.
Here's what confuses me: I thought that with the floating static route set, the package will simply be sent out via g0/0/0 (although I didn't think through what MAC address would be used). But instead an ARP request was sent out for the destination address.
I don't see why the ARP table was consulted for the destination address if a floating static route was set. Did I miss something?
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01-27-2023
05:13 AM
- last edited on
01-29-2023
09:48 PM
by
Translator
Hi there,
You will find that the router will ARP for every destination address leaving via Gi0/0/0 since you have not specified a
next-hop
gateway address. You can get around this by changing the link between the routers to a
point-to-point
link.
I wrote a blog post about this behaviour:
Static route next-hop – CS7 Networks
cheers,
Seb.
01-27-2023
05:13 AM
- last edited on
01-29-2023
09:48 PM
by
Translator
Hi there,
You will find that the router will ARP for every destination address leaving via Gi0/0/0 since you have not specified a
next-hop
gateway address. You can get around this by changing the link between the routers to a
point-to-point
link.
I wrote a blog post about this behaviour:
Static route next-hop – CS7 Networks
cheers,
Seb.
01-27-2023 05:36 AM
Thank you. I mixed up the terminology also, I set up a default route and not a floating static route.
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