Traceroute but no Ping FAQ(wrong?) (fwd)

MegaZone (megazone@livingston.com)
Fri, 29 Nov 1996 05:02:32 -0800 (PST)

Once upon a time Kelley Lingerfelt shaped the electrons to say...
>you state that traceroute takes its source address from the interface it
>is going through and ping takes its source address from the ether0
>interface, as does TCP.

That's correct, and as far as I know is true even in 3.5.

>Below is a short version of my network and below it is a tcpdump after I
>pinged from the Portmaster(pm3) and then I did a traceroute from the pm3
>to a machine called penguin.

You might want to change that machine name... since there is a product
called PM-3, it is bound to cause confusion in support issues, etc...

> W1 |10.1.1.2 +--------------+
> +------+----------+
> | pm3 |(Portmaster PM2ER)
> | 206.100.243.129 |
> +-------+---------+
>Output of tcpdump at penguin
>
>03:30:27.657244 10.1.1.2 > penguin.cococo.net: icmp: echo request
>03:30:27.657404 arp who-has cccroute1.cococo.net tell penguin.cococo.net
>03:30:27.658946 arp reply cccroute1.cococo.net is-at 0:0:c:76:2e:e4
>03:30:27.659015 penguin.cococo.net > 10.1.1.2: icmp: echo reply
>03:30:35.237658 10.1.1.2 > penguin.cococo.net: icmp: echo request
>03:30:35.237782 penguin.cococo.net > 10.1.1.2: icmp: echo reply
>03:30:35.456118 pm3.cococo.net.1072 > penguin.cococo.net.62015: udp 64 [ttl 1]
>03:30:35.456284 penguin.cococo.net > pm3.cococo.net: icmp:
>penguin.cococo.net udp port 62015 unreachable [tos 0xc0]

*shrug*

Beats me - but as you say traceroute works but ping doesn't, and I know
how the ComOS behaves (unless this got switched and no one bothered to
document it - not likely), the problem you describe has *always* in my
experience been caused by the different source addresses.

I have no idea how or why tcpdump is picking up the other address.

-MZ

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