[sf-lug] Got router? / Where *is* that ("other") router? (linuxmafia.com)

[Michael Paoli]

So, I noticed earlier, when linuxmafia.com had bit earlier been ungraciously
disconnected from the Internet by AT&T ...

When I did a traceroute from my host(s) at home,
I only saw one hop beyond host itself.

Now, Rick and I, happening to be on same ISP, I'd expect there might
be quite few hops between.  But I was kind'a expecting - and also
after connectivity was reestablished, to see gateway/default router,
on both our ends, just short of each end (host).

Well, that is seen, ... kind'a ... yes, and no:

$ traceroute -n linuxmafia.com.
traceroute to linuxmafia.com. (198.144.195.186), 30 hops max, 60 byte packets
  1  198.144.194.233  66.500 ms  68.621 ms  70.789 ms
  2  198.144.195.186  120.738 ms  123.962 ms *
$ ip -4 r s | fgrep default
default via 198.144.194.233 dev br0
$ ssh -ax linuxmafia.com. 'hostname; traceroute -n www.sf-lug.org.; ip  
-4 r s | fgrep default'
linuxmafia.com
traceroute to www.sf-lug.org. (198.144.194.238), 30 hops max, 40 byte packets
  1  198.144.195.185  14.168 ms  17.066 ms  24.416 ms
  2  198.144.194.238  41.424 ms  48.065 ms  49.892 ms
default via 198.144.195.185 dev eth2
$ arp -n | fgrep 198.144.194.233
198.144.194.233          ether   00:03:6c:7b:24:70   C                     br0
$ ssh -ax linuxmafia.com. '/usr/sbin/arp -n | fgrep 198.144.195.185'
198.144.195.185          ether   00:03:6c:7b:24:70   C                  
     eth2
$

In the above, I show traces (traceroute) run from each end ... after
connectivity has been restablished (I may not use same host on my end
in each case, but in all cases, same subnet, same default gateway
router on my end).

But alas, only see one router between ... despite IP address of each
of our respective default gateway routers being distinct.

Well, checking further ... same Ethernet MAC address on both,
so ... it *is* the same router for both, just has multiple IP
addresses, so in each case the traceroute shows just one (the one
towards the origin side of the traceroute).  And since it is same
router, just the one hop between is seen.

Anyway, thought some folks might find that interesting.