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-   -   Traceroute fails at first hop = Mac or router? (http://www.mac-forums.com/forums/internet-networking-wireless/218983-traceroute-fails-first-hop-mac-router.html)

Phyllis21 11-01-2010 07:19 AM

Traceroute fails at first hop = Mac or router?
 
I'm in eastern Australia, on a fast cable plan from Telstra. This Mac is hard wired to the Telstra-supplied Motorola SBG900 router, while three other Macs connect to it via an Apple network/Airport Extreme.

Everything is working fine, except for some latency issues in an online game (World of Warcraft) played on this Mac. As part of my investigation of that, I used Network Utility to perform a traceroute, initially to the game server then to various other sites. Same result in each case - the first hop, and every subsequent hop, is 3 asterisks = failure.

So I spoke to Telstra, and the not-overly-impressive tech eventually told me that this result means the problem is with my Mac, not the router.

But the same first-hop-failure occurs when I try a traceroute from any of the other Macs, which connect wirelessly. I'm thinking, as your average IT dolt, that this might be because the Mac network connects to the modem via the hard-wired Mac anyway, so maybe the tech can still be right.

Does his insistence that it is not a router problem, make sense? If it IS my Mac, how do I find out what the problem is?

P.S. Running OS X 10.6.4, on

Model Name: iMac
Model Identifier: iMac8,1
Processor Name: Intel Core 2 Duo
Processor Speed: 2.8 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache: 6 MB
Memory: 4 GB
Bus Speed: 1.07 GHz
Boot ROM Version: IM81.00C1.B00

chscag 11-01-2010 07:27 PM

I'm here in the US but I'm betting that your ISP networks in Australia are not very different from ours. In my experience with trouble shooting network difficulties, a traceroute failure is almost always an ISP problem not that of the router or computer.

Of course the techs you speak with (like the ones here in the US) will never admit fault and will always try to blame it on your computer. Or, they will say it's because you have a Mac. :Angry-Tongue:

Not much you can do except try to "educate" them. Good luck with it. O:)

Let us know....

Phyllis21 11-01-2010 09:57 PM

Thank you.

The first hop should be the router, shouldn't it? Which would mean that if the first hop fails, the problem is within my own network, or the router itself?

Let's hope it's the latter, because I am getting a new router.

cwa107 11-01-2010 10:05 PM

Quote:

Originally Posted by Phyllis21 (Post 1133904)
Thank you.

The first hop should be the router, shouldn't it? Which would mean that if the first hop fails, the problem is within my own network, or the router itself?

Let's hope it's the latter, because I am getting a new router.

The first hop is the ISP's router, not your own.

This should be pretty obvious because your router is going to have a private IP like 192.168.0.1 or 192.168.1.1.

What is the first IP it fails at?

Just a guess, but I can almost guarantee that the ISP denying ICMP for security reasons. Otherwise, the problem wouldn't manifest as slow ping times, it would be no connectivity at all.

cwa107 11-01-2010 10:10 PM

Here's an example traceroute to google.com from my ISP:

Code:

1  174.60.138.1 (174.60.138.1)  8.108 ms  8.748 ms  9.122 ms
 2  te-1-2-ur01.lowerswatera.pa.panjde.comcast.net (68.87.215.17)  16.785 ms  8.976 ms  10.989 ms
 3  te-4-3-ur02.lowerpaxton.pa.panjde.comcast.net (68.85.40.85)  8.110 ms  10.034 ms  9.646 ms
 4  te-9-3-ur01.lowerpaxton.pa.panjde.comcast.net (68.85.41.161)  9.940 ms  9.601 ms  9.580 ms
 5  te-8-2-ar01.lowerpaxton.pa.panjde.comcast.net (68.85.40.1)  11.993 ms  10.080 ms  15.945 ms
 6  te-1-3-ar02.ivyland.pa.panjde.comcast.net (68.85.158.182)  13.405 ms  16.067 ms  16.865 ms
 7  te-0-4-0-4-ar01.ivyland.pa.panjde.comcast.net (68.85.34.93)  14.443 ms  13.843 ms  11.724 ms
 8  pos-0-9-0-0-ar01.401nbroadst.pa.panjde.comcast.net (68.86.208.33)  13.864 ms  15.785 ms  18.023 ms
 9  pos-0-0-0-0-cr01.mclean.va.ibone.comcast.net (68.86.90.9)  22.583 ms  21.965 ms  21.508 ms
10  pos-0-0-0-0-pe01.ashburn.va.ibone.comcast.net (68.86.86.26)  22.658 ms  22.037 ms  30.784 ms
11  75.149.231.62 (75.149.231.62)  51.933 ms  54.464 ms  60.313 ms
12  209.85.240.136 (209.85.240.136)  33.849 ms  33.675 ms  30.469 ms
13  66.249.94.46 (66.249.94.46)  49.702 ms  31.792 ms
    66.249.94.54 (66.249.94.54)  118.995 ms
14  iad04s01-in-f99.1e100.net (72.14.204.99)  29.557 ms  31.957 ms  126.027 ms

My router's IP is 192.168.0.1 - you'll notice it doesn't show that IP at all. It's straight out to 174.60.138.1, which is likely the IP of the closest router on Comcast's local segment.

The reason it skips your router is because it's only showing hops along the WAN, not the LAN.

Phyllis21 11-01-2010 11:03 PM

Aha, OK. Very interesting.

Thank you.

vansmith 11-01-2010 11:04 PM

It may show your router's IP - it shows mine. Here is the output of my own traceroute to google.com. Note line one which is indeed my router. As to why it's there - your guess is as good as mine.
Code:

traceroute to www.l.google.com (209.85.225.147), 64 hops max, 52 byte packets
 1  my.router (192.168.1.1)  3.643 ms  0.818 ms  0.728 ms
 2  10.2.0.1 (10.2.0.1)  2.777 ms  2.585 ms  2.683 ms
 3  208.76.108.13 (208.76.108.13)  11.161 ms  20.443 ms  10.190 ms
 4  bb1.yyz01.3z.ca (208.68.88.1)  15.766 ms  10.719 ms  12.909 ms
 5  gw-google.torontointernetxchange.net (198.32.245.6)  14.676 ms  13.736 ms  16.560 ms
 6  216.239.47.114 (216.239.47.114)  15.649 ms  11.151 ms  11.942 ms
 7  216.239.46.162 (216.239.46.162)  27.210 ms
    216.239.46.160 (216.239.46.160)  38.030 ms  28.595 ms
 8  72.14.232.141 (72.14.232.141)  48.271 ms  38.860 ms  39.609 ms
 9  209.85.241.37 (209.85.241.37)  42.211 ms  37.962 ms  38.812 ms
10  72.14.239.18 (72.14.239.18)  47.989 ms
    66.249.95.138 (66.249.95.138)  52.067 ms
    209.85.248.106 (209.85.248.106)  60.533 ms
11  iy-in-f147.1e100.net (209.85.225.147)  36.687 ms  46.672 ms  37.046 ms


Phyllis21 11-02-2010 02:16 AM

Thanks Van.

But I want certainty, dammit! :)

Hopefully any wild accusations I made to my ISP, will at least goad them into action...

cwa107 11-02-2010 08:11 AM

Quote:

Originally Posted by vansmith (Post 1133936)
It may show your router's IP - it shows mine.

That's really interesting. I've never seen a local "router" show in a traceroute before. Routers are pretty loosely defined these days, but I didn't think traceroute would show anything that wasn't using a true routing protocol.

dtravis7 11-02-2010 08:45 AM

Mine is not showing my router either. I used both traceroute from the terminal and the network utility. Exactly the same.


traceroute to Google (74.125.19.103), 64 hops max, 40 byte packets
1 bras2-l0.skt2ca.sbcglobal.net (151.164.187.3) 44.357 ms 42.943 ms 42.545 ms
2 dist2-vlan50.skt2ca.sbcglobal.net (68.120.211.67) 40.901 ms 41.551 ms 40.971 ms
3 ppp-151-164-39-79.rcsntx.swbell.net (151.164.39.79) 42.325 ms 41.178 ms 40.752 ms
4 ex2-p8-0.pxpaca.sbcglobal.net (151.164.98.47) 46.328 ms 42.941 ms 46.283 ms
5 74.125.48.1 (74.125.48.1) 45.581 ms 45.118 ms 43.918 ms
6 216.239.49.250 (216.239.49.250) 50.075 ms 50.771 ms 46.309 ms
7 209.85.251.94 (209.85.251.94) 45.967 ms 46.412 ms 62.112 ms
8 nuq04s01-in-f103.1e100.net (74.125.19.103) 45.114 ms 45.486 ms 45.062 ms

vansmith 11-02-2010 10:06 AM

I wonder if it's dependent on the router you're using. I also wonder if it has something to do with a particular feature set on the server that is causing it to be "counted". Mine is a fairly standard configuration along with two virtual servers and the built in print server enabled.

Phyllis21 11-03-2010 12:33 AM

Quote:

Originally Posted by vansmith (Post 1134060)
I wonder if it's dependent on the router you're using.

I wonder, as well. I just tested it on my brother's system - iMac, hard-wired to the same ISP, 3 suburbs from here. The only difference is that it's a new NetGear router, whereas mine is Motorola (and at least 2 years old).

The traceroute went through without a problem on his system, and the first hop was not his router.

ukchucktown 11-03-2010 11:57 AM

A router, technically speaking, has two IP addresses. That address may be an internal address or public, it depends on your network setup. As for vansmith's output:

Quote:

1 my.router (192.168.1.1) 3.643 ms 0.818 ms 0.728 ms
2 10.2.0.1 (10.2.0.1) 2.777 ms 2.585 ms 2.683 ms
The first thing I noticed was the two private networks, 192.168.1.0 and 10.2.0.0. That's why you see both addresses most likely, there's a router between the two private networks before the packet jumps to the public network on hop 3. The * in traceroute is not really a failure. It generally means a firewall is blocking ICMP packets used by traceroute or the packet TTL expired before it made it back to the originating host.

Phyllis21 11-03-2010 04:46 PM

That's interesting, my memory is that the first hop on my brother's trace route was to a 10.something address. That might have been his router in disguise?

But how do you explain dtravis7's linked trace route? First hop seems to be an internet address.

ukchucktown 11-03-2010 04:59 PM

Maybe dtravis7 is direct connected to the Internet through his modem, no router between his computer and the modem. I'm not sure. The main point is traceroute sends ICMP packets to gateways in your route and they respond. Look at mine, the first address (obfuscated) in the list is the public IP of my router. It does not show the private IP, only the public IP. The private IP of my router is 192.168.0.1.

Quote:

1 68.*.*.* (68.*.*.*) 8.789 ms 8.536 ms 9.989 ms
2 te-9-4-ur01.jamesisle.sc.chrlstn.comcast.net (68.85.123.5) 9.425 ms 9.145 ms 9.622 ms
3 te-8-1-ar02.charleston.sc.chrlstn.comcast.net (68.86.144.61) 11.657 ms 9.870 ms 9.196 ms
4 pos-1-2-ar02.savannah.ga.savannah.comcast.net (68.86.250.125) 19.547 ms 19.573 ms 32.740 ms
5 te-8-1-ar01.savannah.ga.savannah.comcast.net (68.86.250.1) 19.233 ms 20.540 ms 19.155 ms
6 te-7-4-ar02.augusta.ga.augusta.comcast.net (68.86.164.21) 25.367 ms 21.565 ms 33.327 ms
7 pos-0-10-0-0-cr01.charlotte.nc.ibone.comcast.net (68.86.90.189) 26.585 ms
pos-0-11-0-0-cr01.charlotte.nc.ibone.comcast.net (68.86.91.237) 26.712 ms
pos-0-10-0-0-cr01.charlotte.nc.ibone.comcast.net (68.86.90.189) 27.274 ms
8 pos-3-14-0-0-cr01.atlanta.ga.ibone.comcast.net (68.86.85.213) 33.751 ms 31.862 ms 30.761 ms
9 pos-0-1-0-0-pe01.56marietta.ga.ibone.comcast.net (68.86.86.86) 43.708 ms 32.078 ms 30.768 ms
10 75.149.231.86 (75.149.231.86) 42.294 ms 40.932 ms 44.656 ms
11 72.14.239.100 (72.14.239.100) 47.295 ms 45.717 ms 46.281 ms
12 209.85.254.241 (209.85.254.241) 61.842 ms 90.425 ms 61.285 ms
13 209.85.253.169 (209.85.253.169) 44.748 ms
209.85.253.157 (209.85.253.157) 45.528 ms
209.85.253.169 (209.85.253.169) 55.006 ms
14 yw-in-f147.1e100.net (74.125.47.147) 43.304 ms 41.829 ms 43.332 ms



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