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brenkehoe
Beginner
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Message 1 of 12

Packet Loss

Seem to be getting a lot of packet loss from 31.55.185.177. Any ideas ? started 2 days ago

 

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11 REPLIES 11
Sage
Sage
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Message 2 of 12

Re: Packet Loss

You aren't actually getting packet loss, the router is not responding to ICMP requests. ICMP requests are treated as low priority.

 

All your packets were handed over to the next router.

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brenkehoe
Beginner
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Message 3 of 12

Re: Packet Loss

well something is wrong somewhere thats for sure. Even if its not at that hop. Wouldnt it be at 100% if no ICMP requests ? Anything else i can do to narrow it down ?

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oakserver
Aspiring Expert
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Message 4 of 12

Re: Packet Loss

How do you tell the difference between packet loss and packets that had no ICMP response then?

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Sage
Sage
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Message 5 of 12

Re: Packet Loss

When looking at a tracert check the destination first. If it has recieved all the packets then you have had no packet loss no matter what is recorded on the way to the destination.

 

All routers on the path to the destination treat ICMP (packet) requests as low priority so any router along the path may appear to be dropping packets if it is busy doing it's job. Passing the packet onto the next router.

 

Some routers in the path may be configured to respond at all.

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pgregg
Aspiring Contributor
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Message 6 of 12

Re: Packet Loss

You answer is factually incorrect. I'll provide a better answer below.
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Sage
Sage
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Message 7 of 12

Re: Packet Loss

I look forward to it. Especially when you explain there is packet loss if all packets reach the destination.

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pgregg
Aspiring Contributor
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Message 8 of 12

Re: Packet Loss

Only windows uses ICMP as default when doin traceroute. Unix systems use UDP.

How a traceroute works is the sending system generates a packet to the target IP with a TTL of 1.

The first router that gets it, decrements the TTL and if it is zero will respond with a ICMP Time Exceeded, with the sender IP of that router IP.

The next packet is set with a TTL of 2. The first router decrements the TTL and passes it on.

The next guy decrements, sees it is zero and responds ICMP Time Exceeded.

Repeat until you've hit the target IP for your traceroute.

 

This allows you to identify the hops between you and the target IP.

 

Indeed some routers may not respond at all - in which case you'll never see their IP.

 

All traceroutes to google.com

 

Here, I'm seeing definate loss (at UDP level - so if I have UDP loss, I'll have TCP loss): IPv6

 

                              My traceroute  [v0.85]
nas03 (::)                                               Wed Aug  2 21:03:31 2017
Keys:  Help   Display mode   Restart statistics   Order of fields   quit
                                         Packets               Pings
 Host                                  Loss%   Snt   Last   Avg  Best  Wrst StDev
 1. broadband.bt.com                    0.0%   532    1.0   1.0   0.5  15.6   1.2
 2. ???
 3. 2a00:2302::1103:100:36             88.1%   531   56.6  79.0  56.0 359.2  53.0
 4. 2a00:2302::1103:100:3f             24.5%   531   67.5  94.8  54.5 370.7  75.1
 5. 2a00:2380:3013:8000::1a            23.5%   531   66.6  93.5  51.9 372.3  76.2
 6. 2a00:2380:13::19                   20.5%   531   59.2  94.4  55.1 369.3  73.9
 7. 2a00:2380:2015:1000::f              1.1%   531   61.4  93.1  51.7 372.8  76.3
 8. 2001:4860:0:1103::1                 1.1%   531   58.8  95.7  55.0 376.9  76.6
 9. 2001:4860:0:1::1dab                 2.1%   531   57.9  89.6  52.4 372.4  72.6
10. lhr35s07-in-x0e.1e100.net           2.1%   531   65.7  89.8  52.0 373.5  72.6

Same route with IPv4 UDP:

 

 

                              My traceroute  [v0.85]
nas03 (0.0.0.0)                                          Wed Aug  2 21:05:32 2017
Keys:  Help   Display mode   Restart statistics   Order of fields   quit
                                         Packets               Pings
 Host                                  Loss%   Snt   Last   Avg  Best  Wrst StDev
 1. 172.16.0.1                         23.0%    88    0.8   0.9   0.7   2.3   0.1
 2. ???
 3. 31.55.185.181                      87.4%    88   64.3  70.7  56.1 170.8  33.6
 4. 31.55.185.188                       1.1%    88   61.4  65.8  52.4 276.7  28.1
 5. core2-hu0-10-0-0.colindale.ukcore.  0.0%    88   56.8  69.1  54.2 346.8  39.4
 6. 195.99.127.81                       0.0%    88   76.3  70.6  56.7 247.7  27.3
 7. 109.159.253.67                      0.0%    88   79.4  70.8  55.8 180.3  23.1
 8. ???
 9. 216.239.58.223                      0.0%    88   55.0  67.1  52.6 306.5  34.2
10. lhr25s14-in-f14.1e100.net           0.0%    88   59.7  67.7  52.2 306.5  38.0

Not so much...

 

 

Ok, lets try IPv4 using TCP:

 

                                       My traceroute  [v0.85]
nas03 (0.0.0.0)                                                            Wed Aug  2 21:06:10 2017
Keys:  Help   Display mode   Restart statistics   Order of fields   quit
                                                           Packets               Pings
 Host                                                    Loss%   Snt   Last   Avg  Best  Wrst StDev
 1. 172.16.0.1                                            0.0%    64    1.1   1.1   0.9   2.0   0.0
 2. ???
 3. 31.55.185.177                                        50.8%    64  2658. 3862. 719.9 9697. 2548.
 4. 31.55.185.176                                         3.1%    64  2072. 1667. 654.5 2966. 626.1
 5. core1-hu0-10-0-0.colindale.ukcore.bt.net              3.1%    64  2069. 1804. 673.3 5651. 923.4
    195.99.127.118
    core1-hu0-8-0-1.colindale.ukcore.bt.net
    195.99.127.114
    core1-hu0-0-0-1.colindale.ukcore.bt.net
    core1-hu0-17-0-1.colindale.ukcore.bt.net
    core2-hu0-17-0-5.colindale.ukcore.bt.net
    195.99.127.216
 6. 62.172.103.49                                         3.2%    63  2153. 1748. 677.3 5600. 836.5
    peer1-hu0-19-0-2.slough.ukcore.bt.net
    195.99.127.85
    peer1-et-1-1-0.redbus.ukcore.bt.net
    peer1-hu0-1-0-6.slough.ukcore.bt.net
    peer1-hu0-10-0-2.slough.ukcore.bt.net
    peer6-hu0-6-0-2.telehouse.ukcore.bt.net
    peer1-hu0-9-0-4.slough.ukcore.bt.net
 7. 195.99.126.187                                        3.2%    63  2151. 1692. 716.2 3614. 733.3
    109.159.253.67
    peer5-te0-0-0-32.telehouse.ukcore.bt.net
    195.99.126.185
    195.99.126.105
 8. 108.170.246.225                                       3.2%    63  2155. 1752. 736.2 5583. 863.8
    108.170.246.193
 9. 72.14.234.133                                         3.2%    62  2153. 1813. 754.4 5590. 916.1
    72.14.234.131
10. lhr35s04-in-f14.1e100.net                             3.2%    62  2149. 1733. 774.4 3723. 670.5

Ouch.

 

 

Trying again with a 1KB TCP packet size:

                                       My traceroute  [v0.85]
nas03 (0.0.0.0)                                                            Wed Aug  2 21:08:34 2017
Keys:  Help   Display mode   Restart statistics   Order of fields   quit
                                                           Packets               Pings
 Host                                                    Loss%   Snt   Last   Avg  Best  Wrst StDev
 1. 172.16.0.1                                            4.5%    44    1.0   1.1   0.9   2.1   0.2
 2. ???
 3. 31.55.185.181                                        72.1%    44  787.8 3033. 787.8 8032. 2590.
 4. 31.55.185.180                                         4.5%    44  2469. 1388. 697.0 4166. 606.7
 5. core1-hu0-8-0-1.colindale.ukcore.bt.net               4.7%    44  2020. 1330. 657.6 4243. 584.2
    195.99.127.114
    core1-hu0-0-0-1.colindale.ukcore.bt.net
    195.99.127.216
    core2-hu0-8-0-5.colindale.ukcore.bt.net
    core2-hu0-9-0-0.colindale.ukcore.bt.net
    core2-hu0-17-0-5.colindale.ukcore.bt.net
    195.99.127.118
 6. 195.99.127.81                                         4.7%    44  2055. 1250. 636.5 2055. 343.4
    peer1-et-1-1-0.redbus.ukcore.bt.net
    peer1-et-10-3-0.telehouse.ukcore.bt.net
    peer1-et-1-3-0.telehouse.ukcore.bt.net
    62.172.103.49
    195.99.127.87
    195.99.127.83
    peer1-hu0-9-0-4.slough.ukcore.bt.net
 7. 195.99.126.105                                        4.7%    44  2087. 1257. 633.1 2258. 371.5
    195.99.126.187
    peer5-te0-0-0-32.telehouse.ukcore.bt.net
    195.99.126.185
    109.159.253.67
 8. 108.170.246.193                                       4.7%    44  2130. 1367. 609.9 4030. 583.8
    108.170.246.225
 9. 209.85.241.169                                        4.9%    41  2187. 1274. 612.3 2187. 357.2
    209.85.242.21
10. lhr26s05-in-f14.1e100.net                             4.9%    41  2225. 1381. 716.0 4076. 568.9


Yeah, not awesome.

 

PS. I found this post after my internet connection just went to hell.

 

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pgregg
Aspiring Contributor
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Message 9 of 12

Re: Packet Loss

Most interesting in those stats is actually not the loss. It is the average RTT being more than 1 second for all hops for TCP maxing out at 9.7 seconds. Thats a pretty hellish round trip time for 1KB.

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pgregg
Aspiring Contributor
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Message 10 of 12

Re: Packet Loss

OP's screenshot does demonstrate a 3% packet loss.

 

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