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mtrai
join:2004-12-16
Panama City, FL

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mtrai

Member

[Equip] Questions and findings user bridge mode ( I use the DPC 3939 )

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Got a few questions and been curious about some things.

I use the DPC 3939 (home). I had some time this morning and been testing on and off for about 6 hours. From all the testing the DPC 3939 ping drops by a large margin if placed in user bridge mode. Screen shots to follow. I have tested it not in user bridge mode with all wireless bands enabled, no 2.4 with 5.0 band working, and no wireless, as well user enabled bridge mode.

The First screen is with just the 2.4 band disabled.
The second screen is both wireless bands disabled.
The 3rd screen is USER ENabled Bridge.

These results have been consistent all mourning. (About the last 6 hours)

As you can see the speeds stay within in any margin of error. It has been like this all morning while testing.

There is a large difference in the ping (hope I explain this right) from enabling User Bridge mode versus shutting one or both bands of wireless.

I know the ping will not make a huge difference in general internet usage, mainly in online gaming which I do.

With all that said why would there be a large difference?

Also my IP address geo location changes from Florida when in non bridged to Kansas when in bridge? ( Yes my IP address does change when switching from non bridged to user bridge which obviously is why my geo loc changes)

Hoping maybe some others that test this out will do so and lets us know the findings.

One last thing to note when I enable user bridge mode the xfinity wifi spot is broadcasting. Scratch this. After further investigation the xfinity wifi network is a neighbors. A neighbor just recently got Comcast and that is what I was picking up. (Just got done testing with my eMTA unplugged)

cbrigante2
Wait til Next Year
Premium Member
join:2002-11-22
North Aurora, IL

cbrigante2

Premium Member

Any chance your firewall is enabled (which would go away in bridge mode)?

owlyn
MVM
join:2004-06-05
Newtown, PA
Netgear CM2050V
Netgear RBRE960
Netgear RBSE960

owlyn to mtrai

MVM

to mtrai
My speedtest pings generally come in at around 12. I am always in Bridge mode. Being that your location is changing, the test is probably choosing a different server that it thinks is closer. Try using the test at »speedtest.comcast.net/ and pick the same server for each test.
mtrai
join:2004-12-16
Panama City, FL

mtrai to cbrigante2

Member

to cbrigante2
Firewalls disabled with all testing weather wireless, partial wireless, or bridge mode enabled.
mtrai

mtrai to owlyn

Member

to owlyn
I used the same test server for every test.

My question that I am trying to understand is why the ping would change so much between enabling bridge mode and not enabling bridge mode.

owlyn
MVM
join:2004-06-05
Newtown, PA

1 recommendation

owlyn

MVM

Your theoretical location is changing, so it is probable that your path to the server ia different. Try running a tracert in both modes. I bet you get different paths.
mtrai
join:2004-12-16
Panama City, FL

mtrai

Member

SNAP...forgot to check that. Great idea.
mtrai

mtrai

Member

God I can't believe I did not remember to check tracert.

That resolved all questions.

IT is not the actual eMTA working different in bridge and non bridge mode. It is the actual location of the IP.

The online maps show the bridge IP address in Kansas, however it is actually in Atlanta, which is the server I have used for all my testing.

In non bridge mode my IP address is always out of Tallahassee, FL.

Anyway thanks for prodding my aging memory with using tracert.

NetFixer
From My Cold Dead Hands
Premium Member
join:2004-06-24
The Boro
Netgear CM500
Pace 5268AC
TRENDnet TEW-829DRU

1 recommendation

NetFixer

Premium Member

said by mtrai:

God I can't believe I did not remember to check tracert.

That resolved all questions.

IT is not the actual eMTA working different in bridge and non bridge mode. It is the actual location of the IP.

The online maps show the bridge IP address in Kansas, however it is actually in Atlanta, which is the server I have used for all my testing.

In non bridge mode my IP address is always out of Tallahassee, FL.

Anyway thanks for prodding my aging memory with using tracert.

The rDNS names you see in a traceroute are mostly irrelevant. A network admin will usually try to keep them relevant, but when equipment and/or IP address blocks gets shuffled around, sometimes the old PTR records are not immediately changed. It is also impossible that simply changing your gateway into bridged mode would actually result in you magically being transported to another city -- there is only one physical cable going from your residence to the same physical CMTS router in the Comcast network.

Your difference in ping times to the speed test server is simply due to the fact that your gateway box (and your secondary router or directly attached PC) will get different IP addresses because their MAC addresses are different (a DHCP server assigns IP addresses based on the MAC address of the client). That different IP address can (and often does) mean that traffic to/from that IP address will take different routes on the Internet.

Here are sample traceroutes I just did to www.dslreports.com. First using my normal router, and then using my secondary router -- these results are not drastically different (but you can see that the initial hops are different, and there is an additional hop with the secondary router), but I have seen cases where a different IP address/IP subnet on the same physical connection would have drastically different routing paths:
C:\>tracert www.dslreports.com
 
Tracing route to www.dslreports.com [64.91.255.98]
over a maximum of 30 hops:
 
  1    <1 ms    <1 ms    <1 ms  gw1.dcs-net.lan [192.168.9.254]
  2     8 ms     8 ms     8 ms  107.3.232.1
  3     8 ms     8 ms     9 ms  xe-10-0-0-32767-sur04.murfreesboro.tn.nash.comcast.net [68.86.151.53]
  4    13 ms    29 ms    17 ms  xe-0-0-9-0-ar01.goodslettvll.tn.nash.comcast.net [68.86.176.105]
  5    19 ms    19 ms    19 ms  he-5-5-0-0-cr01.56marietta.ga.ibone.comcast.net [68.86.90.101]
  6    31 ms    31 ms    31 ms  he-0-6-0-0-cr02.chicago.il.ibone.comcast.net [68.86.86.245]
  7    29 ms    31 ms    32 ms  be-10406-cr01.350ecermak.il.ibone.comcast.net [68.86.84.210]
  8    30 ms    28 ms    29 ms  pos-0-5-0-0-pe01.529bryant.ca.ibone.comcast.net [68.86.88.2]
  9    29 ms    28 ms    29 ms  50.242.150.126
 10    35 ms    35 ms    35 ms  lw-dc3-core1-te8-16.rtr.liquidweb.com [209.59.157.244]
 11    35 ms    36 ms    35 ms  lw-dc3-dist15-po5.rtr.liquidweb.com [69.167.128.241]
 12    36 ms    43 ms    36 ms  www.dslreports.com [64.91.255.98]
 
Trace complete.
 
C:\>tracert www.dslreports.com
 
Tracing route to www.dslreports.com [64.91.255.98]
over a maximum of 30 hops:
 
  1    <1 ms    <1 ms    <1 ms  gv2.dcs-net.lan [192.168.20.1]
  2     8 ms     8 ms     9 ms  68.53.40.1
  3    23 ms     9 ms     8 ms  68.85.135.61
  4     8 ms     8 ms     8 ms  xe-11-0-1-0-sur04.murfreesboro.tn.nash.comcast.net [68.86.148.126]
  5    10 ms    10 ms    35 ms  xe-0-0-11-0-ar01.goodslettvll.tn.nash.comcast.net [162.151.9.65]
  6    19 ms    19 ms    19 ms  he-5-4-0-0-cr01.56marietta.ga.ibone.comcast.net [68.86.90.189]
  7    30 ms    30 ms    31 ms  he-0-6-0-0-cr02.chicago.il.ibone.comcast.net [68.86.86.245]
  8    29 ms    31 ms    31 ms  be-10406-cr01.350ecermak.il.ibone.comcast.net [68.86.84.210]
  9    29 ms    29 ms    29 ms  hu-0-10-0-1.pe03.350ecermak.il.ibone.comcast.net [68.86.86.6]
 10    29 ms    29 ms    28 ms  50.242.150.130
 11   108 ms    42 ms    35 ms  lw-dc3-core1-te8-16.rtr.liquidweb.com [209.59.157.244]
 12    36 ms    35 ms    35 ms  lw-dc3-dist15-po5.rtr.liquidweb.com [69.167.128.241]
 13    35 ms    35 ms    43 ms  www.dslreports.com [64.91.255.98]
 
Trace complete.
 
mtrai
join:2004-12-16
Panama City, FL

mtrai

Member

Thanks..it seems I have developed some cobwebs upstairs if you know what I mean. Thanks. I was looking at it all wrong. This time I ran tracert with command prompts vs gui to see what actually is going on .

Bridge mode is indeed faster but for not the reasons I was thinking.

While I am in bridge mode I have 2 less hops, and as you said it does indeed take a slightly different route.

Just trying to figure out the whys..lol
warpc0re
join:2014-11-03
Lynnwood, WA

warpc0re

Member

said by mtrai:

Bridge mode is indeed faster but for not the reasons I was thinking.

While I am in bridge mode I have 2 less hops, and as you said it does indeed take a slightly different route.

Just trying to figure out the whys..lol

This makes sense. The latency in bridge mode is lower, because the DCP3939 is having to do much less work than it would in gateway mode.

In bridge mode the DCP3939 is simply forwarding ethernet frames.

In gateway mode, the DCP3939 functions as an actual router, and processes each packet to make decisions about forwarding, filtering, NAT'ing, etc... That action adds latency.