Wireshark-users: Re: [Wireshark-users] localhost versus url
From: Tony Anecito <adanecito@xxxxxxxxx>
Date: Thu, 10 Mar 2011 10:42:05 -0800 (PST)
Thanks Jaap I was looking into that and I believe you are right even about the 
relationship with OSI!

Best Regards,
-Tony



----- Original Message ----
From: Jaap Keuter <jaap.keuter@xxxxxxxxx>
To: Community support list for Wireshark <wireshark-users@xxxxxxxxxxxxx>
Sent: Thu, March 10, 2011 11:36:29 AM
Subject: Re: [Wireshark-users] localhost versus url

Hi,

Well, the relationship with OSI layers is a bit awkward, but if you want to talk 

layers, you end up circumventing the Datalink and Physical Layers when going 
through the loopback. The Network Layer determines that the packet doesn't need 
to go to a physical network interface, but rigtht back into the network stack.

Thanks,
Jaap

On 03/10/2011 07:12 PM, Tony Anecito wrote:
> Hi Jaap,
>
> Many thanks that makes sense. I do have a router with a set of static ips
> provided by my isp and one of the ips is registered with godaddy and is tied 
to
> my own domain name and that was what I was using prior to using localhost. I 
>did
> notice on wireshark when using my domain I would see what you described.
>
> I wonder what layers of the OSI 7 layer model is bypassed? I would think the
> first three (1-3) would be bypassed?
>
> Thanks,
> -Tony
>
>
>
> ----- Original Message ----
> From: Jaap Keuter<jaap.keuter@xxxxxxxxx>
> To: Community support list for Wireshark<wireshark-users@xxxxxxxxxxxxx>
> Sent: Thu, March 10, 2011 12:19:12 AM
> Subject: Re: [Wireshark-users] localhost versus url
>
> Hello Tony,
>
> Assuming your domain name is resolved to your public IP address on the outside
> of the firewall/NAT, your assumption is right.
>
> When entering localhost in the URL, that's resolved to 127.0.0.1, your local
> machines loopback interface. No Ethernet networking involved, so watching with
> Wireshark won't show this traffic at all (unless capturing the on the loopback
> interface on a !Windows machine).
>
> When entering the FQDN in the URL, that's resolved to your outside address.
> Browser traffic flows to that address first, then comes back to access the
> Apache server. Now you'll see the traffic when you capture on the network
> interface, once going out and once coming in.
>
> In the circumstance that there's no NAT involved (so your outside address is
> your interface address) you still end up with more delay that going through 
the
> loopback interface. The extra DNS interactions, and probably additional safety
> measures of your platform, take away a little time for every object retrieved.
>
> Thanks,
> Jaap
>
> On 03/09/2011 11:11 PM, Tony Anecito wrote:
>> Hi All,
>>
>> I was running some performance tests last week and noticed with the client 
app
>> running on the same server or apache web server machine the response time was
>> much better when using localhost in the url versus my domain name. I assumed
>> somehow the connection is bypassing my router and connecting to the apache
>> process directly. Is that so and if not what should I see on Wireshark if
>> anything? Or is even the tcp/ip stack short circuited?
>>
>> Thanks,
>> -Tony

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