Configuring MTU size.

[zerophase]

I'm just trying to figure out which ethernet ports connect to my pc. I already have the computer setup to use 9000 mtu size, but don't know which port on the routers end I need to adjust. I'm pretty sure it's one of the ethX ports.

Do I also need to change the mtu size of the lo, fwd, or vlan?

 

[red_pope]

I'm just trying to figure out which ethernet ports connect to my pc. I already have the computer setup to use 9000 mtu size, but don't know which port on the routers end I need to adjust. I'm pretty sure it's one of the ethX ports.

Do I also need to change the mtu size of the lo, fwd, or vlan?

Lately I work on this matter at home in my own network. After reading thoroughly there is few things to consider to make it work.

1- Are you using ADSL, FIBER or Cable.? Im using ADSL, Internally in my own home lan it works very nicely. All my PC are using gigabit cards and my switch is able to handle the load. Including my own bought Adsl router.

But when it comes to ADSL there is limitations. You have to read thoroughly and understand that not every server in the WWW is plausible with it. Once you have a good base band, with a specific server in the web All it does improves is your base band not your broadband. You have to test every PC until you find a good MTU.

Your VLAN stays the same. I do have a VLAN WITH 3 PC'S AT HOME.

 

[zerophase]

I'm using cable. I'm just trying to configure my mtu for lan transfers.

 

[red_pope]

I'm using cable. I'm just trying to configure my mtu for lan transfers.

When you mention LAN, you meant to say> Internally or outside in the WWW?

 

[red_pope]

I'm using cable. I'm just trying to configure my mtu for lan transfers.

Ill get it, basically you want to increase you MTU locally at your home. well, yes you can locally. The tricky part, handling it, outside in each individually World Wide server. If I was going to transfer files locally among my computers, Ill change the MTU. but remember anything outside in the WWW web is another story. You have to troubleshoot it from your end. Don't worry about the ports, is all about all large files from the standard size file.

How much have you read about MTU?
Here is a few web articles that I read on that matter.

https://supportforums.cisco.com/discussion/12042806/understanding-mtu-adsl#comment-9318061
http://www.dslreports.com/faq/5793
http://www.kitz.co.uk/adsl/MTU2.htm
http://www.bestyoucanget.com/optimizemtu.htm
http://www.dslreports.com/faq/5793
http://www.adslnation.com/support/knowledgebase/ht003.php
http://www.dslreports.com/tweaks/MTU/
http://www.dslreports.com/faq/16120
ADSL Troubleshooting

http://www.internode.on.net/support/faq/adsl/adsl_troubleshooting/#MTU

 

[zerophase]

When you mention LAN, you meant to say> Internally or outside in the WWW?

I'm trying to configure internal mtu sizes. I just want to make sure I configure the ethernet port on the router connected to my computer. I have other devices connected to other ports, which I don't want to change the mtu for.

 

[red_pope]

I'm trying to configure internal mtu sizes. I just want to make sure I configure the ethernet port on the router connected to my computer. I have other devices connected to other ports, which I don't want to change the mtu for.

The computer that you want to use and connect, using MTU are for local. meaning your home network use or outside in the WWW, meaning internet?

 

[zerophase]

It's for local use.

 

[zerophase]

I'm basically looking for a command that I can ssh into the router, and run to figure out which ethernet port I need to adjust. 4 ethernet ports are listed, as well as vlans and such. I need to figure out which out of the list shown by ip link connects to the computer that's backing up files to a drive connected to the router.

 

[red_pope]

It's for local use.

That could be a problem, once you change the MTU size in your PC and in specially your ISP router, it is a consider a universal change, not specific port driven, only you could always access your ISP router and explore the settings. I do not use cable, only ADSL.

But I do use a 12 port Gigabits manageable switch and able to control the switching.. but in your case you are using your ISP cable router for all your LAN computer connections.

Is your cable modem Ethernet ports gigabits?

 

[red_pope]

I understand your comments.
Sorry I miss out your reply

 

[zerophase]

Yes, they're gigabit.

 

[zerophase]

My cable modem only has 1 ethernet port, which plugs into my router.

 

[red_pope]

I know how to telnet into my switch and my personal ADSL router securely, and able to change, modify and view my PORTS traffic and monitor it. I could even use my own secure VPN, access remotely and change my settings.

What kind of router you have?

Yes, they're gigabit.

 

[zerophase]

I have an Asus AC5300.

 

[red_pope]

Here is an Idea, If you could use your router to forward ports on that specific machine, just look at the back of the router manually trace the LAN coming from your specific PC and take notes on what Ethernet port is connect to. It should be label as etho1, etho2 etc. The labeling. it my vary from manufacture.

Once you identify the port telnet and access your GUI inside the router, go to the forward ports settings and redirect that specific PC to where you want it to go. MTU HAS NOTHING TO WITH IT! MTU is done at your nick cards, not your ports configuration.

I hope I did help you. Good Luck

 

[zerophase]

That's the problem the ports are labeled as 1 -4 on the back of router, but I don't know which ports they correspond to on the command line. Which is why I'm looking for a way to trace the path taken on the network.

 

[red_pope]

That's the problem the ports are labeled as 1 -4 on the back of router, but I don't know which ports they correspond to on the command line. Which is why I'm looking for a way to trace the path taken on the network.

Netstat
https://technet.microsoft.com/en-us/library/bb490947.aspx

further reading
https://superuser.com/questions/730...orrect-concerning-the-actual-path-to-a-target

he most important thing to remember is that routes are not static. By design, routes on the public internet are changing all the time. Sometimes routes change due to load balancing; sometimes they change because a node goes down; sometimes they change because routers decide literally at random to change the routing rules (just to shake things up).
From the perspective of an end-user who does not have System Administrator-level access to every single intermediate router and internet hub between the origin and destination of a packet, you have to treat it kind of like the Heisenberg Uncertainty Principle.
Things to consider:

1. Based on the declared IP "destination" in your packet, intermediate routers may decide to route you differently. Therefore, if a traceroute is an attempt to sequentially map the routers between source and destination, a traceroute can be thrown way off course by having routes take different paths depending on which node you're trying to reach.
2. Not all routers will listen for ICMP or UDP pings. They may choose to silently ignore this traffic and just drop it at the NIC (often to help combat DDoS). This can frustrate your attempt to map a route.
3. Even if you successfully map a route, and all intermediate nodes reply to your pings and don't attempt to play with your mapping attempt, the route may change for the next packets you send using some "real" protocol (or even if you attempt a traceroute a second time).
4. QoS may cause normally-behaving networks to route traffic differently. For instance, VoIP or streaming video may take one path, while regular web browsing may take another.
5. The type of traffic may cause the routing to differ. For instance, even without considering QoS, you may get a different path for FTP than you get for SSH. The intermediate nodes can exercise any discretion whatsoever (anything from a totally random selection of routes, to a malicious attempt to slow down your traffic, to an honest attempt to make your connection faster by routing to the node with the least load) when determining where to route your traffic from each hop.
6. In theory, intermediate routers could also, if they so desired, turn your traceroute attempt into an infinite cycle: node A points to node B, node B points to node C, and node C points back to node A. There is nothing stopping the routers from doing this (I'm not sure why they would choose to, but it's a possibility) for packets detected as "traceroutes" (ICMP or UDP pings). It can do this to attempt to foil your efforts, or for any other reason.

The Multipath Discovery Algorithm is useful, but it cannot overcome these theoretical limitations.
Basically, in order to determine a path, you have to send one or more packets. Those packets can be routed in any way the intermediate nodes see fit. But as soon as you send another packet, there is absolutely nothing stopping the routers from changing the path. This is sort of a networking analogy of the Heisenberg Uncertainty Principle.
Paths are ephemeral and transient. You should not rely on information received from a traceroute for anything important, except to diagnose a connectivity issue on a network where you already have deep knowledge of the topology (on a complicated corporate LAN, for instance), and can control the behavior of the participating nodes. If any of the participating nodes aren't "yours" (if you can't log into them with system administrator privileges), the results of the traceroute are effectively arbitrary.
On the other hand, if all of the participating nodes are yours, you can, as administrator, control the exact behavior of each node. For instance, you can enable ICMP, and set up static routes (routes that don't change). You can then be confident that your traceroute is accurate. But if you put a load balancer in the middle, then you will have to be aware of the load balancer's behavior and the way that it can switch routes pretty much as needed (although it generally isn't random and generally doesn't try to deceive you on purpose).

 

[ColinTaylor]

red_pope doesn't appear to understand that you are not sending any data over the internet, only from the PC to the routers USB drive.

You can't normally change just one LAN port because they are combined to form a single VLAN and then attached to a bridge interface (br0).

# robocfg show
Switch: enabled gigabit
Port 0: 1000FD enabled stp: none vlan: 2 jumbo: off mac: a4:4c:11:8b:93:da
Port 1:   DOWN enabled stp: none vlan: 1 jumbo: off mac: 00:00:00:00:00:00
Port 2: 1000FD enabled stp: none vlan: 1 jumbo: off mac: a0:b3:cc:df:1f:cb
Port 3:  100FD enabled stp: none vlan: 1 jumbo: off mac: 00:a0:96:ca:f0:f6
Port 4: 1000FD enabled stp: none vlan: 1 jumbo: off mac: 94:de:80:c5:79:52
Port 8: 1000FD enabled stp: none vlan: 1 jumbo: off mac: bc:ee:7b:c3:78:a8
VLANs: BCM53115 enabled mac_check mac_hash
   1: vlan1: 1 2 3 4 8t
   2: vlan2: 0 8u


# brctl show
bridge name     bridge id               STP enabled     interfaces
br0             8000.bcee7bc378a8       yes             vlan1
                                                        eth1
                                                        eth2

# ifconfig vlan1
vlan1      Link encap:Ethernet  HWaddr BC:EE:7B:C3:78:A8
           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
           RX packets:6053912 errors:0 dropped:0 overruns:0 frame:0
           TX packets:6233573 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:0
           RX bytes:392025068 (373.8 MiB)  TX bytes:338226335 (322.5 MiB)

# ifconfig br0
br0        Link encap:Ethernet  HWaddr BC:EE:7B:C3:78:A8
           inet addr:192.168.1.1  Bcast:192.168.1.255  Mask:255.255.255.0
           UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
           RX packets:12404949 errors:0 dropped:0 overruns:0 frame:0
           TX packets:19233123 errors:0 dropped:0 overruns:0 carrier:0
           collisions:0 txqueuelen:0
           RX bytes:703385412 (670.7 MiB)  TX bytes:2659635050 (2.4 GiB)

This is for the N66U. The interface names and VLANs will be different for your router.

 

[red_pope]

ColinTaylor you said:

red_pope doesn't appear to understand that you are not sending any data over the internet, only from the PC to the routers USB drive.

Apparently some people are just selective, tampering and absent minded, pointing readers. Does he said anything or mention anything, about a USB drive? unless I'm inhaling some pollutant in the air coming from your arsed...