VM - fex mtu size

Similar Questions

• How to choose right for the WAN Interface MTU size?

  Hello

  I would like to know How to determine the right size MTU to set in the properties of the WAN interface (in my case, NSA appliances).

  First of all. I noticed that with SonicOS Enhanced 5.9.x, there is a Tool of diagnosis called PMTU discovery:

  

  This tool is not available with SonicOS Enhanced 5.8.x.

  I guess using this built-in tool is a way to determine the right MTU size to apply.

  Second, for SonicOS versions that do not have this tool and to understand just how to manually determine the size MTU, I would like to know what is the method to follow.

  On the Internet, I found this method by using the ping-f-l command. Once you have determined the largest possible packet size, it ask you to Add 28 to that number and you get the MTU size to define the interface.

  Case study:

  In my business, there are 2 sites: 1 in China and 1 in South Korea. Both have a firewall SonicWALL NSA.

  To determine the MTU size that is applicable from the Chinese site, I get the same results with the 2 methods mentioned above.

  With the help of the PMTU discovery:

  I get 2 IPs: 8.8.8.8 and the Korean FW IP WAN. I get the same result: 1500.

  

  

  However, I noticed that the MTU size should be set to its maximum (1500) of size on the properties of the interface WAN for this test to work properly. Indeed, when I put in 1404 to test, PMTU discovery find 1404 such as MTU size:

  

  

  With the help of ping - f - l:

  When you use the ping with FW Korea WAN IP method, I found 1472 as the maximum packet size:

  

  According to the method I've read on the Internet, adding 28 will make me a MTU of 1500, same size as the PMTU discovery method.

  My question is: can you confirm that these 2 methods are correct determine the MTU size to set the WAN interface? Especially the one with the ping command? If not, how do?

  Thanks in advance for your comments.

  I can tell you that as technicians, we use the way to CMD line to adjust the MTU on WAN interfaces. We saw this as a number to work with.

  Thank you
  Ben D
  #Iwork4Dell

• Test on IPSEC Tunnel MTU size

  How can I test the MTU size, through an IPSEC tunnel to an ASA 5520 to an ASA 5510? I have fears that problems with my equipment are due to the insufficient MTU size.

  You can use extended ping to see the size of the package you can send through the tunnel with little DF

  game do not fragment. for ex: -.

  If you have two windows machines, one on each side of the vpn with ip add 10.2.2.10 and 10.3.3.10.

  Ping 10.2.2.10 to help: -.

  Ping 10.3.3.10

  success of the response

  Ping 10.3.3.10-l 1500 f {where-l 1500 sets the MTU to 1500 and f said do not fragment}

  package has need to be fragmented but df set

  package has need to be fragmented but df set

  Ping 10.3.3.10-l 1300 f

  the fragmentation of packets needs but df set

  Ping 10.3.3.10 l - 1270 f

  success of the response

  success of the response

  Thank you

  Manish

• ESXi MTU sizes?

  Hi people, this will be a quick and apologize if it has been asked before (probably). I mainly use the MTU 1500 bytes size on all my (VM) networks - vSwitches & dVSwitches. I never heard of the obligation to change it (the Jumbo frames side). The links are all links from trunk for the marking of VLAN is made on the side of ESXi.

  Today, this article has been brought to my attention, especially the following:

  microHOWTO: IEEE 802. 1 q VLAN tutorial

  "

  • To use the network layer standard of MTU of 1500 bytes, the equipment must support a link layer MTU to less than 1 522 bytes.
  • If the link MTU layer were limited to the standard value of 1518 bytes the MTU of network layer must be reduced to 1496 bytes to compensate.

  "

  I'm no expert, but it's new to me. I was incorrect and should be using 1518?

  Thanks in advance and greetings

  Steve

  No, you don't need to change anything. MTU is usually called the size of the maximum payload of a frame ethernet without layer 2 headers. The 802. 1 header q VLAN adds 2 bytes and a prefixed byte 2 additional protocol identifier is necessary to point out that this is a 802. 1 q tagged image, thereby increasing the maximum total size of 1518 to 1522, but not changing not the actual payload, aka MTU size.

  Any network device of the last decade able to use VLANs should automatically allow for a maximum total size to 1522 bytes.

• Jumbo frames, change the MTU size without VM guest tension

  I'm trying to disable jumbo frames, specifically to change the size of the mtu to 1500 (instead of 9000) in vcenter on some hosts. Some hosts run esxi 4.1, others are running esxi 5.0. I wonder if it is absolutely necessary to turn off the virtual machines that are connected to the iscsi san network while making this change, or is it relatively safe to make this change, while VMS are running.

  Each VM has active multipathing, 2 vswitches with 1 NIC associated with each.

  I know how to make the changes, regarding my questions whether it is possible to safely make changes while VMS still access the SAN.

  Yes, it is something that I do in my lab quite frequently without using maintenance mode. Memaad notes, maintenance mode is always preferable to avoid unnecessary risks, but it's finally to you.

  See you soon.

• Change the MTU size to vmkernels on dvSwitch

  Hi all

  I have about 40 ESX hosts that belong to dvswitches different 6 and 6 different groups. Each host has 6 vmknics created for the dvswitch and all have value mtu of 1500. Can someone help me with a cli script to change all vmks 9000 MTU?

  Please let me know if additional information is required

  Thanks in advance.

  Try it like this.

  $MtuSize = 9000
  foreach($dvSw in (Get-VirtualSwitch -Distributed -Datacenter MyDC)){
    $dvSw.ExtensionData.Config.Host | %{
      $esx = Get-View $_.Config.Host    foreach($pnic in $_.Config.Backing.PnicSpec){
        $netSys = Get-View $esx.configManager.networkSystem      foreach($vnic in $netSys.NetworkConfig.Vnic | where {$_.Spec.DistributedVirtualPort}){
          $spec = [VMware.Vim.HostVirtualNicSpec]$vnic.spec        $spec.mtu = $MTUSize        $netSys.UpdateVirtualNic($vnic.Device,$spec)
        }
      }
    }
  }
  

  It will update the MTU value of each vnic connected to a dvSwitch

• Fix the size of the MTU for the E4200 using DSL?

  I wanted to check the MTU size manual correct setting for the E4200 using DSL.  An indifferent Linksys Tech told me that the correct MTU size should be manual to 1375. I am running firmware v1.0.01 basically, I have a Mac connected to the E4200 and 2 wireless computers.  I would like to get the best speed of the Internet I can, wire and wireless.  What do you suggest me? Thank you.

  See here

• Setting MTU on Linksys SRW2024

  How do you define the MTU size on the Linksys SRW2024 concert switch?

  Thank you!

  The MTU size is necessary to allow the passage of executives more than 1500. I found the necessary setting on the Admin page to enable frames. In order to be a layer 2 switch, this isn't the answer. You must enable frames more than 1500 to allow their passage.

• Trouble with my MTU settings

  I use a WRT54G for online for a xbox360 and computer connectivity. Three days ago my power went out, he came back the same day. Since then, whenever I try to play online with my Xbox 360 it says "MTU test failed" and says my MTU settings are too low.

  I tried several ways to solve this problem and none have worked up so I thought I would try here also. I'm always looking for other ways to fix it but if anyone has any useful advice, please report it.

  BTW my 360 and the computer are connected to my router, which is connected to my modem is an Arris cable modem.

  Follow this, it will surely work...

  Open an Internet Explorer browser page. In the address bar type - 192.168.1.1
  Leave the name blank user & admin password usage, it will open your router configuration page...

  Then click on the tab "Games and Applications" and click void
  tab "Port Range forwarding"
  (1) on the first line in the box, type Application in "Xbox", start box
  type in 88, in the end box, type 88, in the Protocol keep both in ip
  type in address 192.168.1.20 and give a check mark on the enable box. Click on save settings.

  (2) on the second line in the Application in "Xbox Live" box type in run box
  type in 3074, in type of box in 3074, Protocol keep both in ip
  type in address 192.168.1.20 and give a check mark on the enable box. Click on save settings.

  Once you return to the page setup, click the status tab. Take a note of DNS1 and DNS2.

  Click Setup... Change the MTU to manual and change the MTU size to 1452... Click Save

  Parameters.

  Now to assign the ip address given on your xbox
  IP address :-192.168.1.20
  :-255.255.255.0 subnet mask
  default gateway:-192.168.1.1

  To set the static IP address on the X - Box go to the network settings on the X - Box... Also assign the dns

  address on the xbox in the same way...

  Turn off your router and the X - Box... Wait a minute... Turn on the router first... Wait a

  minute... Test your X - Box... It needs to connect...

• HOW TO ADJUST SETTINGS MTU FOR VISTA?

  HOW TO CHANGE THE MTU SETTINGS?

  Hello

  You use a command prompt

  Start - type in the search-> CMD box find top - make a RIGHT CLIC on - RUN AS ADMIN

  Change the MTU in Windows Vista
  http://www.Kitz.co.UK/ADSL/vistaMTU.htm

  How to set manually the size MTU in Windows XP 2003 2000 Vista
  http://www.windowsreference.com/Windows-XP/how-to-manually-set-the-MTU-size-in-Windows-XP-2003-2000-Vista/

  ------------------------------------------------------

  A good program that can help the MTU value and other parameters.

  Try this - download - SAVE - TweakMaster Pro - go to where you put it - right click on -RUN AS ADMIN

  TweakMaster Pro - 30 days eval
  http://www.TweakMASTER.com/register.php

  Run it - MTU change advanced optimization settings - network adapters - for everything you need.

  I hope this helps.

  Rob Brown - MS MVP - Windows Desktop Experience: Bike - Mark Twain said it right.

• MTU on line ADSL via VPN

  Hi, I use PIX501s with os6.3 (3). They are connected to the internet via ADSL (pppoe). Firewalls are deployed in the Center and network spoke in the Center which is a VPN 7140 router. There are among the sites of links from site to site VPN. There are all Windows domain controllers that need to replicate with the central domain controller in local LANs. It seems that all the rays can ping the host server and vica versa but replication and the remote desktop connection does not work. The access provider ADSL told us to use 1454bytes as MTU on the external interfaces. If I put all the MTU on the PIX and the Central 7140 to 1100 (which should be small enough for ADSL) it does not help. But if I set the MTU size on the central domain controller Windows Server (whith that must replicate all servers spoke and who must be reached via desktop remotely), everything works fine, but this is not a nice.

  How can I know the PIX or the VPN router to connect the correct MTU settings for Windows servers? Or how can I adjust the MTU on the CISCO devices that work?

  The configs are attached

  What OS and what level of service pack is currently running on your domain controllers?

  If it is win 2000 Service Pack 2 from this link:

  http://support.Microsoft.com/default.aspx?scid=kb;en-us;301337

  indicates that the server will ignore requests to lower the mtu when the request comes from a server (or gateway) on the same subnet as the host windows. SP3 resolves this problem.

  I'll do some more research on the Microsoft site and see what I come up with. It seems that your problem might be this or something similar. However, the dc hub seems to be controlling the mtu size, so even if a remote client establishes a replication, the hub dc want to use its mtu and not that of the client, which should be lower as the pix should see the negotiation of mss of tcp and lower according to the interface mtu.

  I'll post what I find.

• VPN and MTU issues

  Recently, I have set up a 1721 running IOS c1700-k9o3sy7 - mz.122 - 15.T5.bin

  This router terminated a VPN with another router, a 1721 with the exact same version of IOS. This router has initially been connected via a WAN link on eth0 wireless. We moved their on a t1 as the main interface with the wireless as a backup. Then we had to

  -Configure a loopback - its ip address device would end the vpn

  -make the source of the vpn packages come from the loop

  -Configure static routes w / higher administrative distance

  Do all this we tested VPN - they worked. Unplugged at t1 connection and traffic moves on the wireless. We checked the vpn clients could connect. Everything worked ok...

  Except when you move large files between hosts behind fa0 via the vpn to the guests at the bottom. To prove the vpn worked and routing was in place, we could telnet from a host behind fa0 via the vpn to a remote host and you connect... Then, we would try an ftp files more. We could connect to the ftp server BUT once a file transfer started things would hang.

  We opened a Cisco tac case and it turned out that the addition of

  IP tcp adjust-mss 1300

  the interface fa0 fixed all - file transfer worked.

  My question why would be reduced aid package size? The vpn add some packages generals cauing more large packages to remove?

  A clue was here, BUT it's PPPoE - no VPN...

  http://www.Cisco.com/univercd/CC/TD/doc/product/software/ios122/122newft/122tcr/122twr/wftbrda.htm#1064471

  I'm looking to explain why this reduced MTU size worked. I would of never figured this out on my own...

  Here's the running-config, we used. Don't forget that everything worked (switching between WAN, vpn, NAT connectivity link) except the transfer of files and when large amounts of data was pushed over the line as MS-sharing files/printers, emails with attachments (a few hundred k). The only change is a line at the fa0 interface.

  version 12.2

  horodateurs service debug uptime

  Log service timestamps uptime

  encryption password service

  !

  hostname HPARFD

  !

  queue logging limit 100

  logging buffered debugging 8192

  enable secret 5

  enable password 7

  !

  abc username password

  clock timezone CST - 6

  clock to summer time recurring CDT

  AAA new-model

  !

  !

  AAA authentication login userauthen local

  AAA authorization groupauthor LAN

  AAA - the id of the joint session

  IP subnet zero

  !

  !

  no ip domain search

  IP domain name blahblah.net

  IP-name server

  IP-name server

  !

  audit of IP notify Journal

  Max-events of po verification IP 100

  property intellectual ssh time 60

  !

  !

  !

  !

  crypto ISAKMP policy 1

  md5 hash

  preshared authentication

  !

  crypto ISAKMP policy 2

  md5 hash

  preshared authentication

  !

  crypto ISAKMP policy 3

  BA 3des

  preshared authentication

  Group 2

  !

  crypto ISAKMP policy 10

  md5 hash

  preshared authentication

  test3030 key crypto isakmp address No.-xauth

  ISAKMP crypto key address 0.0.0.0 test3131 0.0.0.0

  crypto ISAKMP client configuration address pool local ourpool

  !

  ISAKMP crypto client configuration group whatever

  key

  pool ourpool

  ACL 101

  !

  !

  Crypto ipsec transform-set esp - esp-md5-hmac rptset

  Crypto ipsec transform-set esp - esp-md5-hmac trans2

  Crypto ipsec transform-set esp-3des esp-md5-hmac v35clientset

  !

  Crypto-map dynamic dynmap 10

  Set transform-set v35clientset

  Crypto-map dynamic dynmap 20

  Set transform-set trans2

  !

  !

  card crypto rtp-address Loopback0

  crypto isakmp authorization list groupauthor rtp map

  client configuration address card crypto rtp initiate

  client configuration address card crypto rtp answer

  RTP 1 ipsec-isakmp crypto map

  defined by peers

  Set transform-set rptset

  match address 115

  map rtp 50-isakmp ipsec crypto dynamic dynmap

  !

  !

  !

  !

  interface Loopback0

  Description loopback address is NOT dependent on any physical interface

  IP 255.255.255.255

  no ip proxy-arp

  NAT outside IP

  No cutting of the ip horizon

  !

  interface Ethernet0

  secondary description - wireless WAN link

  255.255.255.252 IP address

  no ip proxy-arp

  NAT outside IP

  No cutting of the ip horizon

  Half duplex

  crypto rtp map

  !

  interface FastEthernet0

  Description connected to EthernetLAN

  IP 255.255.255.0

  no ip proxy-arp

  IP tcp adjust-mss 1300

  ^ ^ ^ Tac added cisco work around

  IP nat inside

  automatic speed

  !

  interface Serial0

  first link description WAN - t1

  255.255.255.252 IP address

  no ip proxy-arp

  NAT outside IP

  random detection

  crypto rtp map

  !

  router RIP

  version 2

  passive-interface Loopback0

  passive-interface Serial0

  passive-interface Ethernet0

  network

  No Auto-resume

  !

  IP local pool ourpool

  IP nat inside source overload map route sheep interface Loopback0

  IP classless

  IP route 0.0.0.0 0.0.0.0 Serial0

  IP route 0.0.0.0 0.0.0.0 Ethernet0

  IP route 255.255.255.0 Serial0

  IP route 255.255.255.0 Ethernet0 200

  IP route 255.255.255.0 Serial0

  IP route 255.255.255.0 Ethernet0 200

  IP route 255.255.255.0 Serial0

  IP route 255.255.255.0 Ethernet0 200

  no ip address of the http server

  no ip http secure server

  !

  !

  !

  remote_access extended IP access list

  permit tcp any any eq 22

  permit tcp 0.0.0.255 any eq telnet

  TCP refuse any any eq telnet

  allow an ip

  !

  access-list 1 permit 0.0.0.255

  access-list 100 permit ip 192.168.0.0 0.0.0.255 host

  access-list 100 permit ip 192.168.0.0 0.0.0.255 host

  access-list 100 permit ip 192.168.0.0 0.0.0.255 host

  access-list 101 permit ip 0.0.0.255 10.2.1.0 0.0.0.255

  access-list 101 permit ip 192.168.0.0 0.0.255.255 10.2.1.0 0.0.0.255

  access-list 199 permit tcp a whole Workbench

  access-list 199 permit udp any one

  access-list 199 permit esp a whole

  access-list 199 permit ip 192.168.0.0 0.0.0.255 0.0.0.255

  !

  sheep allowed 10 route map

  corresponds to the IP 110

  !

  Enable SNMP-Server intercepts ATS

  RADIUS server authorization allowed missing Type of service

  alias exec sv show version

  alias exec sr show running-config

  alias exec ss show startup-config

  alias con exec conf t

  top alias show proc exec

  alias exec br show ip brief inter

  !

  Line con 0

  exec-timeout 0 0

  password 7

  line to 0

  line vty 0 4

  exec-timeout 0 0

  password 7

  Synchronous recording

  transport input telnet ssh rlogin udptn stream

  !

  NTP-period clock 17180059

  NTP server

  end

  You can check the following site for more explanation:

  http://www.Cisco.com/en/us/Tech/tk827/tk369/technologies_tech_note09186a0080093f1f.shtml

  HTH...

• Size of df ping 1400-failed

  Hello

  I tried to ping with mtu size 1400 via VPN tunnel in vain.

  Size of Kim #ping 192.168.2.1 df 1400

  Send 5, 1400-byte ICMP echoes 192.168.2.1, time-out is 2 seconds:
  Packet sent with the DF bit set
  MAGNETTE
  Success rate is 0% (0/5)

  Can I know why is so? and how will this affect my system if MTU failed to 1400?
  

  My tunnel mtu is set to 1400

  SH crypto ipsec his:

  Path mtu 1452, ip mtu 1452, ip mtu BID Dialer0

  Thank you

  It is more or less correct...

  You don't want to change the IP MTU on a default interface, what you would like to change is the TCP MSS of 1322 inside the router's interface/LAN interface. He will negotiate a lower during the negotiation of the TCP MSS value, when the TCP packet is encrypted by the GRE/ESP or ESP packet, and therefore going through the interface MTU (usually 1 500 bytes) very well.

• MTU!

  Hello

  I installed VPN(HUB-spoke) and the VPN connection is OK. Ping is also OK. But when I access the websites of H.O via VPN, the page does not appear.

  That's the problem with the MTU size?

  My router is a Cisco ISR 2821 with IOS 12.3 (11) T3. This router acts as the firewall and VPN devices.

  Does router cisco automatically changes the MTU size for VPN tunnel, when the wan interface is used for the VPN and internet access with the NAT/PAT settings?

  -Aline

  Vpn IPSec traffic adds about 70 bytes for headers in tunnel mode (20 for the new ip header, 24 for the header ah / esp and around 10-20 more if GRE is used). IPSec VPNs also encapsulate and then fragment, so if you block the fragmented traffic to the HO and then we saw the issue of not getting the trafifc.

  With 12.3 IOS T, I believe that there is a command to use a tcp mss/mtu of adjustment, or a substitution of DF (to unplugged the DF bit to allow the fragmentation of the image) on the crypto card and/or the outgoing interface for the router to make the adjustment.

  Search Path MTU can not take place if only icmp traffic you allow echo and echo-reply. If you allow inaccessible messages that pmtu can work and you should be able to view the pages. However, that open security holes in order to substitute the mtu/df is the best way to proceed.

  Run this test to see if the mtu is causing this issue: on a workstation, set its mtu equal to or less than 1400 max and see if you can view the pages.

  If mtu is the case, one or two of these links can help you to understand and resolve the issue.

  http://www.Cisco.com/en/us/products/SW/iosswrel/ps1839/products_feature_guide09186a00804247fc.html#wp1052526

  http://www.Cisco.com/en/us/customer/products/SW/iosswrel/ps1839/products_feature_guide09186a0080115533.html

  Let me know if you need more information.

• VPN IPSec L2L between IOS and PIX 6.3 - MTU issue?

  The side of the remote control (customer) is behind the 6.3 (5) PIX. And the side of the head end (server) is 2911 IOS on 15.0.

  The IPSec tunnel rises very well and passes traffic. However, there is a server which are not fully accessible. Note, it is mainly the web traffic.

  Client initiates a connection to the http://server:8000. They receive a redirect to go to http://server:8000 / somepage.jspa. Package caps show the customer acknowledges the redirect with a SYN - ACK response, but then the connection just hangs. And no other packets are received in return. I noticed that the redirected page is a .jsp and other pages that work OK are not. I also noticed that some MTU and TCP MSS configurations on the side of the head that are in place for another GRE VPN tunnel with another site. So I got in the way of the fragmentation of packets. The side PIX has all the standard configurations of IPSec as well as default MTU on the interface of the inside and outside.

  When the MTU is set manually on the client computer to 1400, the access to the works of http://server:8000 / somepage.jspa very well. So I need to tweak the settings of PIX. I tried to adjust the MTU size on and abroad the interface as well as the parameter "sysopt connection tcp - mss. I don't know what else to do here.

  Here is a summary of the MTU settings on the head of line:

  End of the head:

  int tunnel0 (it's the GRE tunnel)

  IP mtu 1420

  source of tunnel G0/0

  dest X.X.X.X

  tunnel path-mtu-discovery

  card crypto vpn 1

  tunnel GRE Description

  blah blah blah

  card crypto vpn 2

  Description IPSec tunnel

  blah blah blah

  int g0/0 (external interface)

  no ip redirection

  no ip unreachable

  no ip proxy-arp

  Check IP unicast reverse

  NAT outside IP

  IP virtual-reassembly

  vpn crypto card

  int g0/1 (this is the interface to the server in question)

  no ip redirection

  no ip unreachable

  no ip proxy-arp

  IP nat inside

  IP virtual-reassembly

  IP tcp adjust-mss 1452

  HA, sorry my bad. Read the previous post wrong.

  (Note: Yes, the SMS on the tunnel interface should be 40 bytes less than MTU).

  Do not twist the MTU, not for TCP problems (not as the first step), it is safer to play with the MSS. MTU may depend on other things (OSPF for example).

  Make a sweep of a ping with DF bit set with the size (from 1300 bytes for example). By doing this, you want to check what is the maximum size of the package, which you can test through the IPsec tunnel. Once you have this value consider - subtract 40 and this defined as value MSS of the LAN interface (and adjust the value of PIX if you can).

  M.