DSR Direct Routing Loopback Adapters in Windows Server 2008

Recently I ran across an interesting networking issue when using a DSR load balancing setup when converting from Windows Server 2003 to Windows Server 2008. It seems that microsoft has changed the way that the TCP/IP stack functions, so that when we went to configure the loopback adapters and setup IIS to run our websites, the server was unreachable. Worse it had a negative effect on routing to our production servers, since the server in question runs as an auxillary server for the production sites.


Anyhow, we finally found a great article that chronicles the issues, and how to correct them. It all boils down to a couple of commands on the command line to correct it:

netsh interface ipv4 set interface "net" weakhostreceive=enabled


netsh interface ipv4 set interface "loopback" weakhostreceive=enabled


netsh interface ipv4 set interface "loopback" weakhostsend=enabled

esxcfg-vswitch - Virtual Switch Configuration tool

NAME

esxcfg-vswitch - VMware ESX Server Virtual Switch Configuration tool 

COPYRIGHT

VMware ESX Server is Copyright 2006 VMware, Inc. All rights reserved. 

SYNOPSIS

esxcfg-vswitch OPTIONS [VSWITCH] 

DESCRIPTION

esxcfg-vswitch provides an interface for adding, removing, and modifying virtual switches and their settings. By default, there is a single virtual switch called vSwitch0. 

OPTIONS

-a -add 

Add a new virtual switch to the system. It requires a virtual switch name to be provided. 

-d -delete 

Delete a virtual switch. This will fail if any ports on the virtual switch are still in use by VMkernel networks, vswifs, or VMs. 

-l -list 

List all virtual switches and their port groups. 

-L -link 

Add an uplink to a virtual switch. This will attach a new unused physical NIC to a virtual switch. 

-U -unlink 

Remove an uplink from a virtual switch. This will remove a NIC from the uplink list of a virtual switch. If it is the last uplink, physical network connectivity for that switch will be lost. 

-p -pg 

Provide the name of the portgroup for the '--vlan' option. "ALL" can be specified to operate on all portgroups of a virtual switch. 

-v -vlan 

Set the VLAN ID for a specific portgroup of a virtuals switch Using the option "0" will disable VLAN for this portgroup. Requires that the --pg option is also specified. 

-c -check 

Check to see if a virtual switch exists. The program prints a "1" if it exists; otherwise it prints "0". 

-A -add-pg 

Add a new portgroup to a virtual switch with the given name. 

-D -del-pg 

Delete a portgroup. This operation will fail if the portgroup is in use. 

-C -check-pg 

Check to see if the name given is in use for a portgroup. The program prints a "1" if it exists; otherwise prints "0". 

-r -restore 

Used at system startup to restore configuration. This should not be run by users. 

-h -help 

Print a simple help message. 

EXAMPLES

Add a Virtual Switch called vswitch1: 

esxcfg-vswitch -a vSwitch1

Add a Portgroup called 'Production' to vSwitch0:

esxcfg-vswitch -A Production vSwitch0

Add a physical network card, vmnic3, to vSwitch0:

esxcfg-vswitch -L vmnic3 vSwitch0

To remove the vlan id completely, just set it to 0 (in case you have set it by accident on an access port)

esxcfg-vswitch vSwitch0 -v 0 -p “Service Console”

To set a vlan id on the service console (in case you forgot to define this during the installation)

esxcfg-vswitch vSwitch0 -v X -p “Service Console” (enter the vlan number where X is)

Of course make sure to check which vSwitch the Service Console is on (and the name of the Service Console) with esxcfg-vswitch -l

Recover ASA Software from ROMMON

Just putting these commands in a handy place since this seems to happen more often than I thought...
rommon #1> ADDRESS=192.168.1.10
rommon #2> SERVER=192.168.1.1
rommon #3> GATEWAY=192.168.1.1
rommon #4> IMAGE=asa800-232-k8.bin
rommon #5> PORT=Ethernet0/0
rommon #6> tftp