The Route Distinguisher (RD) and the Route Target (RT) can be somewhat confusing to someone who is trying to learn the concept on MPLS. In this post, I will try and explain what RD and RT are in relation to MPLS.
To answer this question, we will use the following diagram.
As you can see from the Diagram, Router A and Router B, namely Customer A and Customer B are sending the same overlapping 172.16.0.0/24 prefix into the ISP network. The ISP running MPLS, has the responsibility to take the routes from London and hand over the routes to the appropriate customers in New York.
Let’s try and concentrate on this specific aspect of MPLS where the provider network (ISP) is responsible for keeping the Customer routes unique yet identifying who owns a specific route. This is where RD and RT comes into play.
What the Route Distinguisher (RD) does is actually in the word itself, where it distinguishes the route by adding a 64-bit value in addition to the 32-bit IP making a 96-bit VPNv4 address. Therefore, the ISP can distinguish each and every route regardless of whether the 32-bit IP is overlapping.
Now the ISP can distinguish the routes, how does the ISP knows who sent which route? This is where the Router-Target (RT) comes into play. The RT is a 64-bit community value which is sent along with the update.
This way the ISP running MPLS network can distinguish each route by having the Route Distinguisher (RD) while the Route-Target will enable the ISP to know who the specific route actually belongs to.
T he following Exim mail servers error was encountered while sending out mails. The original error was experienced by Gravity Forms WordPress plugin. However, I was able to test it out by using command line to rule out the plugin.
firstname.lastname@example.org R=virtual_aliases: No Such User Here
The debug message I received via Gravity Forms is the following. This confirms the mail has been passed on from WordPress to the mail server.
2016-03-25 11:06:04.042599 - DEBUG --> GFCommon::send_email(): Result from wp_mail(): 1
2016-03-25 11:06:04.042748 - DEBUG --> GFCommon::send_email(): Mail was passed from WordPress to the mail server.
2016-03-25 11:06:04.153172 - DEBUG --> GFFormDisplay::handle_confirmation(): Sending confirmation.
Before I go any further, I would like to give some background information on domain.com, which the following aspects are hosted as below.
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Even though I am a big advocate on promoting IPv6, I have came across Debian’s APT / apt-get stuck with the following message. I believe it is due to an issue on the serve concerning the FQDN
http.debian.net and security.debian.org. The easy way to fix is to force APT to use IPv4 as opposed to IPv6.
0% [Connecting to http.debian.net (2a01:4f8:151:555d::42)] [Connecting to security.debian.org (2610:148:1f10:3::73)]
echo 'Acquire::ForceIPv4 "true";' | tee /etc/apt/apt.conf.d/99force-ipv4
On Cisco ASA, You cannot have DHCPd and Relay configured at the same time.
- You can either add a relay server and add the DHCP scopes.
- You can add different DHCP scope to the ASA DHCPd.
Visco VIRL sometimes throw the following error stating KVM acceleration is not available on hosts running ESXi.
KVM acceleration is not available
INFO: Your CPU does not support KVM extensions
KVM acceleration can NOT be used
You can also run the kvm-ok command to find the status of KVM accleration.
This is due to a missing setting on ESXi Guest OS and the following parameter needs to be added VM’s .VMX configuration file.
Please make sure the VM is shut down before making the change.
vhv.enable = “TRUE”
You can also add this parameter to
/etc/vmware/config of the host, but it is not imperative you should do it.
The following object-group consists the latest IANA ROOT DNS Servers which can be used on the Cisco ASA firewalls.
object-group network IANA-ROOT-DNS
description IANA Root DNS Servers (IPv4/IPv6)
network-object host 184.108.40.206
network-object host 2001:503:ba3e::2:30
network-object host 220.127.116.11
network-object host 2001:500:84::b
network-object host 18.104.22.168
network-object host 2001:500:2::c
network-object host 22.214.171.124
network-object host 2001:500:2d::d
network-object host 126.96.36.199
network-object host 188.8.131.52
network-object host 2001:500:2f::f
network-object host 184.108.40.206
network-object host 220.127.116.11
network-object host 2001:500:1::803f:235
network-object host 18.104.22.168
network-object host 2001:7fe::53
network-object host 22.214.171.124
network-object host 2001:503:c27::2:30
network-object host 126.96.36.199
network-object host 2001:7fd::1
network-object host 188.8.131.52
network-object host 2001:500:3::42
network-object host 184.108.40.206
network-object host 2001:dc3::35
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