Inter as l2vpn option calculator
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Today I have a very interesting topic to discuss. Actually, I came across some customer issue and I had to dig deeper into the platform level of to find out the root cause.
But, then lately I realized that L2vpn vpls inter as option brokerage should share the concept with everyone. So here it is. Handling link and node failures.
Lets discuss a very generic problem which will help understand in a simple way the "need for FRR". Now, Consider an IGP network using a link-state protocol. SPF has to run once when the link goes down and again when the link comes back up. After the headend recomputes the new path. SPF has to be run again for the prefixes routed over the tunnel situation where autoroute is in placethus making convergence time even worse than in a pure IP network.
Automatic Protection Switching APS is one solution to recover quickly from link failures but comes with an additional cost. Cisco came up with mechanisms to deal with the problem of how to make the MPLS TE tunnel resistant to failures and those mechanisms were collectively called Fast Reroute. Protection - in the context of fast restoration, is having procedures in place l2vpn vpls inter as option brokerage, when applied to selected resources, ensuring minimal traffic loss. Protection can be classified into two categories: In this post, I will be specifically discussing about Link protection.
The other topics shall be covered in l2vpn vpls inter as option brokerage posts. If you consider high bandwidth links carrying critical traffic, with TE deployment, the LSP's over those links also become critical.
These LSP's might be carrying critical information or time-sensitive data that requires real-time response. It would be highly preferred to protect these LSP's. FRR allows you to protect your TE tunnels which are carrying sensitive data and also which are not.
A pre-signaled backup tunnel is created to bypass the protected links. Link protection means that, when a link goes down, the LSP's that would have gone over that link are sent across some other path. We are trying to protect the link between R1 and R2. Below are the details of the base configuration. Rest all other interfaces are Gigabit Interfaces. Thus we are trying to protect the LSP created by this Tunnel. Also, please note that the path-option is dynamics and no other constrained is specified, so for path calculation will be based on the IGP.
Since R1 and R2 are directly connected, thus, the link between R1 and R2 will be treated as the primary path. Now, lets consider the configuration of the backup tunnel. If you see the above configuration, you can see l2vpn vpls inter as option brokerage the backup tunnel is configured with an explicit path-option. But in the explicit-path we see that the we have an exclude-address statement which is the ip of R2 physically connected interface to R1.
Please note that FRR helps the restoration of the traffic in just 50 ms. Lets now have a look at some of the outputs. If you still have any queries, please reply me on this blog post. I shall be happy to clarify those doubts. If you want some other example, please let me know as well. Hi Genie, this is interesting stuff and the language used here is very simple.
The labs mentioned with the setup details are very helpful in doing the hands on and the concept clear. Keep posting useful stuff like this. Can I post a question. I see that "tunnel mpls traffic-eng fast-reroute" is enabled on the Primary Tunnel Do we need this command for those Tunnel which we want to protect?
Or this should be enabled on all the Tunnel interfaces on head end router? Have been banging my head on FRR link protection for few days. But finally got to understand the concept through your blog. If we want to have FRR at mid-points. So I just need to have this command on mid-point router "mpls traffic-eng backup-path Tunnel" and rest of things will be taken care by TE? Hello Nik Thanks for posting questions. Please don't say sorry for posting question.
Please feel free them to post as many as you have. Now coming to your first question. By enabling this command we tell the primary tunnel that there is already a backup tunnel in case there is any failure on the Tunnel LSP.
There may be different causes to it. This post is basically about Link protection. That means, within the path of the TE tunnel, there will be a link which we are trying to protect as the Tunnel is supposed to carry critical data traffic. Now, we protect a link which in case of any failure, l2vpn vpls inter as option brokerage to the protected path. So there is a backup LSP already prepared vie the backup tunnel path so that in case the primary link l2vpn vpls inter as option brokerage, the Tunnel wont go down or impact the traffic, rather it will shift to the backup LSP and reoptimize.
So based on your question, this command should be enabled on the Tunnel which we want to protect. Regarding your second question, - The command that you mention is put on the l2vpn vpls inter as option brokerage which we want to protect. That shall cover all that section. Hope your questions have been answered. Please let me know if you have any other questions.
Morning Genie, Can you please shed some light on "mpls traffic-eng backup-path Tunnel X" If my understanding is correct then this command would be applied on the interface for which we want to create backup of Primary tunnel LSPs? Hi Nik Thanks for asking the question. As mentioned previously, this command is added on the link which is being protected. The backup Tunnel is created on the same node on which the protected link is. There are multiple kind of protection that we can created.
Path protection and Local protection. Local protection has two categories 1 Link Protection 2 Node protection. So over here this command is being used for Local protection but Path Protection.
Protecting LSPs l2vpn vpls inter as option brokerage not discussed yet in this section. I will try to cover them later. If so,will the configuration differ much Thanks.
Hello Sabriye Thanks for your question. If you see the configuration, you will notice that the headend and tailend routers are both the directly connected nodes and we are here trying to protect the link between these two nodes.
So, if the link fails, the purpose is to already have a path over which the traffic could shift. I am back with further more discussion in continuation to l2vpn vpls inter as option brokerage previous post on MPLS.