From CCIE R&S to CCIP

While it's still fresh in my mind, I thought I'd put a little guide together for those who already have their R&S CCIE and want to work on the CCIP. One of the struggles I've found is there is very little study material out there geared directly toward the CCIP, aside of course from the exams that overlap with CCNP and CCVP.

I'd recommend taking the exams in the following order:
1. BSCI. If you already have a CCNP, you may have already passed the exam. I do find it strange that a CCIE R&S doesn't waive this requirement. I last passed the BSCI in 2002, so I needed to retake this. The only topic in the exam that is not really covered by R&S is IS-IS. This is a topic on the service provider blueprint, so take the opportunity to get some studying done on it.

2. QoS. You should already be pretty familiar with QoS from the CCIE R&S.

3. For the brave, go for BGP+MPLS. I will definitely say I found this to be one of the toughest exams I've taken. It's certainly up there on the CCIE Written calibur of exams. There are lots of very tricky questions that you have to pay close attention to. There's also an abundance of questions from obscure topics that I would have expected to be a small part of the exam.

4. Otherwise, go for BGP separately from MPLS. I did take the BGP exam as well, and found it to be MUCH simpler than BGP+MPLS. Of course having a CCIE R&S means you should already know BGP pretty well. Now I never did take the MPLS exam, so I cannot comment on it.

For BGP+MPLS, the following resources are very helpful. Make sure to know them inside and out. There were some more obscure topics that I could only find covered in the these links.

MPLS Virtual Private Network Enhancements
BGP Case Studies
Cisco Express Forwarding Overview
Configuring Cisco Express Forwarding
BGP: Frequently Asked Questions
MPLS Configuration on Cisco IOS Software (Book)

Also make sure to spend some time on MPLS technology labs from your vendor of choice. Internetwork Expert has a great price on an SP bundle, which includes Class on Demand.

Good luck!

RFC 3439

I'm normally not a big fan of reading RFCs. Aside from the funnier ones I've provided links for to the right, I tend to find them way to dry and academic. Short of pulling some information out, such as the meaning of a particular field in TCP, I almost never even look at RFCs.

In the SP Written blueprint, Cisco specifically mentions RFC 3439. Amazingly, I'm finding it very readable and interesting.

http://www.rfc-archive.org/getrfc.php?rfc=3439

Finally! CCIP Complete!

I finally managed to pass BGP+MPLS tonight. I figured out most of the trick questions and brushed up on the topics I needed to and finally got through this. It took me a whopping 5 attempts to pass! I've never needed more than 2 attempts to pass an exam before. Not even the R&S CCIE lab itself.

Now it's time to start working on the SP Written. One look at the blueprint and I'll need to focus on the following topics:

• Service Provder Network General
• ATM, POS, DPT/RPR
• ISIS
• High Availability
• High End Product

Holding Pattern

Since it's taken me so long to get the CCIP, I went ahead and took 350-001 again to recertify my CCIE. I just squeaked by, but I didn't study at all for the exam. I still find that exam particularly annoying.

So I've been back an forth trying to decide if I want to even bother with the CCIP or not. I think I'm going to take another stab at either the MPLS exam or the BGP+MPLS exam. I just don't feel up to studing for the SP written yet.

MPLS VPNs with BGP Site-Of-Origin Complete

This was an interesting lab that took a bit of research for me to understand what was happening.

When we use as-override, the intention is to work around the loop prevention mechanism of eBGP so that a CE router will accept a route from another CE router with the same AS.

But sometimes that loop prevention mechanism is still needed. This typically occurs when two CE routers have a backdoor (i.e. non-PE) connection to each other, in addition to the PE connection.

Such a connection can create a routing loop when used in conjunction with as-override. This is because the PE router strips the originating AS and then advertises the route back out to the other CE. This CE router has no idea that this is the same route it is learning from its backdoor neighbor, so a routing loop can be created.

To prevent this, the site-of-origin (soo) extended community can be set via a route-map. No filtering is required, everything happens automatically once it is set. When a PE router learns a route with an SOO set, it will not advertise another route with the same SOO set to its CE neighbor.

The catch to this is that the backdoor route cannot be used as a redundant connetion to the other CE router. If the MPLS connection drops, traffic cannot be rerouted dynamically through the other CE router.

To check if SOO is set on the PE router, use sh ip bgp vpnv4 all X.X.X.X

MPLS VPNs and VRF Export Map Complete

The Export Map allows much more granular control over which networks get advertised to which vpnv4 prefixes. There's a great example at http://www.cisco.com/en/US/docs/ios/mpls/command/reference/mp_e1.html#wp1012602

I learned a bit more about the order of operations of MPLS during this exercise. I mistakenly forgot to import the route-targets on R3. During troubleshooting, I noticed that the routes that were supposed to be imported were not present in sh ip bgp vpnv4 all. Apparently this table does not get populated until the specific route-targets are imported by a vrf.

MPLS VPNs with Extranets Complete

I was pretty surprised I got this one right the first time. It's simply a matter of getting the route target imports and exports correct.

I think I'm still a little fuzzy on the transition from an IP address to a route descriptor to a route-target, and how they all interoperate with routing protocols and redistribution.

This lab did help to tie it together somewhat. I suppose my understanding is that it goes something like this:

When an interface is setup for vrf forwarding, it is no longer part of the global routing table. Instead, the router performs a lookup to get more details about the vrf that the interface is an instance of. It goes to the vrf configuration and finds the route descriptor, which is uses to relate this interface to IGPs and ipv4 BGP. Then, it sends out a BGP vpnv4 route for each export target. These export targets get flooded throughout the BGP vpnv4 peers, which should encompass all PE routers. Finally, with these vpnv4 routes flooded, the import route-target is used to load the remote vpnv4 routes into the particular vrf routing table.