Strategy check! :)

If, you actually look at my blog not many posts below you will find that I had posted a brief topic wise break-up for BGP ..which is also referred to as the expanded blueprint for BGP. Now I did that 1) because BGP was tending to be a very vast topic for me to tackle 2) I just wanted to be sure, how much of BGP to expect on CCIE RnS lab. I had also decided to score off the completed topics as I would go through.

Now this approach came to me, after going through many many blogs and success stories. Untill recently a similar approach was posted on the IEBlog as well. So I am happy that I was headed in the right direction. Although what I am still finding difficult is how to hold up so much of info about these technologies that I have completed mastering. Which has made me add the following to my strategy, listen to audio lectures every night before you sleep and build ready reckoner charts for a group of features of a specific technology. Now this should make it simpler for me to hold up all those nitty gritty details about a specific protocol. :)

I will be doing those tech reckoner charts, early in the morning before my day starts & will try to keep them posted here. As far as the audio lectures are concerned, I have acquired IPExperts Audio Class, which seems to have voice of Scott Morris.

So are you guys set as well!?

Happy new year to all!!

Hey,

Wish you all a Merry Christmas and a Happy New Year!! What better way than, saying it with this e-card from cisco. Oh look look ..its snowing here as well. :D

Have a blast!!

BGP CheatSheet.

While I was doing some casual surfing, this is what I found. It made me remind of the texbuddy charts that I use to use for my CCNA prep/quick revision. Well inspite of it being of very basic nature, I still thought its a good one.

Wouldn't we all love one for all the technologies including all the details about them at the CCIE level, I mean a one stop chart. Makes me wonder what that chart would be like!? Perhaps, its time for those CCIE course prep vendors to come up with. :P

And ya, all credits for the work go to Jeremy Stretch. If you want a pdf version of it you can get one from his site.

Internetwork Expert WB VOL 1 - BGP Lab 10

10)BGP Bestpath Selection – Origin

Objective: Modify the BGP Origin code in AS 2 so that traffic from R3’s Ethernet segment going to VLAN 5 is first sent to R1.

Ok, when it comes to ORIGIN ..here is the order of preference IGP-> EGP-> INCOMPLETE. Using this logic I first examined the routing table of R3 and configured it with the below shown configuration.

access-list 1 permit 155.1.5.0 0.0.0.255

route-map NEW_ORIGIN permit 10
set origin egp 1

router bgp 2
neighbor 155.1.0.5 route-map NEW_ORIGIN in
end

Worked like a charm, although over here the WB changes the ORIGIN to ? ie INCOMPLETE!! And also since our objective clearly says that this only needs to be done for traffic going to VLAN 5 from R3, it wouldn’t hurt to match on that specific network prefix using that mentioned access list 1. I just left it out here though, hmm ok next.

Internetwork Expert WB VOL 1 - BGP Lab 9

9)BGP Bestpath Selection – MED

Objective: Configure the BGP MED in AS 1 so that traffic from R3’s Ethernet segment going to VLAN 5 is first sent to R1.

Ok, this above objective is slightly tricky! Actually before I give my solution for this problem I would like to throw some quick light on concept of WEIGHT, LOCAL_PREFERENCE and MED.

Now this is what, WEIGHT is used for: When we have two paths/links ending up on a single router, and you want to influence the way your traffic leaves your AS from this router then you can make use of the WEIGHT attribute. Higher the value of WEIGHT, the more likelihood of that path being chosen or in other words higher the WEIGHT better it is.

LOCAL PREFERENCE, is just like WEIGHT ..the only difference here is that in case of WEIGHT its scope was restricted to a router which in case of LOCAL PREFERENCE is restricted to an entire AS! So, when we have multi-homed AS we can change the LOCAL PREFERENCE attribute to influence how traffic leaves our AS. Again higher the value of LOCAL PREFERENCE better it is.

In case of MED, it is an attribute that you use to manipulate how traffic enters your multi-homed AS! Lower value of MED the better it is, and scope is only limited to an AS.

Now, let us carefully read our objective ..What it is asking you is to influence the way traffic leaves AS 2 and you know you need to achieve this by using MED, but what you can’t do is change this value of MED on the routers of AS 2. Hence we change the value of MED on AS 1 routers and then have them send these changes in the outbound updates. This is the config that was done on R5 and R4, actually its really not required on R4 ..but no harm with some extra configuration and getting in lines with the objective.

On R5,

access-list 1 permit 155.1.37.0 0.0.0.255

route-map NEW_MED permit 10
match ip address 1
set metric 100

router bgp 1
neighbor 155.1.0.3 route-map NEW_MED out
end

And on R4,

access-list 1 permit 155.1.37.0 0.0.0.255

route-map NEW_MED permit 10
match ip address 1
set metric 50

router bgp 1
neighbor 155.1.146.1 route-map NEW_MED out
end

Right, now on to the next lab.

Internetwork Expert WB VOL 1 - BGP Lab 8

8)BGP Bestpath Selection – Local Preference

Objective: Configure the BGP Local Preference attribute in AS 2 so that traffic from R3’s Ethernet segment going to VLAN 5 is first sent to R1.

Ok, this was simple as well. Below is the config,

route-map NEW_LOCAL_PREF permit 10
match ip address 1
set local-preference 50

access-list 1 permit 155.1.5.0 0.0.0.255

router bgp 2
neighbor 155.1.0.5 route-map NEW_LOCAL_PREF in

I could have also, applied slightly different logic. Instead, increase the local-pref value for updates being received from R1. That also would have served the purpose.

Bgp topics to be covered!

1) Establishing Peerings

• TCP Transport
• Update Source

2) Authentication

3) EBGP

4) iBGP

• Route Reflection
• Confederation
• Next-Hop Processing

Next-Hop Self
Route-Map

• iBGP Synchronization

Redistribution into IGP
BGP over GRE

5) Bestpath Selection

• Weight
• Local Preference
• AS-Path Prepending
• MED

6) Originating Prefixes

• Network Statement
• Redistribution
• Aggregation

Summary-Only
Suppress-Map
Unsuppress-Map
Filtering Specifics
Filtering Aggregate

• Conditional Route Injection

7) Default Originate

8) Communities

• No-Export
• No-Advertise
• Local-AS
• Numbered
• New Format
• Local AS

9) Conditional Advertisement

10) Outbound Route Filtering

11) Dampening

12) Peer Groups

13) Regular Expressions

14) Remove Private AS

16) Timers

17) Fast External Fallover

18) Max Prefix

Hmm, I plan on completing all this in around next 12 days! Let's see how far can I get.