Category: By Barooq
Have not been writing. Well, I am and will be on break during November. Annual Leaves and Sister's Wedding :)

BGP communties Problem. Solved, and a lesson to learn

By Barooq
Well, everyone always talks about knowing the technology well and that exactly was the problem :P
BGP community attributes are non-transitive, means WE HAVE TO SEND THESE TO OTHER BGP SPEAKERS, EVEN IBGP SPEAKERS

I wasn't sending the attribute from R3 to R1 and viceversa :S
Though a lot of time wasted, but a lesson to learn :)
KNOW your technologies well

BGP communties problem

Category: By Barooq

Here is the scenario diagram…
Configure using community No-Export so that hosts on R3’s Ethernet have access to VLANs 5 and 43 but AS 1 and AS 3 cannot reach VLANs 43 and 5 respectively.
Here is my configuration of R4 and R5
router bgp 1
no synchronization
bgp log-neighbor-changes
network mask
neighbor remote-as 2
neighbor send-community
neighbor route-map SET-COMMUNITY out
no auto-summary
access-list 1 permit
route-map SET-COMMUNITY permit 10
match ip address 1
set community no-export
route-map SET-COMMUNITY permit 20


router bgp 3
no synchronization
bgp log-neighbor-changes
neighbor remote-as 2
neighbor send-community
neighbor route-map SET-COMMUNITY out
no auto-summary
access-list 1 permit
route-map SET-COMMUNITY permit 10
match ip address 1
set community no-export
route-map SET-COMMUNITY permit 20
Now everything appears to be fine as I check on R1 and R2 which are neighbors of R4 and R5 respectively

R1#sh ip bgp
BGP routing table entry for, version 3
Paths: (1 available, best #1, table Default-IP-Routing-Table, not advertised to
EBGP peer)
Advertised to update-groups:
3 from (
Origin IGP, metric 0, localpref 100, valid, external, best
Community: no-export


R2#show ip bgp
BGP routing table entry for, version 2
Paths: (1 available, best #1, table Default-IP-Routing-Table, not advertised to
EBGP peer)
Advertised to update-groups:
1 from (
Origin IGP, metric 0, localpref 100, valid, external, best
Community: no-export
But still R5 and R4 see these routes in their routing table and are able to ping each other…
R4#show ip bgp
BGP table version is 8, local router ID is
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete

Network Next Hop Metric LocPrf Weight Path
*> 0 2 1 i
*> 0 2 i
*> 0 32768 i

Now R4 shouldn’t be able to see network but it does :S

R4#ping source

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to, timeout is 2 seconds:
Packet sent with a source address of
!!!!!Success rate is 100 percent (5/5), round-trip min/avg/max = 108/213/316 m
Same is the case with R5. It sees and reaches network advertised by R4…
Any help will be appreciated…


Seems eveyone has bad times, not just me :P

By Barooq
I had a torrid time with BGP regular expressions...
Maybe I was going in too much detail but the bottom line is that I had to stop. I took a week's break, which fit perfectly with Eid and Holidays and after that I am back to studies...
Did quite a bit of BGP, 3 more days and hopefully it'll be done.
During the period when I was down, reading other blogs, I realized that everyone stumbles on CCIE journey... At least CCIEPURSUIT and ETHAN BANKS suggest that.
These and other blogs have been not only a means of great info, but also motivation.
Can't thank them enough

Its such a good feeling: Of not being the only person who suffers on the way. I actually thought of myself as a complete buffon :P Not now, I am back on track. This months Targets: Complete BGP and Multicast.

BGP AS Path filters are making me wish I were never born :(

Category: , By Barooq
I've been putting off prefix based BGP filteting throughout my networking life.
I never worked in an ISP, my work mostly comprised of Enterprise campus and data networks design, implementation and support and a lots of compressed voice over ATM, for GSM providers.
So, I never cared for BGP as such. Read a little, and read enough for CCNP.
NOW, when I am trying to get through BGP in detail, I just cannot ...
Maybe its a bad week :S
Maybe its Ramadan and because of fasting, during the day I cannot concentrate.
Maybe because in the night, I smoke like a chimney to account for the whole day passed without a smoke and it messes with my head.
Whatever the reason is, BGP stares in my face like the big monster :(
Before I started the prep, my initial thought was that QOS and Multicast will give me a hard time.
Now it looks, I may never be able to complete BGP.
Its been such a bad day, and from the looks of it, next week won't be better even

Status Update

Category: By Barooq
Again a very good week.
My targets were to cover OSPF and IGP redistrbution, and I was able to complete these.
OSPF took more time than I imagined, and redistrbution a lot lesser.
Maybe since I am only doing advance technology labs for the while and network is never too complex, redistrbution has been easy.
Next Week Targets: BGP (basic), Multicast.

OSPF Network Type Loopback

By Barooq
Reading across, I found something I didnt know and which I think is very cool.

Ref to RFC 2328

" looped back.
The interface may be looped back in hardware or software. The interface will be unavailable for regular data traffic. However, it may still be desirable to gain information on the quality of this interface, either through sending ICMP pings to the interface or through something like a bit error test. For this reason, IP packets may still be addressed to an interface in Loopback state. To facilitate this, such interfaces are advertised in router-LSAs as single host routes, whose destination is the IP interface address.[4]"

Which simply means that no matter what is the subent mask of my loopback address, it'll be advertised as host route in the OSPF domain, or say a loopback of will appear as
" is subnetted, 1 subnets"

SO, what if I want my actual subnet mask to be advertised ?
All i have to do is to put "ip ospf network point-to-point" in loopback interface config.

A good week

Category: By Barooq
Well while he previous week was hazardous in the sense that I couldn't do anything, this week has been good.
Completed almost everything related to switching, did IE advance technology switching labs. Also completed EIGRP, IE Eigrp advance technology labs and from the work book did arounf 6 or 7 random labs concerning EIGRP and Switching.

Next week Targets: OSPF, Route redistribution.

Something to cheer !

Category: By Barooq
Today, rather yesterday was bad day. Got to sleep at 6.A.m and was up at 11 again for office.
The series of fuck-ups continued.
In short, wasn't able to do anything with CAT6513's failed module.
CWM installation failed, even a solaris guy who graciously tried to help me couldn't know why. I keep cursing myself for recommeding this bloody NMS to customer. If only I knew I had to install it :( and I wish for once things happen the way installation documentation says they'd.

Came back home at 6 and decided to wrestle with dynamips. I've been foolishly asking around for dynamips help, and today I decided to give it a go.

From a bad day arrives my moment of cheer:)
I've been finaly able to get dynamips running and made .net files for firsr 4 IEWB labs :)
Its a different story that my notebook almost explodes at 6th router instant.

Tomorrow again after work, have to go to a dinner.
Lolzz, thought about backing out only to realize, it was me who invited all :D

Hopefully on thursday and Friday ( Weekend here) will get to complete switching at least.

A kick in the nads

By Barooq
Last night, while chalking out my plans so ambitiously, i must have somehow offended god of the fucks ups.
Its 1:20 am in night and I am still at work.
16 port Gbic module for core switch has mysteriously gone down. From reseating, resetting, resetting SUPs to upgrading IOS I've tried everything. And nothing is working.
TAC engineer (I used to be awfully impressed by any one with email id ending at, but all illusions wither :D), who is an idiot, has no clue what he is suggesting.
And my employer thinks that because I am a 'Cisco guy', not solving this problem means I don't know anything.
Gosh, what does a hardware failure have to do with switching anyway. Anyway, unless we hear something definitve from TAC, there is no going home, which means, tomorrow is ruined already :D
Will start studying from Wednesday :P

Week 1 Targets ( 02/09/2007-07/09/2007)

Category: By Barooq
1) Read CCNP BCMSN excluding Wireless ( 2 Days)
2) Watch BSCI trainings (RIP, EIGRP, OSPF) (Thursday and Friday)
3) Pratice switching and these protocols (Wednesday and Friday)


Category: , By Barooq
I've been working with Cisco for around two years and had been involved in design and implementation of LAN/WAN networks for a while.
Currently on a sojourn to middle east for big bucks, I feel this is the perfect time to study my brains out for a year.
Unable to keep a strict schedule I hope this blof helps me maintain a pace :)

Aim: CCIE lab attempt in August 2008, Written in Jan 2008

Preparation Level 0-10 scale: 0

Topics to cover in Semptember:
Realistically:Switching, Frame Relay, IP Routing (Static, RIP, EIGRP,OSPF)
This is the stuff I supposedly know, so shouldn't be a problem.
Ambitiously: Also cover BGP Fundamentals/Multicast Fundamentals

Good Areas: Switching, WAN, Ip routing IGP
Weak Areas: BGP, Route distribution, Security
Worst Areas: IPv6, Multicast, QOS, IP services

Study Material for the month: Cisco Press CCNP books, TCP/IP Vol1, Partners E learning connection BSCI

and BCMSN online trainings and online labs, Internetworkexpert Advance Technology Labs.

Lab hours: Complete online labs for CCNP on Cisco's website partner's E learning connection, Practice at work.

My Advantages: Access to Trainings
My Disadvantages: No home lab, all practice has to be done while on work. (Cant afford home lab and dynaipms is too messy)

Blog Inspiration: CCIE Pursuit , The CCIE Lounge

Where I stand compared to other Bloggers: Nowhere