Cisco Tips & Tricks

October 25, 2009

BGP Regular expressions / Public route-servers

Filed under: bgp, ccie, IP Routing — ciscotips @ 5:28 am

I was looking at some older posts at Groupstudy and Dale  posted the link to public route-servers. I agree the best way to practice regular-expressions for CCIE is to use one of the following public route-servers.

From: http://www.cymru.com/Documents/secure-bgp-template.html

 route-views.oregon-ix.net
 ner-routes.bbnplanet.net
 route-server.cerf.net
 route-server.ip.att.net
 route-server.east.attcanada.com
 route-server.west.attcanada.com
 route-server.cbbtier3.att.net
 route-server.gblx.net
 route-server.as5388.net
 route-server.savvis.net
 route-server.colt.net
 route-server.opentransit.net
 route-server.gt.ca
 public-route-server.is.co.za (South African routes only)
 route-server.belwue.de
 route-views.on.bb.telus.com
 route-views.ab.bb.telus.com
 route-server.ip.tiscali.net
 route-server.wcg.net
 route-server.manilaix.net.ph
 route-server.ip.ndsoftware.net
 route-server.utah.rep.net
 route-server.he.net
 zebra.swinog.ch

Just telnet to one of the above route-servers and you can login via guest/anonymous account. There you go and you can use some basic show commands.

October 18, 2009

System MTU / ip ospf mtu-igonore

Filed under: ccie, IP Routing, ospf, Switching — ciscotips @ 6:54 pm

I was working on OSPF lab and suddenly on my 3560’s I saw a OSPF adjacency errors.

%OSPF-5-ADJCHG: Process 1, Nbr 192.168.10.1 on
FastEthernet0/0 from EXSTART to DOWN, Neighbor Down: Too many
retransmissions

%OSPF-5-ADJCHG: Process 1, Nbr 192.168.10.1 on
FastEthernet0/0 from DOWN to DOWN, Neighbor Down: Ignore timer expired

Suddenly I realized that may be I have MTU issues as I just completed a Q-in Q lab and changed my switch MTU ,  but to double check

I thought of checking a “debug ip ospf events” … and here it was.

OSPF: Rcv DBD from 192.168.10.1 on
FastEthernet0/0 seq 0x12A6 opt 0x52 flag 0x7 len 32  mtu 1504 state
EXSTART

OSPF: Nbr 192.168.10.1 has larger interface MTU

There are multiple ways to fix this, you can either issue “system mtu 1500” on switches or use an interface level command on Routers “Ip ospf mtu-ignore” . or the third one will be to change MTU on router interfaces ( Least preferred).

when value is changed, it will not be stored in neither running-config
nor startup-config. On Catalyst 3550, this information is stored in a
separate file on the flash. On Catalyst 3560, you can’t see it, unless
you do “show system mtu”.

“system mtu 1500” on switches is the default command. Even when value is changed, it will not be stored in  running-config  or startup-config. On Catalyst 3550, this information is stored in a separate file on the flash. On Catalyst 3560, you can’t see it, unless you do “show system mtu”.

This is one of the well-know gotchas on the actual lab exam.You have to know how to solve this. Hence, when configuring routing protocols on switches, make sure you know what the MTU is.

One important thing to note is that you might break stuff in the lab if you were suppose to configure MTU for q-in q lab and later you changed “System MTU” in your switch to fix OSPF issue.

You can also use system mtu routing 1500 in your switch to fix OSPF issue as this will be only used for routing but for Q-in-Q lab switch MTU will be still used as 1504.

IMHO,Best way to fix this in the lab would be “ip ospf mtu-ignore” under the interface on your router.

MTU  has to be the same on both ends of the link before the neighbor can form adjacency.

July 16, 2009

Cisco Learning Network for your CCIE

Filed under: bgp, ccie, cisco, IP Routing, ospf — ciscotips @ 3:20 pm

Excellent resource to master IP routing ( IGP’s and BGP) with following free Lab resources from Cisco Learning Network. These labs are used for training Cisco TAC .

https://cisco.hosted.jivesoftware.com/docs/DOC-1318

You will need a CCO username/password to access these free labs.

Thanks!

June 10, 2009

Cisco Revising CCIE R&S Certification

Filed under: bgp, ccie, cisco, IP Routing, Technology and Software — ciscotips @ 8:10 pm

The upcoming Version 4.0 of Cisco CCIE® Routing and Switching certification will test hands-on troubleshooting, Multiprotocol Label Switching (MPLS), and VPN networking

 

To reflect the growth of the network as a service platform, Cisco is revising the certification requirements for CCIE Routing & Switching (CCIE R&S)–the expert level certification for network engineers. The new requirements were developed with assistance from Cisco enterprise customers and reflect the expectations of employers across industries.

 

The competencies required for CCIE R&S v4.0 certification were released on May 5, 2009, and are available on the Cisco Learning Network under the CCIE R&S v4.0 Written Exam topics and CCIE R&S v4.0 Lab Exam topics. Exams based on the new requirements are scheduled for release on October 18, 2009, and will immediately replace the currently available v3.0 exams. Candidates who plan to take their exams on October 18, 2009, or later should prepare using the new v4.0 exam topics.

 

Both the written and lab exams will be refreshed with new questions and will cover MPLS and VPN networking. The written exam will add scenario-based questions to the multiple choice questions, and the lab will now require hands-on troubleshooting of preconfigured networks, in addition to configuration. Exam duration and pricing will remain the same, with the two-hour written exam at USD$350 and the eight-hour lab at USD$1400.

 

A beta version of the new CCIE R&S v4.0 written exam (351-001) will be available to all customers in the July–August 2009 timeframe at a discounted price of USD$50. An announcement will be made when scheduling begins.

 

Cisco 360 Learning Program Updates Available

Cisco 360 Learning Program components aligned to the new CCIE R&S certification standards will be available on May 11, 2009.  All current students will have access to the new materials throughout their subscription period.  New materials include additional lessons on MPLS and troubleshooting, enhanced coverage of these topics in the instructor-led workshops, an updated Practice Lab Workbook for self-paced practice, and new Performance Assessments that gauge skill level and offer mentoring feedback.

 

CCIE Assessor, the first CCIE R&S practice lab, will be retired on June 5, 2009, and will be replaced by the 10 eight-hour assessment labs available through the Cisco 360 Learning Program. Find out more

 

Frequently Asked Questions

1  –  Q: What exactly is being changed on the CCIE R&S written exam?

 

A: The CCIE R&S v4.0 written exam will be refreshed with new questions to reflect the current job role expectations of employers. Scenario-based questions will be added to the multiple choice questions. New topics include the skills associated with planning and evaluating network changes, implementing MPLS, Layer 3 VPN, IPv6, EIGRP and multicast; and configuring performance-based routing.  More information is available on the CCIE Written Exam Overview page.

 

 

2  –  Q: What exactly is being changed on the CCIE R&S lab exam?

A: The CCIE R&S v4.0 lab exam will be refreshed with new questions to reflect the current job role expectations of employers. The equipment in the testing lab will be updated with Cisco 1800 and 3800 Series Integrated Services Routers running Cisco IOS® Software Version 12.4(T) and Cisco Catalyst® 3560 Series Switches running Cisco IOS Version 12.2 Advanced IP Services. The biggest change will be the testing of hands-on troubleshooting for the first two hours of the eight-hour exam. Candidates will be presented with a series of trouble tickets for preconfigured networks, and they will need to diagnose and resolve the network fault or faults—a realistic and challenging job task. Candidates who finish the troubleshooting section early can move on to the configuration section, but they will not be allowed to go back to the troubleshooting section, since their equipment will need to be reinitialized for the configuration portion of the exam.

To make time for new material, CCIE R&S v4.0 exams will put less emphasis on equipment operation and concepts generally understood at the professional level. These skills are still assumed, but will not be the sole objective of CCIE test questions. Go to the Lab Exam Study/Learn section for more information.

 

 

3  –  Q: Now that the CCIE R&S v4.0 has been announced, can I still take the CCIE R&S v3.0 exam? How long will it be valid?

 

A: The CCIE R&S v3.0 written exam will be available through October 17, 2009, at all Pearson VUE testing centers. Passing the v3.0 written exam qualifies a candidate to take any available version of the CCIE R&S lab exam. As with all CCIE written exams, a passing score on v3.0 written exam will remain valid for three years, as long as the candidate attempts the lab exam once within the first 18 months. If the lab is not attempted, the written exam becomes invalid and the candidate will have to retest using whatever written exam is available at that time.

 

 

4  –  Q: If I take the CCIE R&S written beta test in July or August 2009, will I still be able to schedule the CCIE R&S v3.0 lab exam?

 

A: Scores on CCIE written beta tests are not available until 4 to 6 weeks after the close of the beta period. At this time, there is no guarantee the CCIE R&S v3.0 lab exam will still be available when a beta test candidate receives his or her score. Beta testers should plan on taking the CCIE R&S v4.0 lab test to achieve certification.

 

 

5  –  Q: If I don’t pass the CCIE R&S v4.0 written beta exam, can I take it again in five days?

 

A: No, a candidate can only take a CCIE written beta test once during the beta testing period.

 

 

 

6  –  Q: Will there be any changes to the recently-added Core Knowledge portion of the exam, the part with the short-answer questions?

 

A: The questions in the Core Knowledge section of the lab exam may cover any area on the CCIE R&S v4.0 Lab Exam topics.

 

 

 

7  –  Q: What can a candidate expect in the troubleshooting portion of the lab exam?

 

A: Troubleshooting is allotted two of the eight hours required for the CCIE lab exam. Candidates will be presented with a series of trouble tickets for preconfigured networks and will need to diagnose and resolve the fault or faults. As with previous CCIE labs, the network will need to be up and running for the candidate to receive credit.  Candidates who finish the troubleshooting section early can move on to the configuration section, but they will not be allowed to go back to the troubleshooting section.

 

 

8  –  Q: Does a candidate have to pass both the troubleshooting and configuration sections in order to pass the entire CCIE R&S v4.0 lab exam and earn a CCIE?

 

A: Candidates will receive a single pass/fail grade on the entire exam, including both configuration and troubleshooting. Failing score reports will give an indication of where the candidate scored lower, to help the candidate prepare for another attempt.

 

 

9  –  Q: Will the CCIE R&S mobile lab exam also be updated?

 

A: Yes, CCIE R&S mobile labs use the same lab version as Cisco office locations, and they will switch to the v4.0 lab exam on October 18, 2009 as well.

 

 

10  –  Q: Which exam will be used for recertification?

 

A: As of October 18, 2009, CCIEs who take the CCIE R&S written exam for recertification will be given the v4.0 exam and should prepare using the exam topics found on the Cisco Learning Network.

 

 

11  –  Q: Are the previous Cisco 360 components applicable to the CCIE R&S v4.0 exams? Should candidates studying for CCIE R&S v4.0 exams wait for the new Cisco 360 materials to begin work?

 

A: The learning components available at first launch of Cisco 360 are still relevant to candidates studying for the CCIE R&S v4.0 certification exams. No Cisco 360 Learning Program components are being retired.  There is no need for candidates to wait for revised Cisco 360 material to begin their study and practice. The subscription model ensures that Cisco 360 customers can take advantage of all new content as it is released and do not need to wait.

October 27, 2008

Compute an access-list to match even or odd networks

Filed under: Access-lists, ccie, IP Routing, Router, security, Technology and Software — ciscotips @ 10:16 pm

One of my old student who is preparing for CCNP asked me on how to write an access-list for permitting/denying even or odd networks. So I am just pasting my email reply to him

Here is a simple tip to write an access-list for even or odd networks.

Lets say we are asked to permit all odd or permit all even for 192.168.1.0/24 ?

We’ll play the game with last octet or I should say the least significant bit of last octet.

-If it is 0, the IP address will be Even

-If it is 1, the IP address will be Odd 

192.168.1.00000001 = 192.168.1.1 – odd

192.168.1.00000011 = 192.168.1.3  – odd

192.168.1.00000010 = 192.168.1.2   even

192.168.1.00000100 = 192.168.1.4   even

FOR Even Networks

The IP address will be 192.168.1.0

With the wild card mask as 0.0.0.254

254 = 11111110

Here, 0 means DO CARE of the last bit in IP address (must be ZERO)

Hence ACL will be

access-list 1 permit 192.168.1.0  0.0.0.254

For Odd Networks

The IP address will be 192.168.1.1

With the wild card mask as 0.0.0.254

254 = 11111110

Here, 0 means DO CARE of the last bit in IP address (must be ONE)

Hence ACL will be

access-list 1 permit 192.168.1.1 0.0.0.254
 

  

October 24, 2008

Day 3, 4 and 5 of Narbik’s Bootcamp

Filed under: bgp, ccie, IP Routing, QOS, Technology and Software — ciscotips @ 6:22 pm

Sorry for posting late, Narbiks bootcamp was fun. Its worth attending his bootcamp if you are somewhere in the mid-tier of your CCIE preparation. Narbik recommends to cover Soups-to-nuts before you attend his bootcamp and he is right., otherwise it can be too much of information for you in 5 Days. Here is what he covered in last three days.

Day 3:- BGP

It was a big day for me. Day 3 is a BGP day, youy have  almost 200 pages worth of BGP labs. Narbik’s BGP  lecture style is totally different then the conventional CCIE Instructors. He doesn’t start BGP with Attributes or BGP states. He attacks on BGP optimization and then buiold you towards attributes and other advance topics. Simply awesome. He will start with MSS ( Maximum segment size) , Scan time, Advertising Interval and then take you to Memory pools, templates and Peer-groups. At last he will talk about BGP states, Aggregation, Attributes and some awesome route-filtering techniques. I will say that was my best BGP class.

Day 4:- RIPv2 and QoS

Another big day which was dedicated to Qos and 2 hours worth of lecture for RIP v2.  He showed what RIPv2 is worth of. People normally ignore RIP but if you know what all you can do with RIP. You will never be disappointed to use it for your small size network. He covered optimization, RIP updates,Filtering,redistribution,authentication  building it on some advanced scenarios.

Qos:- Qos

Qos was never my strong topic, although I am using it regularly in my job but I always struggled on few advanced topics. I should not have a problem in Qos after attending Narbik’s lecture.  Narbik started Qos with Queuing. He covered, CBWFQ, LLQ, filtering,CBWRED,Shaping, CAR,policing and SRR. Pretty good lecture indeed!

FInal Day ( Day 5 Multicast and CCIE lab tips).

Narbik covered multicast Addressing, Delievery Methods, Manipulating MCast Traffic, Dense,sparse modes, MSDP,ANycast and udp helper. I still have to work on Multicast labs but I am sure  I can practice on it  and grasp what I need most for my Lab.

As I am going through Narbik’s Advance 6 volume CCIE workbooks, I will try to post tips and tricks on various technologies going forward.

October 14, 2008

Narbik’s Bootcamp Day-1

Filed under: ccie, IP Routing, Router — ciscotips @ 7:35 pm

This is my first ever training class of Cisco. I never knew what to expect. Most of the guys have either attended boot-camps from other vendors or have attended other cisco classes in the past. For me its all for the first time. Without bragging I must say Narbik class is full of tips and tricks 🙂 . People say no to experiments AND do exactly what is specified in doc cd but Narbik is different. He recommendsless commands to accomplish the task. Simply do what is meaningful. Don’t do things which doesn’t mean anything?

The first day was 60-70% hands on as Narbik handed us 5 volumes of Advance CCIE R&S workbook. and a seperate bootcamp workbook. First day we did basic switching hands on and then Narbik went through Security topics ( Theory/White board… no slides/projectors). Here is the list

Vlan Mapping
MAC Floding
DHCP snooping
IP source-guard
DAI
MAC ACL’s
VLAN ACL’s
Private VLan’s

And some Great Tips on FR, which I’ll probably share in my later posts.

January 31, 2008

Cisco Open source tools

Filed under: cisco, IP Routing, security, Switching, Technology and Software — ciscotips @ 3:13 am

I came across a great resource, Cisco-centric Open Source Community (COSI). COSI is an Internet-based community that develops free Cisco tools and makes them available for download from its Web site. There are almost 50 utilities available for download. The scripts and utilities all include documentation, and the community has developed all of these tools to work with Cisco IOS routers, switches, firewalls, or CiscoWorks management software.

COSI’s Web site also offers other advantages. Clicking the link to download a script takes you to a community download page, which also features discussion forums for questions and support of these tools. It’s important to remember that Cisco’s Technical Assistance Center (TAC) doesn’t support these tools, so you must count on your own skills and the help of others in the community.

A tradeoff: These tools are not ideal for new Cisco IOS users or anyone who doesn’t have some Linux experience. Many of these tools help automate more advanced Cisco admin tasks when administering a midsize to large Cisco network

October 24, 2007

E1/E2 routes in OSPF

Filed under: IP Routing, ospf, Router — ciscotips @ 7:41 am

In OSPF we have 2 types of external routes. E1 and E2

For example 

R1#show ip route
Codes: C – connected, S – static, I – IGRP, R – RIP, M – mobile, B – BGP
D – EIGRP, EX – EIGRP external, O – OSPF, IA – OSPF inter area
N1 – OSPF NSSA external type 1, N2 – OSPF NSSA external type 2
E1 – OSPF external type 1, E2 – OSPF external type 2, E – EGP

Route redistribution is the process of taking routes learned via one routing protocol and injecting those routes into another routing domain. (Static and connected routes can also be redistributed.) When a router running OSPF takes routes learned by another routing protocol and makes them available to the other OSPF-enabled routers it’s communicating with, that router becomes an Autonomous System Border Router (ASBR). Let’s say R1 is running both OSPF and RIP. R4 is in the same OSPF domain as R1, and we want R4 to learn the routes that R1 is learning via RIP. This means we have to perform route redistribution on the ASBR. The routes that are being redistributed from RIP into OSPF will appear as E2 routes on R4:R4#show ip route ospfO E2 5.1.1.1 [110/20] via 172.34.34.3, 00:33:21, Ethernet06.0.0.0/32 is subnetted, 1 subnets

E2 is the default route type for routes learned via redistribution. The key with E2 routes is that the cost of these routes reflects only the cost of the path from the ASBR to the final destination.  It will not reflect the correct “Cost” or path. 

Now if  we want the cost of the routes to reflect the entire path, not just the path between the ASBR and the destination network. The routes must be redistributed into OSPF as E1 routes on the ASBR, as shown here.

.
R1(config)#router ospf 1
R1(config-router)#redistribute rip subnets metric-type 1
Now on R4, the routes appear as E1 routes and have a larger metric, since the entire path cost is now reflected in the routing table.O E1 5.1.1.1 [110/94] via 172.34.34.3, 00:33:21, Ethernet06.0.0.0/32 is subnetted, 1 subnets

August 27, 2007

Routing Basics

Filed under: IP Routing — ciscotips @ 3:43 am

One of my team member was asking me the question on routing decision. I thought of putting up here ..Any routing decision is based on the following rules.

1) Longest prefix length :- If we have two different routes in a routing table  for a same network, the longest prefix match is selected. lets say we have both 172.16.0.0/16 & 172.16.16.0/24 in the routing table.  In this case 172.16.16.0/24 will be selected.

2) AD ( Administrative distance) :- If longest prefix match cannot be considered for example if we have two routes with same prefix length then Route with lowest AD will be considered. Incase we have a same route learnt from IGRP and OSPF, IGRP route will be considered as it has alower AD(100) then OSPF (110).

3)Meteric:- If routes have same prefix length and same AD then a route with a better meteric is considered. In OSPF, cost~bandwidth is a meteric where as hop count is meteric for RIP.

4) Load sharing:- In case all the above three conditions match then  data  will be load balanced between the routes.

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