June 21, 2009 2 Comments

We are Living in a Multicast World and I am a Multicast Girl

I’ve spent most of this weekend, save for a trip downstate to visit the farmer’s stands, studying Integrated IS-IS and Multicast, two very different topics.  At first, I was whining beyond belief at having to study IS-IS.  I’d heard it was a difficult topic and I also knew that it is rarely seen outside ISP’s.  Since I’ve never worked for an ISP and don’t work for one now, it seemed irrelevant.  However, I actually really enjoyed studying it and I’m looking forward to playing with it in the lab.  IS-IS offers one of those rare glimpses back into the foundation of the internet and also gives you a chance to consider what networking today might have been like had different decisions been made and the founders gone with OSI and it’s many protocols rather than IPv4.

Multicast has also been interesting and definitely seems relevant as we at work for our server team to virtualize and move a server that hosts an important multicast application.  I’m looking forward to sharing what I’ve learned with my teammates as we prepare for that change.  I’d also like to push for us to move from PIM sparse-dense mode on our routers to just PIM sparse-mode, unless anyone has any reasons why not.

Lastly, I’m thinking of a fun competition here.  Like many of those out there studying for certifications, I often have to leave home and all its chaos to be able to concentrate on my studies.  This means I’m always looking for the best public place to study.  I’m thinking that each week I should have a competition between two study venues to see which one ends up on top.  I’m willing to add suggestions from comments on this one, too.  This week I did Panera vs. Starbucks and here are the results!

Panera - WINNER - free wifi (time limits during peak hours), relatively quiet, lots of natural light, even power strips provided.  Good food and free refills on sodas.  So far this is my go-to study place.

Starbucks - LOSER - While the coffee is great, there are few healthy snack options.  Wifi is available for a nominal fee, but I was able to steal Panera’s from there.  Biggest drawback - High noise level both from music and blenders.

Next week, I’m planning on doing Public Library vs. Bookstore.  Here are a few match-ups I have planned:

Crystal (think White Castle in the south) vs. Local Hookah Bar - Both have free wifi and both have food…will greasy sliders win out over a hookah pipe and a drink for study nirvana?  We’ll find out!

My criteria for a study site to try…

1.  Must have a place to sit and not be bothered for at least 2 hours straight (no mosh pits or dance clubs)
2.  Must have access to a place to plug in a laptop.
3.  Must have enough lighting to read and enough quiet to possibly do so.
4.  Wifi is a definite plus.  Must be either free or available for a nominal fee to count.

Feel free to make suggestions for study venues in the comments section.  I am even considering a Beach vs. City Park match-up if I can figure out how to make sure I don’t get sand in my laptop and that my battery will last long enough.   :)

June 20, 2009 No comments

Multi-Area OSPF LSA Types

I started off my studies today with some review of multi-area OSPF before I dive back into IS-IS, which is definitely proving to be a challenging topic.  One of the toughest things for me to grasp about OSPF so far as been the different LSA types that routers use, which routers use them and which ones stay within a specific area.  Below is a table to try to help make this a bit clearer in my own mind:

LSA Type 1 - Sent by All OSPF Routers - Stays within one area - Also called Router Link States
LSA Type 2 - Sent by BDR’s Only - Stays within one area - Also called Net Link States
LSA Type 3, 4 - Sent by ABR’s Only - travels outside areas - Type 3 is also called a Summary Net Link State and is a Inter-Area Summary Route - Type 4 is also called a Summary ASB Link State and is a route to the ASBR
LSA Type 5,7 - Sent by ASBR’s Only - Travels outside areas - Type 5 is also called External Link State and is a route that has been redistributed into OSPF - Type 7 only exists within a NSSA and is translated into a type 5 LSA when it leaves the NSSA, otherwise it is the same as a type 5.
LSA Type 6 - This is reserved for Multicast OSPF, which is not current supported by Cisco

Let me just write out some of those acronyms…

ABR - Area Border Router - Connects OSPF areas and has at least 1 interface in each area.  Route summarization happens here.
ASBR - Autonomous System Border Router - Connects 1 routing domain to another, often with a different routing protocol.  This router does redistribution of external routes into the OSPF domain.
NSSA - Not-So-Stubby-Area - Essentially, this is the same as a Stubby Area, except that it contains an ASBR and a link to an external network.  Otherwise, it has only one path into the rest of the OSPF network.
LSA - Link State Advertisement - the messages that OSPF routers send each other to update their topology tables.

June 18, 2009 3 Comments

The Lab of the Real World

I don’t know if it is coincidence or not, but it seems to happen often enough that I’m beginning to wonder. It seems like I will get ready to study something for an exam and then all of a sudden there is a need for me to practice this skill in the real world, often before I even get a chance to study it or practice it in the lab. Real life can be funny like that…it often just doesn’t respect training schedules enough to wait until I am on the right chapter! Today, I ended up spending most of the afternoon helping TAC and another engineer troubleshoot issues he was having with a multicast configuration. Sometimes just having a fresh pair of eyes on a problem can help. It also helped a ton that we got one of those great TAC engineers that not only is great at troubleshooting but also enjoys teaching. Needless to say, I learned a lot about multicast today that I might not have picked up so well from just reading a book or a nice clean lab environment…let me try to sum it up.

1. Make sure your RP is reachable from all the parts of the network that the multicast group will need to reach. In our case, the loopback interface being used for the RP was not being advertised in OSPF. This is a pretty quick showstopper!
2. Make sure ALL layer 3 interfaces that the multicast traffic might need to pass are configured for your PIM mode. This includes vlan interfaces as well.
3. Watch out for static mroute entries on switches. These can be just as insidious as regular static routes and can be just as tough to weed out of the network. If your RP is advertised correctly by your routing protocol, then you should not need a static mroute statement and should avoid them like the plague.
4. Static RP statements are a different story. I can’t remember if we had these on our ASR’s, but we did find it necessary to update them on the other switches for the group to appear in a “show ip pim mroute.”

I got some good links from the TAC engineer and a glowing recommendation for the “Developing IP Multicast Networks Vol. 1″ book from Cisco Press. He says at RTP they pretty much regard it as the multicast bible. Add another one to my Amazon wish list. I’ll add those links to this post tomorrow as well as add them to the CCNP section. The best thing I got out of this, though, was some good practice time making something work and a chance to help out a teammate. Now, time to sleep…

June 14, 2009 No comments

First OSPF Lab…In the Beginning, There Was Area 0…

ospftopology11Ok, I have to apologize to the good people at Wordpress.  It looks like my issues with uploading images in version 2.71 was more about having installed Google Gears in a vain attempt to get my poor other blog which I upgraded to 2.8 working.  Anyhow, above is the topology I was working with at home this weekend. Routers R1, R2, R3, and R4 each have an interface in the broadcast network connected to the switch.  This broadcast network is area 0.  Each of these routers has various loopback interfaces configured and advertised in OSPF in different areas.  The point-to-point link between R2 and R5 is area 51 and is configured for OSPF.  The link between R1 and R5 is another broadcast ethernet segment and is configured as area 2.  I plan on adding a network off of R5 in a new area that will need a virtual connection back to area 0 just for fun and hopefully a NBMA segment off one of the other routers to play with setting RouterID’s to rig a DR election and using neighbor statements.  Below are the outputs of “show run”, “show ip protocol”, and “show ip route” for each of the routers, with the output trimmed a bit for brevity.

R1
*****Output Omitted*****
!
interface Loopback1
description LAN
ip address 192.168.1.1 255.255.255.0
!
interface Loopback2
description LAN
ip address 192.168.5.1 255.255.255.0
!
interface FastEthernet0/0
description SW0
ip address 172.16.1.1 255.255.255.240
duplex auto
speed auto
!
interface FastEthernet1/0
description R5
ip address 192.168.10.1 255.255.255.252
duplex auto
speed auto
!
*****Output Omitted*****
!
router ospf 1
router-id 1.1.1.1
log-adjacency-changes
network 172.16.1.0 0.0.0.15 area 0
network 192.168.1.0 0.0.0.255 area 2
network 192.168.5.0 0.0.0.255 area 2
network 192.168.10.0 0.0.0.3 area 2
!
*****Output Omitted*****

R1#sh ip proto
Routing Protocol is “ospf 1″
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Router ID 1.1.1.1
It is an area border router
Number of areas in this router is 2. 2 normal 0 stub 0 nssa
Maximum path: 4
Routing for Networks:
172.16.1.0 0.0.0.15 area 0
192.168.1.0 0.0.0.255 area 2
192.168.5.0 0.0.0.255 area 2
192.168.10.0 0.0.0.3 area 2
Reference bandwidth unit is 100 mbps
Routing Information Sources:
Gateway Distance Last Update
2.2.2.2 110 00:10:05
4.4.4.4 110 00:10:05
3.3.3.3 110 00:10:05
Distance: (default is 110)

R1#sh ip route
*****Output Omitted*****

Gateway of last resort is not set

192.168.8.0/32 is subnetted, 1 subnets
O IA 192.168.8.1 [110/2] via 172.16.1.4, 00:11:14, FastEthernet0/0
192.168.9.0/30 is subnetted, 1 subnets
O IA 192.168.9.0 [110/65] via 172.16.1.2, 00:11:14, FastEthernet0/0
192.168.10.0/30 is subnetted, 1 subnets
C 192.168.10.0 is directly connected, FastEthernet1/0
172.16.0.0/28 is subnetted, 1 subnets
C 172.16.1.0 is directly connected, FastEthernet0/0
192.168.4.0/32 is subnetted, 1 subnets
O IA 192.168.4.1 [110/2] via 172.16.1.4, 00:11:15, FastEthernet0/0
C 192.168.5.0/24 is directly connected, Loopback2
192.168.6.0/32 is subnetted, 1 subnets
O IA 192.168.6.1 [110/2] via 172.16.1.2, 00:11:15, FastEthernet0/0
192.168.7.0/32 is subnetted, 1 subnets
O IA 192.168.7.1 [110/2] via 172.16.1.3, 00:11:16, FastEthernet0/0
C 192.168.1.0/24 is directly connected, Loopback1
192.168.2.0/32 is subnetted, 1 subnets
O IA 192.168.2.1 [110/2] via 172.16.1.2, 00:11:16, FastEthernet0/0
192.168.3.0/32 is subnetted, 1 subnets
O IA 192.168.3.1 [110/2] via 172.16.1.3, 00:11:16, FastEthernet0/0
R1#

R2
*****Output Omitted*****
!
interface Loopback1
description LAN
ip address 192.168.1.1 255.255.255.0
!
interface Loopback2
description LAN
ip address 192.168.5.1 255.255.255.0
!
interface FastEthernet0/0
description SW0
ip address 172.16.1.1 255.255.255.240
duplex auto
speed auto
!
interface FastEthernet1/0
description R5
ip address 192.168.10.1 255.255.255.252
duplex auto
speed auto
!
*****Output Omitted*****
!
router ospf 1
router-id 1.1.1.1
log-adjacency-changes
network 172.16.1.0 0.0.0.15 area 0
network 192.168.1.0 0.0.0.255 area 2
network 192.168.5.0 0.0.0.255 area 2
network 192.168.10.0 0.0.0.3 area 2
!
*****Output Omitted*****

R1#
R1#
R1#sh ip proto
Routing Protocol is “ospf 1″
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Router ID 1.1.1.1
It is an area border router
Number of areas in this router is 2. 2 normal 0 stub 0 nssa
Maximum path: 4
Routing for Networks:
172.16.1.0 0.0.0.15 area 0
192.168.1.0 0.0.0.255 area 2
192.168.5.0 0.0.0.255 area 2
192.168.10.0 0.0.0.3 area 2
Reference bandwidth unit is 100 mbps
Routing Information Sources:
Gateway Distance Last Update
2.2.2.2 110 00:14:48
4.4.4.4 110 00:14:48
3.3.3.3 110 00:14:48
Distance: (default is 110)

R1#
R1#
R1#sh ip route
Codes: C - connected, S - static, 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
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

192.168.8.0/32 is subnetted, 1 subnets
O IA 192.168.8.1 [110/2] via 172.16.1.4, 00:15:36, FastEthernet0/0
192.168.9.0/30 is subnetted, 1 subnets
O IA 192.168.9.0 [110/65] via 172.16.1.2, 00:15:36, FastEthernet0/0
192.168.10.0/30 is subnetted, 1 subnets
C 192.168.10.0 is directly connected, FastEthernet1/0
172.16.0.0/28 is subnetted, 1 subnets
C 172.16.1.0 is directly connected, FastEthernet0/0
192.168.4.0/32 is subnetted, 1 subnets
O IA 192.168.4.1 [110/2] via 172.16.1.4, 00:15:36, FastEthernet0/0
C 192.168.5.0/24 is directly connected, Loopback2
192.168.6.0/32 is subnetted, 1 subnets
O IA 192.168.6.1 [110/2] via 172.16.1.2, 00:15:36, FastEthernet0/0
192.168.7.0/32 is subnetted, 1 subnets
O IA 192.168.7.1 [110/2] via 172.16.1.3, 00:15:37, FastEthernet0/0
C 192.168.1.0/24 is directly connected, Loopback1
192.168.2.0/32 is subnetted, 1 subnets
O IA 192.168.2.1 [110/2] via 172.16.1.2, 00:15:37, FastEthernet0/0
192.168.3.0/32 is subnetted, 1 subnets
O IA 192.168.3.1 [110/2] via 172.16.1.3, 00:15:37, FastEthernet0/0
R1#

R3
*****Output Omitted*****
!
interface Loopback1
description LAN
ip address 192.168.3.1 255.255.255.0
!
interface Loopback2
description LAN
ip address 192.168.7.1 255.255.255.0
!
interface FastEthernet0/0
description SW0
ip address 172.16.1.3 255.255.255.240
duplex auto
speed auto
!
*****Output Omitted*****
!
router ospf 1
router-id 3.3.3.3
log-adjacency-changes
network 172.16.1.0 0.0.0.15 area 0
network 192.168.3.0 0.0.0.255 area 3
network 192.168.7.0 0.0.0.255 area 3
!
*****Output Omitted*****

R3#
R3#
R3#sh ip proto
Routing Protocol is “ospf 1″
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Router ID 3.3.3.3
It is an area border router
Number of areas in this router is 2. 2 normal 0 stub 0 nssa
Maximum path: 4
Routing for Networks:
172.16.1.0 0.0.0.15 area 0
192.168.3.0 0.0.0.255 area 3
192.168.7.0 0.0.0.255 area 3
Reference bandwidth unit is 100 mbps
Routing Information Sources:
Gateway Distance Last Update
4.4.4.4 110 00:28:13
2.2.2.2 110 00:25:21
1.1.1.1 110 00:20:29
Distance: (default is 110)

R3#
R3#
R3#sh ip route
Codes: C - connected, S - static, 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
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

192.168.8.0/32 is subnetted, 1 subnets
O IA 192.168.8.1 [110/2] via 172.16.1.4, 00:28:57, FastEthernet0/0
192.168.9.0/30 is subnetted, 1 subnets
O IA 192.168.9.0 [110/65] via 172.16.1.2, 00:26:05, FastEthernet0/0
192.168.10.0/30 is subnetted, 1 subnets
O IA 192.168.10.0 [110/2] via 172.16.1.1, 00:21:13, FastEthernet0/0
172.16.0.0/28 is subnetted, 1 subnets
C 172.16.1.0 is directly connected, FastEthernet0/0
192.168.4.0/32 is subnetted, 1 subnets
O IA 192.168.4.1 [110/2] via 172.16.1.4, 00:28:57, FastEthernet0/0
192.168.5.0/32 is subnetted, 1 subnets
O IA 192.168.5.1 [110/2] via 172.16.1.1, 00:28:57, FastEthernet0/0
192.168.6.0/32 is subnetted, 1 subnets
O IA 192.168.6.1 [110/2] via 172.16.1.2, 00:28:58, FastEthernet0/0
C 192.168.7.0/24 is directly connected, Loopback2
192.168.1.0/32 is subnetted, 1 subnets
O IA 192.168.1.1 [110/2] via 172.16.1.1, 00:28:58, FastEthernet0/0
192.168.2.0/32 is subnetted, 1 subnets
O IA 192.168.2.1 [110/2] via 172.16.1.2, 00:28:58, FastEthernet0/0
C 192.168.3.0/24 is directly connected, Loopback1
R3#

R4
*****Output Omitted*****
!
interface Loopback1
description LAN
ip address 192.168.4.1 255.255.255.0
!
interface Loopback2
description LAN
ip address 192.168.8.1 255.255.255.0
!
interface FastEthernet0/0
description SW0
ip address 172.16.1.4 255.255.255.240
duplex auto
speed auto
!
*****Output Omitted*****
!
router ospf 1
router-id 4.4.4.4
log-adjacency-changes
network 172.16.1.0 0.0.0.15 area 0
network 192.168.4.0 0.0.0.255 area 4
network 192.168.8.0 0.0.0.255 area 4
!
*****Output Omitted*****

R4#
R4#
R4#sh ip proto
Routing Protocol is “ospf 1″
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Router ID 4.4.4.4
It is an area border router
Number of areas in this router is 2. 2 normal 0 stub 0 nssa
Maximum path: 4
Routing for Networks:
172.16.1.0 0.0.0.15 area 0
192.168.4.0 0.0.0.255 area 4
192.168.8.0 0.0.0.255 area 4
Reference bandwidth unit is 100 mbps
Routing Information Sources:
Gateway Distance Last Update
3.3.3.3 110 00:32:46
2.2.2.2 110 00:29:47
1.1.1.1 110 00:24:55
Distance: (default is 110)

R4#
R4#
R4#sh ip route
Codes: C - connected, S - static, 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
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

C 192.168.8.0/24 is directly connected, Loopback2
192.168.9.0/30 is subnetted, 1 subnets
O IA 192.168.9.0 [110/65] via 172.16.1.2, 00:30:34, FastEthernet0/0
192.168.10.0/30 is subnetted, 1 subnets
O IA 192.168.10.0 [110/2] via 172.16.1.1, 00:25:42, FastEthernet0/0
172.16.0.0/28 is subnetted, 1 subnets
C 172.16.1.0 is directly connected, FastEthernet0/0
C 192.168.4.0/24 is directly connected, Loopback1
192.168.5.0/32 is subnetted, 1 subnets
O IA 192.168.5.1 [110/2] via 172.16.1.1, 00:33:33, FastEthernet0/0
192.168.6.0/32 is subnetted, 1 subnets
O IA 192.168.6.1 [110/2] via 172.16.1.2, 00:33:33, FastEthernet0/0
192.168.7.0/32 is subnetted, 1 subnets
O IA 192.168.7.1 [110/2] via 172.16.1.3, 00:33:34, FastEthernet0/0
192.168.1.0/32 is subnetted, 1 subnets
O IA 192.168.1.1 [110/2] via 172.16.1.1, 00:33:34, FastEthernet0/0
192.168.2.0/32 is subnetted, 1 subnets
O IA 192.168.2.1 [110/2] via 172.16.1.2, 00:33:34, FastEthernet0/0
192.168.3.0/32 is subnetted, 1 subnets
O IA 192.168.3.1 [110/2] via 172.16.1.3, 00:33:34, FastEthernet0/0
R4#

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