root port vs designated port

It's probably easy to configure a switch to be a root switch. However, I've just realized that I missed something that I didn't understand the concept of what the root switch is.

There are two type of port, i.e.:

1. root port
2. designated port

Root port is a port telling us the path toward the root switch. While designated port is a port in direction of leaving away from the root switch.

By that definition, a root port will always a pair with designated port on its direct neighbor switch. And when a switch doesn't have any root port, it is definitely the root switch itself.

Day #1 - root bridge and VLAN path

It's about the time to start again the CCIE journey that I've skipped for quite a while. Unfortunately I have to start everything again from zero. The good news, I think that I can start quicker at this time. I used to spend more time on GNS3, but at this time this is not an issue anymore.

Well, today I've started with some bridging configuration. And I decided to write all notes here to help me remembering the lesson

Q: How to configure a switch to be root bridge
A: Here are some items that I noticed

• configure at the global configuration
• command is spanning-tree vlan XXX root primary

Q: how to prevent VLAN traverse to a switch?
A: Here are the noted points

• by restricting the VLAN on the interface level
• use switchport command

Enough for today. Will continue tomorrow.

Cisco Regular Expression

Below is the important table need to be noted for regular expression in Cisco.

Use \ (backslash) to match the character as is.

source: here

Character		Special Meaning
period	.	Matches any single character, including white space.
asterisk	*	Matches 0 or more sequences of the pattern.
plus sign	+	Matches 1 or more sequences of the pattern.
question mark	?	Matches 0 or 1 occurrences of the pattern.
caret	^	Matches the beginning of the input string.
dollar sign	$	Matches the end of the input string.
underscore	_	Matches a comma (,), left brace ({), right brace (}), left parenthesis, right parenthesis, the beginning of the input string, the end of the input string, or a space.
brackets	[]	Designates a range of single-character patterns.
hyphen	-	Separates the end points of a range.

Redistribution problem

1. Examine if there is a filter applied to the interface that could prevent the distribution

2. The route may be non installed because of there is another route wit better metric

Debug: Authentication Error

*Mar 1 01:20:49.775: %TCP-6-BADAUTH: No MD5 digest from 192.10.1.254(179) to 192.10.1.10(21793) (RST)

The message above is generated on TCP port 179.

From there, we can guess of who generated this message.

OSPF interception

To avoid interception on a segment between two OSPF nodes, do the following:

- configure the ospf intrface as nonbroadcast

- configure the nodes to be neighbor each other

To verify the settings:

# show ip ospf interface interface

# debug ip ospf hello

OSPF priorty 0

An OSPF router with 0 priority will never be a BDR or DR.

Furthermore, giving 0 priority to an OSPF router will remove the DR/BDR status from it immediately and will trigger a new election.

CCIE written passed

After several times postponing to take the exam, I finally decided to take the exam on 11 Jan 2009 and passed it.

I know that passing the written exam doesn't mean anything except that now I can register for the lab exam. However, considering my hard work to prepare this exam, I should celebrate this achievement :D

Now it's the time to read the blueprint for the lab and learn harder on the lab exam preparation.

RootGuard

RootGuard prevents a port to be a ND (non designated) port. So the port should always be designated. If the port receive a better BPDU, the port will become root-inconsistent state and the port will be blocking

LoopGuard

LoopGuard need to be enabled on Root Ports and Alternate Ports. When the port is not receiving BPDU, then the port will become a Loop-Inconsistent blocking state.

Looks simple, but unfortunately the sample answer of a question I got didn't match with my answer. Need to dig more about this.

Administrative Distance

When there are multiple routing protocols running on a router, and each protocols has a route then a route to the destination, then the router will select a path with the lowest administrative distance. So, the table below need to be remembered.

Route Source	Default Distance Values
Connected interface	0
Static route	1
Enhanced Interior Gateway Routing Protocol (EIGRP) summary route	5
External Border Gateway Protocol (BGP)	20
Internal EIGRP	90
IGRP	100
OSPF	110
Intermediate System-to-Intermediate System (IS-IS)	115
Routing Information Protocol (RIP)	120
Exterior Gateway Protocol (EGP)	140
On Demand Routing (ODR)	160
External EIGRP	170
Internal BGP	200
Unknown*	255

ODR (On-Demand-Routing)

Q: What is ODR ?
A: On-Demand Routing is not a routing protocol. It uses Cisco Discovery Protocol (CDP) to propagate the IP prefix. ODR is a perfect solution for hub and spoke topology when the spoke routers act as stub routers by connecting to no other router other than the hub. If you only use Cisco routers in your network, running Cisco IOS® 11.2 or later, you can use ODR. If you are running dynamic protocols (for instance, if you are an ISP), ODR is not suitable for your network environment

Q: How can I configure ODR ?
A: Configure the router odr command in the hub router and turn off any dynamic routing protocols in the spoke routers. Spoke routers automatically start to advertise their subnets using CDP. You do not need the router odr command on spoke routers

More info about ODR ? Check on this link

Roadmap - Written

I think guest the best way to create a Road map is based on the blueprint.
So I copied the blueprint here and will put the date on each topic

1. General Networking Theory
   1. General Routing Concepts
      1. Link State and Distance Vector Protocols
      2. Split Horizon
      3. Summarization
      4. Classful and a Classless routing protocol
      5. Routing decision criteria
   2. Routing Information Base (RIB) and Routing Protocols Interaction
      1. Administrative Distance
      2. Routing Table
      3. RIB and Forwarding Information Base interaction
   3. Redistribution
      1. Redistribution between routing
      2. Troubleshooting routing loop
   
   
2. Bridging and LAN Switching
   1. Spanning Tree Protocol (STP)
      1. 802.1d
      2. 802.1w
      3. 802.1s
      4. Loopguard
         
      5. Rootguard 5-nov-2007
         
      6. Bridge Protocol Data Unit (BPDU) Guard 5-nov-07
         
      7. Storm Control
      8. Rapid Spanning Tree Protocol (RSTP)
      9. Unicast flooding
      10. STP port roles, failure propagation and loopguard operation
   2. LAN Switching
      1. Trunks
      2. VLAN Trunking Protocol (VTP) administrative functions
   3. Ethernet
      1. Speed
      2. Duplex
      3. Ethernet
      4. Fast Ethernet
      5. Gigabit Ethernet
   
   
3. IP
   1. Addressing
      1. Subnetting
      2. Hot Standby Routing Protocol (HSRP)
      3. Gateway Load Balancing Protocol (GLBP)
      4. Virtual Router Redundancy Protocol (VRRP)
      5. Network Address Translation (NAT)
   2. Services
      1. Network Time Protocol (NTP)
      2. Dynamic Host Control Protocol (DHCP)
      3. Web Cache Communication Protocol (WCCP)
   3. Network Management
      1. Logging and Syslog
   
   
4. IP Routing
   1. OSPF
      1. Standard OSPF area
      2. Stub area
      3. Totally stub area
      4. Not-so-stubby-area (NSSA)
      5. Totally NSSA
      6. Link State Advertisement (LSA) types
      7. Adjacency on a point-to-point and on a multi-access (broadcast)
      8. OSPF graceful restart
      9. Troubleshooting failing adjacency formation to fail
      10. Troubleshooting of external route installation in the RIB
   2. BGP
      1. Protocol on which BGP peers communicate
      2. Next Hop
      3. Peering
      4. Troubleshooting of BGP route that will not install in the routing table
   3. EIGRP
      1. Best path
      2. Loop free paths
      3. EIGRP operations when alternate loop free paths are available and when it is not available
      4. EIGRP queries
      5. Manual summarization
      6. Auto-summarization
      7. EIGRP Stubs
      8. Troubleshooting of EIGRP neighbor adjacencies
   4. Policy Routing
      1. Concept of policy routing
   
   
5. QoS
   1. Modular QoS command-line (MQC) applied to:
      1. Network-Based Application Recognition (NBAR)
      2. Class-based weighted fair queueing (CBWFQ) / Modified Deficit Round Robin (MDRR)
      3. Policing
      4. Shaping
      5. Marking
      6. Random Early Detection (RED)
   
   
6. WAN
   1. Frame Relay
      1. Local Management Interface (LMI)
      2. Traffic Shaping
      3. HUB and Spoke routers
      4. Dynamic Multipoint VPN (DMVPN)
      5. DE
   
   
7. IP Multicast
   1. Internet Group Management Protocol (IGMP) v2
   2. Group addresses
   3. Shared Trees
   4. Source Trees
   5. Protocol Independent Multicast (PIM) Mechanic
   6. PIM Sparse Mode
   7. Auto-RP
   8. Anycast RP
   
   
8. Security
   1. Extended IP access lists
   2. Unicast Reverse Path Forwarding (uRPF)
   3. IP Source Guard
   4. Context Based Access Control (CBAC)
   
   
9. MPLS (New)
   1. Label Switching Router (LSR)
   2. Label Switched Path (LSP)
   3. Route Descriptor
   4. Label Format
   5. Label imposition/disposition
   6. Label Distribution
   
   
10. IPv6 (New)
    1. IPv6 Addressing and types
    2. IPv6 Neighbor Discovery
    3. Basic IPv6 functionality protocols
    4. IPv6 Multicast and related Multicast protocols
    5. Tunneling Techniques
    6. OSPFv3
    7. EIGRPv6