RIP Advertisements

RIP only advertises routes that are loaded in the routing table. This can lead to interesting results with route redistribution.

Private VLAN

• VTP doesn't propagate private VLAN information (transparent mode required)
• VLAN database mode is NOT supported
• Only the primary VLAN runs spanning-tree (community and isolated VLANs don't run their own STP instance)
• Strictly used for L2 filtering - L3 communication b/n hosts may still be possible

Example:

vlan 2
private-vlan primary
private-vlan association 4

vlan 4
private-vlan isolated

int fa0/1
switchport private-vlan host-association 2 4
switchport mode private-vlan host

int fa0/2
switchport private-vlan mapping 2 4
switchport mode private-vlan promiscuous

int fa0/3
switchport private-vlan host-association 2 4
switchport mode private-vlan host

Split Horizon in EIGRP

Unlike RIP, split horizon is never automatically disabled in EIGRP. Consequently, if you have a hub-and-spoke frame setup with EIGRP overlayed, make sure you disable split horizon with the interface level command:

ccie(config-if)#no ip split-horizon eigrp 100

RIP Triggered

• Only send information on link when there is a change in routing database
• Periodic updates are suppressed
• Command ('ip rip triggered') is required on both sides of the link
• Must be a point-to-point link

OSPF Demand Circuit

• No periodic heartbeat keepalives (hellos)
• 'Do not age' flag is set on all LSAs so the paranoid 30 min timer doesn't expire
• Updates will only be sent when there is a change in the OSPF topology
• Must be a point-to-point link for OSPF
• Command is only needed on one side

Calculating Burst

According to the Doc CD:

norm-burst = cir / 8 (to convert to bytes) * 1.5
max-burst = cir / 8 (to convert to bytes) * 2

Frame Relay End-to-End Keepalives

Polling the other side of the VC can be done through the use of the map-class.

4 Ways to Derive L3-to-L2 Mappings in Frame Relay

1. Inverse-Arp
2. Frame-Relay Map cmd
3. Point-to-Point interface
4. PPPoFR

WRED in MQC Conditions

In order to configure WRED in MQC, one of two conditions must exit:

1. There must be a bandwidth reservation statement within a class

OR

2. The default-class must be running weighted fair queueing


Consequently, you may have to use the match not command to isolate the traffic you want (match not protocol ftp - move it to NON_ClassDefault and then FTP will be only thing remaining in class-default) and then enable fair-queue and random-detect in class-default.

Refer to IE Lab 6 Task 7.2

4 Ways to Originate BGP Prefixes

There are four ways to originate BGP prefixes:

1. Redistribute static route
2. Network command
3. Aggregate-address command
4. Inject-map

Methods of Filtering Updates

Any of the following methods will allow you to filter routes:

1. Distribute List
2. Offset List
3. Distance command

Stub Breakdown

Stub Area Gotcha

When configuring the stub area, don't forget to watch out for Loopbacks that were redistributed via connected w/ route-map. If you accidentally configure it as a stub area instead of NSSA, you will lose that route from the domain.

Extended VLANs Reminder

When you are using VTP transparent mode, the VLAN configuration is stored in the running-config/startup-config, instead of in vlan.dat file. The extended VLANs (1006-4094) can be trunked through VTP server and client switches, but no ports can become members of these vlans.

Reflexive ACLs Limitation

Remember that traffic originated from a router that has a reflexive ACL applied will not be evaluated. You need to explicitly permit the necessary traffic (routing protocol traffic, telnet, ICMP, etc.) on the inbound list.

Useful Grep #1

To help with seeing subnet mask issues:

Rack1R6#sh int ! i is up!Internet
Ethernet0/0 is up, line protocol is up
Internet address is 141.1.36.6/24
Ethernet0/1 is up, line protocol is up
Internet address is 141.1.6.6/24
Serial1/0 is up, line protocol is up
Internet address is 54.1.1.6/24
Loopback0 is up, line protocol is up
Internet address is 150.1.6.6/24

OSPF - No Virtual Link across Stub Area

A virtual-link cannot transit a stub area. In these cases, you will need to create a GRE tunnel to bridge the discontiguous area to an area 0 router. The task should hint at this by permitting you to create an additional subnet.

RIP - enabling unicast-only updates

Unlike OSPF, configuring the neighbor statement in RIP doesn't stop the transmission of broadcast/multicast (RIPv1 and RIPv2 respectively) update packets. Instead, it just sends an additional unicast update for the statically configured neighbors. In order to stop the transmission of broadcast/multicast updates and only send unicast updates you have to use the passive-interface command alone with the neighbor command. (IE)

Configuring FRTS disables fair queueing

WFQ needs to be enabled for RSVP. WFQ is the default queueing strategy on serial interfaces under 2.048 Mbps, but enabling FRTS on an interface disables fair queueing. (IE)

Passive Interface

The network statement does three things. First off the network statement advertises the networks configured on the interfaces that the network statement encompasses. These could be one or more networks. Secondly it enables the sending of updates or hellos, depending on the routing protocol used, outbound on the interface/interfaces. Lastly it allows updates or hellos to be received and processed inbound on the interface/interfaces.

The passive interface stops only one of these steps and that is the second step. It does not stop the advertisement of the network by the protocol or stop the receiving of inbound updates or hellos. Of course with any protocol that uses hellos that protocol will require a neighbor relationship to be formed before updates can be sent/received. (From B.D.)