Implementing Advanced EIGRP
3 Advanced Basic Configuration
- 3.1 EIGRP over NBMA Networks
- 3.2 Enabling EIGRP Authentication
- 3.3 Best Practices
3.1 EIGRP over NBMA Networks
- Each Router is connected to a shared bandwidth
- This is called a PVC (permanent virtual connection)
- The connected participants uses numbers(DLCI) to communicate
- DLCI = data link connection identifier
- Communication over the cloud uses numbers instead of MAC addresses
- Each PVC has its own bandwidth limitation – called CIR(committed information rate)
- Different PVC’s can come in on a single physical interface
- the DLCIs numbers must be different in one Frame Relay cloud
- EIGRP can use “Pseudo-Broadcasts” or manual neighbors
- Broadcasts were denied
- Multicast messages were denied
- Multicast address were 126.96.36.199 to form neighbor relationship
- Pseudo Broadcast, because the broadcast were limited of the use of DLCIs. So it is called a Pseudo-Broadcast.
Later, there will be explained in the LAB.
- With multipoint you save subnets. With point-to-point not
- Using the neighbor command in the routing process, you change a multicast address into a unicast address.
- One manual neighbor statement disables multicast.
- Split Horizon can be an issue
- figure 2 – Hub and Spoke. If a Router MD# sends a routing advertisement, the router AZ# who recieved this packet,
send the advertisement not back on the same interface, where he gets the advertisement. So – CA#
do not know everything about the networks from MD#.
- Split Horizon – Disabled on physical interfaces
- Split Horizon – Enabled on Sub-interfaces
How DLCIs work
• X.25 (this was the first protocol of frame relay – followed by)
Frame Relay PVC Design
How EIGRP handles NBMA
EIGRP Frame Relay Configuration
• Configure EIGRP using AS 25 for the shown network. All networks should be announced via EIGRP
• Each office should generate an efficient EIGRP summary route to minimize routing table entries.
• Configure the HQ router to utilize up to 30% more of the allocated serial interface bandwidth then
3.2 Enabling EIGRP Authentication
• Enable authentication between all EIGRP routers. You should use two authentication keys:
3.3 Best Practices
- 3.3.1 Eavesdropping on EIGRP neighbors
- 3.3.2 Understanding the Query Process
- 1. Summary Routes
- .2 stub configuration
3.3.1 Eavesdropping on EIGRP neighbors
3.3.2 Understanding the Query Process
Look at figure 3.
When network 172.30.1.0 goes down, R2# send a query messages to all Routers and so on.
This causes an enormous control traffic of eigrp. R2 keep in for minimum 3 minutes in stuck in active mode. All other Routers reply with a Query Reply.
There are two methods to correct this problem.
1. The summary route will be send with a query to a neighbors router. But they don’t reply with a query,
2. Go into the router process for eigrp 25 and configure a stub.
R2(config-router)#eigrp stub ?
connected Do advertise connected routes
leak-map Allow dynamic prefixes based on the leak-map
receive-only Set IP-EIGRP as receive only neighbor
redistributed Do advertise redistributed routes
static Do advertise static routes
summary Do advertise summary routes
If you hit enter, the default value is ‘connected’ and ‘summary’