EIGRP Over Frame Relay

EIGRP Over Frame Relay
NBMA
Non Broadcast Multi Access
Cannot send broadcasts
can emulate broadcasts
unable to send multi-cast traffic
EIGRP, RIP, OSPF use multicast
Split Horizon Issues
Solutions
Disable Split Horizon
Use Sub Interface
Split Horizon Issues with Multipoint
Uses Inverse ARP
Maps local DLCI to remote IP Address
Enables emulation of broadcast traffic
on by default
If disabled frame maps must be used
Types:
Point to Point
Point to Multipoint (default)
Uses Virtual Circuits
PVC's
Permanent Virtual Circuits
CIR
Committed Information Rate
assigned link speed by ISP
LMI
Local Management Interface
Keep Alive Mechanism
Shows if PVC's are Active or Passive
Provides DLCI Identifier
Three Types of LMI's:
1. Cisco
2. Ansi
3. ITU-T
Supports Multiple Topologies
Full Mesh
Partial Mesh
Hub & Spoke
Commands
"encapsulation frame-relay"
"show frame relay map"
Disable Inverse ARP
"no frame-relay inverse arp"
Clear Frame Mappings
"clear frame-relay map"
Map Frame Relay (under interface)
"frame-relay map 'ip address' 'local dlci #' broadcast"
Map Frame Relay to Sub-interface
#interface 'interface #' multipoint
#ip address '_______'
#frame-relay map ip 'ip address' 'local DLCI #' broadcast
Disable Split Horizon (under sub-interface)
#no ip split-horizon eigrp 'AS #'
Switch from Multicast to Unicast
#router eigrp 'AS #'
#neighbor 'ip address' 'interface #'
Frame Relay Point to Point (sub-interfaces)
Must use different subnets for each PVC
Commands
#interface 'interface #' point to point
#frame-relay interface-dlci 'local DLCI #'
ip address 'ip address of interface'
No Frame Mappings on point to point to configure
No Split Horizon issues
Frame Relay Bandwidth Utilization
EIGRP uses up to 50% of bandwidth for traffic
Bandwidth can be modified on the interface
Point To Point Interfaces
Treated as T1 (1.5 MBPS) interface
Configure to reflect true bandwidth
Use " #bandwidth 'link speed' " to modify bandwidth
Helps keep EIGRP traffic from flooding the interface
Called "Bandwidth Pacing"
Configure Sub-Interfaces
separate subnets
On Spoke routers change bandwidth to calculation for each PVC on main interface
Use "ip bandwidth-percent" command on sub-interfaces to match 50% of available link speed
Multi Point Interfaces
Bandwidth on physical interface divided by the number of neighbors
Example: 1 Hub @ 256kbps with 10 Spoke Routers connected
256/10 = 25.6 kbps
To calculate bandwidth for Hub interface multiply slowest link speed x number of neighbors
" #interface 'interface #' "
" #bandwidth 'link speed' "
Commands
Change percentage used for EIGRP traffic
" #ip bandwidth-percentage eigrp 'AS#' 'bandwidth%' "
Hybrid Bandwidth
Combine multiple PVC's of the same speed onto 1 interface
Configure the slowest link on a separate Point to Point interface
Commands:
Hub: " #interface 'interface #' multipoint
" #bandwidth 'link speed' "
Hub: " #interface 'interface #' point to point "
" #bandwidth 'link speed' "
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