Optimized Edge Routing (OER): Configuration Example

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Thu, 10/17/2013 - 13:18
Jul 3rd, 2012
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Introduction

Otimized Edge Routing (OER) also known as Performance Routing (PFR) ia an alternative way of routing traffic. OER/PfR selects a path based on the performance of the path and hence optimizing the connections. For example, an OER enabled edge router connected with two ISP can perform load sharing by transmitting data to 2nd ISP when it detect conjestion over 1st ISP link. OER/PfR can measure parameters such as delay, throughput, loss and reachability, among others, pre-determined policies to select the best performing path, and route packets accordingly.


OER has two components: a Master Controller (MC) and one or more Border Routers (BR). The Master Controller is the decision maker, whereas the border routers are edge routers with exit interfaces at the network edge. Border routers are either used to access the Internet or used as WAN exit links. OER communication between the master controller and the border routers is carried separately from routing protocol traffic. This communication is protected by Message Digest 5 (MD5) authentication. Each border router has both an external interface, which is connected, for example, to an ISP by a WAN link, and an internal interface that is reachable by the master controller.

Prerequisite

  • Understanding of IP Routing Protocol
  • CEF must be enabled on participating routers

Summary

In this document Router R1, R2 and R3 forms an OSPF neighbor relationshio (Area 0) and acting as internal network.

Router R1 from OER perspective being the Master Controller (MC) and the Border Router (BR). There could be scenarios where MC and BR are two different identities. However for simplicity I have choosen R1 to act as both i.e. MC and BR. The two components taks over TCP connection authenticated via MD5. Router R1 has redundant connection to R4 through interface (FastEthernet 1/0 and Serial 0/0).

Router R4 is the provider router which is injecting default route  0.0.0.0/0 into R1 via FastEthernet 0/0, making this path primary and  Serial 0/0 secondary path.

NOTE: All configurations are tested on Cisco 3745 Router operation on IOS Version 12.4(15)T14  Advance IP Services version.

Objective
  1. Configure R1 as the OER Master Controller and Border Router.
  2. FastEthernet 0/0 and FastEhetnet 0/1 interface of R1 are marked as Internal Interface.
  3. FastEthernet 1/0 and Serial 0/0 interface of R1 are marked as External Interface.
  4. Any ICMP traffic to 4.4.4.4/32 (Lo0 of R4) going from R1 should use the primary link (i.e through FastEthernet 1/0 interface of R1).
  5. Any telnet traffic (port 19) to 44.44.44.44/32 (Lo1 of R4)going from R1 should use the secondary link (i.e through Serial 0/0 interface of R1).

Topology diagram

Topology Diagram.bmp

Configuration


R1-->MC and BR Configuration


key chain OER

key 1

   key-string CISCO

!

oer master

policy-rules OER

logging

!

border 1.1.1.1 key-chain OER

  interface Serial0/0 external

  interface FastEthernet1/0 external

  interface FastEthernet0/1 internal

  interface FastEthernet0/0 internal

!

learn

  periodic-interval 0

  monitor-period 1

no max range receive

mode route control

!

oer border

local Loopback0

master 1.1.1.1 key-chain OER


R1--> OER Policy Configuration


ip access-list extended ICMP-TRAFFIC

permit icmp any host 4.4.4.4

ip access-list extended TELNET-TRAFFIC

permit tcp any host 44.44.44.44 eq chargen

!

oer-map OER 10

match traffic-class access-list ICMP-TRAFFIC

set next-hop 172.14.14.4

!

oer-map OER 20

match traffic-class access-list TELNET-TRAFFIC

set next-hop 172.16.14.2

!


Note: For complete configurations, see attached text files (Config-R1, Config-R2, Config-R3, Config-R4).

Verification Commands

show oer master

show oer master.bmp

Note: The output is truncated, for complete output of the command "show oer master" see attached file

show oer master border detail

show oer master border detail.bmp

show oer master traffic-class

show oer master traffic-class.bmp

References

Setting Up OER Network Components

Optimized Edge Routing Configuration Guide, Cisco IOS Release 12.4T

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