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Amit Barik
Beginner

Load Balancing in MPLS VPN BGP and EIGRP SOO

Load Balancing in MPLS VPN BGP and EIGRP SOO

I have two questions regarding MPLS VPN

# QUESTION1: With Route Reflector in ISP Core and "maximum-paths" BGP configured at PE, I wish to achieve load balancing within the Core. However, I note the following:

## With "PE1#show ip cef vrf" command I can see that there are two paths to the customer CE2 network, but only one is being used as seen by traceroute from CE1 or with "PE1#show ip vrf exact-route". Why?

# QUESTION2: I have configured EIGRP SOO on PE2 and PE3 to avoid routing loop, but after using all the possible debug commands I don't see any "loop detected" message at PE2/PE3/CE2?

## I am sure EIGRP SOO is preventing the routing loop as I see that without SOO "PE#debug ip bgp vpnv4 unicast updates" shows a lot of messages indicating there is loop, but after configuring SOO, the network becomes stable and I don't see any BGP update messages

## But my only question is why i don't see any "loop detected" debug message

## I am using the debug commands on PE/CE: debug ip bgp vpnv4 unicast updates, debug ip eigrp vrf *

It will be great if you can help me out....

I have configured the network in GNS3 with IOS "Version 12.2(33)SRC6"

I have the network with following setup:

# All the interfaces have subnet of format: 10.0.$LocalRouterNo$RemoteRouterNo.$LocalRouterNo/24

# All routers have loopback lo0: $LocalRouterNo.0.0.1/32

# Customer Site1 CE1:

## R1/CE1 (AS1) - R2/PE1 (AS234) run EBGP

## R1/CE1 is advertising 1.0.0.1/32

## R2/PE1 has fa1/0 in VRF 1 with RD/RT

### RD 234:2

### RT import/export 234:2

### RT import 234:3

### RT import 234:4

# Customer Site2 CE2:

## R5/CE2 - R3/PE2 and R5/CE2 - R4/PE3 are in EIGRP AS345

## R5/CE2 is advertising 5.0.0.1/32

## R3/PE2 has fa1/1 in VRF 5 with RD/RT

### RD 234:3

### RT import/export 234:3

### RT import 234:2

### RT import 234:4

## R4/PE3 has fa1/1 in VRF 5 with RD/RT

### RD 234:4

### RT import/export 234:4

### RT import 234:2

### RT import 234:3

# ISP AS234

## R2/PE1, R3/PE2, R4/PE3 are in AS234

## R2/PE1 is RR Server for R3/PE2 & R4/PE3 Clients

## BGP is redistributed into EIGRP on R3 and R4

## EIGRP is redistributed into BGP with specific metric on R3 and R4

# Interfaces of PE at PE2/R3-CE2 is configured with sitemap 3 that sets SOO to 1:3

# Interfaces of PE at PE3/R4-CE2 is configured with sitemap 4 that sets SOO to 1:4

Configurations and the network GNS3 file have been attached or at https://www.dropbox.com/s/r998iffgg7luqo3/Lab11.zip

If this link is broken contact me please

Sample snippets showing load balancing not working:

<source>

! Two paths

R2#show ip cef vrf 1 5.0.0.1/32 detail

5.0.0.1/32, epoch 0, per-destination sharing

  recursive via 3.0.0.1 label 22

    nexthop 10.0.23.3 FastEthernet1/1

  recursive via 4.0.0.1 label 20

    nexthop 10.0.24.4 FastEthernet2/0

R2#

! But only one is used

R2#show ip cef vrf 1 exact-route 1.0.0.1 5.0.0.1

1.0.0.1 -> 5.0.0.1 => label 22 label implicit-null TAG adj out of FastEthernet1/1, addr 10.0.23.3

R2#

R1#traceroute 5.0.0.1 source lo0

Type escape sequence to abort.

Tracing the route to 5.0.0.1

  1 10.0.12.2 76 msec 124 msec 252 msec

  2 10.0.35.3 [AS 234] [MPLS: Label 22 Exp 0] 156 msec 72 msec 72 msec

  3 10.0.35.5 [AS 234] 352 msec *  308 msec

R1#

</source>

1 REPLY 1
Amit Barik
Beginner

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