Technology Lab

VRRP + MSTP Lab Case

H3CSwitching

Vrrp+MSTP Lab Case

1. VRRP Experiment

1.1 Experimental Topology

Figure 1-1 Topology Overview

Notes:

Unless otherwise specified, SWA corresponds to the device labeled A in the topology, and SWB corresponds to the device labeled B.

In the same subnet, the host ID of the IP address corresponds to the device number.

For example, if SWA is in subnet 192.168.1.0/24, its IP address is 192.168.1.252, SWB is 192.168.1.253, etc.

VLAN10 subnet: 192.168.1.0/24

VLAN20 subnet: 192.168.2.0/24

Virtual gateway:

VLAN10 -> 192.168.1.254

VLAN20 -> 192.168.2.254

1.2 Experimental Requirements

Configure IP addresses and gateways according to the topology.

Create VLAN10 and VLAN20 on SWA, SWB, SWC, and SWD.

All inter-switch links should allow VLAN10 and VLAN20 to pass.

Configure VRRP on SWA and SWB:

SWA acts as the Master gateway for VLAN10.

SWB acts as the Master gateway for VLAN20.

SWA and SWB act as backups for each other.

Configure uplink interface tracking:

If the uplink fails, VRRP role switching must be triggered automatically.

In addition to VRRP, MSTP is deployed among SWA, SWB, SWC, and SWD.

The MSTP design is as follows:

MSTP Instance	VLAN Mapping	Root Bridge
Instance 1	VLAN10	SWA (Primary)
Instance 2	VLAN20	SWB (Primary)

SWA is Instance 1 primary, Instance 2 secondary

SWB is Instance 2 primary, Instance 1 secondary

All devices belong to the same MST region:

Region name: h3c

Revision-level: 0

This ensures that all switches are part of the same MST region and share consistent instance calculations.

1.3 Configuration Steps

1.3.1 IP Address Configuration

(Omitted for brevity - configured according to topology plan.)

1.3.2 VLAN and Trunk Configuration

(Omitted for brevity - ensure VLAN10 and VLAN20 are allowed on all inter-switch trunk links.)

1.4 VRRP Configuration

1.4.1 Design Analysis

According to the requirement:

SWA must be the Master for VLAN10.

SWB must be the Master for VLAN20.

Default VRRP priority is 100.

Therefore:

SWA priority in VLAN10 must be greater than 100.

SWB priority in VLAN20 must be greater than 100.

Virtual IPs:

VLAN10 -> 192.168.1.254

VLAN20 -> 192.168.2.254

1.4.2 Configuration on SWA

Configure SWA as Master for VLAN10 and Backup for VLAN20.

[SW-A]interface Vlan-interface10
 ip address 192.168.1.252 255.255.255.0
 vrrp vrid 10 virtual-ip 192.168.1.254
 vrrp vrid 10 priority 120

[SW-A]interface Vlan-interface20
 ip address 192.168.2.252 255.255.255.0
 vrrp vrid 20 virtual-ip 192.168.2.254

1.4.3 Configuration on SWB

Configure SWB as Master for VLAN20 and Backup for VLAN10.

[SW-B]interface Vlan-interface10
 ip address 192.168.1.253 255.255.255.0
 vrrp vrid 10 virtual-ip 192.168.1.254

[SW-B]interface Vlan-interface20
 ip address 192.168.2.253 255.255.255.0
 vrrp vrid 20 virtual-ip 192.168.2.254
 vrrp vrid 20 priority 120

1.5 Verification - Normal State

Check VRRP status on both switches.

[SW-A]display vrrp

[SW-B]display vrrp

Expected output for SWA:

VLAN10 -> Master (priority 120)

VLAN20 -> Backup (priority 100)

Expected output for SWB:

VLAN10 -> Backup (priority 100)

VLAN20 -> Master (priority 120)

This confirms that the load-sharing gateway design works correctly.

1.6 VRRP Interface Tracking (Failure Detection)

1.6.1 Design Analysis

By default, interface failure does not automatically trigger VRRP switching.

Therefore, we configure:

Interface tracking

Priority reduction when uplink fails

Current priorities:

Device	VLAN	Priority
SWA	VLAN10	120
SWB	VLAN10	100

To trigger failover, priority must drop below 100.

So we configure:

priority reduced30

120 - 30 = 90 -> lower than 100 -> role switches.

1.6.2 Configure Tracking on SWA

Track uplink interface GE1/0/2.

[SW-A]track 1 interface GigabitEthernet1/0/2

[SW-A]interface Vlan-interface10
 vrrp vrid 10 track 1 priority reduced 30

1.6.3 Configure Tracking on SWB

Track uplink interface GE1/0/3.

[SW-B]track 1 interface GigabitEthernet1/0/3

[SW-B]interface Vlan-interface20
 vrrp vrid 20 track 1 priority reduced 30

VRRP Track Function

The track function monitors a physical interface state.

If the tracked interface fails:

VRRP priority is reduced

This may trigger Master/Backup switchover

This allows gateway failover to follow uplink status, preventing traffic blackholing.

1.7 Failure Test

1.7.1 Simulate Uplink Failure on SWA

[SW-A]interface GigabitEthernet1/0/2
 shutdown

Check VRRP status:

[SW-A]display vrrp

Expected:

VLAN10 priority drops to 90

VLAN10 state becomes Backup

Check SWB:

[SW-B]display vrrp

Expected:

VLAN10 becomes Master

1.7.2 Recovery Test

Bring interface back:

[SW-A]interface GigabitEthernet1/0/2
 undo shutdown

If preemption is enabled (default behavior), SWA will regain Master role for VLAN10.

2. MSTP Configuration

2.1 Design Objective

Without MSTP:

One physical redundant link may be fully discarded

Only one path forwards traffic

The other path carries no traffic -> bandwidth waste

With MSTP:

Different VLANs map to different instances

Each instance can have a different root

A port may be:

Discarding in Instance 1

Forwarding in Instance 2

This achieves Layer 2 load balancing.

2.2 MSTP Configuration on SWA

SWA:

Instance 1 -> Primary root

Instance 2 -> Secondary root

[SW-A]stp globalenable

[SW-A]stp region-configuration
 region-name h3c
 revision-level 0
 instance 1 vlan 10
 instance 2 vlan 20
 active region-configuration
 quit

[SW-A]stp instance 1 root primary
[SW-A]stp instance 2 root secondary

2.3 MSTP Configuration on SWB

SWB:

Instance 2 -> Primary root

Instance 1 -> Secondary root

[SW-B]stp globalenable

[SW-B]stp region-configuration
 region-name h3c
 revision-level 0
 instance 1 vlan 10
 instance 2 vlan 20
 active region-configuration
 quit

[SW-B]stp instance 1 root secondary
[SW-B]stp instance 2 root primary

2.4 MSTP Configuration on SWC and SWD

Access switches only need to:

Enable MSTP

Join the same region

Map VLANs to instances

They do NOT configure primary/secondary root.

[SW-C]stp globalenable
[SW-C]stp region-configuration
 region-name h3c
 revision-level 0
 instance 1 vlan 10
 instance 2 vlan 20
 active region-configuration
 quit

Same configuration on SWD.

2.5 Trunk and Access Port Configuration

Inter-switch Links (SWA-SWB-SWC-SWD)

All interconnection interfaces must be trunk:

port link-type trunk
port trunk permit vlan all
undo port trunk permit vlan 1
stp edged-port

Access Ports

SWC downlink -> VLAN20

SWD downlink -> VLAN10

[SW-C]interface GigabitEthernet1/0/1
 port link-type access
 port access vlan 20

[SW-D]interface GigabitEthernet1/0/1
 port link-type access
 port access vlan 10

3. MSTP Verification

3.1 Check MSTP State - Instance 1

On SWA:

display stp

Expected on instance 1:

Root type: Primary root

On SWB:

Root type: Secondary root

On SWC / SWD:

RootPort selected toward SWA

3.2 Check MSTP State - Instance 2

On SWB:

display stp

Expected on instance 2:

Root type: Primary root

On SWA:

Secondary root

On SWC:

You can observe:

One interface is DISCARDING in MSTI 2

Another interface is forwarding

mstp2 state.png

9-swc mstp2 forwarding.png

Notice:

In MSTI 2:

Port4 (HGE1/0/3) -> DISCARDING (Alternate)

But in MSTI 1:

The same physical link may be Forwarding.

This proves:

鉁?Load balancing across VLANs

鉁?No link is permanently wasted

4. Traffic Verification

4.1 Configure VPC

On VPC6 (VLAN20 side):

ip 192.168.2.10 255.255.255.0 192.168.2.254

Ping Loopback0 on SWE:

ping 8.8.8.8

Ping successful.

4.2 Packet Capture Analysis

Capture traffic on SWC.

Observation:

Traffic path:

VPC6

-> SWC

-> HGE1/0/4

-> SWB

-> SWE

Now verify SWC MSTP table:

display stp