Brocade FastIron Ethernet Switch Platform and Layer 2 Switching Configuration Guide - Manual (Page 187)

Switch S1
!
lag "1" static id 1
ports ethernet 3 ethernet 4
primary-port 3
deploy
!
vlan 100 by port
tagged ethe 3 to 4
router-interface ve 100
!
interface ve 100
ip address 100.1.1.100 255.255.255.0
!
MCT for VRRP or VRRP-E
A simple MCT topology addresses resiliency and efficient load balancing in Layer 2 network topologies.
To interface with a Layer 3 network and add redundancy in Layer 3, MCT is configured with Virtual
Router Redundancy Protocol (VRRP). The standard VRRP mode is master-backup, and all traffic is
forwarded through the master. In VRRP-E server virtualization, multiple VRRP standby devices are
supported, and each device can be configured to route to an upstream Layer 3 network. This provides
efficient deployment for both Layer 2 and Layer 3 networks.
The MCT device that acts as backup router needs to ensure that packets sent to a VRRP or VRRP-E
virtual IP address can be Layer 2-switched to the VRRP-E master router for routing. The VRRP or
VRRP-E backup learns the VMAC while processing the VRRP hello message from the VRRP master.
Both data traffic and VRRP or VRRP-E control traffic travel through the ICL unless the short-path
forwarding feature is enabled (VRRP-E only).
Layer 3 traffic forwarding from CEPs to CCEPs
Traffic destined to the CCEPs from the client or the CEPs follows normal IP routing on both master and
backup devices. By default, the best route should not involve the ICL link. Only when the local CCEP is
down is traffic re-routed to pass through the ICL link.
Layer 3 traffic forwarding from CCEPs to CEPs
For Layer 3 forwarding to work on MCT devices, a dynamic trunk must be configured on the MCT client.
VRRP/VRRP-E and VRRP-E2 SPF should be enabled, if required. Routes should be statically
configured on the MCT cluster devices for all member VLANs.
If VRRP is deployed or VRRP-E is deployed without the short path forwarding feature on the VRRP-E
backup, it is likely that almost 50% of CCEP to CEP traffic (and as much as 100% of traffic in the worst
case) can pass through the ICL from the backup to the master device. This fact should be considered
when designing ICL capacity in the network.
ARP resolution
ARP resolution is initially done through the ICL if the S1 MAC address is not already known on the
CCEP at A. When the MDUP message from the cluster peer device moves the S1 MAC from the ICL to
the CCEP, ARP is also moved.
If S1 triggers an ARP request, it generally does so for the default gateway address (virtual IP address if
VRRP is deployed). This ARP request can reach A directly from S1 or through B.
Switch S1
FastIron Ethernet Switch Platform and Layer 2 Switching Configuration Guide 187
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