Cisco Cisco Nexus 5010 Switch Guida Alla Progettazione

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MST Configuration

For data-center-to-data-center connectivity, it is advisable that MST be used as the Spanning Tree Protocol and

that two MST regions be defined, each one with its own regional root, as follows (the device names refer to

Figure 8):

●

Data Center 1: MST region 1, with N7kA as the regional root, 7kB as the regional secondary root

●

Data Center 2: MST region 2, with N7kC as the regional root, N7kD as the regional secondary root

HSRP Configuration

The routing configuration for the extended VLANs can be accomplished with two HSRP groups that have four

different priorities for each group. Basically, this means that local servers use the local HSRP gateway, and if both

gateways of a given site fail, the remote site can take over the processing.

Figure 9 illustrates the concept. HSRP group 1 is active and standby in DC1 and listen mode in DC2. HSRP

group 2 instead is active and standby in DC2 and in listen mode in DC1.

The programming of the HSRP MAC is as follows:

G 60 0000.0c07.ac3c static - False False sup-eth1(R) << group that is
active or standby

* 60 0000.0c07.ac3d static - False False Po30 << group that is listen
mode (i.e. active or stdby in the remote DC)

If traffic from a server in DC1 is directed to the gateway 1.1.1.1 (HSRP group 1) it gets routed locally. If a server

(a VM as an example) from DC1 moves to DC2 and sends traffic with a destination MAC of HSRP group 1, DC2

bridges it to DC1 where HSRP group 1 is active for this traffic to be routed.

If a server in DC2 uses the gateway 1.1.1.2 (HSRP group 2), the traffic directed to the HSRP group 2 is routed

locally in DC2. Similarly if a VM from DC2 moves to DC1 and sends traffic to HSRP group 2 (1.1.1.2), the traffic is

bridged from DC1 to DC2 where HSRP group 2 is active for this traffic to be routed.

Figure 9. HSRP Groups and Priorities in an Extended Data Center