Advice

[Tareq Emad Al Asfoor]

Hi all , 

Kindly have two question and i hope i found answer for them 

1- Why do we always place STP root switch and VRRP gateway at the distribution layer in the campus networks? What is the design implication if it were placed in the access layer instead? 

2- Which one is more suitable for the Internet edge, HRSP or GLBP for the topology below and why ?

Kind Regards, 

Tariq.E

[Georg Pauwen]

Hello,

to partially answer your question: the placement of the STP root is crucial for optimal traffic flow. Typically, distribution switches are placed in the middle of the network, and are not connected to end devices, so any access layer network changes are less likely to affect distribution layer switches.

Whether you want to use HSRP or GLBP depends on what you want to achieve. GLBP does load balancing, so in general, it is the better option. That said, GLBP is Cisco proprietary, so it only works on Cisco devices...

[Joseph W. Doherty]

#1 The reason for placing the STP root in the center is, if you have redundant paths, it avoids STP making a longer path for some edge devices to other edge devices. I.e. it helps to insure STP creates a "star" topology centered near the core of the network.

(https://www.youtube.com/watch?v=op-mp6eP3tc)

#2 From FW to the routers, there's no advantage to GLBP assuming the FW is using but just one MAC. (NB: if the FW supported static routes, you could use mHSRP and have a static route point to both routers. In theory, this would split your traffic 50/50.)