Exam 350-401 topic 1 question 42 discussion

GLBP and MHSRP ------Correct

I'm going for B and C. VRRP - and HSRP suffer from that fact that they both have one primary/master router which provides the _single_ default gateway (single VIP, single virtual MAC) MHSRP provides two Virtual IPs, so end hosts would have to be configured with two default gateways - not common for end hosts. The same concept would apply to multiple VRRP groups. GLBP provides one virtual IP and multiple virtual MAC Addresses; the ARP replies from the Active Virtual Gateway to the hosts will use all the virtual MACs (one for each virtual forwarder) in round robin fashion, so B is correct. which leaves VSS, where both ML Switches form a single virtual switch and no FHRP is required at all to use them both.

VSS isnt a FHRP

Multiple HSRP Groups The multiple HSRP (MHSRP) groups feature was added in Cisco IOS release 10.3. This feature further enables redundancy and load-sharing within networks and allows redundant routers to be more fully utilized. While a router is actively forwards traffic for one HSRP group, it can be in standby or in the listen state for another group. As of Cisco IOS release 12.0(3.4)T, you can use the use-bia command with multiple HSRP groups enabled. Refer to Load Sharing with HSRP to configure HSRP and take advantage of multiple paths.

B&D , well B is obviously correct answer, whereas A or E are incorrect because host can be configured to use a single gateway only. This leaves C&D , and I think D is correct as the load balancing configuration described here fits the requirement: https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3560/software/release/12-2_25_se/configuration/guide/3560scg/swhsrp.pdf

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst6500/ios/15-4SY/config_guide/sup6T/15_3_sy_swcg_6T/virtual_switching_systems.pdf page 4-19/20. The RP on the active supervisor engine runs the Layer 3 protocols and features for the VSS. Both chassis perform packet forwarding for ingress traffic on their interfaces. If possible, ingress traffic is forwarded to an outgoing interface on the same chassis, to minimize data traffic that must traverse the VSL. Because the standby chassis is actively forwarding traffic, the active supervisor engine distributes updates to the standby supervisor engine PFC and all standby chassis DFCs. The supervisor engine on the active chassis runs the IPv4 routing protocols and performs any required software forwarding. Routing updates received on the standby chassis are redirected to the active chassis across the VSL. Hardware forwarding is distributed across all DFCs on the VSS. The supervisor engine on the active chassis sends FIB updates to all local DFCs, remote DFCs, and the standby supervisor engine PFC.

The two technologies that allow every end host in a VLAN to use both gateways are: B. GLBP (Gateway Load Balancing Protocol) D. MHSRP (Multigroup Hot Standby Router Protocol) Here's why: GLBP (Gateway Load Balancing Protocol): GLBP allows multiple routers to act as a single virtual gateway for a VLAN. It assigns a virtual MAC address to the group and distributes virtual IP addresses among the routers. End hosts use the virtual MAC address as their default gateway. GLBP uses a load-balancing algorithm to distribute traffic among the routers, allowing for efficient use of multiple gateways. MHSRP (Multigroup Hot Standby Router Protocol): MHSRP is an extension of HSRP that allows multiple HSRP groups to share the same virtual IP address. Each HSRP group has its own virtual MAC address. End hosts can be configured to use different HSRP groups as their default gateway. This allows for load sharing and redundancy, as traffic can be distributed among multiple gateways.

VSS does not directly allow every end host in a VLAN to use both distribution layer switches as default gateways. It’s a switch-level solution, not a gateway redundancy/load-balancing protocol, so it doesn’t meet the requirement.

The two technologies that allow every end host in a VLAN to use both gateways are: B. GLBP (Gateway Load Balancing Protocol) GLBP allows multiple routers to share a virtual IP while distributing traffic across them, enabling load balancing and redundancy. D. MHSRP (Multigroup Hot Standby Router Protocol) MHSRP is an extension of HSRP that enables multiple HSRP groups on the same VLAN, allowing different hosts to use different gateways and distribute traffic. Explanation of Other Options: A. VRRP (Virtual Router Redundancy Protocol) – Provides redundancy but does not allow load balancing; only one router is active at a time. C. VSS (Virtual Switching System) – Used to merge two physical switches into a single logical switch but does not provide per-VLAN gateway load balancing. E. HSRP (Hot Standby Router Protocol) – Provides redundancy but does not allow load balancing; only one router is active at a time. Thus, the correct answers are B. GLBP and D. MHSRP.

answer BD

A lot of the discussion I’m reading here is making reference to Load Balancing/Sharing as reasons for the answer but the Question doesn’t mention or ask for this. We just need to identify the Technologies that will allow every host to use both Gateways. VRRP & HSRP both present a Virtual IP that will only be present on 1 device at a time, so that would eliminate both. MHSRP, presents 2 VIP’s, with the design idea being that half your users will get 1 VIP the other half the 2nd VIP. Again this would eliminate it as an option. This only leaves GLBP & VSS as our options. GLBP, everyone seems to agree is correct. With VSS, as I understand it, the Switches will be seen as a single logical switch so a Host could communicate with either switch and its data would be passed between the Switches, for forwarding, thereby in my opnion meeting the Question criteria of allowing a Host to use Both Gateways

MHSRP While not as dynamic as GLBP, MHSRP allows for load sharing by assigning different groups of routers to handle traffic for different sets of hosts or VLANs. This way, there is some form of load balancing by manually distributing the traffic between different HSRP groups.

VSS and GLBP are the only two technologies, among the options provided, that offer load balancing and redundancy.

two TECHNOLOGIES, not two FHRP protocols.... BC

MHSRP allows only SINGLE active router for a specific VLAN.

The answers are BD

im going with B & C