first-hop redundancy protocols and the exam

TWXTWX Posts: 259Member
So the class work paid for mentioned first-hop redundancy protocols like HSRP, VRRP, and GLBP, but did not have us do any work with them in labs at all, and didn't really provide us with even command examples.

Has anyone seen these in exams? If so, did it more seem like they want the candidate to just know that such concepts exist, or did they seem to want more knowledge out of the candidate than that?

I'm trying to be vague so no one feels like they're violating the NDA by answering...

Comments

  • TWXTWX Posts: 259Member
    Another HSRP question...

    If I am using two routers to link two networks, is there a way to bond HSRP such that only one router at a time is primary on the two interfaces to the two networks?

    I brought up two routers. Both routers F0/0 interfaces are on 172.16.100.0/24, on .3 and .4 for the real address, .2 for the standby address. Both routers F0/1 interfaces are on 172.16.4.0/24, .2 and .3 for the real address, .1 for the standby address. Currently Router B (higher real IP for both) has primary on 172.16.100.0, while Router A (lower IP for both) has primary on 17.16.4.0. The PC I put on the 172.16.4.0 network successfully pulled an IP via IP Helper from the DHCP server and is successfully navigating through the network out through NAT to the Internet.

    So far it's not actually a problem, but I'm curious if there's a way to force one router do take both at the same time. If it matters I set the same standby group for both F0/0 and F0/1, to try to help coax this, no dice.
  • atorvenatorven Posts: 319Member
    Configure the one that you want to be active all the time with a higher priority than the other router, also enable preemption on the same router.
  • Phileeeeeeep651Phileeeeeeep651 Posts: 179Member ■■□□□□□□□□
    You could try changing Router B fa0/0's priority to see if that will force it to take over. Try standby "whatever group 172.16.4.0 is in" priority 0-255 , under router b's fa0/0. Priority 100 should be default.

    Took a look at the CCNA and ICND2 syllabus and all it says for FHRP's is recognize, so most likely no config, just concepts.
    Working on: CCNP Switch
  • james43026james43026 Posts: 303Member
    I believe the CCNA is more concerned with knowing what they are, and how to identify from a host, if you are connected to a default gateway using an FHRP, based on the MAC address of the default gateway. Not with configuration of any FHRPs
  • TWXTWX Posts: 259Member
    Well, have been playing with it anyway. On each router had F0/0 monitoring F0/1 and vice-versa but forgot to specify a decrement. Added the decrement and it's better. Now the only downtime is OSPF related as it takes time to failover, about fifteen seconds when both routes are equal cost. I might play with the costs to give priority to one to see how it handles that.
  • james43026james43026 Posts: 303Member
    Are you talking about an OSPF route through the network segment running the FHRP?
  • TWXTWX Posts: 259Member
    Decided to make a diagram.



    Don't know if this will display...

    Entire network has OSPF running, one area.

    DHCP comes from the ASBR on the left and all routers with user networks have IP Helper configured. The L3 Switch has several routers and their networks connected to it and is the DR for the area. The two switchports that connect from L3 Switch to Routers A and B as access ports on VLAN 100. SVI on L# for VLAN 100 is 172.16.100.1.

    Router A is 172.16.100.3 on f0/0, and 172.16.4.2 on f0/1.

    Router B is 172.16.100.4 on f0/0 and 172.16.4.3 on f0/1.

    Both routers are connected to an unmanaged 5-port Netgear Switch that I had laying around. The PC pulled 172.16.4.11/24 from the DHCP pool from the router acting as DHCP server on the left. I can SSH in to ping with cygwin, but Microsoft's ping utility doesn't give sequence numbers and doesn't show sub-millisecond speeds so once it scrolls off it's not as useful.

    The server on the left does syslog and acts as a ping target and ping source. It does have ping sequence numbers and sub-millisecond ping data.

    relevant IP route data from the L3 switch...
    O        172.16.4.0/24 [110/11] via 172.16.100.4, 22:17:57, Vlan100
                           [110/11] via 172.16.100.3, 22:14:43, Vlan100
    C        172.16.100.0/24 is directly connected, Vlan100
    L        172.16.100.1/32 is directly connected, Vlan100
    
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