Cisco protocol tie breaking gone mad

EdTheLadEdTheLad Member Posts: 2,111 ■■■■□□□□□□
in CCIE
This is one of my pet peeves with Cisco, why couldn't they make everything use the highest ip address as the tie breaker.
These are all i could think of right now, please add to the list icon_smile.gif

Root-bridge, lowest BID
root port election, lowest sender port wins
BGP bestpath, prefer from neighbor with lowest RID
IGMP Querier prefer lowest ip
BGP/OSPF RID highest loopback ip or highest regular ip
BGP TCP session est , highest ip is client
PIM DR highest ip address
HSRP Active router highest ip
Networking, sometimes i love it, mostly i hate it.Its all about the $$$$
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Comments

  • ZartanasaurusZartanasaurus Member Posts: 2,008 ■■■■■■■■■□
    Don't forget LACP. :)
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  • reaper81reaper81 Member Posts: 631
    Cisco can't control everything though. It's up to the authors of the standards. STP, BGP, PIM are open standards. HSRP is Cisco's baby though.
    Daniel Dib
    CCIE #37149
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  • carterw65carterw65 Member Posts: 318 ■■■□□□□□□□
    Good point reaper. This topic has always been one of my pet peeves too.
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  • Danielh22185Danielh22185 Member Posts: 1,195 ■■■■□□□□□□
    reaper81 wrote: »
    Cisco can't control everything though. It's up to the authors of the standards. STP, BGP, PIM are open standards. HSRP is Cisco's baby though.

    Indeed, many of those protocols are not Cisco Proprietary.
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  • NetworkVeteranNetworkVeteran Member Posts: 2,338 ■■■■■■■■□□
    EdTheLad wrote: »
    This is one of my pet peeves with Cisco, why couldn't they make everything use the highest ip address as the tie breaker.
    BGP/OSPF RID highest loopback ip or highest regular ip
    BGP TCP session est , highest ip is client
    PIM DR highest ip address
    HSRP Active router highest ip

    L3 protocols do tend to choose the highest IP address.
    Root-bridge, lowest BID
    root port election, lowest sender port wins
    Bridges are L2 and don't necessarily have IPv4 addresses.
    PIM DR highest ip address
    IGMP Querier prefer lowest ip
    In IGMPv1 both DR and Querier roles go to the same router, the one with the highest IP address. In IGMPv2/v3, they divide out the roles, because it's best to leverage the resources of multiple routers if you have them.

    If you know the reasons behind the exceptions they're easier to recall. :)
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  • powmiapowmia Users Awaiting Email Confirmation Posts: 322
    This is why we use priorities to make these deterministic without having to remember all of them (of course, this is a certification forum and those elections are always on exams).

    Don't forget.... IS-IS -> DIS = highest MAC if no priority is configured.
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