Enterasys SecureStack C2

split-horizon poison
SecureStack C2 Configuration Guide 17-7
Mode
Routerconfiguration:C2(su)‐>router(Config‐router)#
Usage
Bydefault,RIPversion2supportsautomaticroutesumm arization,whichsummarizes
subprefixestotheclassfulnetworkboundarywhencrossingnetworkboundaries.Disabling
automaticroutesummarizationenablesCIDR,allowingRIPtoadvertiseallsubnetsandhost
routinginformationontheSecureStackC2device.Toverifywhichroutesaresummarizedforan
interface,
usetheshowiproutecommandasdescribedin“showiproute”onpage16‐13.The
reverseofthecommandre‐enablesautomaticroutesummarization.
Example
ThisexampleshowshowtodisableRIPautomaticroutesummarization:
C2(su)->router(Config)#router rip
C2(su)->router(Config-router)#no auto-summary
split-horizon poison
Usethiscommandtoenableordisablesplithorizonpoison‐reversemodeforRIPpackets.Theno
formofthiscommanddisablessplithorizonpoisonreverse.
Syntax
split-horizon poison
no split-horizon poison
Parameters
None.
Defaults
None.
Mode
Routerconfiguration:C2(su)‐>router(Config‐router)#
Usage
Splithorizonpreventspacketsfromexitingthroughthesameinterfaceonwhichtheywere
received.Poison‐reverseexplicitlyindicatesthatanetworkisunreachable,ratherthanimplyingit
bynotincludingthenetworkinroutingupdates.Thisfunctionisdisabledbydefault.
Example
ThisexampleshowshowtodisablesplithorizonpoisonreverseforRIPpacketstransmittedon
theVLAN1interface:
C2(su)->router(Config)#router rip
C2(su)->Router1(Config-router)#no split-horizon poison
Note: This command is necessary for enabling CIDR for RIP on the SecureStack C2 device.