Plugga CCNP Route--BGP
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BGP
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Tough Questions
- "aggregate-address" does not need to be synchronized, bute there *must* be at least one subnet of it, that exists in the routing table
- Split-horizon rule states that iBGP routes are never propagated to other iBGP peers (conclusion: use full mesh to solve this)
- "Always-compare-med" forces the router to compare MEDs from different AS'es
- BGP uses TCP port 179. Notifications are always bad [and (sometimes?) breaks the connection??]
- State table:
- Idle -- BGP not enabled
- Connect -- Waits for TCP connection
- Active -- Open is Sent but connection still *not* established. Waiting for a connection
- OpenSent -- OpenSent message is sent
- OpenConfirm
- Established
- A static route is preferred method (over IGP), when finding eBGP-neighbor
- Path selection
- highest Weight
- highest Local pref
- origin local router (0.0.0.0) (network command etc)
- shortest AS-path
- prefer IGP over EGP origin
- prefer lowest med
- ...
- Lowest Router ID
- LAST: lowest neighbor IP-address
- "neighbor x.x.x.x send-community" ???
- BGP features:
- Enable feature with (memory intensive) "neighbor x.x.x.x soft-reconfiguration-inbound"
- show ip bgp neighbor x.x.x.x | include [Rr]oute [Rr]efresh
- Above two is mutually exclusive !! (ena eller andra)
- HUR KÖR JAG KOMMANDOT ??
- Kom ihåg att läsa ordet "not" !! (:-)
- Kom ihåg att alltid dubbelkolla Route-Maps om det är implicit deny vid route redistribution