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Routed link vs trunk link and EIGRP preference

victor888
Level 1
Level 1

Hi,

Just wondering if EIGRP chooses between routed vs trunked links with difference priorities and why?

The scenario could be two links from a 3750 connected to 3 hops each way with the same BW each way but one link attached to this 3750 is routed whilst another is trunked.  How does EIGRP prefer its path and why?

Any suggestions would be appreciated.

Thanks

2 Replies 2

Reza Sharifi
Hall of Fame
Hall of Fame

Hello Victor,

EIGRP is routing protocol.  It looks at the layer-3 IP address.  So whether you have one switch or 2 switches in the middle or no switches all (just 2 routers) it is the same.

router-------L2-switch------- L2-switch----------router

router-------router

Here is doc on EIGRP:

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080093f07.shtml

HTH

Reza

Giuseppe Larosa
Hall of Fame
Hall of Fame

Hello Victor,

EIGRP adds delay on link and checks for minimal BW on path so the question becomes what delay is associated to a routed interface (L3 interface on its own) compared to the delay for an SVI interface Vlan ?

the one with the lowest delay wins given that both have bandwidth equal or greater of minimum BW on path as stored in the EIGRP update.

you can even end up with two equal cost paths one via a routed point-to-point link and one via a L2 trunk if parameters match.

note: Also mininum MTU on path is checked.

Hope to help

Giuseppe

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