An Alcatel-Lucent 7750 SR receives a route from an eBGP peer without a MED. What MED value is sent to iBGP peers?

Question

Options

• A100
• B250
• CThe IGP cost
• DNone

• B
  4% (1)
• C
  4% (1)
• D
  91% (21)

Explanation

Option D is correct because MED (Multi-Exit Discriminator) is an optional, non-transitive BGP attribute - if no MED is present in the eBGP advertisement, the 7750 SR has nothing to forward, and by default it does not generate or insert one when reflecting the route to iBGP peers. The attribute is simply absent from the iBGP update.

Why the distractors are wrong:

• A (100) and B (250): The 7750 SR has no factory default MED of 100 or 250 - neither value is injected automatically when a MED is missing.
• C (IGP cost): Setting MED equal to IGP cost can happen (e.g., via metric-out igp or when redistributing connected/static routes), but this requires explicit configuration - it is not the default behavior when the eBGP peer simply omits the MED attribute.

Memory tip: Think of MED as a relay baton - if your eBGP peer doesn't hand it to you, you have nothing to pass to your iBGP peers. "No MED received = No MED sent" (unless you configure the router to create one).

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