BGP MED in "show ip bgp"

Just a quick questions..

 

Does anyone knows why sometimes the IOS puts a 0 in metric and some times it just a blank space? (in a show ip bgp output) I know that a missing MED is defaulted to 0, but what are the rules for the "show ip bgp" command? At first I thought that it shows a 0 for iBGP routes, but I've seen it too in eBGP routes (but not all of them), so i'm kinda confused.

 

thanks in advance!

Comments

  • If anyone is interested in this little detail, that couldnt let me sleep :P:

     

    I solved it through trough trial&error, made some scenarios and here is the resulting rules:

    1.- If the prefix is comming from a iBGP peer and the metric is not set, the "show ip bgp" shows MED = 0.

    2.-
    If the prefix is comming from a eBGP peer, the metric is not set, and
    that eBGP peer is the originator of the prefix (by means of
    redistribution or network statement), the "show ip bgp" shows MED = 0

    3-. If the metric has been modified, then for every prefix from iBGP and eBGP the MED is shown.


    3.- Else, MED = null (not shown)

  • If anyone is interested in this little detail, that couldnt let me sleep :P:

     

     Totally understand this.

     

    Isn't something similar with local_pref value? For example, show ip bgp will show local pref of 100 for iBGP peers and will show nothing for eBGP peers, even though default value is 100 as well. But if  you go do show ip bgp A.B.C.D for that specific prefix it will show you 100. Same with MED, if you do  show ip bgp A.B.C.D it will show med of 0.

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