Punt/Glean Adjacency

mistabrumley89mistabrumley89 Member Posts: 356 ■■■□□□□□□□
in CCNP
Anyone have a link to a detailed description of these? Haven't really ran into anything of my liking.
Goals: WGU BS: IT-Sec (DONE) | CCIE Written: In Progress
LinkedIn: www.linkedin.com/in/charlesbrumley
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  • SecurityThroughObscuritySecurityThroughObscurity Member Posts: 212 ■■■□□□□□□□
    glean - destinations are attached to multi-access media, for which MAC rewrite string are unavailable.
    for example, router directly connected to a subnet with multiple hosts. so it maintains a prefix for the subnet instead of individual host prefixes - the subnet prefix pointed to a glean adj. when packets arrived the adjacency table is gleaned for the specific prefix.
    punt - special handling when CEF is not supported for the packets
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  • lrblrb Member Posts: 526
    The book called "Cisco Express Forwarding" is your best bet but this DOC isn't too bad How to Choose the Best Router Switching Path for Your Network - Cisco

    As a bit of a side note, CEF glean adjacencies are also critical to how DMVPN Phase 2 works to enable spoke-to-spoke comms. The router purposely marks the entry in the FIB as glean so that when the first packet needs to be sent spoke-to-spoke, it triggers an NHRP resolution request to map the public IP address to the internal IP address that advertised the route.
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  • mistabrumley89mistabrumley89 Member Posts: 356 ■■■□□□□□□□
    Thanks for the responses. Pretty spot on for what I was looking for. Brownie points.
    Goals: WGU BS: IT-Sec (DONE) | CCIE Written: In Progress
    LinkedIn: www.linkedin.com/in/charlesbrumley
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