Ask the Expert

IMPORTANT MODERATION NOTICE

This community is currently under full moderation, meaning  all posts will be reviewed before appearing in the community. Please expect a brief delay—there is no need to post multiple times. If your post is rejected, you'll receive an email outlining the reason(s). We've implemented full moderation to control spam. Thank you for your patience and participation.

Expand all | Collapse all

Encapsulation and packet processing

  • 1.  Encapsulation and packet processing

    Posted 04-30-2021 20:24
    Greetings, as I am getting further into my JNCIE-SP studies, I am going deeper into the processes behind some of the configuration to better understand how they are applied at the processing level.  Out of all my experience with Junos, encapsulation types are one of the topics I can find little info on how it translates to packet processing.  This is less of configuration but more on the nitty gritty into Junos and hardware.

    There are a variety of encapsulation types but only a few I am looking for clarity on and how it affects the processing at the packet level, both egress and ingress. My understanding is the following:

    IFD/IFL:
    • encapsulation - processing of L2/L2.5 fields ONLY. Ex. Ether2, 802.1q, MPLS label, PPP. 
    IFD:
    • flexible-vlan-tagging - Inspect frame for 802.1q header(s). Frames can contain 1 or 2 VLAN headers and are associated with an IFL for further processing.
    • flexible-ethernet-services - Inspect frame and process multiple encapsulation types. Allows for multiple encapsulation methods at the IFL
    • ethernet-bridge - Process all frames with MAC learning/VLAN for forwarding in bridge domains
    • ethernet-ccc - Process all frames. Ingress, encapsulate frame in an additional ethernet header with MPLS label
    IFL
    • vlan-bridge - Process 802.1q frames associated with IFL, perform MAC learning  for forwarding in bridge domains
    • vlan-ccc - Process 802.1q frames associated with IFL. Ingress, encapsulate frame in an additional ethernet header with MPLS label. VLAN tag may or may not be preserved.
    • vlan-vpls - Process 802.1q frames associated with IFL, perform MAC learning and encapsulate frame in an additional ethernet header with MPLS label.

    My question primarily applies to just Ethernet and less so of ATM/Frame-relay. Any Juniper detailed resources or correction on my understanding is greatly appreciated.