RE: Types of packet modifications allowed for networks

From: Darden, Patrick S. (no email)
Date: Mon Jun 02 2008 - 08:21:20 EDT

  • Next message: Joel Jaeggli: "NANOG 42 Lightning Talk submission reminder..."

    I'm not aware of any hard rules regarding this. I'll include yours below:

    --packet fragmentation due to inconsistent MTUs and/or bandwidth (e.g. moving from ATM at 150Mbps to a fractional DS3 at 3.088Mbps)
    --ttl changes from hop to hop
    --dest ip changes from hop to hop
    --PAT/NAT changes in last network borders (e.g. routing traffic to appropriate endpoints (servers) or starting points (workstations))
    --PAT/NAT changes in "last" host (e.g. it hits ext ip port 4443, gets changed to newip:443 and forwarded on)
    --firewall changes in buffer/mother network (e.g. protective network or DMZ)--these could be almost anything, most frequent would be morons who completely block ICMP--you should probably count anti-spam and anti-virus (layer 4 but affects layer 3 dramatically) but these are usually advertised features subscribed to by the customers (as opposed to secret "features" that only come out due to customer outrage)
    --header checksum changes after contents changes (e.g. dip at a router)

    Meh, not sure I was helpful.
    --p


  • Next message: Joel Jaeggli: "NANOG 42 Lightning Talk submission reminder..."





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