Skip to main content

Multi-layer Switching Exceptions – Packets that Need further Processing

There are some packets that are not forwarded directly by Multi layer switches, but are required further processing. To forward packets using the simultaneous decision processes, the packet must be “Multi Layer Switch-ready” and must require no additional decisions. For example, CEF can directly forward most IP packets between hosts. This occurs when the source and destination addresses (both MAC and IP) are known already and no other IP parameters must be manipulated.
Other packets cannot be directly forwarded by CEF and must be handled in more detail. This is done by a quick inspection during the forwarding decisions. 

If a packet meets criteria such as the following, it is flagged for further processing and sent to the switch CPU for process switching:
  • ARP requests and replies
  • IP packets requiring a response from a router (TTL has expired, MTU is exceeded,
  • fragmentation is needed, and so on)
  • IP broadcasts that will be relayed as unicast (DHCP requests, IP helper-address functions)
  • Routing protocol updates
  • Cisco Discovery Protocol packets
  • IPX routing protocol and service advertisements
  • Packets needing encryption
  • Packets triggering Network Address Translation (NAT)
  • Other non-IP and non-IPX protocol packets (AppleTalk, DECnet, and so on)

Comments

Popular posts from this blog

a file I/O error has occurred while accessing vmware converter

While converting physical Windows 7 machine to Virtual machine of infrastructure type, I got this error. The error seems it is unable to read/write source or destination datastore.

I have installed VMware-converter-en-6.2.0-8466193 on Windows 7 physical machine with option locally selected. (not at server/client option)

All of my ESXi servers are connected to the vCenter Server, so I had to use vCenter Server's IP address to send this physical machine to the virtual world.

The issue i found was with the dns resolution to the vCenter Server's hostname. Since I am not using the same dns server on the Windows 7 client machine. So I updated the host entries manually for the vCenter Server's hosname to it IP address.

After adding dns eteries to the hostfile of windows 7, I am not getting this "a file I/O error has occurred while accessing vmware converter" and the migration has started.

Connection control operation failed for disk 'ide1:0'

I was getting this error while removing Operating System ISO image mounted on the Virtual Machine.

What worked for me, is
1. Uncheck the "Connected and Connect at power on" from Device Status.
2. Then Change the Device type from "Datastore ISO File to Client Device" Radio Button
3. and press OK to save the changes.

Note:- I was able to remove the mounted ISO only by directly logging to the ESXi at https://esxi-ip-address/ui

where it asks

"The guest operating system has locked the CD-ROM door and is probably using the CD-ROM, which can prevent the guest from recognizing media changes. If possible, eject the CD-ROM from inside the guest before disconnecting. Disconnect anyway and override the lock?"

You need to select yes to eject the CD-ROM and then remove the ISO file successfully.

GNS3 Docker Error while creating node: Docker has returned an error: Cannot connect to host docker:80

Error while creating node: Docker has returned an error: Cannot connect to host docker:80 ssl:False [No such file or directory]

After adding docker template for Alpine Linux in gns3, you get above mentioned message when you want to use alpine linux in GNS3.

To get rid of this message you have to install Docker by following below link
curl -fsSL https://get.docker.com/ | sh

If you do not have curl installed then instal curl first with below command.apt-get install curl
After installing Docker you need to add your user name in the docker group with the following command. $ sudo usermod -aG docker your_username

Verify if the docker service is started with following command$ service docker status
If docker is not started then start with following command $ sudo service docker start
Logout from GNS3 Virtual Machines and log back. Start gns3 and use alpine linux.