All geek questions in one place

Swich table in case of CRC error

I'm really confused about how the basic idea of ​​updating the switch table works. In the event of an incorrect CRC, it is still updating SMAC to use it next time, maybe? Maybe because the error may be there (SMAC), the switch disables the SMAC with the message?

Another thing, what happened first, update the table or first send a message in case of saving and forwarding?

+1
source share
1 answer

first look at this image

enter image description here

Scenario: PC1 10.0.0.2try Ping PC3 10.0.0.4:

  • ARP- (BroadCast) PC1, - , , , , PC2, PC3 ok, , 10.0.0.4, PC3 , , ?

. Wireshark

ARP Message (Broadcast) : SIP (Source IP) | DIP (Destination IP) | SMAC(Source Mac) | FF:FF:FF:FF:FF:FF (Destination MAC ~> BroadCast Message).

ok PC3?

ARP Protocol, SMAC (11:11:11:11:11:11) | DMAC (33:33:33:33:33:33)

Switch CAM TABLE :

enter image description here

ok .. Frame Check Sequence (FCS) . send upper-layer data , , source destination, detection error recovery , , ethernet , FSC , node . , , , node , FCS FCS, , , , , CRC , , , CRC , FCS, , CAM TABLE, - , , CAM TABLE clear mac address-table dynamic or static, , FCS CRC , , https://en.wikipedia.org/wiki/Frame_check_sequence

, ? SMAC?

CAM TABLE

enter image description here

, PC1 ping ip-, 10.0.0.5

enter image description here

ok CAM TABLE

enter image description here

, SMAC

Ok PC3

enter image description here

CAM TABLE

enter image description here

, CAM TABLE try clear mac-address-table dynamic static

enter image description here

+1

Source: https://habr.com/ru/post/1607576/

More articles:


All Articles