Добрый день
Имеем такую топологию на участке сети(во вложениях для наглядности):
Ядро - DGS-3620 - DGS-3627g - коммутаторы доступа
На узле(3627):uplink 10g, downlink - 10x1g. Оверсабскрибшна нет.
У абонентов низкая скорость: 30-50 мбит от 100.
Наблюдаем корреляцию роста трафика и ошибок на порту.
hol prevention включен. Подозрения на hol_drop
Show error ports:
Port number : 1
RX Frames TX Frames
--------- ---------
CRC Error 0 Excessive Deferral 0
Undersize 0 CRC Error 0
Oversize 0 Late Collision 0
Fragment 0 Excessive Collision 0
Jabber 0 Single Collision 0
Drop Pkts 164308 Collision 0
Symbol Error 0
Buffer Full Drop 0
ACL Drop 24815
Multicast Drop 0
VLAN Ingress Drop 26417
Port number : 3
RX Frames TX Frames
--------- ---------
CRC Error 0 Excessive Deferral 0
Undersize 0 CRC Error 0
Oversize 0 Late Collision 0
Fragment 0 Excessive Collision 0
Jabber 0 Single Collision 0
Drop Pkts 80148 Collision 0
Symbol Error 0
Buffer Full Drop 0
ACL Drop 3
Multicast Drop 0
VLAN Ingress Drop 1656
Port number : 6
RX Frames TX Frames
--------- ---------
CRC Error 0 Excessive Deferral 0
Undersize 0 CRC Error 0
Oversize 0 Late Collision 0
Fragment 0 Excessive Collision 0
Jabber 0 Single Collision 0
Drop Pkts 180390 Collision 0
Symbol Error 0
Buffer Full Drop 0
ACL Drop 0
Multicast Drop 0
VLAN Ingress Drop 1657
Port number : 7
RX Frames TX Frames
--------- ---------
CRC Error 0 Excessive Deferral 0
Undersize 0 CRC Error 0
Oversize 0 Late Collision 0
Fragment 0 Excessive Collision 0
Jabber 0 Single Collision 0
Drop Pkts 185443 Collision 0
Symbol Error 0
Buffer Full Drop 0
ACL Drop 24855
Multicast Drop 0
VLAN Ingress Drop 26458
Port number : 10
RX Frames TX Frames
--------- ---------
CRC Error 0 Excessive Deferral 0
Undersize 0 CRC Error 0
Oversize 0 Late Collision 0
Fragment 0 Excessive Collision 0
Jabber 0 Single Collision 0
Drop Pkts 111511 Collision 0
Symbol Error 0
Buffer Full Drop 0
ACL Drop 0
Multicast Drop 0
VLAN Ingress Drop 1657
Port number : 11
RX Frames TX Frames
--------- ---------
CRC Error 0 Excessive Deferral 0
Undersize 0 CRC Error 0
Oversize 0 Late Collision 0
Fragment 0 Excessive Collision 0
Jabber 0 Single Collision 0
Drop Pkts 183169 Collision 0
Symbol Error 0
Buffer Full Drop 0
ACL Drop 0
Multicast Drop 0
VLAN Ingress Drop 1658
Port number : 12
RX Frames TX Frames
--------- ---------
CRC Error 0 Excessive Deferral 0
Undersize 0 CRC Error 0
Oversize 0 Late Collision 0
Fragment 0 Excessive Collision 0
Jabber 0 Single Collision 0
Drop Pkts 1617 Collision 0
Symbol Error 0
Buffer Full Drop 0
ACL Drop 0
Multicast Drop 0
VLAN Ingress Drop 1617
Port number : 13
RX Frames TX Frames
--------- ---------
CRC Error 0 Excessive Deferral 0
Undersize 0 CRC Error 0
Oversize 0 Late Collision 0
Fragment 0 Excessive Collision 0
Jabber 0 Single Collision 0
Drop Pkts 26724 Collision 0
Symbol Error 0
Buffer Full Drop 0
ACL Drop 24882
Multicast Drop 0
VLAN Ingress Drop 26490
Port number : 14
RX Frames TX Frames
--------- ---------
CRC Error 0 Excessive Deferral 0
Undersize 0 CRC Error 0
Oversize 0 Late Collision 0
Fragment 0 Excessive Collision 0
Jabber 0 Single Collision 0
Drop Pkts 26728 Collision 0
Symbol Error 0
Buffer Full Drop 0
ACL Drop 24880
Multicast Drop 0
VLAN Ingress Drop 26499
Port number : 15
RX Frames TX Frames
--------- ---------
CRC Error 0 Excessive Deferral 0
Undersize 0 CRC Error 0
Oversize 0 Late Collision 0
Fragment 0 Excessive Collision 0
Jabber 0 Single Collision 0
Drop Pkts 25063 Collision 0
Symbol Error 0
Buffer Full Drop 0
ACL Drop 24882
Multicast Drop 0
VLAN Ingress Drop 24882
При выключении hol_prevention растут buffer full drop на аплинке
Port number : 25
RX Frames TX Frames
--------- ---------
CRC Error 0 Excessive Deferral 0
Undersize 0 CRC Error 0
Oversize 0 Late Collision 0
Fragment 0 Excessive Collision 0
Jabber 0 Single Collision 0
Drop Pkts 645299 Collision 0
Symbol Error 0
Buffer Full Drop 474432
ACL Drop 0
Multicast Drop 0
VLAN Ingress Drop 1672
Command: show utilization cpu
CPU Utilization
-------------------------------------------------------------------------------
Five seconds - 2 % One minute - 2 % Five minutes - 2 %