2009-12-06

Question of the day

вопрос:

может ли VTP передавать информацию о private-vlan map?

ответ:
да, в версии VTP 3

кстати, эта версия таки реализована на IOS (ранее она была только на CatOS):
кроме того третья версия поддерживает:
* распространение vlan-instance map для MST
* private-vlan
* extended vlan range
* множество других функций по контролю и управлению самим VTP

2009-12-03

Question of the day

вопрос:

всегда ли bpdufilter работает одинаково?

ответ:
нет. конечно, bpdufilter должен приводить к одному результату: прекращению отправки и обработки bpdu на порту. но. есть два варианта настройки:
* (config)# spanning-tree portfast bpdufilter default
* (config-if)# spanning-tree bpdufilter enable
первый включает bpdufilter по-умолчанию на всех portfast портах
второй - принудительно на интерфейсе.
так вот, первый вариант работает следующим образом: сначала отправляются 11 (одинадцать, не больше и не меньше) bpdu, и только затем, если не были обнаружены ответы, включается фильтр :)


SW1#sh span int fa0/1 de
Port 3 (FastEthernet0/1) of VLAN0146 is designated forwarding
Port path cost 19, Port priority 128, Port Identifier 128.3.
Designated root has priority 32914, address 000f.90fd.a280
Designated bridge has priority 32914, address 001d.4614.cc80
Designated port id is 128.3, designated path cost 19
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
The port is in the portfast mode
Link type is point-to-point by default
Bpdu filter is enabled by default
BPDU: sent 0, received 0
SW1#
%LINK-3-UPDOWN: Interface FastEthernet0/1, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/1, changed state to up
SW1#sh span int fa0/1 de
Port 3 (FastEthernet0/1) of VLAN0146 is designated forwarding
Port path cost 19, Port priority 128, Port Identifier 128.3.
Designated root has priority 32914, address 000f.90fd.a280
Designated bridge has priority 32914, address 001d.4614.cc80
Designated port id is 128.3, designated path cost 19
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
The port is in the portfast mode
Link type is point-to-point by default
Bpdu filter is enabled by default
BPDU: sent 3, received 0
SW1#sh span int fa0/1 de
Port 3 (FastEthernet0/1) of VLAN0146 is designated forwarding
Port path cost 19, Port priority 128, Port Identifier 128.3.
Designated root has priority 32914, address 000f.90fd.a280
Designated bridge has priority 32914, address 001d.4614.cc80
Designated port id is 128.3, designated path cost 19
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
The port is in the portfast mode
Link type is point-to-point by default
Bpdu filter is enabled by default
BPDU: sent 11, received 0
SW1#sh span int fa0/1 de
Port 3 (FastEthernet0/1) of VLAN0146 is designated forwarding
Port path cost 19, Port priority 128, Port Identifier 128.3.
Designated root has priority 32914, address 000f.90fd.a280
Designated bridge has priority 32914, address 001d.4614.cc80
Designated port id is 128.3, designated path cost 19
Timers: message age 0, forward delay 0, hold 0
Number of transitions to forwarding state: 1
The port is in the portfast mode
Link type is point-to-point by default
Bpdu filter is enabled by default
BPDU: sent 11, received 0

как мы видим, несмотря на то что "Bpdu filter is enabled by default" счетчик отправленных bpdu растет, и замирает на отметке 11.