02-15-2008 09:43 AM - edited 03-05-2019 09:11 PM
Dear Netpro!
what this command mean and where we would use it:SW2(config-if)#switchport host ?
<cr>?
2) channel-group questioms?
if the questions stead for PAGP <=> THE MODE would be Desirable
for LCAP the Mode would be Active.
for IEEE The Mode would be ON
am i correct?what else?
many 10xs
02-15-2008 09:57 AM
Ya Haj Sayed:
Ingleezeetuk mish nafa3! LOL
Anyway, for LACP, which is an open standard, the choices you have when you configure ports to negotiate an etherchannel are Passive and Active.
If two neighboring ports are configured for Active, an etherchannel will be established.
If one side is set for Active and the other for Passive, an etherchannel will also be formed.
If both sides are set for Passive, an etherchannel will NOT be formed, since each side will be waiting for the other to begin negotiating.
Now for PaGP, which is Cisco's etherchannel protocol, the choices are Desirable and Auto.
If two neighboring ports are configured for Desirable, an etherchannel will be established.
If one side is set for Desirable and the other for Auto, an etherchannel will also be formed.
If both sides are set for Auto, an etherchannel will NOT be formed, since each side will be waiting for the other to begin negotiating.
As for configuring them for "on," there will be NO negotiating and both sides MUST be configured for "on" for the etherchannel to form. Moreover, my Lebanese friend, if one side is set for "on" and the other is set for "desirable" or "Auto," a broadcast storm/bridging loop may occur and cause a big outage. So, be careful.
Lastly, as for the switchport host command, it is used to optimize the connection for a host. For the most part, that means disabling the autonegotiation feature. Doing that, plus configuring the port for portfast, will decrease the time it will take for the port to start forwarding traffic when a host is plugged in to it.
HTH
Victor
02-15-2008 10:51 AM
yeh
who r you?y look Arabic!and from Lebanon too!introduce ur Self!ALMOUHIM AL-CONCEPT YA 7AJ?
MANY 10XS
02-15-2008 11:44 AM
> Moreover, my Lebanese friend, if one side is set for "on" and the other is set for "desirable" or "Auto,"
> a broadcast storm/bridging loop may occur and cause a big outage. So, be careful.
Nope, switchports would go into err-disable as those etherchanneling modes are incompatible.
02-15-2008 12:16 PM
Are you sure about that, Mr Edison? Accoridng to a Cisco document, what i wrote is the case...unless Cisco is wrong. :-)
02-15-2008 12:30 PM
hey Lamav.pls be normal in This Forum.BTW Y Forgat to Introduce ur Self...
10xs
02-15-2008 01:05 PM
Now, you are making me work and I even said that I liked you, forget that now.....
Switch 1
interface FastEthernet0/13
channel-group 1 mode on
!
interface FastEthernet0/14
channel-group 1 mode on
!
Switch 2
interface FastEthernet0/13
channel-group 1 mode desirable
!
interface FastEthernet0/14
channel-group 1 mode desirable
Now, I'm going to log my session
pod2-sw2#conf t
Enter configuration commands, one per line. End with CNTL/Z.
pod2-sw2(config)#int ran f0/13-14
pod2-sw2(config-if-range)#shut
pod2-sw2(config-if-range)#
xxxxxxx>1
[Resuming connection 1 to sw1 ... ]
pod2-sw1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
pod2-sw1(config)#int ran f0/13-14
pod2-sw1(config-if-range)#shut
pod2-sw1(config-if-range)#
xxxxxxx>2
[Resuming connection 2 to sw2 ... ]
1w2d: %LINK-5-CHANGE
pod2-sw2(config-if-range)#no shut
pod2-sw2(config-if-range)#
xxxxxxx>1
[Resuming connection 1 to sw1 ... ]
%LINK-5-CHANGED: Interf
pod2-sw1(config-if-range)#no shut
pod2-sw1(config-if-range)#
%LINK-3-UPDOWN: Interface FastEthernet0/13, changed state to up
%LINK-3-UPDOWN: Interface FastEthernet0/14, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/13, changed state to up
pod2-sw1(config-if-range)#
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/14, changed state to up
pod2-sw1(config-if-range)#
%LINK-3-UPDOWN: Interface Port-channel1, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel1, changed state to up
pod2-sw1(config-if-range)#
%PM-4-ERR_DISABLE: channel-misconfig error detected on Fa0/13, putting Fa0/13 in err-disable state
%PM-4-ERR_DISABLE: channel-misconfig error detected on Fa0/14, putting Fa0/14 in err-disable state
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/13, changed state to down
%LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/14, changed state to down
%LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel1, changed state to down
02-15-2008 01:39 PM
Edison, it may have to do with the version of code being run.
After all, I got th einformation regarding this broadcast loop from Cisco and anothe rsenior engineer on this forum...
Anyway, if it does shut down, thats good.
02-15-2008 01:41 PM
Hmm, that behavior is being there for ages in all switches:
http://www.cisco.com/en/US/tech/tk389/tk621/technologies_tech_note09186a00806cd87b.shtml
There are various reasons for the interface to go into errdisable. The reason can be:
*
Duplex mismatch
*
Port channel misconfiguration
*
BPDU guard violation
*
UniDirectional Link Detection (UDLD) condition
*
Late-collision detection
*
Link-flap detection
*
Security violation
*
Port Aggregation Protocol (PAgP) flap
*
Layer 2 Tunneling Protocol (L2TP) guard
*
DHCP snooping rate-limit
*
Incorrect GBIC / Small Form-Factor Pluggable (SFP) module or cable
*
Address Resolution Protocol (ARP) inspection
*
Inline power
02-15-2008 01:49 PM
BTW, I think you got the quote from this:
(same quote is actually in every channel-group documentation not just the 3560).
You should use care when using the on mode. This is a manual configuration, and ports on both ends of the EtherChannel must have the same configuration. If the group is misconfigured, packet loss or spanning-tree loops can occur.
Notice that it says "if the group is misconfigured". It means if members of a port-channel are misconfigured (different speed and duplex on each interface), the configuration will still accept the mode on etherchanneling. It does not check for integrity from the members of the channel.
For instance,
interface f0/1
speed 10
duplex half
interface f0/2
speed 100
duplex full
Those interfaces above will form a bundle if configured with mode on.
If you use PAgP or LACP, there is some intelligence built-into the protocol to check for common values (like the ones from the above interfaces) and they won't form a bundle if they aren't the same.
That's what they are trying to say in this document.
02-15-2008 02:08 PM
Fair enough. Sounds reasonable. Thanks for that clarification.
Now go answer the question I asked you in the 'ip subnet vs broadcast domain' thread. :-)
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide