02-19-2010 01:34 AM - edited 03-04-2019 07:33 AM
Hi to All,
need to configure EtherChannel on 2 wan site with the following enviroment:
On the 1st site there're 2 Cross-Stack Catalyst 3750
On the 2nd site there're 2 Cross-Stack Catalyst 3750
The connection between the 2 sites consist of 2 Gigabit links: the wan provider tell me MTU is end to end 9192 bytes
A) If I try to use the EtherChannel Without PAgP or LACP all is OK:
3750switchstackA(config)#interface range gigabitethernet 1/0/23 - 24
3750switchstackA(config-if)#channel-group 1 mode on
3750switchstackA(config-if)#switchport trunk encapsulation dot1q
3750switchstackA(config-if)#switchport mode trunk
B) If I try to use the EtherChannel With LACP the etherchannel NEVER go up !
3750switchstacka(config)#interface range gigabitethernet 1/0/23 - 24
3750switchst(config-if-range)#channel-group 1 mode active
3750switchst(config-if-range)#switchport trunk encapsulation dot1q
3750switchst(config-if-range)#switchport mode trunk
The question:
the problem is the 3750 interfaces MTU ?
the LACP need a bigger MTU on my 3750 switches (need to change it) ?
3750switchstackA#sh system mtu
System MTU size is 1500 bytes
System Jumbo MTU size is 1500 bytes
Regards,
Roberto Taccon
Solved! Go to Solution.
02-19-2010 04:42 AM
Hi Roberto,
LACP is an L2 control protocol, there is no encapsulation done by LACP. The LACP peers send out the special PDU to remote peer to verify if the peer is alive.
You can find out whether SP allow LACP frame by turn on debug lacp on your switch. Configure LACP mode active on both ends, and turn on debug LACP. If your provider allows the LACP control frame, you should be able to see "LACP packet received" and "Send LACP-PDU packet" from the debug output.
HTH,
Lei Tian
02-19-2010 01:58 AM
MTU must be configured only on port channel interfaces and this MTU is propagated to the bundled ports. Make sure you are using LACP on both sides and the MTU match also on both sides.
02-19-2010 02:27 AM
Hi,
the interface Port-channel 1 is configured with defaul MTU 1500.
How I can modify it ?
Is there any INTERFACE command to modify it ?
Need to modify the system MTU (which one MTU/routing/Jumbo) ?
3750switchstackA#sh int po1
Port-channel1 is up, line protocol is up (connected)
Hardware is EtherChannel, address is 0013.7f59.6619 (bia 0013.7f59.6619)
Description: 3750switchstackA
MTU 1500 bytes, BW 2000000 Kbit, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 1000Mb/s, link type is auto, media type is unknown
input flow-control is off, output flow-control is unsupported
Members in this channel: Gi1/0/25 Gi2/0/24
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:00, output 19:21:09, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
30 second input rate 0 bits/sec, 0 packets/sec
30 second output rate 0 bits/sec, 0 packets/sec
2505117 packets input, 3513326395 bytes, 0 no buffer
Received 55871 broadcasts (55871 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 55871 multicast, 0 pause input
0 input packets with dribble condition detected
974779 packets output, 113948767 bytes, 0 underruns
0 output errors, 0 collisions, 7 interface resets
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 PAUSE output
0 output buffer failures, 0 output buffers swapped out
itmil-calinf0r2-sw01DCMItoDCVR#
3750switchstackA(config)#system mtu ?
<1500-1998> MTU size in bytes
jumbo Set Jumbo MTU value for GigabitEthernet or TenGigabitEthernet interfaces
routing Set the Routing MTU for the system
3750switchstackA(config)#system mtu
02-19-2010 03:15 AM
using system mtu global config will affect all interfaces.
Try
conf t
int Port-channel 1
mtu ?
I think you can setup mtu on the portchannel itself.
02-19-2010 03:33 AM
You cannot set the mtu on interface level. you have to do it globally. OK. There is no mtu on the protchannel to decrease mtu. You cannot setup the mtu under the portchannel. What you need to do is configure system mtu [setup your mtu) This will affect all ports under the portchannel. The port channe interface inherits the mtu from the physical interface when the interface becomes active.
Config t
system mtu
02-19-2010 03:16 AM
Hi Roberto,
You need to consult your service provider make sure the SP can transparently pass LACP/pagp control frame. If SP block the control frame, you will not be able to use LACP/pagp.
HTH,
Lei Tian
02-19-2010 03:41 AM
The SP tell me: "the 2 wan links are transparent to the switches, the MTU is 9192 (MTU ethernet: with ethernet Header).
If the default MTU is 1500 bytes and the trunk 802.1Q requires an extra 4 bytes: the default interfaces MTU will be 1504 bytes... why the switch tell me 1500 bytes ?
How many extra bytes require LACP (are there any docs) ?
Are there any option to verify the MTU within the switch ?
How I can modify the MTU for only the Port-channel (channel of 2 Gigabit interfaces) ?
***
3750switchstackA#sh int po1
Port-channel1 is up, line protocol is up (connected)
Hardware is EtherChannel, address is 0013.7f59.6619 (bia 0013.7f59.6619)
Description: ** 3750switchstackA **
MTU 1500 bytes, BW 2000000 Kbit, DLY 10 usec,
***
ON THE PO1 interface there isn't a MTU command (also on the GE interface)
3750switchstackA(config)#int po1
3750switchstackA(config-if)#?
Interface configuration commands:
arp Set arp type (arpa, probe, snap) or timeout
bandwidth Set bandwidth informational parameter
bgp-policy Apply policy propagated by bgp community string
carrier-delay Specify delay for interface transitions
cdp CDP interface subcommands
dampening Enable event dampening
default Set a command to its defaults
delay Specify interface throughput delay
description Interface specific description
duplex Configure duplex operation.
energywise EnergyWise interface configurations
eou EAPoUDP Interface Configuration Commands
exit Exit from interface configuration mode
flowcontrol Configure flow operation.
help Description of the interactive help system
hold-queue Set hold queue depth
ip Interface Internet Protocol config commands
ipv6 IPv6 interface subcommands
isis IS-IS commands
iso-igrp ISO-IGRP interface subcommands
keepalive Enable keepalive
l2protocol-tunnel Tunnel Layer2 protocols
link Configure Link
load-interval Specify interval for load calculation for an interface
logging Configure logging for interface
macro Command macro
max-reserved-bandwidth Maximum Reservable Bandwidth on an Interface
mvr MVR per port configuration
neighbor interface neighbor configuration mode commands
network-policy Network Policy
nmsp NMSP interface configuration
no Negate a command or set its defaults
service-policy Configure QoS Service Policy
shutdown Shutdown the selected interface
snmp Modify SNMP interface parameters
source Get config from another source
spanning-tree Spanning Tree Subsystem
speed Configure speed operation.
storm-control storm configuration
switchport Set switching mode characteristics
timeout Define timeout values for this interface
transmit-interface Assign a transmit interface to a receive-only interface
tx-ring-limit Configure PA level transmit ring limit
vtp Enable VTP on this interface
3750switchstackA(config-if)#
Thanks to all,
Roberto Taccon
02-19-2010 03:47 AM
READ MY COMMENT ABOVE......
02-19-2010 04:42 AM
Hi Roberto,
LACP is an L2 control protocol, there is no encapsulation done by LACP. The LACP peers send out the special PDU to remote peer to verify if the peer is alive.
You can find out whether SP allow LACP frame by turn on debug lacp on your switch. Configure LACP mode active on both ends, and turn on debug LACP. If your provider allows the LACP control frame, you should be able to see "LACP packet received" and "Send LACP-PDU packet" from the debug output.
HTH,
Lei Tian
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