10-14-2010 05:58 PM - edited 03-06-2019 01:32 PM
For the first time I have been trying remote span by the manual, but cannot use it.
As soon I enter °monitor session 1 destination remote vlan XX", connectivity for the monitored vlan ceases.
When I negate the command, connecitivity resumes immediately.
If I monitor a source port instead or a vlan, the same happens, no more connectivity throught that port.
Vlan XX is configured as remote span and this information is propagated by VTP to all switches-
The same happens if I do the command on the VTP server switch.
The monitored port or vlan only have some hundreds PPS traffic.
I have tried with various 2960 and 3750 with up to date IOS.
Local span works just fine.
Why that may be happening ?
10-14-2010 11:48 PM
Paolo,
I do not feel competent at all to give any guidance to a veteran like you but at least I can try to replicate the problem in my lab and tell you if I arrived at the same issue. I have a couple of 2960 and 3560 switches here. Can you tell me the precise IOS version you were using, and also, can you post relevant parts of the configuration that ultimately cause the monitored object (port or source VLAN) to lose connectivity, including the RSPAN session configuration itself?
Best regards,
Peter
10-14-2010 11:51 PM
Hi Paolo,
Can you post the following when its active, where x is your remote vlan and y is your spanned vlan :
- show vlan-id
- show monitor
- show vtp status
- show vtp pruning
- show int trunk
- show spanning-tree vlan
- show spanning-tree vlan
RSPAN is pretty straight forward, there shouldnt be a reason for the source traffic to stop unless the RSPAN traffic is passing on the same port and affecting the flow somehow.
/ijay
10-15-2010 06:08 AM
Thank you all for your replies.
Please see the session below. 10.3.1.72 is a remote host reached via Vlan 253, but not directly within vlan 253.
Vlan 253 and vlan 7 are both active in the same port Gi1/0/19 going to the root of STP.
This is a 3750 wtih 12.2(53)SE2
FG-SW-ACDC#ping 10.3.1.72 repeat 1
Type escape sequence to abort.
Sending 1, 100-byte ICMP Echos to 10.3.1.72, timeout is 2 seconds:
!
Success rate is 100 percent (1/1), round-trip min/avg/max = 126/126/126 ms
FG-SW-ACDC#conf t
Enter configuration commands, one per line. End with CNTL/Z.
FG-SW-ACDC(config)#monitor session 1 source vlan 253 rx
FG-SW-ACDC(config)#monitor session 1 destination remote vlan 7
FG-SW-ACDC(config)#do ping 10.3.1.72 repeat 1
Type escape sequence to abort.
Sending 1, 100-byte ICMP Echos to 10.3.1.72, timeout is 2 seconds:
.
Success rate is 0 percent (0/1)
FG-SW-ACDC(config)#do sh vlan id 7
VLAN Name Status Ports
---- -------------------------------- --------- -------------------------------
7 RSPAN active Gi1/0/1, Gi1/0/19, Gi1/0/21
Gi1/0/23
VLAN Type SAID MTU Parent RingNo BridgeNo Stp BrdgMode Trans1 Trans2
---- ----- ---------- ----- ------ ------ -------- ---- -------- ------ ------
7 enet 100007 1500 - - - - - 0 0
Remote SPAN VLAN
----------------
Enabled
Primary Secondary Type Ports
------- --------- ----------------- ------------------------------------------
FG-SW-ACDC(config)#do sh monitor
Session 1
---------
Type : Remote Source Session
Source VLANs :
RX Only : 253
Dest RSPAN VLAN : 7
FG-SW-ACDC(config)#do show vtp status
VTP Version capable : 1 to 3
VTP version running : 2
VTP Domain Name : FAIRBANKS
VTP Pruning Mode : Enabled
VTP Traps Generation : Disabled
Device ID : 001c.b0ad.3c80
Configuration last modified by 10.60.2.1 at 10-14-10 15:40:31
Feature VLAN:
--------------
VTP Operating Mode : Client
Maximum VLANs supported locally : 1005
Number of existing VLANs : 26
Configuration Revision : 105
MD5 digest : 0x37 0x25 0x36 0xAD 0xDA 0x1A 0xF6 0x27
0x47 0x97 0xC1 0xC5 0x2D 0x5F 0x44 0x56
FG-SW-ACDC(config)#do sh int trunk
Port Mode Encapsulation Status Native vlan
Gi1/0/1 on 802.1q trunking 1
Gi1/0/19 on 802.1q trunking 1
Gi1/0/21 on 802.1q trunking 1
Gi1/0/23 on 802.1q trunking 1
Port Vlans allowed on trunk
Gi1/0/1 1-4094
Gi1/0/19 1-4094
Gi1/0/21 1-4094
Gi1/0/23 1-4094
Port Vlans allowed and active in management domain
Gi1/0/1 1-7,9-10,14-15,17,19,23-24,50,99-101,201,253-254
Gi1/0/19 1-7,9-10,14-15,17,19,23-24,50,99-101,201,253-254
Gi1/0/21 1-7,9-10,14-15,17,19,23-24,50,99-101,201,253-254
Gi1/0/23 1-7,9-10,14-15,17,19,23-24,50,99-101,201,253-254
Port Vlans in spanning tree forwarding state and not pruned
Gi1/0/1 1-7,9-10,14-15,17,19,23-24,50,99-101,201,253-254
Gi1/0/19 1-7,9-10,14-15,17,19,23-24,50,99-101,201,253-254
Gi1/0/21 1,4,19,50
Gi1/0/23 1-7,9-10,14-15,17,19,23-24,50,99-101,201,253-254
FG-SW-ACDC(config)#do sh spanning-tree vlan 7
VLAN0007
Spanning tree enabled protocol rstp
Root ID Priority 24583
Address 0026.99fc.f380
Cost 19
Port 19 (GigabitEthernet1/0/19)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32775 (priority 32768 sys-id-ext 7)
Address 001c.b0ad.3c80
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi1/0/1 Desg FWD 19 128.1 P2p
Gi1/0/19 Root FWD 19 128.19 P2p
Gi1/0/21 Desg FWD 19 128.21 P2p
Gi1/0/23 Desg FWD 4 128.23 P2p
FG-SW-ACDC(config)#do sh spanning-tree vlan 253
VLAN0253
Spanning tree enabled protocol rstp
Root ID Priority 33021
Address 0011.92aa.1780
Cost 27
Port 19 (GigabitEthernet1/0/19)
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 33021 (priority 32768 sys-id-ext 253)
Address 001c.b0ad.3c80
Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Aging Time 300 sec
Interface Role Sts Cost Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi1/0/1 Desg FWD 19 128.1 P2p
Gi1/0/19 Root FWD 19 128.19 P2p
Gi1/0/21 Desg FWD 19 128.21 P2p
Gi1/0/23 Desg FWD 4 128.23 P2p
FG-SW-ACDC(config)#no monitor session 1
FG-SW-ACDC(config)#do ping 10.3.1.72 repeat 1
Type escape sequence to abort.
Sending 1, 100-byte ICMP Echos to 10.3.1.72, timeout is 2 seconds:
!
Success rate is 100 percent (1/1), round-trip min/avg/max = 118/118/118 ms
10-15-2010 07:05 AM
Paolo
Config looks fine at first look. Which switch have you configured the destination session on and how is that connected to this switch.
Also when you do a ping have you tried with more than one packet.
Finally is the 3750 you have seutp the source session on doing the inter-vlan routing. If so can you post -
"sh ip int br"
and
"sh ip ro" from this switch.
Jon
10-15-2010 07:24 AM
Thank you for your reply John.
jon.marshall wrote:
Paolo
Config looks fine at first look. Which switch have you configured the destination session on and how is that connected to this switch.
Well, that it irrelevant. One is supposed to be able to configure the monitored switch independently from the destination one, and have no negative consequence if no switch have monitor sopurce to the rspan vlan.
Also when you do a ping have you tried with more than one packet.
One ping or many makes no difference, also the users report connectivity failure.
Finally is the 3750 you have seutp the source session do the inter-vlan routing. If so can you post -
"sh ip int br"
and
"sh ip ro" from this switch
No, it is a pure layer 2 switch, and nothing unsual is observed with the above commands.
Nothing appears in loggin either.
10-15-2010 07:36 AM
p.bevilacqua wrote:
Thank you for your reply John.
jon.marshall wrote:
Paolo
Config looks fine at first look. Which switch have you configured the destination session on and how is that connected to this switch.
Well, that it irrelevant. One is supposed to be able to configure the monitored switch independently from the destination one, and have no negative consequence if no switch have monitor sopurce to the rspan vlan.
Also when you do a ping have you tried with more than one packet.
One ping or many makes no difference, also the users report connectivity failure.
Finally is the 3750 you have seutp the source session do the inter-vlan routing. If so can you post -
"sh ip int br"
and
"sh ip ro" from this switch
No, it is a pure layer 2 switch, and nothing unsual is observed with the above commands.
Nothing appears in loggin either.
You are right in what you say about being to create them independently but what if in between this switch and the destination switch there was a misconfiguration that could potentially lead to an STP issue. With RSPAN you need to be aware of the entire path. Remember that once you have configured the source session that traffic will be flooded within vlan 7. It may not have anywhere to go in terms of a destination port but it still gets sent to all switches configured with vlan 7 on it.
Jon
10-15-2010 08:30 AM
You are right in what you say about being to create them independently but what if in between this switch and the destination switch there was a misconfiguration that could potentially lead to an STP issue. With RSPAN you need to be aware of the entire path. Remember that once you have configured the source session that traffic will be flooded within vlan 7. It may not have anywhere to go in terms of a destination port but it still gets sent to all switches configured with vlan 7 on it.
Jon
If there is a misconfiguration I am not sure what it could be. There are no redundant links in this network, and STP settings are left at the default. Only the monitored vlan or port is affected, all the rest continue working. But, I will check again based on the possiblity that STP breaks.
10-15-2010 05:44 PM
I've also tried this quickly in the lab. I'm not running the same version, or RSTP, but RSPAN on 3750 works. The fact that only the spanned VLAN is affected points to STP breaking somewhere.
10-16-2010 07:55 AM
Thank Ian for your testing.
I have reviewed the STP topology. In fact, due to an oversight, root for VLAN 253 was not the same as for VLAN 7, as can be seen in the trace.
So, I have corrected that, and repeated the test, with no changes.
Observed STP on the root bridge (that is also the routing core), there are no changes whatsoever with monitoring enabled or not.
The monitored switch is adjacent to the root bridge.
I think I will handle this to the TAC and update the thread if they can find a resolution.
10-15-2010 05:12 AM
I had something very similar. But using 3750's and 2 6513s at the core. Remote span a Port in VLAN 2... destination
vlan 60... vlan 60 was a remote span vlan... it killed all traffic to vlan2. Turned the SPAN off and
connectivity returned instantally. Was never able to go back and test. Nothing fancy just odd.
10-15-2010 08:47 AM
I am way new to this so slap me if I am wrong.... :-)
On the source switch you have
FG-SW-ACDC(config)#monitor session 1 source vlan 253 rx
FG-SW-ACDC(config)#monitor session 1 destination remote vlan 7
On the destination switch wouldn't you need this?
monitor session 1 source remote vlan 7
monitor session 1 destination interface interface_id
Mike
10-15-2010 08:53 AM
burleyman wrote:
I am way new to this so slap me if I am wrong.... :-)
On the source switch you have
FG-SW-ACDC(config)#monitor session 1 source vlan 253 rx
FG-SW-ACDC(config)#monitor session 1 destination remote vlan 7
On the destination switch wouldn't you need this?
monitor session 1 source remote vlan 7
monitor session 1 destination interface interface_id
Mike
As mentioned above, it is not necessary to configure the second set of commands to manatain normal operation of the monitored VLAN or interface..
In other words, connectivity must not be afftected by destination switch presence.
In other words again, the monitored or source switch is not aware of the presence of zero, one or more destination switches, and must continue working indipendently.
That is what the documentation indicates, and my logical understanding of how things should be.
10-15-2010 09:07 AM
I was getting it out of the CCNP Switch book...maybe I misread it.
Here is what I read....
On Cisco IOS-based Catalyst switches, use the following commands in configuration mode to configure RSPAN.
On the source switch:
monitor session session source {interface interface-id | vlan vlan-id} [,][-] {rx | tx | both}
monitor session session destination remote vlan vlan-id
On the destination switch:
monitor session session source remote vlan vlan-id
monitor session session destination interface interface-id [encapsulation {dot1q | isl}] [ingress vlan vlan-id]
Mike
10-15-2010 09:16 AM
Mike
What Paolo is saying is that the 2 are independant of each other ie. you can configure the source session without actually configuring the destination session. All that happens then is that the traffic is flooded throughout the RSPAN vlan but obviously doesn't end up at the destination port because you haven't configured that. But it shouldn't stop the source session working as such.
Obviously it wouldn't make much sense to do this but the logic is that by only configuring the source session it shouldn't have the effect Paolo is seeing ie. stopping traffic in the monitored vlan.
Jon
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