Perdue You can try by subnetting between VLAN 12 & 22.
regards,
Charli
On 8/9/06, [EMAIL PROTECTED] <
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Today's Topics:
1. IntraVLAN communications - 50% of pings time out (Perdue Shared)
2. Re: IntraVLAN communications - 50% of pings time out
(Perdue Shared)
3. Re: SNMP Question (Michael Senno)
----------------------------------------------------------------------
Message: 1
Date: Tue, 8 Aug 2006 08:23:03 -0700 (PDT)
From: Perdue Shared <[EMAIL PROTECTED]>
Subject: [OSL | CCIE_RS] IntraVLAN communications - 50% of pings time
out
To: [email protected]
Message-ID: <[EMAIL PROTECTED] >
Content-Type: text/plain; charset="iso-8859-1"
I have two switches (switchA & switchB) that are connected with a trunked link (VLANs 12, 22 transversing the trunk). HSRP is configured on both of the switches, and SwitchA is the HSRP active for both VLANs.
VLAN 12:
10.166.12.0 /24
SwitchA - 10.166.12.2
SwitchB - 10.166.12.3
HSRP VIP - 10.166.12.1
SwitchA is Active, Switch B is Standby
VLAN 22:
10.166.22.0 /24
SwitchA - 10.166.22.2
SwitchB - 10.166.22.3
HSRP VIP - 10.166.22.1
SwitchA is Active, Switch B is Standby
Now there is a host in VLAN 22, on switchB - IP address 10.166.22.123 . If I ping this host from any other host within VLAN 22, I see a 50% packet loss (!.!.!.!.!.). However, if I ping the host from any host outside of the network (for instance, ping from 10.166.12.1), I do not see any packet loss whatsoever. There is another host in VLAN 22, 10.166.22.126 that does not see any packet loss. 22.126 is off of switchB as well.
I see packet loss even if I ping .123 from 22.1 and 22.3:
switcha#ping
Protocol [ip]:
Target IP address: 10.166.22.123
Repeat count [5]: 10
Datagram size [100]:
Timeout in seconds [2]:
Extended commands [n]: y
Source address or interface: 10.166.22.1
Sending 10, 100-byte ICMP Echos to 10.166.22.123, timeout is 2 seconds:
!.!.!.!.!.
Success rate is 50 percent (5/10), round-trip min/avg/max = 1/1/4 ms
So as I'm troubleshooting this, I guess I have some remedial questions. Host 10.166.22.123 receives an ICMP request packet from 10.166.22.3. If host .123 wants to send an ICMP reply packet to 22.3 (which is the switchB VLAN22 interface), it would send an ARP request out to the 255.255.255.255 address (if it doesn't already know the MAC address for the host - which it should since it just received a packet from the host), and should receive a response back with the correct mac-address. Then the .123 host should create a frame with the destination MAC address that it received in the ARP request and will forward the ICMP packet to switchB, which should then notice that the packet is destined for itself. Am I missing something in this process? Since the communications remain within the single network, the CEF adjacency table would not come in to play, correct? I apologize if this is remedial -- I'm just trying to get an idea of why this packet loss would occur - and
only involve one host. The most baffling part, is that there is no packet loss when pinging the host from a different network.
BTW - The network configuration of the host machine has been verified.
I have sniffed ICMP on the trunk between the two switches and this is what I saw:
Sniff Test #1 - When sending 10 pings from 10.166.22.2 (switchA) to host 10.166.22.123 (connected to switchB) - I see 10 requests and 10 replies in Ethereal.
Sniff Test # 2When sending 10 pings from 10.166.22.3 (switchB) to host 10.166.22.123 (connected to switchB) - I see 4 ping replies in Ethereal.
I would have assumed that in Sniff Test#2, I should not have seen any requests or replies. I'm planning on sniffing ARP in addition to ICMP to see what else is going on.
I would appreciate any kind of input or ideas for add'l troubleshooting. I'm finding that I have some misconceptions about how this should be working. Has anyone seen this kind of behavior before
THanks in Advance.
-Tim
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------------------------------
Message: 2
Date: Tue, 8 Aug 2006 09:55:17 -0700 (PDT)
From: Perdue Shared <[EMAIL PROTECTED]>
Subject: Re: [OSL | CCIE_RS] IntraVLAN communications - 50% of pings
time out
To: Perdue Shared <[EMAIL PROTECTED]>,
[email protected]
Message-ID: < [EMAIL PROTECTED]>
Content-Type: text/plain; charset="iso-8859-1"
Please disregard this - the problem was with the host's configuration.
Thanks
Perdue Shared <[EMAIL PROTECTED]> wrote:
I have two switches (switchA & switchB) that are connected with a trunked link (VLANs 12, 22 transversing the trunk). HSRP is configured on both of the switches, and SwitchA is the HSRP active for both VLANs.
VLAN 12:
10.166.12.0 /24
SwitchA - 10.166.12.2
SwitchB - 10.166.12.3
HSRP VIP - 10.166.12.1
SwitchA is Active, Switch B is Standby
VLAN 22:
10.166.22.0 /24
SwitchA - 10.166.22.2
SwitchB - 10.166.22.3
HSRP VIP - 10.166.22.1
SwitchA is Active, Switch B is Standby
Now there is a host in VLAN 22, on switchB - IP address 10.166.22.123 . If I ping this host from any other host within VLAN 22, I see a 50% packet loss (!.!.!.!.!.). However, if I ping the host from any host outside of the network (for instance, ping from 10.166.12.1), I do not see any packet loss whatsoever. There is another host in VLAN 22, 10.166.22.126 that does not see any packet loss. 22.126 is off of switchB as well.
I see packet loss even if I ping .123 from 22.1 and 22.3:
switcha#ping
Protocol [ip]:
Target IP address: 10.166.22.123
Repeat count [5]: 10
Datagram size [100]:
Timeout in seconds [2]:
Extended commands [n]: y
Source address or interface: 10.166.22.1
Sending 10, 100-byte ICMP Echos to 10.166.22.123, timeout is 2 seconds:
!.!.!.!.!.
Success rate is 50 percent (5/10), round-trip min/avg/max = 1/1/4 ms
So as I'm troubleshooting this, I guess I have some remedial questions. Host 10.166.22.123 receives an ICMP request packet from 10.166.22.3. If host .123 wants to send an ICMP reply packet to 22.3 (which is the switchB VLAN22 interface), it would send an ARP request out to the 255.255.255.255 address (if it doesn't already know the MAC address for the host - which it should since it just received a packet from the host), and should receive a response back with the correct mac-address. Then the .123 host should create a frame with the destination MAC address that it received in the ARP request and will forward the ICMP packet to switchB, which should then notice that the packet is destined for itself. Am I missing something in this process? Since the communications remain within the single network, the CEF adjacency table would not come in to play, correct? I apologize if this is remedial -- I'm just trying to get an idea of why this packet loss would occur - and
only involve one host. The most baffling part, is that there is no packet loss when pinging the host from a different network.
BTW - The network configuration of the host machine has been verified.
I have sniffed ICMP on the trunk between the two switches and this is what I saw:
Sniff Test #1 - When sending 10 pings from 10.166.22.2 (switchA) to host 10.166.22.123 (connected to switchB) - I see 10 requests and 10 replies in Ethereal.
Sniff Test # 2When sending 10 pings from 10.166.22.3 (switchB) to host 10.166.22.123 (connected to switchB) - I see 4 ping replies in Ethereal.
I would have assumed that in Sniff Test#2, I should not have seen any requests or replies. I'm planning on sniffing ARP in addition to ICMP to see what else is going on.
I would appreciate any kind of input or ideas for add'l troubleshooting. I'm finding that I have some misconceptions about how this should be working. Has anyone seen this kind of behavior before
THanks in Advance.
-Tim
---------------------------------
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---------------------------------
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------------------------------
Message: 3
Date: Tue, 8 Aug 2006 21:25:24 -0400
From: "Michael Senno" <[EMAIL PROTECTED]>
Subject: Re: [OSL | CCIE_RS] SNMP Question
To: "'Mohamed Farouk'" <[EMAIL PROTECTED]>,
<[email protected]>
Message-ID: < [EMAIL PROTECTED]>
Content-Type: text/plain; charset="us-ascii"
Syslog uses UDP and is inherently unreliable, thus it would not meet the
retransmissions requirement. As for your question on snmp vs. traps it seems
the question is always fairly clear. In this particular instance you would
lean toward SNMP since it specifies traps for redundant power supply
failures. This can be specifically added for SNMP, but syslog does not allow
to turn on specific alerts.
My take, at least.
Michael J. Senno
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From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]] On Behalf Of Mohamed Farouk
Sent: Monday, August 07, 2006 9:03 AM
To: [email protected]
Subject: [OSL | CCIE_RS] SNMP Question
Hi Sir
In lab 38, the question states, configure router 6 to send notification
messages to host ..... whenever its redundant power supply fails. R6 will
retransmit the message ih the host does not get it.
When to use logging and when to use the snmp-server?
I know all about the informs and traps difference? and why here we have to
use informs because of the retransmission. My question is what if the second
part is missing "R6 will retransmit the message if the host does not get
it"? is it possible to use the logging traps command.
My question may also be "When to consider that we aer sending to Syslog
Server or snmp server?" Or i will always get a word that will guide to the
required, exactly as the retransmission here?
Thanks/regards
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End of CCIE_RS Digest, Vol 7, Issue 2
*************************************
--
thnks & rgrds,
Sanjay Chalikar
(Eng Name: Charli) - (m) 9223 468245.
