01-29-2009 05:45 AM - edited 03-06-2019 03:44 AM
Hi!
I have 7600 config:
gw#sh run int gi1/31
Building configuration...
Current configuration : 175 bytes
!
interface GigabitEthernet1/31
switchport
switchport trunk encapsulation dot1q
switchport trunk native vlan 6
switchport trunk allowed vlan 6
switchport mode trunk
end
gw#sh run int vlan 6
Building configuration...
Current configuration : 140 bytes
!
interface Vlan6
ip address 1.2.3.9 255.255.255.248
no ip redirects
no ip proxy-arp
ip pim dr-priority 2
ip pim sparse-mode
end
and 6500:
core#sh run int gi5/1
Building configuration...
Current configuration : 217 bytes
!
interface GigabitEthernet5/1
core#sh run int vlan 128
Building configuration...
Current configuration : 202 bytes
!
interface Vlan128
ip address 1.2.3.10 255.255.255.248 secondary
ip address 192.168.1.1 255.255.255.0
no ip redirects
no ip proxy-arp
end
Pings from "gw" to "core":
gw#ping 1.2.3.10
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.2.3.10, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms
But from another side ("core" to "gw"):
core#ping 1.2.3.9
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.2.3.9, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
VLANs is directly connected.
01-29-2009 10:26 AM
Can you try extend ping by specifing source IP as 1.2.3.10 when you ping from "core" to "gw"?
01-30-2009 12:31 AM
core#ping
Protocol [ip]:
Target IP address: 1.2.3.9
Repeat count [5]:
Datagram size [100]:
Timeout in seconds [2]:
Extended commands [n]: y
Source address or interface: 1.2.3.10
Type of service [0]:
Set DF bit in IP header? [no]:
Validate reply data? [no]:
Data pattern [0xABCD]:
Loose, Strict, Record, Timestamp, Verbose[none]:
Sweep range of sizes [n]:
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.2.3.9, timeout is 2 seconds:
Packet sent with a source address of 1.2.3.10
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/1 ms
It seems, that "core" used first ip address on interface to send reply to "gw", when trying to use ordinary ping. Where is the root of problem, or it's normal behaviour?
01-30-2009 07:38 AM
I am not 100% sure if it is the same on all platform. Here is a comment from someone else "An ICMP echo request will be generated by the router itself. In the assembly of the ICMP message by the router, the Source ip address that is used in the creation of the resulting ip ICMP message will be the primary ip address for the interface or sub-interface that the datagram is to be transmitted on. As an aside, routers never generate ip datagrams that use a SECONDARY ip address that may be attached to an interface. It will always use the PRIMARY address."
01-29-2009 11:43 AM
The core's interface gig 5/1 is not even a switchport per your show run:
interface GigabitEthernet5/1
So, the ping from core to gateway I understand why it will fail. But from gw pinging to 1.2.3.10 suggests there is another host responding to that ip address. can you look at show ip arp 1.2.3.10 from the gw and trace where the mac is learned from with "show mac address-table
01-30-2009 12:40 AM
I apologise. There is full config, when I've posted config made it with no attention.
core#sh run int gi5/1
Building configuration...
Current configuration : 217 bytes
!
interface GigabitEthernet5/1
switchport
switchport trunk encapsulation dot1q
switchport trunk native vlan 128
switchport trunk allowed vlan 128
switchport mode trunk
end
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