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Is there a way to “Pass through†a MAC address on a Cisco Switch?
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We have two systems connected together, and the end system (system 2) relies on differentiating packets via MAC address from system 1 (it has two routes).
For testing purposes, we want to put a Cisco switch in the middle. But doing so obviously changes the MAC address presented to system 2.
System 2 cannot be changed to RX a different MAC address.
Is there a way to "pass through" the MAC address on the switch from system 1 to 2, or is it possible to spoof the address on the port facing system 2?
cisco switch mac-address
edited Sep 8 at 10:30
jonathanjo
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asked Sep 7 at 12:50
user10021657
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up vote
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down vote
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We have two systems connected together, and the end system (system 2) relies on differentiating packets via MAC address from system 1 (it has two routes).
For testing purposes, we want to put a Cisco switch in the middle. But doing so obviously changes the MAC address presented to system 2.
System 2 cannot be changed to RX a different MAC address.
Is there a way to "pass through" the MAC address on the switch from system 1 to 2, or is it possible to spoof the address on the port facing system 2?
cisco switch mac-address
edited Sep 8 at 10:30
jonathanjo
5,255222
asked Sep 7 at 12:50
user10021657
311
New contributor
user10021657 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
2
Sounds like the words "switch" and "router" are getting mixed up. Maybe in your lab you're actually using a router with some features turned off to make it seem like a switch, but they are different devices with different characteristics.
– JPhi1618
Sep 7 at 18:26
What model of switch do you have? If it's a so-called "layer 3" switch, you might have a switch with routing facilities enabled, with the same effect as @JPhi suggests.
– jonathanjo
Sep 8 at 10:33
No, definitely a switch, and I cleared up what the request was. Like I mentioned below, it was being tee'd off to something else.
– user10021657
yesterday
add a comment |Â
up vote
1
down vote
favorite
up vote
1
down vote
favorite
We have two systems connected together, and the end system (system 2) relies on differentiating packets via MAC address from system 1 (it has two routes).
For testing purposes, we want to put a Cisco switch in the middle. But doing so obviously changes the MAC address presented to system 2.
System 2 cannot be changed to RX a different MAC address.
Is there a way to "pass through" the MAC address on the switch from system 1 to 2, or is it possible to spoof the address on the port facing system 2?
cisco switch mac-address
edited Sep 8 at 10:30
jonathanjo
5,255222
asked Sep 7 at 12:50
user10021657
311
New contributor
user10021657 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
We have two systems connected together, and the end system (system 2) relies on differentiating packets via MAC address from system 1 (it has two routes).
For testing purposes, we want to put a Cisco switch in the middle. But doing so obviously changes the MAC address presented to system 2.
System 2 cannot be changed to RX a different MAC address.
Is there a way to "pass through" the MAC address on the switch from system 1 to 2, or is it possible to spoof the address on the port facing system 2?
cisco switch mac-address
edited Sep 8 at 10:30
jonathanjo
5,255222
asked Sep 7 at 12:50
user10021657
311
New contributor
user10021657 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited Sep 8 at 10:30
jonathanjo
5,255222
edited Sep 8 at 10:30
jonathanjo
5,255222
edited Sep 8 at 10:30
jonathanjo
5,255222
5,255222
asked Sep 7 at 12:50
user10021657
311
New contributor
user10021657 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked Sep 7 at 12:50
user10021657
311
asked Sep 7 at 12:50
user10021657
311
311
New contributor
user10021657 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
user10021657 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
user10021657 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
2
Sounds like the words "switch" and "router" are getting mixed up. Maybe in your lab you're actually using a router with some features turned off to make it seem like a switch, but they are different devices with different characteristics.
– JPhi1618
Sep 7 at 18:26
What model of switch do you have? If it's a so-called "layer 3" switch, you might have a switch with routing facilities enabled, with the same effect as @JPhi suggests.
– jonathanjo
Sep 8 at 10:33
No, definitely a switch, and I cleared up what the request was. Like I mentioned below, it was being tee'd off to something else.
– user10021657
yesterday
add a comment |Â
2
Sounds like the words "switch" and "router" are getting mixed up. Maybe in your lab you're actually using a router with some features turned off to make it seem like a switch, but they are different devices with different characteristics.
– JPhi1618
Sep 7 at 18:26
What model of switch do you have? If it's a so-called "layer 3" switch, you might have a switch with routing facilities enabled, with the same effect as @JPhi suggests.
– jonathanjo
Sep 8 at 10:33
No, definitely a switch, and I cleared up what the request was. Like I mentioned below, it was being tee'd off to something else.
– user10021657
yesterday
2
2
Sounds like the words "switch" and "router" are getting mixed up. Maybe in your lab you're actually using a router with some features turned off to make it seem like a switch, but they are different devices with different characteristics.
– JPhi1618
Sep 7 at 18:26
Sounds like the words "switch" and "router" are getting mixed up. Maybe in your lab you're actually using a router with some features turned off to make it seem like a switch, but they are different devices with different characteristics.
– JPhi1618
Sep 7 at 18:26
What model of switch do you have? If it's a so-called "layer 3" switch, you might have a switch with routing facilities enabled, with the same effect as @JPhi suggests.
– jonathanjo
Sep 8 at 10:33
What model of switch do you have? If it's a so-called "layer 3" switch, you might have a switch with routing facilities enabled, with the same effect as @JPhi suggests.
– jonathanjo
Sep 8 at 10:33
No, definitely a switch, and I cleared up what the request was. Like I mentioned below, it was being tee'd off to something else.
– user10021657
yesterday
No, definitely a switch, and I cleared up what the request was. Like I mentioned below, it was being tee'd off to something else.
– user10021657
yesterday
add a comment |Â
1 Answer
1
active
oldest
votes
up vote
8
down vote
We hope you will become a contributing member of this community.
Switches do not change MAC addresses, so your application, if it is on the same subnet, will see the sender's MAC address.
If you the application is on a different subnet, then I'm afraid you can't see the sender's MAC. It is stripped off by the router.
answered Sep 7 at 12:56
Ron Trunk
31.4k22667
hmmm, that's what I thought. So either system 1's MAC is wrong, or it's being tee'd off to something else first in the switch, before being sent to system 2
– user10021657
Sep 7 at 14:16
3
As I said, switches do not change MAC addresses.
– Ron Trunk
Sep 7 at 15:06
1
Not only do switches not change MAC addresses, they work based on MAC addresses, so they are crucially reliant on correct MAC addresses. A switch that changes MAC addresses would be so completely, utterly, fundamentally broken that it would never get into the hands of a customer.
– Jörg W Mittag
Sep 7 at 17:57
@JörgWMittag I think that's a bit extreme. Routers don't typically change IP addresses, but they can when doing NAT. Similarly, switches can do layer 2 NAT of MAC addresses. Among other things, that capability is sometimes used to bridge wireless LANs at layer 2 when, for one reason or another, WDS is not an option. It's definitely not typical though.
– David Schwartz
Sep 7 at 19:06
@JörgWMittag Plenty of experience with MOXA equipment begs to differ.
– chrylis
Sep 7 at 21:40
add a comment |Â
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
8
down vote
We hope you will become a contributing member of this community.
Switches do not change MAC addresses, so your application, if it is on the same subnet, will see the sender's MAC address.
If you the application is on a different subnet, then I'm afraid you can't see the sender's MAC. It is stripped off by the router.
answered Sep 7 at 12:56
Ron Trunk
31.4k22667
hmmm, that's what I thought. So either system 1's MAC is wrong, or it's being tee'd off to something else first in the switch, before being sent to system 2
– user10021657
Sep 7 at 14:16
3
As I said, switches do not change MAC addresses.
– Ron Trunk
Sep 7 at 15:06
1
Not only do switches not change MAC addresses, they work based on MAC addresses, so they are crucially reliant on correct MAC addresses. A switch that changes MAC addresses would be so completely, utterly, fundamentally broken that it would never get into the hands of a customer.
– Jörg W Mittag
Sep 7 at 17:57
@JörgWMittag I think that's a bit extreme. Routers don't typically change IP addresses, but they can when doing NAT. Similarly, switches can do layer 2 NAT of MAC addresses. Among other things, that capability is sometimes used to bridge wireless LANs at layer 2 when, for one reason or another, WDS is not an option. It's definitely not typical though.
– David Schwartz
Sep 7 at 19:06
@JörgWMittag Plenty of experience with MOXA equipment begs to differ.
– chrylis
Sep 7 at 21:40
add a comment |Â
up vote
8
down vote
We hope you will become a contributing member of this community.
Switches do not change MAC addresses, so your application, if it is on the same subnet, will see the sender's MAC address.
If you the application is on a different subnet, then I'm afraid you can't see the sender's MAC. It is stripped off by the router.
answered Sep 7 at 12:56
Ron Trunk
31.4k22667
hmmm, that's what I thought. So either system 1's MAC is wrong, or it's being tee'd off to something else first in the switch, before being sent to system 2
– user10021657
Sep 7 at 14:16
3
As I said, switches do not change MAC addresses.
– Ron Trunk
Sep 7 at 15:06
1
Not only do switches not change MAC addresses, they work based on MAC addresses, so they are crucially reliant on correct MAC addresses. A switch that changes MAC addresses would be so completely, utterly, fundamentally broken that it would never get into the hands of a customer.
– Jörg W Mittag
Sep 7 at 17:57
@JörgWMittag I think that's a bit extreme. Routers don't typically change IP addresses, but they can when doing NAT. Similarly, switches can do layer 2 NAT of MAC addresses. Among other things, that capability is sometimes used to bridge wireless LANs at layer 2 when, for one reason or another, WDS is not an option. It's definitely not typical though.
– David Schwartz
Sep 7 at 19:06
@JörgWMittag Plenty of experience with MOXA equipment begs to differ.
– chrylis
Sep 7 at 21:40
add a comment |Â
up vote
8
down vote
up vote
8
down vote
We hope you will become a contributing member of this community.
Switches do not change MAC addresses, so your application, if it is on the same subnet, will see the sender's MAC address.
If you the application is on a different subnet, then I'm afraid you can't see the sender's MAC. It is stripped off by the router.
answered Sep 7 at 12:56
Ron Trunk
31.4k22667
We hope you will become a contributing member of this community.
Switches do not change MAC addresses, so your application, if it is on the same subnet, will see the sender's MAC address.
If you the application is on a different subnet, then I'm afraid you can't see the sender's MAC. It is stripped off by the router.
answered Sep 7 at 12:56
Ron Trunk
31.4k22667
answered Sep 7 at 12:56
Ron Trunk
31.4k22667
answered Sep 7 at 12:56
Ron Trunk
31.4k22667
answered Sep 7 at 12:56
Ron Trunk
31.4k22667
31.4k22667
hmmm, that's what I thought. So either system 1's MAC is wrong, or it's being tee'd off to something else first in the switch, before being sent to system 2
– user10021657
Sep 7 at 14:16
3
As I said, switches do not change MAC addresses.
– Ron Trunk
Sep 7 at 15:06
1
Not only do switches not change MAC addresses, they work based on MAC addresses, so they are crucially reliant on correct MAC addresses. A switch that changes MAC addresses would be so completely, utterly, fundamentally broken that it would never get into the hands of a customer.
– Jörg W Mittag
Sep 7 at 17:57
@JörgWMittag I think that's a bit extreme. Routers don't typically change IP addresses, but they can when doing NAT. Similarly, switches can do layer 2 NAT of MAC addresses. Among other things, that capability is sometimes used to bridge wireless LANs at layer 2 when, for one reason or another, WDS is not an option. It's definitely not typical though.
– David Schwartz
Sep 7 at 19:06
@JörgWMittag Plenty of experience with MOXA equipment begs to differ.
– chrylis
Sep 7 at 21:40
add a comment |Â
hmmm, that's what I thought. So either system 1's MAC is wrong, or it's being tee'd off to something else first in the switch, before being sent to system 2
– user10021657
Sep 7 at 14:16
3
As I said, switches do not change MAC addresses.
– Ron Trunk
Sep 7 at 15:06
1
Not only do switches not change MAC addresses, they work based on MAC addresses, so they are crucially reliant on correct MAC addresses. A switch that changes MAC addresses would be so completely, utterly, fundamentally broken that it would never get into the hands of a customer.
– Jörg W Mittag
Sep 7 at 17:57
@JörgWMittag I think that's a bit extreme. Routers don't typically change IP addresses, but they can when doing NAT. Similarly, switches can do layer 2 NAT of MAC addresses. Among other things, that capability is sometimes used to bridge wireless LANs at layer 2 when, for one reason or another, WDS is not an option. It's definitely not typical though.
– David Schwartz
Sep 7 at 19:06
@JörgWMittag Plenty of experience with MOXA equipment begs to differ.
– chrylis
Sep 7 at 21:40
hmmm, that's what I thought. So either system 1's MAC is wrong, or it's being tee'd off to something else first in the switch, before being sent to system 2
– user10021657
Sep 7 at 14:16
hmmm, that's what I thought. So either system 1's MAC is wrong, or it's being tee'd off to something else first in the switch, before being sent to system 2
– user10021657
Sep 7 at 14:16
3
3
As I said, switches do not change MAC addresses.
– Ron Trunk
Sep 7 at 15:06
As I said, switches do not change MAC addresses.
– Ron Trunk
Sep 7 at 15:06
1
1
Not only do switches not change MAC addresses, they work based on MAC addresses, so they are crucially reliant on correct MAC addresses. A switch that changes MAC addresses would be so completely, utterly, fundamentally broken that it would never get into the hands of a customer.
– Jörg W Mittag
Sep 7 at 17:57
Not only do switches not change MAC addresses, they work based on MAC addresses, so they are crucially reliant on correct MAC addresses. A switch that changes MAC addresses would be so completely, utterly, fundamentally broken that it would never get into the hands of a customer.
– Jörg W Mittag
Sep 7 at 17:57
@JörgWMittag I think that's a bit extreme. Routers don't typically change IP addresses, but they can when doing NAT. Similarly, switches can do layer 2 NAT of MAC addresses. Among other things, that capability is sometimes used to bridge wireless LANs at layer 2 when, for one reason or another, WDS is not an option. It's definitely not typical though.
– David Schwartz
Sep 7 at 19:06
@JörgWMittag I think that's a bit extreme. Routers don't typically change IP addresses, but they can when doing NAT. Similarly, switches can do layer 2 NAT of MAC addresses. Among other things, that capability is sometimes used to bridge wireless LANs at layer 2 when, for one reason or another, WDS is not an option. It's definitely not typical though.
– David Schwartz
Sep 7 at 19:06
@JörgWMittag Plenty of experience with MOXA equipment begs to differ.
– chrylis
Sep 7 at 21:40
@JörgWMittag Plenty of experience with MOXA equipment begs to differ.
– chrylis
Sep 7 at 21:40
add a comment |Â
user10021657 is a new contributor. Be nice, and check out our Code of Conduct.
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2
Sounds like the words "switch" and "router" are getting mixed up. Maybe in your lab you're actually using a router with some features turned off to make it seem like a switch, but they are different devices with different characteristics.
– JPhi1618
Sep 7 at 18:26
What model of switch do you have? If it's a so-called "layer 3" switch, you might have a switch with routing facilities enabled, with the same effect as @JPhi suggests.
– jonathanjo
Sep 8 at 10:33
No, definitely a switch, and I cleared up what the request was. Like I mentioned below, it was being tee'd off to something else.
– user10021657
yesterday