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question on the interconnections of switches

question on the interconnections of switches# Internet - 有缘千里一线牵

d*i2002-10-09 07:10

1 楼

When multiple switches are connected, how could they realize the routing when
the source and destination requires multihop? simply by MAC address?
If the system is not connected to Internet, say, a cluster system, is router
required in this case? If there is some routing algorithm within the switch,
can I modify it to realize my own routing algorithm?
Thanks!

a*t2002-10-09 07:10

2 楼

when
Clarifying some concepts first:
1. Switch operats on the layer 2, data link layer (of course, the regular
switch, not the layer-3 or layer-4 switch)
2. Router operates on the IP layer, layer 3
So, to answer you question:
Switches don't know the routing. If they are connected to the same subnet,
nothing needs to be done. If they are connected to the different subnet, you
need to put a router between them. Switch isn't counted as a hop, router is.
Same applies to the second question, if no s

【在 d**i 的大作中提到】

: When multiple switches are connected, how could they realize the routing when
: the source and destination requires multihop? simply by MAC address?
: If the system is not connected to Internet, say, a cluster system, is router
: required in this case? If there is some routing algorithm within the switch,
: can I modify it to realize my own routing algorithm?
: Thanks!

r*e2002-10-09 07:10

3 楼

big deal. all just terminalogy differences. bottom line is: both
routing and bridging are just multi-hop forwarding.
stp and any routing protocol all build some forwrading topologies.
stp builds a tree, routing protocol builds a mesh. then individual
route is the shortest path (or whatever path) within corresponding
topology. one real difference is that routing supports route (or
path) aggregation while all routes (or paths) in stp are per-host.
there are people selling layer 3 switches (o

【在 a***t 的大作中提到】

:
: when
: Clarifying some concepts first:
: 1. Switch operats on the layer 2, data link layer (of course, the regular
: switch, not the layer-3 or layer-4 switch)
: 2. Router operates on the IP layer, layer 3
: So, to answer you question:
: Switches don't know the routing. If they are connected to the same subnet,
: nothing needs to be done. If they are connected to the different subnet, you
: need to put a router between them. Switch isn't counted as a hop, router is.

a*t2002-10-09 07:10

4 楼

Therotically, you are partically right. STP and routing protocols are for the
different purposes... (We don't want to discuss the detail, do we?) But in the
real world implementation, and if you look at the majority of the products in
the market palce, layer 2 protocol wouldn't talk to layer 3 protocol. They
have different address space, MAC and IP address (take IP as example, of
course there are IPX and others); IP packet is the payload of the ethernet
frame, layer 2 switch wouldn't see the IP

【在 r*****e 的大作中提到】

: big deal. all just terminalogy differences. bottom line is: both
: routing and bridging are just multi-hop forwarding.
: stp and any routing protocol all build some forwrading topologies.
: stp builds a tree, routing protocol builds a mesh. then individual
: route is the shortest path (or whatever path) within corresponding
: topology. one real difference is that routing supports route (or
: path) aggregation while all routes (or paths) in stp are per-host.
: there are people selling layer 3 switches (o