kory@avatar.com (Kory Hamzeh) (05/10/91)
If I have a TCP/IP stack running on a MAC layer bridge to support SNMP, must the
ethernet interfaces have unique IP addresses?
What if the device was an IP bridge or router?
Thanks,
Kory
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Kory Hamzeh UUCP: avatar!kory or ..!uunet!avatar!kory
INTERNET: kory@avatar.com art@opal.acc.com (Art Berggreen) (05/11/91)
In article <1991May10.054816.3039@avatar.com> kory@avatar.com (Kory Hamzeh) writes: > >If I have a TCP/IP stack running on a MAC layer bridge to support SNMP, must the >ethernet interfaces have unique IP addresses? > >What if the device was an IP bridge or router? If the device is BRIDGING IP datagarams, then the device should act as if it was a host somehow attached to the bridged network. In this mode, the device has a single IP address on the logical IP network being run over the bridged network. If more than one logical IP net is being run on the bridged net, then the node MAY have more than one IP address. It is up to the bridging software to properly forward any internally generated packets out the correct MAC level port(s). If the device is ROUTING IP datagrams, then each MAC level interface should have one (or more) IP addresses associated with the logical IP nets defined separately on each MAC level network. If the device is ROUTING on SOME ports and BRIDGING on the OTHER ports, then a mix of both above mechanisms is used (and the details get very messy). Art
kasten@EUROPA.CLEARPOINT.COM (Frank Kastenholz) (05/13/91)
> From tcp-ip-RELAY@nic.ddn.mil Sat May 11 11:47:48 1991 > From: dog.ee.lbl.gov!hellgate.utah.edu!caen!sdd.hp.com!usc!srhqla!quad1!avatar!kory@ucsd.edu (Kory Hamzeh) > Organization: Avatar Consultants > Subject: TCP/IP, SNMP, and Bridges > Sender: tcp-ip-relay@nic.ddn.mil > To: tcp-ip@nic.ddn.mil > > > If I have a TCP/IP stack running on a MAC layer bridge to support SNMP, must the > ethernet interfaces have unique IP addresses? > > What if the device was an IP bridge or router? > > Thanks, > Kory > > > -- > ------------------------------------------------------------------------------- > Kory Hamzeh UUCP: avatar!kory or ..!uunet!avatar!kory > INTERNET: kory@avatar.com > Kory, Assuming that the device is JUST a bridge it need only have one IP address (Though you could implement it with many if you so chose). An IP router MUST have different IP addresses on its interfaces. Remember, the purpose of an IP Router is to forward packets between different IP networks and different IP Networks have different IP Network/Subnetwork numbers, therefore the addresses will be different. Frank Kastenholz Clearpoint Research Corp.
emv@ox.com (Ed Vielmetti) (05/13/91)
In article <9105131326.AA01179@europa.clearpoint.com> kasten@EUROPA.CLEARPOINT.COM (Frank Kastenholz) writes:
An IP router MUST have different IP addresses on its interfaces. Remember,
the purpose of an IP Router is to forward packets between different
IP networks and different IP Networks have different IP Network/Subnetwork
numbers, therefore the addresses will be different.
I don't think that necessarily follows -- seems to me that KA9Q NOS
gets by (if you so desire) with one IP address for the whole box, and
routing done on a per interface basis. Or am I missing something ?
--Ed08071TCP@MSU.EDU (Doug Nelson) (05/19/91)
> An IP router MUST have different IP addresses on its interfaces. Remember, > the purpose of an IP Router is to forward packets between different > IP networks and different IP Networks have different IP Network/Subnetwork > numbers, therefore the addresses will be different. > >I don't think that necessarily follows -- seems to me that KA9Q NOS >gets by (if you so desire) with one IP address for the whole box, and >routing done on a per interface basis. Or am I missing something ? The question is what address do you use as a gateway address for systems connected to a given interface. For serial lines, there is no problem, since there's only one place to send the data; hence serial lines can easily live without their own IP address. For network interfaces, though, you either need an IP address on the local net, or you have to rely on proxy ARP to find the gateway. Now this all assumes *I'm* not missing something, too. Doug Nelson Michigan State University