[j-nsp] OSPF default problem

Joe Freeman joe at netbyjoe.com
Tue Jan 20 16:51:58 EST 2009


Have you setup NAT on the 3560? What's the config look like on the 3560?
Does the EX4200 have a L3 interface in the vlan with 10.0.0.0? If so, what's
it's address, and what's the address of the 3560? Can you ping one from the
other?

Joe

On Tue, Jan 20, 2009 at 4:44 PM, Cord MacLeod <cordmacleod at gmail.com> wrote:

> You are correct, but I haven't even setup the machine network as of yet.  I
> simply am attempting to get 10.0.0.* to be able to hit the Internet using
> gatway 10.0.0.1.
>
>
>
>
> On Jan 20, 2009, at 12:29 PM, Joe Freeman wrote:
>
>  Without a gateway that exists in both the 10.0.1.0/24 and the 10.0.0.0/23networks, nothing on the
>> 10.0.1.0/24 will be able to hit an address on the 10.0.0.0/24 space.
>>
>> You do realize that 10.0.0.0/23 overlaps with 10.0.1.0/24 so that the
>> gateway will see 10.0.1.0/24 as part of the larger 0.0/23 supernet
>> locally attached and will simply arp for any 10.0.1.0/24 address.
>> However, hosts with 10.0.1.0/24 addresses will see any address on
>> 10.0.0.0/23 as being on a different subnet and as such will attempt to
>> forward that traffic to their default gateway. If the default gateway isn't
>> in the 10.0.1.0/24, no traffic will be sent, and the packet dropped as
>> unreachable.
>>
>> Joe
>>
>> On Tue, Jan 20, 2009 at 3:18 PM, Cord MacLeod <cordmacleod at gmail.com>
>> wrote:
>> This is the setup roughly.  The gateway is a 3560 switch and has a vlan
>> defined for that 10net.  There is also a static route on the internet
>> gateway to point everything 10.0.0.0/23 to 10.0.0.2.  10.0.0.2 being
>> reachable from 10.0.0.1.
>>
>>
>> On Jan 20, 2009, at 1:55 AM, Felix Schueren wrote:
>>
>> Cord MacLeod wrote:
>> As far as the router id, I went back to basics and looked in my junos
>> cookbook and didn't skip a beat when I first set this up and it didn't
>> work.  I just added in all of the steps it suggested, really nothing of
>> consequence.
>>
>> So, 10.0.0.0/24 is the network devices and 10.0.1.0/24 is the machines.
>> That's why I have a /23 on that interface.  Funny part is that
>> particular switch with 10.0.0.2 on it locally can hit the internet and
>> 10.0.0.1.  No other device can nor can I ping 10.0.0.1 with any other
>> source on the local switch.
>>
>>
>> "internet gateway"
>>    |
>>    |
>>  10.0.0.0/23
>>    |
>>    |
>>  "ex4200"
>>    |   \
>>    |    \
>>    |     \
>>  "other1"  "other2"
>>   |         |
>>   10.0.1.0/24
>>   |         |
>> "machines1"  "machines2"
>>
>> is that similiar to your setup? if it is, the "gateway" will most likely
>> not try to reach anything within 10.0.0.0/23 routed, instead just ARPing
>> on it's directly connected interface. From what I saw so far, end
>> machines should be able to send packets to 10.0.0.1, but it appears that
>> 10.0.0.1 can't send any packets back - can you monitor traffic on
>> 10.0.0.1 to verify that?
>>
>> -felix
>>
>>
>> --
>> Felix Schüren
>> Head of NOC
>>
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>


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