From: Victor Cappuccio (cvictor@protokolgroup.com)
Date: Mon Jul 24 2006 - 20:32:19 ART
Hi Guys,
IMO the ip dhcp ping packets is enabled by default, but imagine that the
router with ip add 170.17.162.1 goes off the net, dies, whatever. It would
send ping to that IP address 2 times and without any respond, in a new DHCP
Request it could assign the IP Address.
And yes you can assign the same physical address that other routers has in
VRRP, but his is not true for HSRP.
R3(config)#int e0/0
R3(config-if)#ip add 170.17.162.1 255.255.255.0
R3(config-if)#standby 1 ip 170.17.162.1
% address cannot equal interface IP address
R3(config-if)#!! Hmmm does not work
R3(config-if)#do show run int e0/0
Building configuration...
Current configuration : 91 bytes
!
interface Ethernet0/0
ip address 170.17.162.1 255.255.255.0
half-duplex
end
R3(config-if)#vrrp 1 ip 170.17.162.1
It does take the command.
Saludos,
Victor
-----Mensaje original-----
De: Bill.McKenzie@bisys.com [mailto:Bill.McKenzie@bisys.com]
Enviado el: Lunes, 24 de Julio de 2006 05:40 p.m.
Para: Sami; Victor Cappuccio
CC: ccielab
Asunto: Re: DHCP
In my opinion, with something like this they are looking for the
configuration of it and not just assuming you know that it checks before it
will assign the address. I could be wrong though...
----- Original Message -----
From: Sami [sy1977@gmail.com]
Sent: 07/24/2006 05:25 PM
To: "Victor Cappuccio" <cvictor@protokolgroup.com>
Cc: ccielab@groupstudy.com
Subject: Re: DHCP
Thanks Everyone
Why are you excluding Default gateway address from DHCP pool. I understand
it is not necessay because DHCP ping the IP before assigning to the host.
Could some one let me know is it required to exclude these address from DHCP
pool or not from lab exam point of view.
Thanks
On 7/23/06, Victor Cappuccio <cvictor@protokolgroup.com> wrote:
>
> Hi Sami,
>
> Please allow me on this one:
>
> DHCP is a Service for passing configuration information to hosts on a TCP
> IP
> network as far as I know, and yes you can set 2 Default Gateways via DHCP,
> but you will need to method at the client like Gateway Discovery Protocol
> to
> avoid sending packets to a Dead GW
>
> Something similar as this:
>
> ip dhcp excluded-address 170.17.162.2
> ip dhcp excluded-address 170.17.162.1
> !
> ip dhcp pool MYPOOL
> network 170.17.162.0 255.255.255.0
> default-router 170.17.162.1 170.17.162.2
>
>
> If we add one host in that network, to see the information provided by
> this
> great live saver feature.
>
> Dummy_Host#show ip route | b Gate
> Gateway of last resort is 170.17.162.1 to network 0.0.0.0
>
> 170.17.0.0/24 is subnetted, 1 subnets
> C 170.17.162.0 is directly connected, Vlan666
> S* 0.0.0.0/0 [254/0] via 170.17.162.1
>
> Lets test this,
>
> Dummy_Host#ping 204.12.1.4
>
> Type escape sequence to abort.
> Sending 5, 100-byte ICMP Echos to 204.12.1.4, timeout is 2 seconds:
> .!!!!
> Success rate is 80 percent (4/5), round-trip min/avg/max = 140/141/144 ms
>
> Yeah seems to work
> Now let's shut down the Primary Default Gateway to see what happens
>
> R1(config)#int f0/0
> R1(config-subif)#sh
> R1(config-subif)#
>
> The information from the Routing Table at Dummy host is not erased
>
> Dummy_Host#show ip route | be Gate
> Gateway of last resort is 170.17.162.1 to network 0.0.0.0
>
> 170.17.0.0/24 is subnetted, 1 subnets
> C 170.17.162.0 is directly connected, Vlan666
> S* 0.0.0.0/0 [254/0] via
>
>
> Let's ping the Def-gw?
>
>
> Dummy_Host#ping 170.17.162.1
>
> Type escape sequence to abort.
> Sending 5, 100-byte ICMP Echos to 170.17.162.1, timeout is 2 seconds:
> .....
> Success rate is 0 percent (0/5)
>
> does not work :(
>
> So we need a method of getting redundancy with out needing to shut down
> the
> Interface and renewing the IP Address / Default Gw for providing the
> needed
> redundancy.
>
> At R1 and R2 (or the gateways) interface sitting with the dummy host put
> this
>
> vrrp 1 ip 170.17.162.1
>
> wit only 1 default-router 170.17.162.1 at the ip dhcp pool MYPOOL,
> because
> it's not logic to gave the 2 if you run some other redundancy method used
> in
> your wording.
>
> And that's it
>
> Dummy_Host#ping 170.17.162.1
>
> Type escape sequence to abort.
> Sending 5, 100-byte ICMP Echos to 170.17.162.1, timeout is 2 seconds:
> !!!!!
> Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms
>
> Dummy_Host#ping 204.12.1.4
>
> Type escape sequence to abort.
> Sending 5, 100-byte ICMP Echos to 204.12.1.4, timeout is 2 seconds:
> !!!!!
> Success rate is 100 percent (5/5), round-trip min/avg/max = 112/114/116 ms
>
> Useful debug commands
>
> show arp
> show vrrp
> show ip int
> show ip route
> show ip dhcp bind
> clear arp
> deb arp
> ping (always useful)
>
> are great tools in this scenario.
>
> Try it with a couple of routers it would be fun!!
>
> HTH
> Victor.-
>
> -----Mensaje original-----
> De: nobody@groupstudy.com [mailto:nobody@groupstudy.com] En nombre de Sami
> Enviado el: Domingo, 23 de Julio de 2006 06:26 a.m.
> Para: ccielab@groupstudy.com
> Asunto: DHCP
>
> Group,
>
> Is it possible to provide two default gateway to clients using DHCP ? one
> of the task say provide gateway redendency to DHCP clients but don't use
> HSRP to achieve this...
>
> Thanks
>
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