On Fri, 26 May 2000, Mary Smith wrote:
> I have 2 routers . Router B is set up for Hot Standby
> Router A is 2524, Router B is 2620:
>
> Router A configuration:
> .
> .
> int e0
> ip address 209.49.216.241 255.255.255.248
> standby 1 ip 209.49.216.245
> standby 1 preempt
> standby 1 priority 110
> no ip directed-broadcast
> !
> int s0
> ip address 206.181.61.66 255.255.255.252
> encapsulation ppp
> no fair-queue
> .
> .
> .
>
>
> Roouter B configuration:
>
> .
> .
> int f0/0
> ip address 209.49.216.245 255.255.255.248
> standby 1 ip
> standby 1 preempt
> no ip directed-broadcast
> !
> int s0/0
> ip address 206.181.61.66 255.255.255.252
> encapsulation ppp
> no fair-queue
> .
> .
>
> My questions are:
> (1). Is the above configuration correct ?
No. Router B needs an interface IP address different from the standby.
> (2). If router A go down, router B should up instantly
> ?
No. Even if the config were correct, there is a delay on the order of
a few seconds which is configurable.
> (3). Can I use sam serial ip address on both router ?
Mmmm... Probably not, depending on the rest of your network.
On the ethernet side, you need three ip addresses within the same subnet.
The virtual address is configured on at least one router with the
configuration line "standby 1 ip 209.49.216.245". This will be the
IP address assumed by the active router, and will be used as the
HSRP group's IP address for routing purposes. Each router must also
have its own unique IP address. Your router B should look like:
int f0/0
ip address 209.49.216.242 255.255.255.248
standby 1 ip 209.49.216.245 <this line is optional but helps to debug>
standby 1 preempt
no ip directed-broadcast
(assuming that you don't have another .242 on the network...)
On the serial side, you probably should not be using the same IP address
on both routers, as they'll be going to different networks. Think of HSRP
as an extension of the redundancy of two serial lines.
Say you have two locations linked by a serial line. This has no redundancy.
If the serial line fails, the network goes down. So to add redundancy a
second serial line is added between the locations, and it goes to a second
serial port on the same router at each end. Most protocols will happily
load-balance across multiple equal-cost paths so you now have redundancy
as well as extra capacity. The redundancy in case of a failure of one
line limits the capacity to that of the remaining working line, however.
This protects against the failre of the line, but not the failure of the
router hardware. Enter HSRP. You provide an additional router and
configure HSRP, connecting one serial line to each router. On the
ethernet side, the LAN uses the "virtual address" which can be assumed
by either router based on priority. Ideally, HSRP is also used on the
other end of the serial lines, or the remainder of the WAN is such that
redundancy is achieved by other means.
Of course for the truly paranoid (or robust), the ethernet side needs
to go to multiple switches with fast etherchannel between them in case a
switch fails, redundant servers are behind Local Director failover pairs,
and the whole thing is run from two different power supplies.
There's a nice writeup on HSRP in the documentation.
http://www.cisco.com/univercd/cc/td/doc/cisintwk/ics/cs009.htm
--
Jay Hennigan - Network Administration - [EMAIL PROTECTED]
NetLojix Communications, Inc. NASDAQ: NETX - http://www.netlojix.com/
WestNet: Connecting you to the planet. 805 884-6323
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