[c-nsp] cisco 1721 & load sharing across unequal paths.

Tue Nov 23 10:39:42 EST 2004

Where are you suggesting he use EIGRP?

If he is using NAT to overload on the egress
ISP interfaces the return traffic from the
ISP's will come back to the correct link.

If he uses two static default routes you
shouldn't need any floating routes.  He
wants them both up always as long as the path
is there.  If one goes away traffic would take
the other path.  I didn't interpret it to
mean backup as in a "dial backup" scenario.

I do agree with you on the Object tracking part
to detect when the ISP link is up or down.

The one problem here is that he will have
a 1Mbps leased line and a 8Mbps wireless
connection.  With two static defaults the
router doesn't know the difference and most
likely you will overload the 1Mbps serial
before getting close to the 8Mbps speed.

I think the most optimal solution here would
be static routes with object tracking to
make sure the ISP connections are up.

Then to get the load balancing proportional
to the link speeds use OER.  The only gotcha
here that I'm not sure about is how OER interacts
with NAT.

Rodney

On Tue, Nov 23, 2004 at 04:18:08PM +0100, Tantsura, Jeff wrote:
> 
> Hi,
> 
> You should definitely go for EIGRP as it supports unequal load sharing
> and VLSM.
> Second option would be 1 primary and 1 backup path with floating default
> - in this example wireless is the primary
> ip route 0.0.0.0 0.0.0.0 <next hop IP wireless> 100
> ip route 0.0.0.0 0.0.0.0 <next hop IP serial> 200
> 
> In this case you could also use Reliable Static Routing Backup Using
> Object Tracking
> http://www.cisco.com/en/US/partner/products/sw/iosswrel/ps5413/products_
> feature_guide09186a00801d862d.html
> because if IP next hop is unreachable  but ethernet link is UP backup
> wont kick in.
> 
> Hope this helps,
> Jeff
> 
> With kind regards/ met vriendelijke groeten,
> --------------------------------------------------------
> Jeff Tantsura
> CCIE #11416
> Senior Consultant
> Capgemini Nederland BV
> Tel: +31(0)30 689 2866
> Mob:+31(0)6 4588 6858
> Fax: +31(0)30 689 6565
> --------------------------------------------------------
> 
> 
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of ege iyioglu
> Sent: Tuesday, November 23, 2004 3:15 PM
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] cisco 1721 & load sharing across unequal paths.
> 
> Hi there
> We have a Cisco 1721 router with a serial interface and an ethernet
> interface.. You can find the run and ver info below.
> The serial interface is connected to an ISP through a 1mbit leased line
> connection. The ethernet interface is connected to the inside network.
> We do NAT.
> We'd like to add another ethernet interface and connect it to a wireless
> access point that will receive an 8mbit connection from another ISP.
> Both connections will provide access to the internet.
> We also would like to implement load sharing and redundancy between
> those 2 interfaces (the serial interface and the 2nd ethernet
> interface..) our router has 32 MB of ram. I'm planning to run IGRP or
> EIGRP with the maximum-paths 2 command.
> First of all, do you think this is a feasible scenario that would
> provide load sharing and redundancy? And if it is, would our router's
> cpu and memory be enough for all of this or do we need an upgrade? I'm
> open to suggestions since this is the first time I will be doing this.
> 
> Deep Regards
> Ege
> 
> ------- sh run --------
> Building configuration...
> 
> Current configuration : 1230 bytes
> !
> ! No configuration change since last restart !
> version 12.2
> service timestamps debug uptime
> service timestamps log uptime
> no service password-encryption
> !
> hostname #####
> !
> logging buffered 16380 debugging
> no logging console
> enable password #####
> !
> username ##### callback-dialstring ##### password 0 ##### ip subnet-zero
> ! !
> ! ! chat-script callback ABORT ERROR ABORT BUSY "" "ATDT\T" TIMEOUT 30
> "CONNECT" \c modemcap entry usrmodem:MSC=&FS0=1&C1&D3&H1&R2&B1
> !
> !
> !
> interface FastEthernet0
>  ip address 212.58.x.x 255.255.255.240
>  speed auto
> !
> interface Serial0
>  description #####
>  bandwidth 1024
>  ip address 212.2.x.x 255.255.255.252
>  no ip route-cache
>  no ip mroute-cache
> !
> interface Async5
>  ip address 192.168.x.x 255.255.255.0
>  encapsulation ppp
>  async default routing
>  async mode interactive
>  ppp callback accept
>  ppp authentication pap
> !
> ip classless
> ip classless
> no ip http server
> ip pim bidir-enable
> !
> !
> !
> !
> line con 0
> line aux 0
>  script callback callback
>  login local
>  modem InOut
>  modem autoconfigure type usrmodem
>  transport input all
>  autoselect during-login
>  speed 300
>  flowcontrol hardware
> line vty 0 4
>  password #####
>  login
> !
> no scheduler allocate
> end
> 
> --------- sh ver -----------
> 
> Cisco Internetwork Operating System Software IOS (tm) C1700 Software
> (C1700-SY-M), Version 12.2(8)YJ, EARLY DEPLOYMENT RELEAS E SOFTWARE
> (fc1) Synched to technology version 12.2(8.5)T TAC
> Support: http://www.cisco.com/tac Copyright (c) 1986-2002 by cisco
> Systems, Inc. Compiled Fri 21-Jun-02 15:38 by ealyon Image text-base:
> 0x80008124,
> data-base: 0x80B64A38
> 
> ROM: System Bootstrap, Version 12.2(7r)XM1, RELEASE SOFTWARE (fc1)
> ROM: C1700 Software (C1700-SY-M), Version 12.2(8)YJ, EARLY DEPLOYMENT
> RELEASE SO FTWARE (fc1)
> 
> bilfenrtr uptime is 1 day, 2 hours, 31 minutes System returned to ROM by
> power-on System restarted at 16:27:54 UTC Fri Nov 5 2004 System image
> file is "flash:c1700-sy-mz.122-8.YJ.bin"
> 
> cisco 1721 (MPC860P) processor (revision 0x100) with 29492K/3276K bytes
> of memor y. Processor board ID FOC06330050 (1457551649), with hardware
> revision 0000 MPC860P processor: part number 5, mask 2 Bridging
> software. X.25 software, Version 3.0.0. 1 FastEthernet/IEEE 802.3
> interface(s) 1
> Serial(sync/async) network interface(s) 32K bytes of non-volatile
> configuration memory. 16384K bytes of processor board System flash
> (Read/Write)
> 
> Configuration register is 0x2102
> 
> 
> 
> 
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