[c-nsp] Design Q

[Bruce Pinsky]

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Bruce Pinsky wrote:
| info at beprojects.com wrote:
| | I've got a design question that I am not sure about and was wondering if
| | anybody has any insight.
| |
| | My intention is to have two separate Internet routers running eBGP to
| | two separate upstreams and then iBGP to each other.  On the LAN side,
| | they will each have their own IP, say .2 and .3 and share a HSRP
| | address, say .1.  If I'm on the LAN, my DG is .1.  If I try to go to
| | some random Internet address, I will go to .1 and we'll say that right
| | now, that is router A.  If the address is best reached through it, it
| | will forward the packet.  If it is best reached through B, which it
| | learns via iBGP, it will send an ICMP redirect, assuming they are
| | enabled, and tell me to go to .3 instead, which will forward the packet.
| |   So on my pc, I will build a routing table as I move along.
| |
| | The question is, what do I do if I want to create 4-5 VLAN's.  Say I
| | have a layer3 switch like a 3750.  My initial thought would be to make
| | it the DG for each vlan and it would have a default route of .1.
| | However every time it gets a redirect, it will add it to it's routing
| | table, right?  Now if one of the machines on one of the vlan's is a dns
| | server or web server, theoretically, there could be thousands on
| | different destinations, in which case the L3 switch will have thousands
| | of routing entries and we all know that a lower end switch like the 3750
| | does not have enough memory to hold 100,000 routes.
| |
| | Am I better off setting up the links to the routers as trunks and using
| | sub interfaces?  Or am I way off in my description above?  Or is there
| | some other option?
| |
|
| Take a look at the Gateway Load Balancing Protocol (GLBP) whitepaper at
|
http://www.cisco.com/en/US/partner/tech/tk869/tk769/technologies_white_paper0900aecd801790a3.shtml

|
|
| It describes several techniques and introduces the feature as well.
|

Oh and also take a look at HSRP with ICMP Redirects support at
http://www.cisco.com/en/US/customer/products/sw/iosswrel/ps1834/products_feature_guide09186a00800e9763.html

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bep

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