WAN Gateway - BGP

Unanswered Question
Dec 28th, 2008

Hi all,

We are planning to install a new wan gateway for a new site with 1 Gbps wan link. At any point of time we will have 800+ mbps of traffic. which one to use

WS-X45-SUP6-E on a cat -4500

or

Cisco 7206 VXR with NPE-G2 on 7200.

please give some inputs on this.

thanks

I have this problem too.
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Giuseppe Larosa Sun, 12/28/2008 - 05:32

Hello Subramania,

you have described the amount of traffic that is expected over the link 800 Mbps but you didn't tell what type of BGP session you will have.

C7206VXR with NPE-G2 is stronger on the signalling plane for its 1 to 2GB RAM memory but is weaker on the forwarding plane where its CPU is supposed to be able to move 2 mpps.

the other device is much stronger on the forwarding plane, being a multilayer switch, but it can be short of memory to host CEF tables that reflect a full BGP table.

To make an example a C6500 is supposed to be good for receiving 2 to 3 BGP internet tables with a SUP 720 3BXL or better.

We have for example two chassis with SUP 720 3BXL other collegues have reported to be using SUP720 3CXL

So the amount of routing information received on the BGP session plays an important role too.

Hope to help

Giuseppe

subra4u Sun, 12/28/2008 - 08:03

Hi,

Thanks for the input. we will do peering with 2 isp but not planning for a full table as it will be used for a backup only. all we are looking is for a wan gateway capable of taking upto 1 gbps of traffic.

thanks

Giuseppe Larosa Sun, 12/28/2008 - 11:59

Hello Subramania,

another very important aspect are the features:

as far as I know only C6500 with SUP720 is able to support NAT in hardware.

see

http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.2SX/configuration/guide/intro.html#wp1029188

if your traffic needs to be processed by NAT the performance of a C4500 can fall down because it will NAT in software using its main CPU or it is unsupported (I don't see a NAT chapter in configuration guide)

while there is support for PBR and WCCP

see

http://www.cisco.com/en/US/docs/switches/lan/catalyst4500/12.2/46sg/configuration/guide/intro.html#wp1023637

if the traffic doesn't need to be NATTED and you are not going to receive full routing tables you can use a C4500 and you can use it also for other purposes like being a distribution node in the distribution layer.

A C7200 VXR with NPE-G2 would be a dedicated device for this task.

Hope to help

Giuseppe

Jon Marshall Sun, 12/28/2008 - 12:06

Giuseppe

Just for your info - only the 6500 supports NAT at all. The 4500 will not support NAT either in hardware or software as you suspected.

Hope you had a good xmas :-)

Jon

Giuseppe Larosa Sun, 12/28/2008 - 13:02

Hello Jon,

thanks you

I had a good Christmas with all my family (including sisters, nephews, brothers in law)

Happy New Year

Best Regards

Giuseppe

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