sup720b upgrade or replace?

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Aug 6th, 2007
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Hi,


We have reached the capacity of our FIB table on the 720B. This is due to taking multiple sets of routing information from our peers. At present I can only get 3-4 full routing tables loaded before the router runs out of ram. We also notie performance problems as the router tries to update the fib table with a new peers information from BGP. Should we upgrade to BXL based equipment which will support up to 1,000,000 routes in the hardware table and has double the amount of ram or should we be looking at a different routing platform to handle this.


Thanks,


Richard

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tprendergast Tue, 08/07/2007 - 06:34
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That really depends on your projected usage over the next few s. If you plan on replacing your routing platform in the next 12 months, you may just want to move to heavier hitting dedicated routers. If you would like to preserve this platform, then the 720BXL would be a good option for you. The nice thing is that upgrading to the new SUP will just allow you to do a direct swap with minimal effort, whereas a new routing platform would require some migration efforts, etc.


Hope that helps.

wochanda Tue, 08/07/2007 - 12:15
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It really depends here on what resource you're running out of here. You say you're running out of ram, which means you should see a MALLOCFAIL message when you're downloading the BGP tables. Is this what you're getting?


If so, the fix is as simple as adding RAM to either the SUP or MSFC as needed. Since the order of operations to program our hardware tables is:

1. Download & Process BGP routes

2. Put best routes in routing table

3. Program software CEF tables

4. Program software CEF tables on SUP side

5. Program hardware from SUP's CEF tables


Make sure you pay attention to whether you ran out of memory on the SUP or the MSFC. Whichever one ran out, you'll want to upgrade.



Now if you ran out of memory in hardware, sometimes you'll see a TCAM full message, sometimes packets will take the wrong route, and sometimes you'll see high cpu. If this is the case, there are things you can do on the SUP720-3B to re-allocate your TCAM to allow more routes. What you want to do is:


config t

mls cef maximum-routes ip 220


By default we carve the TCAM to only allow 192k IPv4 unicast routes. The number you specify here allows you to raise that amount (at the expense of IPv4 multicast routes). The max you can do is 239K.


If you have more than 239K routes to put into hardware, or if you're doing a lot of multicast, you'll want to replace these guys with SUP720-3BXL.

wochanda Tue, 08/07/2007 - 12:16
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Forgot to mention, if you do the maximum-routes command you'll need a reload for it to take effect.

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