How many route entries does 3945E or/and 3900 ISR G2 support

[yonxi]

hello guys:

I have a question concerning about how many ospf and bgp route entries does 3945E isr g2 router support?

cheers

tony xi

[Peter Paluch · Accepted solution]

Tony,

This question can't be answered in general. It depends foremost on the amount of available memory in the router. With 256MB of RAM, you can expect that the router can manage roughly tens of thousands of routes. The full BGP routing table (not the BGP database) consumes around 70MB, however, the full BGP RIB on one of the route-views project routers consumes over 1100 MB of RAM (this also depends on the number of BGP peers and the amount of data sent to it by individual BGP neighbors). The exact number is impossible to determine, as it depends on the amount of other control information that the router has to store in its RAM - for example, OSPF LSDB, BGP RIB, the CEF and adjacency tables, etc. etc. etc.

So you can assume that 256MB of RAM should be working for deployments up to the order of tens of thousands but this has to be taken with a very, very rough and unreliable estimate.

Best regards,

Peter

[yonxi]

hello Peter:

thanx for ur response. The detailed requirement of route entries capacity should be 64K for BGP and 5K for OSPF with default DRAM bulit, that is 1GB DRAM.

thus, does the 3945E support of above demand?

cheers

tony xi

[Peter Paluch]

Hello Tony,

Yes, I believe that this hardware configuration would be sufficient. How many BGP peers are to be expected?

Best regards,

Peter

P.S.: Apologize for the typo in the greeting - I've corrected it now.

[yonxi]

Yup. Actually, I have no idea how many bgp peers which custom purpose to. Since that this question is from a bidding parameter validation.

Could you calculate on behalf of me how many BGP peers or/and BGP route entries can be supported with default 1GB DRAM built?

cheers

tony xi

[Peter Paluch]

Tony,

Sadly, no calculations are possible on my part, just rules of thumb.

Let's take it this way: the route-views.routeviews.org is a 7200 router with 2GB of RAM. It has currently 39 active BGP peers, each of them advertising averagely 330,000 prefixes to this 7200. The entire BGP database containing all these prefixes and paths consumes around 1.1 GB of RAM. The router has to hold over 12 million entries in its BGP RIB (not all of them are bestpath entries).

I do not believe that your router will be anywhere near this level of punishment... and hence my estimation that the router will be fine with 1GB RAM, 64k BGP routes and 5k OSPF routes.

Best regards,

Peter

[Simon Pierce]

We have real-world experience of needing to upgrade our 3945e g2 to 2Gb RAM to support and perform normally when consuming the full Internet BGP routing table. With 1Gb RAM, we were not learning all prefixes.

[jskvorc863]

Hi to all

I have Cisco 3945E w/SPE250 (4GE, 3EHWIC, 3DSP, 4SM, 256MBCF, 1GBDRAM, IPB)

if upgrade to 2GB or 4GB memory, can take full BGP feed?, 600k routes is today full BGP table

[Leo Laohoo]

Just to add, the 3900 has a default of 1Gb of DRAM and can go as high as 4Gb of DRAM.

Ordering Guide:  Cisco Integrated Services Routers Generation 2

Look at Table 3.

[Nilo Noguera]

In addition, as per the internal Cisco resources I found it says that the Cisco 3900 ISR with the default 1GB of memory can easily handle 310,000 routes and even a full BGP table with multiple paths is easily handled in 1GB today. 

Thank you for the opportunity to assist you.
 
 
Best regards,
 
 
"Nilz"
Nilo Noguera
.:|:.:|:. Specialist, Cisco Global Virtual Engineering - Cisco Partner Help
http://www.cisco.com/web/partners/tools/ph.html