Question:
I'm looking for some guidance in sizing Cisco routers for different levels of
BGP support. I'm aware that it requires
1 GB of RAM to handle the full BGP routing table, but the processing required
to maintain neighbors/sessions, etc., would be too much for a Cisco 1941 ISR,
for example. I'd like recommended
solutions for the following scenarios:
1) A router that will be
dual-homed to two different ISP's (same speed lnks - let's say 100-Mb each),
and will be maintaining a full routing table to choose the best path based on
BGP path attributes. So, in this case,
the router will not be offering Internet transit services.
2) Same router, but it
will only be storing a select number of Internet routes (for key
sites/businesses - let's say 1,000 routes.)
Still, no transit traffic.
3) Lastly, an ISP router
maintaining full Internet routing table (322K routes as of today), and three
OC3 connections to other ISP neighbors.
The solution:
Hardset requirements:
BGP Full table, Cisco
recommends 1GB of RAM
CEF Requirements (if
enabled [enabled on most by default])256-512MB of RAM
RIB Requirements
(256-512MB)
iBGP = Branch routers
eBGP = WAN/Edge Routers
http://www.cisco.com/en/US/products/hw/routers/ps359/products_tech_note09186a0080110d68.shtml#ts1
http://www.cisco.com/en/US/tech/tk365/technologies_q_and_a_item09186a00800949e8.shtml
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080094a83.shtml
Branch routers have rinky
dink processors, very low throughput and not intended for any type of service
as an edge device for production traffic. Running eBGP, a full table, I would
not even consider looking at any ISR routers. I focus on anything that is for enterprise
and service provider edge applications, in your case: Internet Edge Routers
armed with new
information
- eBGP w/ two ISP's (no
iBGP)
- let's say partial BGP
routes this time (let's go with approximately 1,000)
- OSPF locally, but
minimal OSPF routes (let's say less than 20)
- no other services or
processes
You also have to take
cost into consideration:
This does not justify the
need for a 7200 or a ASR as your requirement does not include a full table,
however, with multiple peers, eBGP, a beefier processor would be needed. The
only router that supports anything above 200Mbps (100Mbps plus 100Mbps
downstream to your network ) is the 3900 series based on packets per second.
Note: The ISR routers feature an ASIC bus, replacing the PCI bus found in older
routers. Please note that unlike ASIC driven switches and routers, the ASIC
found in the ISR line of routers is just for bus operation only. Routing
functions are still fully handled by the CPU
http://www.cisco.com/web/partners/downloads/765/tools/quickreference/routerperformance.pdf
The 2800 routes do not
have the performance to meet 200Mbps.
Customers interested in
purchasing Cisco router or its price, please refer to below links:
