default route Vs BGP

[UCrypto]

Hi ,

I would like to know pros and cons between static route vs BGP between ISP PE router and our customer edge CE routers.if we use our router are low bandwidth and lower hardware capacity (CPU ,RAM ,throughput).May i know Pros and cons

[chrihussey]

Hello,

Static routing is just that. In the absence of the next hop physical interface dropping, the route is active. There are some work arounds to this, but it is not really dynamic and if there is redundancy and alternative / backup routes involved it is harder to achieve. It does require less CPU though.

BGP, like any other routing protocol, is dynamic and provides the ability to re-route traffic if there is redundancy. It can also be controlled in a way to influence routing as one needs. It requires more CPU, but depending on the size of the routing table and requirements, generally it could be wash between the two.

In the end, it there  is no redundancy at the CE, and there is only a single route in an out of the location, static routing would suffice. In instances where there is redundancy with multiple or primary and secondary paths, then BGP would probably the better fit.

Hope this helps.

[Joseph W. Doherty]

In addition to what Chris posted, BGP if often considered if you have two different ISPs. Then, with BGP, your traffic can pick the "best" path.

Multiple Internet BGP, full tables, can impose a load on small routers. What can also be done, if running BGP with your ISP, just take a dynamic default with, or without, a subset of the full BGP route tables. (The later might comprise only networks directly connected to that ISP, again useful if you working with different ISPs.)

Years ago, I found when working with different ISPs, the best combination was accepting a dynamic default from the ISP and using OER (now PfR) to dynamically find the best path. OER actually imposed less load on the ISRs than when I was accepting a full Internet BGP table from both ISPs.

[UCrypto]

i Found internet in some facts. it is correct or another pros and cons ? i have only one ISP which route should i use ?

Static Route	BGP
Less resource usage(CPU,RAM,Bandwidth)	More Secure
Most Stable
No Routing Information ad
cannot get Route information	More resource usage(CPU,RAM,Bandwidth)
Need more configuration

[chrihussey]

If you have only one ISP and a single link to the Internet a default static route should be sufficient. There would really no reason for BGP.

Regards

[UCrypto]

The major different between static route and BGP are - resource usage and routing table only ?

if i have multiple branches and single HUB.( HUB have two internet Link but single ISP )

which one is better ? which benefit  can get more .

[dbeattie · Accepted solution]

In most cases if you have multiple Internet links from one ISP, they will put their own routers in your DC. They will then run a First Hop Resolution Protocol (e.g. HSRP) so that you just need to set up a static default route pointing to their hand-off address. This is fine. Most small-medium companies would work this way. Let the ISP look after all of the complexity. You don't even need CE routers, your external firewall can be configured with the static default route pointing to the ISP's routers.

I have also seen a number of attempts to use BGP when it is not necessary. It often ends up with the techie buying a completely inappropriate router and wondering why it doesn't work. (aka CV polishing)

If you want ISP independence, or multiple independent links with some degree of load sharing (NB not load balancing), yes use BGP, but be aware of the size of router that you need to hold a full table. Consensus puts the table size as over 700k prefixes, so you are looking at an ASR1k or more, regardless of the bandwidth you have bought. I connected to one ISP last year that had 273k prefixes in the local AS alone! You also need to be aware of how your ISP(s) treat your route advertisement. Many of them will modify your advertisements (e.g. through summarisation if you have Provider Assigned addresses -PA- or other manipulation if you have Provider Independent -PI- addresses) that means your intended behaviour gets ignored or even reversed.

Finally, you have the headache of ensuring that your routers are fully hardened because they will be unprotected on the Internet and will undoubtedly be hit by every script-kiddie out there.

Generally, I would suggest that unless you have a good business need for running BGP (mainly due to resilience) don't bother.

I hope this helps. Please come back if you have further questions. If you do go for BGP, I wish you well, your first Internet-BGP installation is usually a lot of fun and a big learning experience.

Regards,

Dave

[UCrypto]

It is my first experience in bgp but i am using my branches router is low end isr 890 series,so i afraid that i doubt my router performance for bgp

[Joseph W. Doherty]

Hmm, I don't know if the 800 series supports BGP, and if it does, unlikely they have the RAM to handle one or more sets of full Internet route tables.