we will now look at how we go about choosing a border router the slide shows the essential features needed for a border router so this would include robust line rate routing so layer 3 forwarding including ipv4 and ipv6 and static routes a strong cpu is essential and large memory is essential as well for management as with the core router we require secure shell simple network management protocol but it's also very very useful to have the ability to look at flow information every vendor has their own version so cisco's netflow juniper's j flow most switches have s flow and there's the ietf standard called ipfix it's also essential to have dynamic routing protocol support through ospf both ospfv2 and ospfv3 or isis that is necessary as well if your campus is using private ipv4 address space internally hardware redundancy can be useful too especially a dual power supply but then we're back to the same question would it be better buying a whole second device to give us far better redundancy options for optional features for example if we're multi-homing we do need full support for bgp avoid devices where the vendor claims they can do fancy net tricks to get your multi-homing this is not industry standard doesn't scale and will leave a very bad experience for the end user bgp is the only way to implement multi-homing so we need full support for bgp if this is going to be an option in the future and i would recommend the ability to carry the full bgp table it's probably not ultimately essential but it's useful to have as it will give your campers the best option for doing traffic engineering at a later date you need support for all the bgp attributes and implementing bgp policies if you're following this series on network startup resource centers learn.nsrc.org site you'll find lots of videos like this one which describe how to use bgp for multi-homing and traffic engineering for sizing a board or router you require a connection to the upstream provider you want to allow for headroom which is far greater than the link capacity bandwidth upgrades will always be needed traffic goes faster than expected whatever you predict you're going to be wrong because user demands especially if you've been improving your campus network the user demands will be such that you'll be doing upgrades very very frequently you also need to deal with denial of service attacks coming from outside now you're not going to deal with those just by yourself you're going to work with your upstream provider to deal with those but you still need to be able to handle those in the first instance the physical chassis size is irrelevant don't be taken in by vendors trying to sell you bigger is better in fact the smaller is better because you've got reduced power and space requirements the border router needs an internal interface to connect to the network core it needs an external interface to connect to the upstream provider two if you're going to plan to go get two providers at a later date and you will find that usually one rack unit by just over an inch and a half is sufficient so let's look at a low-cost example first we've included the microtic ccr 1036 as an example it's got eight gigabit ethernet ports in copper it's got two sfp or sfp plus ports supporting one gig or 10 gig depending what's plugged in and its real-world throughput is well in excess of a gigabit per second just note that bgp only runs on one core so running a full bgp table on this might be a bit of a challenge at the time of making this recording microticket actually released a software beta which allowed bgp to run on multiple cores of this device so in future it might be more suited for the campus border router than it might be right now its v6 implementation we find is incomplete so keep that in mind especially if your campus has fully deployed ipv6 if we look at the high end again typical examples that nsrc has been involved in with over the years include the cisco 7301 and the 7201 in the early 2000s so 2000 to 2010 these were probably the benchmark for a ru border router in many many networks they're no longer supported by cisco but an excellent 1r urt with 3 or 4 gigabit ethernet interfaces respectively we found that the 7301 is probably good for 300 megabits per second in real world with all the features turned on the 7201 is twice the speed cisco will try and promote its isr series as equivalent but considerably more expensive and don't really have the feature set that was useful and made the 7201 so useful 10 years ago these days we find the cisco asr 1000 series has become the effective replacement for the 7201 a popular choice is the asr 10001x notice again one ru it's got two 10 gigabit ethernet ports and six one giga ethernet ports just be aware that the 10 gig ethernet ports are only enabled if you buy a feature license from cisco the default router only has the six one gig ethernet ports activated and its bigger sister is the asr 1002x which are six one gig ethernet ports and three empty slots available for expansion and the device can go up to 36 gigabits per second if the licenses are purchased if we move over to the juniper side of the fence mx-5 and mx80 10 years ago were very popular routers and a lot of network infrastructure one common chassis which is 2ru and the model was upgradable by license there's still very good routers as far as throughput goes but be aware that the control plane is very slow we do not recommend these if bgp is going to be a requirement for you as the control plane is so slow it takes a substantial amount of time for these routers to actually converge the bgp session but for throughput still very good availability today notice that quite quite significant size 2ru reasonable amount of power also needed to run them junipers i suppose in the process of replacing these with the mx 150 which is 1ru throughput of 40 gig and allowing eight ten one hundred thousand copper ports and two sfp so one gig ports and two sfp plus 10 gig ports and at the higher end so the higher throughputs for the biggest campuses probably the cisco asr 9001 and the juniper mx204 both outputs well over 100 gigabits per second supporting 10 gig ethernet, 40 gig ethernet and even 100 gig ethernet interfaces.
© Produced by Philip Smith and the Network Startup Resource Center, through the University of Oregon.
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