BGP Labs: Use BGP Route Reflectors
In the previous BGP labs, we built a network with two adjacent BGP routers and a larger transit network using IBGP. Now let’s make our transit network scalable with BGP route reflectors, this time using a slightly larger network:
BGP Labs: Use BGP Route Reflectors
In the previous BGP labs, we built a network with two adjacent BGP routers and a larger transit network using IBGP. Now let’s make our transit network scalable with BGP route reflectors, this time using a slightly larger network:
netlab 1.7.0: Lab Validation, Fabrics, BGP Nerd Knobs
It’s been a while since the last netlab release. Most of that time was spent refactoring stuff that you don’t care about, but you might like these features:
- You can run automated lab validation tests with the netlab validate command. I will explain how I use that in BGP labs in a few days.
- If you want to build large leaf-and-spine topologies, you’ll love the fabric plugin.
- The bgp.domain plugin allows you to create topologies with multiple sites using the same BGP AS number.
- The bgp.policy plugin got AS-path prepending.
- bgp.originate plugin can be used to originate BGP IPv4 and IPv6 prefixes.
As always, we also improved the platform support:
netlab 1.7.0: Lab Validation, Fabrics, BGP Nerd Knobs
It’s been a while since the last netlab release. Most of that time was spent refactoring stuff that you don’t care about, but you might like these features:
- You can run automated lab validation tests with the netlab validate command. I will explain how I use that in BGP labs in a few days.
- If you want to build large leaf-and-spine topologies, you’ll love the fabric plugin.
- The bgp.domain plugin allows you to create topologies with multiple sites using the same BGP AS number.
- The bgp.policy plugin got AS-path prepending.
- bgp.originate plugin can be used to originate BGP IPv4 and IPv6 prefixes.
As always, we also improved the platform support:
The BGP Origin Attribute
Kristijan Taskovski asked an interesting question related to my BGP AS-prepending lab:
I’ve never personally done this on the net but….wouldn’t the BGP origin code also work with moving one’s ingress traffic similarly to AS PATH?
TL&DR: Sort of, but not exactly. Also, just because you can climb up ropes using shoelaces instead of jumars doesn’t mean you should.
Let’s deal with the moving traffic bit first.
The BGP Origin Attribute
Kristijan Taskovski asked an interesting question related to my BGP AS-prepending lab:
I’ve never personally done this on the net but….wouldn’t the BGP origin code also work with moving one’s ingress traffic similarly to AS PATH?
TL&DR: Sort of, but not exactly. Also, just because you can climb up ropes using shoelaces instead of jumars doesn’t mean you should.
Let’s deal with the moving traffic bit first.
Worth Reading: DNS over IPv6
What happens when you let a bunch of people work on different aspects of a solution without them ever talking to each other? You get DNS over IPv6. As nicely explained by Geoff Huston, this is just one of the bad things that could happen:
Worth Reading: DNS over IPv6
What happens when you let a bunch of people work on different aspects of a solution without them ever talking to each other? You get DNS over IPv6. As nicely explained by Geoff Huston, this is just one of the bad things that could happen:
Worth Reading: Use of HTTPS DNS Resource Records
Around 30 years after we got the first website, the powers that be realized it might make sense to put this is how you access a web server information (including its IPv4 and IPv6 address, and HTTP(S) support information) directly into DNS, using HTTPS Resource Records. It took us long enough 🤷♂️
Worth Reading: Use of HTTPS DNS Resource Records
Around 30 years after we got the first website, the powers that be realized it might make sense to put this is how you access a web server information (including its IPv4 and IPv6 address, and HTTP(S) support information) directly into DNS, using HTTPS Resource Records. It took us long enough 🤷♂️
30 Days Left to Buy ipSpace.net Subscription
When I announced the lifetime ipSpace.net subscription in early September, I also mentioned that you won’t be able to purchase any ipSpace.net subscription after December 31st, 2023.
As of today, you have 30 days left to decide, and don’t wait till the last minute – I plan to turn off the purchasing process sometime during the business hours of December 31st as I hope to have more interesting things to do in the evening.
The BGP Multi-Exit Discriminator (MED) Saga
Martijn Van Overbeek left this comment on my LinkedIn post announcing the BGP MED lab:
It might be fixed, but I can recall in the past that there was a lot of quirkiness in multi-vendor environments, especially in how different vendors use it and deal with the setting when the attribute does exist or does not have to exist.
TL&DR: He’s right. It has been fixed (mostly), but the nerd knobs never went away.
In case you’re wondering about the root cause, it was the vagueness of RFC 1771. Now for the full story ;)
The BGP Multi-Exit Discriminator (MED) Saga
Martijn Van Overbeek left this comment on my LinkedIn post announcing the BGP MED lab:
It might be fixed, but I can recall in the past that there was a lot of quirkiness in multi-vendor environments, especially in how different vendors use it and deal with the setting when the attribute does exist or does not have to exist.
TL&DR: He’s right. It has been fixed (mostly), but the nerd knobs never went away.
In case you’re wondering about the root cause, it was the vagueness of RFC 1771. Now for the full story ;)
BGP Labs: Set BGP Communities on Outgoing Updates
It’s hard to influence the behavior of someone with strong opinions (just ask any parent with a screaming toddler), and trying to persuade an upstream ISP not to send the traffic over a backup link is no exception – sometimes even AS path prepending is not a strong enough argument.
An easy solution to this problem was proposed in 1990s – what if we could attach some extra attributes (called communities just to confuse everyone) to BGP updates and use them to tell adjacent autonomous systems to lower their BGP local preference? You can practice doing that in the Attach BGP Communities to Outgoing BGP Updates lab exercise.
BGP Labs: Set BGP Communities on Outgoing Updates
It’s hard to influence the behavior of someone with strong opinions (just ask any parent with a screaming toddler), and trying to persuade an upstream ISP not to send the traffic over a backup link is no exception – sometimes even AS path prepending is not a strong enough argument.
An easy solution to this problem was proposed in 1990s – what if we could attach some extra attributes (called communities just to confuse everyone) to BGP updates and use them to tell adjacent autonomous systems to lower their BGP local preference? You can practice doing that in the Attach BGP Communities to Outgoing BGP Updates lab exercise.
Can a Router Use the Default Route to Reach BGP Next Hops?
TL&DR: Yes.
Starting with RFC 4271, Route Resolvability Condition:
- A route without an outgoing interface is resolvable if its next hop is resolvable without recursively using the same route.
- A route with an outgoing interface is always considered resolvable.
- BGP routes can be resolved through routes with just a next hop or an outgoing interface.
Can a Router Use the Default Route to Reach BGP Next Hops?
TL&DR: Yes.
Starting with RFC 4271, Route Resolvability Condition:
- A route without an outgoing interface is resolvable if its next hop is resolvable without recursively using the same route.
- A route with an outgoing interface is always considered resolvable.
- BGP routes can be resolved through routes with just a next hop or an outgoing interface.
Worth Reading: Network Automation with GitHub Actions
George Davitiani put together a lovely proof-of-concept using GitHub actions to deploy modified configurations to network devices. Even better, he documented the whole setup, and the way to reproduce it. I’m positive you’ll find a few ideas browsing through what he did.
Worth Reading: Network Automation with GitHub Actions
George Davitiani put together a lovely proof-of-concept using GitHub actions to deploy modified configurations to network devices. Even better, he documented the whole setup, and the way to reproduce it. I’m positive you’ll find a few ideas browsing through what he did.
Worth Reading: Going CCNP Emeritus
Daniel Teycheney decided not to renew his CCNP status and used this opportunity to publish his thoughts on IT certifications. Not surprisingly, I agree with most of the things he said, but I never put it in writing so succinctly.
Red Pill Warning: Reading his blog post might damage your rosy view of the networking industry. You’ve been warned ;)