Screen Recording 2024 07 18 204849

Summary

The video script discusses the concept of 'lift and shift' in data centers, focusing on the process of migrating servers while maintaining connectivity. It explains policy-based routing (PBR) and how it directs packets to specific destinations. The speaker also details the technical steps involved in changing routing configurations, including updating access lists and route maps, to ensure seamless network transitions.

Takeaways

• 😀 The term 'lift and shift' is frequently mentioned, referring to the process of moving servers into a data center environment.
• 🔌 Servers typically need to connect to the data center network (DCN), and in the context of 'lift and shift', they continue to use their old firewalls or paths.
• 🚀 The change being made involves policy-based routing (PBR), which allows for the redirection of packets from servers to different paths based on predefined policies.
• 🛠️ The speaker is making changes to a routing map and an access list, which are crucial components in managing how servers communicate within the network.
• 🌐 The use of wildcard notation in network addresses is explained, helping to understand how subnet masks are represented and interpreted.
• 🚦 The concept of changing the 'next hop' for servers is likened to changing train tracks at a station, emphasizing the redirection of data flow.
• 📈 The speaker discusses the complexity of access lists, noting that some can be very long and contain numerous entries, which can be challenging to manage.
• 🔍 The script mentions the use of 'show IP access list' commands to view current network configurations and monitor network traffic.
• 👥 The speaker references past experiences and colleagues, providing a historical context and personal anecdotes related to network management.
• 🚀 The script concludes with a discussion about preparing for a migration, highlighting the importance of careful planning and coordination in network changes.

Q & A

What is the term 'lift and shift' mentioned in the script?

The term 'lift and shift' refers to the process of moving servers or applications from one environment to another without significant changes to the application code. In this context, it is used to describe the movement of servers into the data center network (DCN).

What is the purpose of connecting servers to the DCN?

Servers generally need to connect to the DCN to ensure proper network integration and communication. This connection is crucial for maintaining the necessary network paths and security measures within the data center.

What is PBR and how does it relate to the script?

PBR stands for Policy Based Routing. It is a method used to control the path that network packets take based on certain policies. In the script, PBR is being used to change the routing path of packets from servers to a different gateway due to an upgrade in the DCN.

What changes are being made to the routing in the script?

The changes involve modifying a route map and an access list to direct packets from servers to a new gateway. This is necessary because the DCN is upgrading some layer three devices, which requires changing one router with another.

What is the significance of the wildcard notation in the script?

The wildcard notation is used to represent subnet masks in a more concise form. In the script, '255.255.255.3' is equivalent to '255.255.252.0', which is further simplified to a /22 CIDR notation, indicating a subnet mask of 255.255.22.0.

What does the script mean by 'show IP route'?

'Show IP route' is a command used in networking to display the routing table of a device. It shows where the device will send packets based on their destination IP addresses.

What is the purpose of changing the access list in the script?

The access list is being changed to standardize and update the network security policies. This ensures that the servers are correctly directed to their new destinations and that the network remains secure.

What is the relationship between the access list and the route map in the script?

The access list is used in conjunction with the route map to determine the path that packets will take. The route map matches the IP addresses in the access list and then applies the routing policies accordingly.

What is the significance of the subnets mentioned in the script (10761, 10762, 10108, 5222)?

These subnets represent different network segments within the data center. The script discusses routing changes for servers located in these subnets, directing them to a new gateway (10108.5222) instead of their current default path.

What is the role of Chris and Bik in the script?

Chris and Bik are team members involved in the network migration process. They are responsible for preparing and executing the changes to the network configuration, ensuring a smooth transition during the migration.

Outlines

00:00

🔄 Lift and Shift in Data Center Networking

This paragraph discusses the concept of 'lift and shift' in the context of data center networking. It explains that servers often need to connect to the data center network (DCN) and that the term 'lift and shift' is frequently used in this scenario. The speaker introduces a device that facilitates this process. The conversation also delves into the technical aspects of connecting servers to the internet through old firewalls or paths, and the need to update these connections as part of the lift and shift process. Policy-based routing (PBR) is introduced as a method to direct packets from servers to specific destinations, rather than following a default route. The speaker outlines the changes involved in updating the routing map and access list to accommodate these new paths, particularly in the context of a data center upgrade.

05:01

🛠️ Configuring Access Lists and Route Maps

In this paragraph, the focus shifts to the technical details of configuring access lists and route maps in a network. The speaker discusses the process of updating an existing access list by erasing it and replacing it with a new one, which is necessary for standardization. The conversation highlights the complexity of managing access lists, especially when they are extensive, as seen in the case of the 'opwdd' agency. The speaker also explains the relationship between route maps and access lists, emphasizing the importance of matching IP addresses in the route map. The paragraph concludes with a discussion about the visibility of network flows and the potential for monitoring and managing these flows through access list configurations.

10:02

🚀 Preparing for Network Migration

This paragraph details the preparations for a network migration. The speaker and their team are ready to proceed with the migration, and the speaker provides a brief overview of the steps involved. They discuss the process of copying and pasting configurations into the network devices, emphasizing the importance of careful coordination to avoid downtime. The speaker also mentions the size of the configuration changes, which are relatively small in this case. The paragraph concludes with the speaker and their team preparing to execute the migration, with a focus on ensuring that the process is smooth and does not disrupt network operations.

Keywords

💡Data Center

A data center is a facility that houses a large number of servers, storage systems, and other computing resources used to manage, process, and store data. In the script, the data center is mentioned as the destination for servers that are being 'lift and shifted,' indicating a migration or transfer of computing resources from one location to another within the data center infrastructure.

💡Lift and Shift

Lift and shift is a term often used in IT to describe the process of moving applications or services from one environment to another without significant changes to the application code. In the context of the script, 'lift and shift' refers to the migration of servers to a new data center network, maintaining their connection to the internet through their existing firewalls or paths.

💡DCN (Data Center Network)

DCN stands for Data Center Network, which is the network infrastructure within a data center that connects servers, storage devices, and other components. The script mentions connecting servers to the DCN, specifically to the new IP 10108, indicating a reconfiguration of network connections during the lift and shift process.

💡Policy Based Routing (PBR)

Policy Based Routing is a method of routing network traffic based on specific rules or policies. In the script, PBR is used to determine how packets from servers are routed to their destinations. The change in PBR involves directing traffic from one gateway to another, which is part of the network upgrade being discussed.

💡Layer Three Device

A layer three device, in networking, operates at the network layer of the OSI model and is responsible for routing data packets. In the script, the mention of layer three devices refers to the upgrade being performed by the DCN, where one router is being replaced with another to improve network functionality.

💡Route Map

A route map in networking is a set of rules that determine how routing decisions are made. In the script, changing a route map is part of the process to alter the routing of network traffic, specifically directing traffic from one gateway to another during the network upgrade.

💡Access List

An access list is a set of rules that control access to a network resource, typically used for security purposes. In the script, modifying an access list is part of the configuration changes needed to implement the new routing policies, ensuring that traffic is correctly directed according to the updated policies.

💡Wildcard Notation

Wildcard notation is a method used in networking to specify a range of IP addresses. In the script, wildcard notation is explained as a way to represent subnet masks, where zeros are replaced by 255s to indicate the range of addresses covered by the mask. This notation is used to define the routing changes in the network upgrade.

💡CIDR Notation

CIDR (Classless Inter-Domain Routing) notation is a method for specifying IP address ranges in a more compact form. In the script, CIDR notation is used to describe the subnet mask of 255.255.22.0, indicating the range of IP addresses that will be affected by the routing changes.

💡VRF (Virtual Routing and Forwarding)

VRF is a technology that allows multiple virtual routing tables to coexist within the same router. In the script, VRF is mentioned in the context of OMH (presumably an organization or department), where traffic from a server is being routed through a specific VRF, indicating the use of VRF for routing decisions.

💡ACL (Access Control List)

An ACL is a list of rules that determine which traffic is allowed or denied based on source and destination IP addresses. In the script, modifying an ACL is part of the configuration changes to implement new routing policies, ensuring that traffic is correctly filtered and directed according to the updated rules.

Highlights

The concept of 'lift and shift' is introduced, referring to moving servers into the data center.

Servers connect to the data center network (DCN) using a new IP address, 10108.

The term 'PBR' (Policy Based Routing) is explained, which involves directing packets from servers to specific destinations.

A change in routing is discussed, involving a switch from one gateway to another due to DCN upgrades.

The explanation of Wild Card notation and its conversion to subnet mask codes.

Servers located in subnet 10761 and 10762 are directed to a new hub instead of the default path.

The analogy of changing train lines to explain the redirection of network traffic.

The process of modifying access lists and route maps in Cisco devices is described.

The importance of standardizing access list names for consistency and clarity.

The complexity of access lists in different agencies, such as OMH and OPWDD, is highlighted.

The discussion of applying access lists to interconnects versus individual subnets.

The mention of the impact of changes on network flows and the ability to monitor them.

The preparation for a migration and the steps involved in testing the new configurations.

The emphasis on the importance of coordination and communication during the migration process.

The caution against downtime and the need to avoid creating issues during configuration changes.

The technical details of the configuration changes, including the specific lines to be entered.

The finalization of the configuration changes and the testing phase to ensure everything is working as expected.

Transcripts

into the data center so that's where the

lift and shift comes from you're going

to hear that term a lot and hence the

this device that you see on the screen

here has it has the name lift and shift

let me know if if you can

see okay so a lots of these devices

servers generally they need to connect

into the dcn data center proper that's

how we call it that's the 10108 the new

IP

um when we put them into the lift and

shift they were still connecting to the

internet using their old firewalls or

the old path that they had in the in

this case OMH the one that the change

are making Trad is

forh and the other um guys on the call

Chris and U bavik are for opwdd a

different agency so you and I we're

going to take care of for AG tonight and

they're going to take care of

opwdd um what's happening is PBR means

policy based routing it in simple terms

packets coming from a

server we decide we tell them where to

go and take a different path if we don't

they going to take a default route or

they going to take a specific route out

to whatever destination they need to go

with the PBR we can decide which

destination they can go and in this case

we're going to

change one Gateway from one gateway to

another because dcn is upgrading some

devices on their side some layer three

device and is basically changing one

router with

another my changes involves only this

we're going to change a um a rout map

and then an an access

list

um and this is exactly how I said that's

a a source where the the servers are

coming from and this is where they want

to go 10108

5222 this is in Wild Card notation so

whatever you see a zero you actually

replace it in your brain with a 255

255 255 - 3 is 252 and then 255 - 255 is

zero that will give you subnet Mas code

255 255

22.0 which is a sl22 cidr notation right

okay that makes a lot more sense so

so when servers are located that are

located in this subnet which is a

sl24

right 10761 and

10762 so 250 servers here and 250

servers here they want to go to 10 52

any of any IP in this subnet they going

to take this that this next hub instead

of going by

default where they are going today

because if you go and say show IP route

and because it's OMH it's in OMH vrf 10

10852

Z this device says I'm going to send you

to 10761

15250

but if the server wants to go to 10

10852 and it's coming from

10761 we going to send it to a different

next hub 1018 4.22

make

sense okay it's like a like a train

right it reaches a train station and we

we shift we change the whatever that

thing is called when they change the

trains to change the lines to go to a

different destination that's all it

is MHM

yeah yeah did I explain it correctly

Chris bran bik it was wonderful Kat very

good you're the best caline ah no I'm

not you are the best B Patel

DNA no no no uh to give you a little bit

of History Chris Brenan and I used to

work with with ofd back in the days like

15 years ago

and bik used to work for OMH he used to

do this stuff I don't know if you now

you didn't do PBR back then OMH did not

have

PBR but

Bank

no no PBX and PBR they're not the same

thing completely different things yes

PBR also is a beer you

know

y not one of the

best couple months

ago so you know you can before you do it

change you can do show IP access list

and

then this name we're going to change

also the names because we need to get

standard

so this is the existing access list

right now so what I'm going to do I'm

going to erase it and then put a new one

in and then put the r map and and

actually uh that statement should be

above

here so I'm going to just copy paste

them in this order so the very first

thing is going to go into the route map

I'm going to erase

the access list that is

matching I'm going to tell you hey match

a new access list IP address

uh you'll

see sometimes Cisco is confusing like

this because we say we have a route map

which we call it this way we have a

priority on the route map and then we

tell it okay what do we want what what

do we want this broad map to do we want

it to match an IP but instead of access

list Cisco decided to say address

because actually you can actually put an

address in here you can put you can put

a subed here but we said okay we're

going to create an access list cuz we

want to add more there are some access

list that are really really long if we

look at uh

opwdd what they did to

me thousands of lines look at this so

this is just one of one of their access

lists oh my God is it finishing there

you go so it's from

here hundreds of lines they added

here you does opw actually has that many

subnets in lift and

shift

CH it's a

lot but don't these

repeat themselves at some

point oh I see what you did in the same

access list you had different

destination as

well that's why that's so big yeah for

the for the da ones they did basically a

single ACL with all of the different

destinations in oh my God not not like

the much better OMH crafted ones no no

of course of course but at least I try

to keep them consistent and they all

each V has their own access list so yeah

it's it's because the on the da side

it's actually applied to an interconnect

not the individual subnets I believe or

at least that's how it was in the

past yeah so I have you know 3135 it's

only 3135 in here and then we have 3149

and it's only 3149 and

3283 you're not going to see a different

IP in this it's always it's the same

sources but the same

destination so yeah

3296 and tonight we're changing

3054 okay

um another way to to look at it uh you

when you do a show IP

access and the name of the access list

it tells you that actually someone is

talking right now see there are two

matches for from this subnet going to

this

destination and from this subnet going

to this

destination and there is a way to

actually see the

flows um but

we we Chang the code I think or

something happened and I cannot do that

show

platform

Hardware he K not not to intentionally

cut you short here but

uh yeah my pre- testers are good I'm

ready to go ahead with the migration so

okay

uh yeah you and bobic get prepped for it

give me about 30 seconds uh just to get

my side set up and then uh same deal as

last time I'll do a three two one go and

Uno on my great the thets and you guys

can paste your configs in yeah yeah yeah

so how big is your config

p uh mine is uh not too much much uh

they are like literally 40 lines 40

lines 40 50 lines okay you put in first

yours and then I I'll put mine okay I'll

share my screen for the time being so

that you know exactly when

yeah it's fine if we if we if it's

downtime a little bit is nobody is is

going to

die I don't want to create issues with

the 6500 us copy pasting config in the

same time

yeah don't forget to say

it you got return the favor oh my God

you shared both

screens cannot see anything I'm my bad

hang on a second that's okay don't worry

about it yeah just no here how about now

it's good

yeah and increase increase the font a

little bit hold control and

roll there you go there you

go all right we ready

it

yeah all right so I'll do

a let me when you're

ready okay I'm ready all right three two

one go

all right I'm done you're done okay let

me put mine in don't save don't save

yeah I'm not I'm not saving don't

worry just exiting

it

okay okay mine it's in

and the permit 5 has a 10 on WE

4.22 next

stop it's already matching packets

okay

tell them to

test all right than thank

you

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