Posted by: Richard @ Configureterminal.com | October 10, 2008

Update

Hi All,

I have to admit that I’ve been an awful blogger recently L (sorry!), I’m hoping to improve things in the near future – since starting @ Cisco I have been studying in sporadic spells of time instead of a fixed 2 hrs each evening which in-turn has caused me to neglect this blog…

Anyway, I’ve got a few little things to update you on:

1) I’ve been tasked with becoming a “semi-specialist” in UC by my manager – this is due to a need for additional LGov UC resource.  What this means as far as I’m concerned is that I have a much bigger gap in knowledge to fill (compared to R&S) and therefore any spare time I have during the working day will more than likely be spent trawling through endless docs and labs making sure I’m up-to the standard I would expect if I were a customer – on a business and technical level that is.  It’s a challenge I’m ready for and I always welcome additional knowledge to store in my memory banks.  It has been said to me in the past that Cisco tends to keep employees outside of their comfort zone – I have a feeling that this also contributed to the decision on what my specialisation will be…  Just to clarify – I do still have the full support of Cisco for my R&S CCIE quest J

2) David Bombal has continued the development of the Command Memorizer tool – it was already a great learning aid and his commitment to the development of it is great to see.  A number of other bloggers in the community have now used the software and some reviews are linked on the product page.

3) A new consolidated source for Enterprise Technical content has been launched on cisco.com – it’s called “Design Zone”.  It’s organized around Network Architectures, Technologies and Vertical Industries and brings Cisco Validated Designs, legacy design guides and SRNDs, white papers, podcasts, videos together in one place – check it out @ www.cisco.com/go/designzone

4) I received an e-mail whilst in the office announcing that Solarwinds Real Time Netflow Analyzer is now free – a great tool to get started with Netflow…

5) From another e-mail –> Ever wanted to search cisco.com, the IOS bug database, or the command lookup tool from the search box in IE or Firefox? –> add the Cisco.com Searches and Tools to Your Browser (instructions are included)

6) Another e-mail –> CCIE SP Mini-Scenarios by Antonio Soares – definitely worth taking a look at if you’re studying or interested in the CCIE SP track

7) I’ve been fortunate enough to come across some great presentations (with audio) down one of the dark corridors of the intranet here at Cisco.  I have watched some advanced (some of it is very advanced!) breakdowns of “Spanning Tree”, “MLS QoS”, and “RACLs/VACLs/PVLANs” – I’m very confident with Spanning Tree and the presentation confirmed that I should be able to deal with any STP tasks thrown at me in the exams, I did however learn one or two new things from the “MLS QoS” and “RACLs/VACLs/PVLANs” breakdowns.
I thought it would be nice to share some ACL theory with you to see whether it is known/used in the wild by anyone?  If not, and you’re currently studying towards the CCIE R&S, I just know you’ll be really happy with me for introducing you to some extremely technical non-blueprint information after reading this J

Let’s start with a simple “Yes or No” question:

Q) You’ve just added an ACE to an ACL and now your being told that your switch’s TCAM is full, will the ACE still be added and processed by the switch?

 

 

 

 

 

A)
Yes, the route processor will process the ACE after the rest of the ACL has been handled by the TCAM


Relatively easy if you’ve read a bit about the subject.  Now, let’s get deep into ACLs, and how they affect hardware resources…

Take a look at the following configuration on a 6500:

10  access-list 101 permit udp 10.0.0.0 0.255.255.255 range 16384 32767 172.16.0.0 0.15.255.255 range 16384 32767
20  access-list 101 permit udp 10.0.0.0 0.255.255.255 range 16384 32767 192.168.1.0 0.0.0.255 range 16384 32767
30  access-list 101 permit udp 10.1.0.0 0.0.255.255 host 192.168.1.1 eq 53
40  access-list 101 permit udp 10.2.0.0 0.0.255.255 host 192.168.1.1 eq 53
50  access-list 101 permit tcp 10.1.0.0 0.0.255.255 10.20.0.0 0.0.7.255 eq 80
60  access-list 101 permit tcp 10.1.0.0 0.0.255.255 10.20.8.0 0.0.3.255 eq 22
70  access-list 101 permit tcp 10.1.0.0 0.0.255.255 10.100.0.0 0.0.15.255 gt 1023
80  access-list 101 permit tcp 10.2.0.0 0.0.255.255 10.200.200.0 0.0.0.3 eq 22
90  access-list 101 permit tcp 10.2.0.0 0.0.255.255 host 192.168.1.2 eq 443

Q1) How many “Mask Patterns” exist in the ACL?
Q2) How many “Mask Slots” will the ACL below consume in the TCAM?
Q3) How many “L4 Ops” are in the ACL?
Q4) How many “LOUs” does the ACL populate?

 

 

 

 

A1)
A “Mask Pattern” is a unique mask length in an ACL.  The unique masks from the ACL above are 255.0.0.0, 255.240.0.0, 255.255.0.0, 255.255.240.0, 255.255.248.0, 255.255.252.0, 255.255.255.0, 255.255.255.252, and 255.255.255.255 (“host”), and therefore, 9 “Mask Patterns” exist.

A2)
A “Mask Slot” stores Mask Patterns.  Each slot has space to hold 8 patterns and slots are created each time space runs out (i.e. 8 patterns = 1 slot, 9 patterns = 2 slots, 16 patterns = 2 slots, 17 patterns = 3 slots etc etc) .  The number of slots used by the ACL above is therefore 2 –> The 9th pattern triggered the 2nd slot.

A3)
A “L4 Op” (“Layer 4 Operation”) is an occurrence of a “gt”, “lt”, “neq”, or “range” keyword in an ACL – all of which require some level of software processing.  eq” is not included as they are dealt-with by hardware.  If the same L4 Op occurs at the same point of two ACEs it only counts as 1 L4 Op (e.g. see lines 10 vs 20 – “range 16384 32767” = 2 Ops and not 4).  The answer to this question is 3 – in lines 10, 20,  and 70.

A4)
A “LOU” (“Logical Operation Unit”) stores L4 Ops.  Each LOU is made-up of two hardware registers.  ACEs that include a “gt”, “lt”, or “neq” consume 1/2 LOU, whereas the “range” keyword consumes one full LOU.  The LOU registers are system wide, the number available is platform independent, they are shared between ACLs and QoS, and if all LOUs are populated additional ACEs are processed entirely in software.  The number of LOUs populated by the ACL above = 2.5 –> 1 + 1 + 0.5

Believe me, that stuff is the just tip of the iceberg!  And my explanations probably don’t tell you everything you need to know to understand what’s going-on.  The general rule is that a hardware limit for each one of the items above exists, and software will be used after the limit has been reached (possibly affecting perfomance).  For more information click here.

8- After having a few questions fired at me by Channel Partners and Customers during my first few days on the job I realised that the answers might be of use to the readers of this blog, here a couple, I’ll try to publish the interesting/useful ones as they come along:

Q1) “Is it possible to field upgrade a Cat 6509 chassis to a 6509-E. Reason for doing this is to install a SUP-720-10G initially with a view to implementing VSS next year. Looking on CCO it says SUP-720-10G is supported in a 6509 chassis but doesn’t confirm this will work with VSS?

After a chat this was translated to:
“Will the VSS SUP720 work in the standard 6509, and if the answer is yes, can a VSL (VSS) be created between a standard 6509 and a 6509E?”

A1)
Yes and Yes: “From a chassis perspective, both E-Series chassis and non E-Series chassis are supported within a Cisco Virtual Switching System environment, with the exception of the Cisco Catalyst 6503 (non E-Series) and Cisco Catalyst 6509-NEB”
“It should be noted that there is no requirement that the two members of the Cisco Virtual Switching System use the same chassis type. The members consisting of the Cisco Virtual Switching System can be different chassis with varying slot counts”

Q2) “The Unified Communications 500 series ‘Baby Call Manager’ – does this support 7941, 7911 & 7921 wireless handsets. The data sheet suggests it does but I’ve got people telling me it doesn’t. Was hoping you could clarify??”

A2)
Yes, it does support “standard” Cisco UCM compatible phones

Posted by: Richard @ Configureterminal.com | September 17, 2008

“Variance” – Understanding The Balancing Act

This is an extract from a comment left by a visitor to a previous post on this blog:

“i was going through the bsci section and found about load balancing …

i set up a network in gns3 and tested loadbalancing with bandwidth and variance command

what exactly is the difference between those two ? both are used for load balancing right..

when we execute bandwidth command it changes bandwidth to our specified value…

when we execute a command say variance 2what happens inside the router? what factors does variance depends upon … does it depend upon k values or any other more factors”


I’ve found in the past that an answer to a question like this immediately pops into my head (it’s etched ‘in-there’ from CCNA/CCNP), but then, after answering it, I would start to think about it in a little bit more detail and before I know it I had a few niggly questions in my head – you know, the kind that stick with you for days… That’s where reading and labbing to find ALL of the answers can be a really useful thing to do. So, here’s a bit of a breakdown…


Actually… before I start, I’ll try to halt any confusion around the terms I will be using now:
– Where “Route” or “Prefix” could be used, I will use the word “Route”
– Where “Distance” or “Metric”/”Metric Value” or “Cost” could be used, I will use the word “Distance” (to keep with the EIGRP theme – I would usually use Cost)

By default, EIGRP will load-balance across all equal distance paths.
Up-to 4 paths will be installed in the routing table by default, but this can be increased up-to a maximum of 6 using the maximum-paths command under the EIGRP process. So far, this is typical of all of the routing protocols except BGP (and static) on the CCIE blueprint. (Just in case you are interested BGP = 1 and static = 6).

The network below is a starting point for an explanation of the specifics of EIGRP load-balancing – specifically support for unequal distance load-balancing (inc. what the variance, bandwidth, delay commands trigger):

In the network above, there is not one but two, equal, best paths between R5 and 10.1.0.0/24:
R5 – R2 – R1
R5 – R3 – R1


Just in case you’re thinking “it all looks the same to me” –> R4 to R5 = a delay of 30000 vs 20000 (that’s R5’s S1/2)

Both routes have been installed into the routing table, the third route hasn’t been installed because the default variance of 1 is being used by R5 –>
A multiplier of “1” = Use routes that are less than the route(s) with the smallest distance multiplied by “1”

The third route hasn’t been discarded by R5, it remains in the EIGRP topology database as a “Feasible Successor” or “FS” (a backup that can be installed in the event of a failure of the primary route(s)) but not in the routing table, here is the output of show ip eigrp topology and show ip route on R5:

R5#show ip eigrp topology
IP-EIGRP Topology Table for AS(100)/ID(192.168.45.5)

Codes: P – Passive, A – Active, U – Update, Q – Query, R – Reply,
r – reply Status, s – sia Status

P 10.1.0.0/24, 2 successors, FD is 27136000
via 192.168.25.2 (27136000/26624000), Serial1/0
via 192.168.35.3 (27136000/26624000), Serial1/1
via 192.168.45.4 (27392000/26624000), Serial1/2
P 192.168.45.0/24, 1 successors, FD is 26368000
via Connected, Serial1/2
P 192.168.35.0/24, 1 successors, FD is 26112000
via Connected, Serial1/1
P 192.168.12.0/24, 1 successors, FD is 26624000
via 192.168.25.2 (26624000/26112000), Serial1/0
P 192.168.13.0/24, 1 successors, FD is 26624000
via 192.168.35.3 (26624000/26112000), Serial1/1
P 192.168.14.0/24, 1 successors, FD is 26880000
via 192.168.45.4 (26880000/26112000), Serial1/2
via 192.168.25.2 (27136000/26624000), Serial1/0
via 192.168.35.3 (27136000/26624000), Serial1/1
P 192.168.25.0/24, 1 successors, FD is 26112000
via Connected, Serial1/0

R5#show ip route
<lines omitted>
D 192.168.12.0/24 [90/26624000] via 192.168.25.2, 00:00:01, Serial1/0
D 192.168.13.0/24 [90/26624000] via 192.168.35.3, 00:00:01, Serial1/1
D 192.168.14.0/24 [90/26880000] via 192.168.45.4, 00:00:01, Serial1/2
C 192.168.45.0/24 is directly connected, Serial1/2
C 192.168.25.0/24 is directly connected, Serial1/0
10.0.0.0/24 is subnetted, 1 subnets
D 10.1.0.0 [90/27136000] via 192.168.35.3, 00:00:01, Serial1/1
[90/27136000] via 192.168.25.2, 00:00:01, Serial1/0
C 192.168.35.0/24 is directly connected, Serial1/1


The Advertised Distance (AD) received from R2 and R3 for 10.1.0.0/24 = 26624000
The Feasible Distance (FD) to 10.1.0.0/24 via R2 and R3 from R5’s perspective = 27136000


The difference between the AD and the FD of a route is the distance to reach the neighbour advertising the route. Therefore, you could say that the FD is the “real distance” and this is reflected in the routing table.

Let’s work out the math for 10.1.0.0/24…

The default (k’s 10100) EIGRP formula for calculating distance =
256(10000000/’SmallestBW’ + ‘SumOfDelays’/10)

R1-R2-R5 Advertised Distance:
10000000/100 = 100000 <– “10000000/’SmallestBW’”
20000 + 20000 = 40000
<– “SumOfDelays”
40000/10 = 4000
<– “/10”
100000 + 4000 = 104000
<– “+”

104000 x 256 = 26624000 <– “256(”

R1-R2-R5 Feasible Distance:
10000000/100 = 100000
20000 + 20000 + 20000 = 60000
60000/10 = 6000
100000 + 6000 = 106000

106000 x 256 = 27136000

Just to confirm the AD vs FD statement above –> 27136000 – 26624000 = 512000 –> 512000/256 = 2000

Have you noticed anything in the calculations above?
The bandwidth portion of the formula hasn’t changed at-all between the two calculations, this is because the lowest bandwidth along the path is used – and once only … this allows me to address one of the sub-questions from the comment; if you are forcing the lowest bandwidth along the entire path it is possible to affect whether a path will or will not be included in load balancing, if it’s not the lowest nothing will change!

Let’s look into that a bit more –> The interface that connects R5 to R3 will now be increased to a bandwidth of 200Kbps (R5 S1/1), the lowest bandwidth along the path remains as 100 (R1 to R3):

As you can now see below, both of the previously installed routes are still the same (and equal), and remain in the routing table:

R5#show ip eigrp topology
IP-EIGRP Topology Table for AS(100)/ID(192.168.45.5)

Codes: P – Passive, A – Active, U – Update, Q – Query, R – Reply,
r – reply Status, s – sia Status

P 10.1.0.0/24, 2 successors, FD is 27136000
via 192.168.25.2 (27136000/26624000), Serial1/0
via 192.168.35.3 (27136000/26624000), Serial1/1
via 192.168.45.4 (27392000/26624000), Serial1/2

P 192.168.45.0/24, 1 successors, FD is 26368000
via Connected, Serial1/2
P 192.168.35.0/24, 1 successors, FD is 13312000
via Connected, Serial1/1
P 192.168.12.0/24, 1 successors, FD is 26624000
via 192.168.25.2 (26624000/26112000), Serial1/0
P 192.168.13.0/24, 1 successors, FD is 26624000
via 192.168.35.3 (26624000/26112000), Serial1/1
P 192.168.14.0/24, 1 successors, FD is 26880000
via 192.168.45.4 (26880000/26112000), Serial1/2
via 192.168.25.2 (27136000/26624000), Serial1/0
via 192.168.35.3 (27136000/26624000), Serial1/1
P 192.168.25.0/24, 1 successors, FD is 26112000
via Connected, Serial1/0

R5#show ip route
<lines omitted>
D 192.168.12.0/24 [90/26624000] via 192.168.25.2, 00:00:01, Serial1/0
D 192.168.13.0/24 [90/26624000] via 192.168.35.3, 00:00:01, Serial1/1
D 192.168.14.0/24 [90/26880000] via 192.168.45.4, 00:00:01, Serial1/2
C 192.168.45.0/24 is directly connected, Serial1/2
C 192.168.25.0/24 is directly connected, Serial1/0
10.0.0.0/24 is subnetted, 1 subnets
D 10.1.0.0 [90/27136000] via 192.168.35.3, 00:00:01, Serial1/1
[90/27136000] via 192.168.25.2, 00:00:01, Serial1/0

C 192.168.35.0/24 is directly connected, Serial1/1


Now, let’s change the bandwidth back to 100Kbps but increase the delay to 3000:

R5#show ip eigrp topology
IP-EIGRP Topology Table for AS(100)/ID(192.168.45.5)

Codes: P – Passive, A – Active, U – Update, Q – Query, R – Reply,
r – reply Status, s – sia Status

P 10.1.0.0/24, 1 successors, FD is 27136000
via 192.168.25.2 (27136000/26624000), Serial1/0
via 192.168.35.3 (27392000/26624000), Serial1/1
via 192.168.45.4 (27392000/26624000), Serial1/2

P 192.168.45.0/24, 1 successors, FD is 26368000
via Connected, Serial1/2
P 192.168.35.0/24, 1 successors, FD is 26368000
via Connected, Serial1/1
P 192.168.12.0/24, 1 successors, FD is 26624000
via 192.168.25.2 (26624000/26112000), Serial1/0
P 192.168.13.0/24, 1 successors, FD is 26624000
via 192.168.35.3 (26880000/26112000), Serial1/1
P 192.168.14.0/24, 1 successors, FD is 26880000
via 192.168.45.4 (26880000/26112000), Serial1/2
via 192.168.25.2 (27136000/26624000), Serial1/0
via 192.168.35.3 (27392000/26624000), Serial1/1
P 192.168.25.0/24, 1 successors, FD is 26112000
via Connected, Serial1/0

Because delay always has an effect on a route’s distance, a clear ‘winner’ now exists; just one route is now in the routing table:

R5#show ip route
<lines omitted>
D 192.168.12.0/24 [90/26624000] via 192.168.25.2, 00:00:01, Serial1/0
D 192.168.13.0/24 [90/26880000] via 192.168.35.3, 00:00:01, Serial1/1
D 192.168.14.0/24 [90/26880000] via 192.168.45.4, 00:00:01, Serial1/2
C 192.168.45.0/24 is directly connected, Serial1/2
C 192.168.25.0/24 is directly connected, Serial1/0
10.0.0.0/24 is subnetted, 1 subnets

D 10.1.0.0 [90/27136000] via 192.168.25.2, 00:00:01, Serial1/0
C 192.168.35.0/24 is directly connected, Serial1/1


The path of R5 – R2 – R1 will be used for traffic flowing from R5 to 10.1.0.0/24, the route via R3 has been relegated to a FS; this means no load-balancing:

When we have this kind of situation it allows us to have a play with the variance command. To use all three paths in a load-balanced setup we need to compare the ‘worst’ distance with the ‘best’ (aka the Successor):

Worst FD = 27392000
Best FD = 27136000

27136000 x 1 = 27136000
Is 27392000<27136000?
NO

27136000 x 2 = 54272000
Is 27392000<54272000?
YES

To include all three paths in a load-balanced setup we need R5 to have a variance value of 2 set, here is the outcome of configuring this:

R5#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R5(config)#router eigrp 100
R5(config-router)#variance 2
R5(config-router)#do show ip eigrp topology
IP-EIGRP Topology Table for AS(100)/ID(192.168.45.5)

Codes: P – Passive, A – Active, U – Update, Q – Query, R – Reply,
r – reply Status, s – sia Status

P 10.1.0.0/24, 1 successors, FD is 27136000
via 192.168.25.2 (27136000/26624000), Serial1/0
via 192.168.35.3 (27392000/26624000), Serial1/1
via 192.168.45.4 (27392000/26624000), Serial1/2
P 192.168.45.0/24, 1 successors, FD is 26368000
via Connected, Serial1/2
P 192.168.35.0/24, 1 successors, FD is 26368000
via Connected, Serial1/1
P 192.168.12.0/24, 1 successors, FD is 26624000
via 192.168.25.2 (26624000/26112000), Serial1/0
P 192.168.13.0/24, 1 successors, FD is 26624000
via 192.168.35.3 (26880000/26112000), Serial1/1
P 192.168.14.0/24, 1 successors, FD is 26880000
via 192.168.45.4 (26880000/26112000), Serial1/2
via 192.168.25.2 (27136000/26624000), Serial1/0
via 192.168.35.3 (27392000/26624000), Serial1/1
P 192.168.25.0/24, 1 successors, FD is 26112000
via Connected, Serial1/0
R5(config-router)#do show ip route
<lines omitted>
D 192.168.12.0/24 [90/26624000] via 192.168.25.2, 00:00:01, Serial1/0
D 192.168.13.0/24 [90/27392000] via 192.168.45.4, 00:00:01, Serial1/2
[90/26880000] via 192.168.35.3, 00:00:01, Serial1/1
[90/27136000] via 192.168.25.2, 00:00:01, Serial1/0
D 192.168.14.0/24 [90/26880000] via 192.168.45.4, 00:00:01, Serial1/2
[90/27392000] via 192.168.35.3, 00:00:01, Serial1/1
[90/27136000] via 192.168.25.2, 00:00:01, Serial1/0
C 192.168.45.0/24 is directly connected, Serial1/2
C 192.168.25.0/24 is directly connected, Serial1/0
10.0.0.0/24 is subnetted, 1 subnets
D 10.1.0.0 [90/27392000] via 192.168.45.4, 00:00:01, Serial1/2
[90/27392000] via 192.168.35.3, 00:00:01, Serial1/1
[90/27136000] via 192.168.25.2, 00:00:01, Serial1/0

C 192.168.35.0/24 is directly connected, Serial1/1


And there you go, all three paths will be used:

Notes. –>
– Variance = Whole numbers only (aka Integers)
– When I say “Worst” I mean the least-preferred FS that you wish to use in load-balancing
– Traffic will by-default be distributed proportionately to the ratios of the distances that are associated with the different routes
— On a per-destination basis

Other stuff

From my understanding of things, delay has is a direct relationship with the default bandwidth/clock rate of an interface – the higher the default bandwidth, the lower the delay. I assume the original intentions were for the delay value to be dynamic in nature – based on Round Trip Time? but, that doesn’t seem to have happened. If we want to affect EIGRPs calculations in its default state we have the option of adjusting bandwidth or delay – delay is usually chosen because it doesn’t affect other functions running on the router – e.g. QoS calculations. Delay is also usually the weapon of choice because it guarantees a change to a route’s distance (see above). If an additional ‘metric contributor’ (k value) is added to the EIGRP distance calculations it can affect whether a path is or is not included in load balancing by effecting a route’s distance.
(Mini-disclaimer –> An offset-list can also be used to affect a route’s distance…)


The Feasibility Condition applies at all times – a route is only eligible for load balancing if it has an AD that is less than the FD of the Successor route(s).

EIGRP also supports load sharing (intelligent load-balancing), multi-interface load splitting allows you to efficiently control traffic that travels across multiple interfaces to the same destination:

traffic-share min
If multiple paths are available to the same destination, only paths with the minimum distance will be used, FS routes will remain in the routing table for quick convergence in the event of a failure. (never more than six and can be controlled by dynamic routing protocol max paths). Extra paths are discarded. If paths are removed from the routing table, pending routes are added automatically.

traffic-share min across-interfaces
Multi-interface load sharing on different interfaces with equal distance paths.
When the maximum path limit has been reached and a new path is installed, the router compares the installed paths.

traffic-share balanced [across-interfaces]
The router distributes traffic proportionately to the ratios of the distances that are associated with different routes (rounds down).
– balanced is the default

To summarise/answer the questions in the comment:

“i set up a network in gns3 and tested loadbalancing with bandwidth and variance command what exactly is the difference between those two ? both are used for load balancing right”
The only link between the bandwidth of an interface (inc. the command itself) and EIGRP is the fact that by default bandwidth is taken into consideration when EIGRP calculates a given route’s distance – hence load balancing can be affected by bandwidth

“when we execute bandwidth command it changes bandwidth to our specified value”
Yes – we enter it in Kbps form, and it is used as a ‘logical’ reference by the router (i.e. you could set the bandwidth of an interface higher than its clock rate if you really wanted to)


“when we execute a command say variance 2 what happens inside the router? what factors does variance depends upon … does it depend upon k values or any other more factors”
Configuring a variance of 2 would tell the router to load balance across any paths that have a distance less than 2x the distance of the best route available (i.e. the successor. Note. the feasible condition still applies). K values affect distance calculation and therefore could affect whether a route’s distance is within 2 x ‘best path’s distance’ or not.

Thank you to Rakesh for the comment/question – it gave me the opportunity to make sure I know the theory. And like always, if anybody notices an error – please let me know J

Posted by: Richard @ Configureterminal.com | September 4, 2008

Nooooooooooooooooooooooooooooooooo!!!!!!!!!!!!!!!!

I was sat at my study desk last night doing my usual thing….. “Oh, I better backup my docs, I’ve not done it in a while” (that’s in my head by the way and not me talking to myself!) –> USB HDD connected –> ‘Start’ – ‘Run’ – ‘SyncToy’ –>

‘Run’ –> “right, back to work” –> “time to explain EIGRP variance” (after a comment from another blogger requesting it – I thought it would be a useful exercise) –> ‘My Documents’…’EIGRP’ –> “WHERE’S IT GONE!”
The directory structure was fine but over the course of a couple of minutes I had lost an incredible number of files… ‘Favorites’ – 50% empty, ‘My Pictures’ – 90%, ‘Cisco Learning’ – 90% (where ALL of my notes, workbooks, dynamips labs, etc resided), ‘Articles’ – 100%, it looked like this:

Basically, what had happened is that due to the fact that I had been an idiot and thought “I might edit a file whilst it’s on the USB HDD” I had left the Microsoft SyncToy mode to synchronisation which means any moves, adds, deletes, and changes are synchronised between two folders – one folder was my login profile inc. ‘My Documents’, the other was a folder called ‘Synchronised’ on my USB HDD.  During the synchronisation my USB HDD had failed and for some stupid reason SyncToy has decided that means everything is empty…  EIGHT months work + a lot more gone in a matter of seconds!  How much of it have I managed to retrieve?  a few old versions of my notes up-to BGP from a .pst file that hadn’t been lost, but nothing else!  That means no QoS, Multicast, MPLS,  IPv6 etc etc – probably the areas I need to focus on most!  I have tried file restoration from my c: drive without any luck and the USB HDD now spins for a few seconds and then gives up.

Sometimes life throws challenges like this at you so I’m just going to have to get on with it, but what I have learned from this experience is that I need to go back to backing-up my backups J

Posted by: Richard @ Configureterminal.com | September 3, 2008

The last few weeks

Weeks 29 to 34 à “No excuses now”

 


Weeks 29 to 34 Study Time (estimated):

Study Hours = 26 inc.
Lab Hours = 3Total study time so far:
Total Study Hours = 355  inc.
Total Lab Hours = 23.5

What I have studied during the last 4 weeks:
“Bridging and LAN Switching”
“TCP/IP”
“IP Routing” inc. RIP, EIGRP, + OSPF

Recent test scores:
None (CCIE QuickFire Workbook only – about 85% correct first time)


After a few weeks of not being able to put the number of hours I would like to into studying I can now see the light at the end of the tunnel.  I am hoping that everything should return to ‘normal’ from now on – I have just returned from the last of the trips-away scheduled for during my first few weeks at Cisco (2-day training course) and will now be at home in the evenings for the immediate future.  Within the limited number of study hours I have managed to do over the last few weeks I have used some of the time to start and finish documenting (inc. labbing) all of the methods of route filtering for RIP that I can think of/find, and also to start doing the same thing for EIGRP – the idea being that I will complete the task for each routing protocol on the CCIE R&S blueprint.
I recognised a while back that I was in desperate need of some way of ‘mixing-up’ my learning, and so, I decided to spend some time working through creating some ‘pretty’ images that depict various configuration practices – allowing me to mix theory with some CLI time
J


I have traffic blackholing/droping, advert filtering, and neighbor adjacency prevention on my todo list in addition to the route filtering I am working on now.
Here is what I’ve put-together for RIP Route Filtering:


Please note.  It’s a large image/file that needs some zooming to be readable – it might be worthwhile downloading it first.
Please please please leave a comment if I have missed any methods/made any mistakes
J


I plan to complete the EIGRP image, work through OSPF, and then finish with BGP.

Leanne continues to be a star – I don’t mention her enough on this blog – without her support (inc. a kick up the **** every now and again) I would really struggle to stay focused on the prize at stake.  It was a very personal goal of mine in the past but now I’m also looking around at Cisco and realising that I have so much catching up to-do! – the amount the people around me know not only about technologies/protocols but the Cisco hardware itself is quite astonishing!  And R&S is just “the basics” in many people’s eyes!

Lastly, I thought I would share some pics from last week – my first visit to San Francisco, and my first GSM:


This is just before Rick Justice’s Hollywood style entrance (John Chambers closed the show)


A view of the Bay Bridge from the restaurant hosting my team’s get-together dinner – the sheer size of it is a sight to behold – the island to the left isn’t the end of it!


San Francisco @ Night – taken from the lift/elevator of the hotel I was staying in (nobody else was in the lift at the time!)

Oh, and it was my daughters first day at school today!  Wow, I can’t believe how quickly she has grown-up!

Posted by: Richard @ Configureterminal.com | August 15, 2008

My trip to San Jose, California

I travelled to San Jose last week to attend Cisco’s “New Hire Field Training” event.  The event was a big success; I visited the HUGE campus @ San Jose for the first time (well, actually it was my first trip to the US full-stop) and experienced the wonder that is the San Jose “Executive Briefing Center”.  This included a full demo of the “Telepresence Experience

(The display quality and audio distribution is simply awesome!)
and the chance to stand in front of a MASSIVE 7940! (sorry no pics).  We were also demo’d some fancy UC solutions, a mobility inc. location tracking solution, as well as a DC/SP solution featuring a CRS-1 – now that is one BIG router!  We watched an IronPort demo on glass panels that turned into a PC display!

and we also had the opportunity to visit the Cisco TV centre
J
It was also a chance for us to meet some of the great minds within Cisco – the speakers were incredible, although, “death by powerpoint” sprang to mind at some points during the week…
If I’m totally honest however, the basis of the event being a success month-after-month is probably down-to the relationships it allows a “new hire” to build; I met some great people from all over the world, including but not limited to – America, Russia, Sweden, Trinidad, Brazil, Germany, and the Netherlands.  I plan to keep in-touch with many of them.
I had two low points during the week (not bad for me
J); the first being when I made the statement “My laptop seems be charging really slowly! it’s like it’s half the rate it normally does” –> I got a reply something like “That’s because it’s 110 volts over here” –> doh L
The other low point was the level of ‘geek excitement’ (not pretty!) I displayed when entering the Cisco Shop! – I ended up buying a new folder, two new shirts, and a sweatshirt – it could have been a lot more!
J  I’ve been told that’s normal but people get really good at sneaking into the shops when no-one is looking…  Numerous freebies were also handed-out at during an evening event, looking back now I’m thinking I may have took too much advantage of that lol
We all got a great insight into the message that the chiefs at Cisco send down to the staff and it was very nice to hear; the ethics of the company were highlighted more-than-once, in addition to Cisco’s desire to help businesses succeed (mini-disclaimer: you may be reading this and have had different experiences/have a different opinion but you can take comfort in the fact that the right message is being broadcasted internally)
I started studying again yesterday evening and barring any major stumbling blocks I plan to continue until my new exam date of September 30th.   My return to the States at the end of the month might be one of those stumbling blocks but the exam date I have chosen should give me some flexibility on that front.  The CCIE QuickFire workbook is a great help, here are a few more questions extracted from it:

INTERFACE BUNDLING QUESTIONS:

1) LACP = {“Proprietary” | “Open Standard ‘standard'”}
1a) What is the maximum number of interfaces supported in a port-channel by LACP?
1b) What is the maximum number of standby interfaces supported by LACP?
1c) PDU’s are sent over the {“Lowest” | “Highest”} numbered VLAN on a trunk
1d) DTP and CDP packets are sent over the {“Lowest No.” | “Highest no. ” | “All”} bundle member(s)

2) PAGP = {“Proprietary” | “Open Standard ‘standard'”}
2a) What is the maximum number of interfaces supported in a port-channel by PAGP?
2b) What is the maximum number of standby interfaces supported by PAGP?
2c) PDU’s are sent over the {“Lowest” | “Highest”} numbered VLAN on a trunk
2d) DTP and CDP packets are sent over the {“Lowest No.” | “Highest No. ” | “All”} bundle member(s)

3) The default priority of a standby interface is {‘number’}
3a) The interfaces with the {“lowest” | “highest”} priorities will be used

4) {LACP | PAGP} supports the silent attribute

5a) The two channel-group command options for LACP are {“‘keyword’ and ‘keyword'”}
5b) The two channel-group command options for PAGP are {“‘keyword’ and ‘keyword'”}
5c) The other two channel-group command options are {“‘keyword’ and ‘keyword'”}

 

 

 

 

 

 

 

 

 

INTERFACE BUNDLING ANSWERS:

1) Open Standard 802.3ad
1a) 8
1b) 8
1c) Lowest
1d) All

2) Proprietary
2a) 8
2b) 0
2c) Lowest
2d) All

3) 32768
3a) Lowest

4) PAGP

5a) Active and Passive
5b) Auto and Desirable
5c) On and Off

I’m so desperate to get hands-on now!  I just keep telling myself that the amount of time I’m spending on the theory now will be advantageous in the long-run.

Lastly, for anybody involved in ‘NHFT August 2008’ reading this post (the host, the event organisers, the speakers, the attendees, etc) –> Thank You J

Posted by: Richard @ Configureterminal.com | July 22, 2008

Week 28 Summary

Week 28 à “An exciting future for me and my family lies ahead”


Week’s Study Time:

Study Hours = 8 inc.
Lab Hours = 0

Total study time so far:
Total Study Hours = 329  inc.
Total Lab Hours = 20.5

What I have studied during the last 2 weeks:
EIGRP
OSPF

Recent test scores:
Boson ExSim tests…

 

I’ve completed my second day at Cisco today, and I’ve been incredibly impressed with how streamlined everything is here!  Everything is in place just to let you get on with what you are employed to do – no distractions, and they really look after you 🙂

Everybody I have come into contact with so-far has been very pleasant and has gone out of their way to help me, glancing around the canteen/restaurant during lunch makes me realise I’m in the company of some of the sharpest minds in the industry – quite intimidating (I’ve been told that is a normal feeling to have – especially with the surroundings @ Bedfont Lakes).

 

I had this idea in my head at the beginning of this week (29) that I would be able to continue studying during my first few days at Cisco – how wrong was I!  You wouldn’t believe how many systems I need to get setup on, not to mention the amount of “New-Hire” and “SE” information I need to read through, unfortunately, studying is going to have to take a back-seat for a little while.  Starting a new job and CCIE level studying just don’t go-together 😦

Realistically, I think I should be aiming to pick-up where I left things next week, and that may possibly cause me to take a look at my written exam date again….
(Although, I will have to ask myself how many times I will allow myself to put the date back? – once so far)

 

Here are a couple of great links thatI have come-across within the Cisco ‘blogosphere’ over the last few days:
1) EBGP Load Sharing @ the NIL Wiki
2) Integrated Routing and Bridging Example @ Cisco Network Engineer

 

And, here are a few sample questions from my workbook, why not test yourself?
I’ll give you an idea of what is being covered by these questions –> 1) = Process Switching…

1) Router Switching Path/Method Option 1
1a) The {“item”} computes the CRC

2) Router Switching Path/Method Option 2
2a) The {“item”} computes the CRC (except the first packet)
2b) Entries are added to the {“item”}
2c) What form of load balancing is the only one supported?
2d) Which command enables this switching method on an interface?

3) Router Switching Path/Method Option 3
3a) Creates a copy of the routing table called the {“name”}
3b)  What is the arrangement of the table above called?
3c) Pointers to the {“item”} are added to the table above
3ca) Entry type 1 in this table
3cb) Entry type 2 in this table
3cc) Entry type 3 in this table
3cd) Entry type 4 in this table
3ce) Entry type 5 in this table
3cf) Unknown information entry description in this table
3d) Both tables reside on the route processor (RP) and are stored in {“location”}
3e) What is the command to enable this switching method globally?
3f) What is the command to enable this switching method on an interface?
3g) What is the default load balancing method for this switching method?
3h) If configured on an inbound int, the packet {will | will not} always be switched in the same way on the outbound int

Scroll down for my answers (correct or not)……

 

 

 

 

 

 

 

 

ANSWERS:
1) Process Switching
1a) Route Processor

2a) Interface Processor
2b) Route Cache
2c) Per-Destination
2d) ip route-cache

3) CEF
3a) FIB
3b) mtrie
3c) Adjacency Table
3ca) Null
3cb) Glean
3cc) Punt
3cd) Discard
3ce) Drop
3cf) Unresolved
3d) DRAM
3e) ip cef
3f) ip route-cache cef
3g) Per-Destination
3h) will

 

I’m going to apologise in advance –> expect to hear even less from me over next couple/few weeks (nothing out of the ordinary their then!)

Posted by: Richard @ Configureterminal.com | July 16, 2008

“To Read”

I had a read through the documentation for Cisco’s recent 12.4(20)T IOS release yesterday, one or two bloggers have posted demonstrations of some of the new features, but here is a list of what I picked-out from the new software feature list and added to my “toread.txt” document:

Application Inspection and Control for SMTP
Configuring Multicast VPN Inter-AS Support
Configuring BGP Neighbor Session Options
Subscription-based Cisco IOS Content Filtering
Embedded Packet Capture
Flexible Netflow
IOS Firewall H.323 Support
Implementing IPv6 for Network Management
Per-VRF Assignment of BGP Router ID
Object Groups for ACLs
User Based Firewall Support
VRF aware Cisco IOS IPS
WCCP Layer 2 Forwarding, Redirection and Return

The main page for IOS release can be found by clicking on the first hyperlink in this post J

Posted by: Richard @ Configureterminal.com | July 16, 2008

Week 27 Summary

Week 27 à “How have I managed to create >400 questions for a routing protocol I have seen described as “SIMPLE” in the past!?”


Week’s Study Time:

Study Hours = 14 inc.
Lab Hours = 0

Total study time so far:
Total Study Hours = 321  inc.
Total Lab Hours = 20.5

What I have studied during the last 2 weeks:
RIPv2
EIGRP
OSPF

Recent test scores:
Numerous Boson ExSim tests….


I’ve made some big strides towards getting my workbook to a point where I can use it as a ‘learning-tool’.  OSPF is now finished
à just 400+ questions later!  A small number of the questions are simply statements copied from my notes and “is” has been changed to the option “{is | is not”} à they won’t ever be challenging questions but they will make sure I think about the specific point.  I’m planning to work through BGP over the next few nights, and then take the time to work through the workbook time-after-time….  I think it’s important I pause after the core switching and routing questions I have put-together to make sure I know the theory inside out (especially for my upcoming written exam).

 

Here are some great links I have come-across within the Cisco ‘blogosphere’:
1) Notes from the Routing TCP/IP books taken by a very talented individual that goes by the name of Stretch (@ Packetlife)
2) Another one from Packetlife
àVisualizing Tunnels
3) Ever heard “We’d better hard-code speed and duplex”
à Greg Ferro @ EtherealMind has sparked a debate following his article….
4) A new venture by Arden Packeer to serve the CCIE online community
à CCIE Magazine
5) Internetwork Expert’s NEW Online Community
6) A new feature introduced in 12.4(20)T explained here
à IOS Packet Capture!

 

If I can find the time, I plan to put-together a “Route Filtering Options” diagram for all of the routing protocols on the R&S blueprint(s) during the next couple of weeks.  The idea being that it will complement the “Summarisation” and “Default Routes” diagrams I have previously posted.

 

Here are a few sample questions from my workbook, why not test yourself?

1) On a NBMA network, if the neighbour State is “Down”, the hello interval is the same as the {“name”}
1a) What is the default value of the ‘interval’ above?

2a) MTU mismatch (router to switch) à Configuration option 1 (on the switch)
2b) MTU mismatch (router to switch)
à Configuration option 2 (on the switch)
2c) MTU mismatch (router to switch)
à Configuration option 3

3a) Which neighbor keywords can be used to stop LSAs from being sent out of a point-to-multipoint interface yet still allow adjacencies to form on it?
3b) Which interface-level command can be used to stop LSAs from being sent out of all other interface types yet still allow adjacencies to form?

4a) Secondary IP network advertisement {does | does not} rely on the advertisement of an interface’s primary IP network
4b) Adjacencies {can | cannot} be formed over/using secondary IP networks (addresses)

Scroll down for my answers (correct or not)……..

 

 

 

 

 

 

 

 

 

 

 

 

 

ANSWERS:
1) PollInterval
1a) 120 seconds

2a) system mtu 1500
2b) system mtu routing 1504
2c) ip ospf mtu-ignore

3a) database-filter all out
3b) ip ospf database-filter all out

4a) does
4b) cannot

Posted by: Richard @ Configureterminal.com | July 15, 2008

At long last….

….we have object-groups for Cisco IOS ACLs!

Head-over to “Object Groups for ACLs” @ CCIE in 3 months to find out more 🙂

Posted by: Richard @ Configureterminal.com | July 8, 2008

Week 25 and Week 26 Summary

Weeks 25 + 26 à “Time to come-up for some air!”


Week’s Study Time:

Study Hours = 16 inc.
Lab Hours = 0

Total study time so far:
Total Study Hours = 307  inc.
Total Lab Hours = 20.5

What I have studied during the last 2 weeks:
EIGRP
OSPF

Recent test scores:
Numerous Boson ExSim tests….


Wow, I’ve got a lot on at the moment!  CCIE studies, working my notice, and PCI DSS have taken over our (as in my family’s) lives completely!  I tried my best to keep-up the momentum I gained from the evenings a couple of weeks ago but it just ‘hasn’t happened’
à I’ve been regularly almost drifting into a sleep whilst converting my notes into questions each evening à I’m just hoping that it’s still all going-in at some level J
I’ve not been fortunate enough to start winding down my activities at work, it’s ended-up being the complete opposite!  Anybody who has come across “PCI” will know exactly why I’m struggling with studies and posting to this blog at the moment (?)
à everything we need to do to meet PCI standards has to be done post-12am, a 6am journey home is a real possibility…. dull headaches …. lax studying…. not enough sleep….
I bet I’m in for a real shock when I reach lab prep! (I need my sleep)

One task I had been given by my manager this last week was to prepare a lab for engineers applying for my current job; the idea being that we gauge a candidate’s competency of all things Cisco.  I can’t disclose the details of the lab right now (for obvious reasons), but I intent to upload it sometime in the near future – maybe it will save somebody some time in the future – it’s not extremely difficult, more a test of the basics:
– “Physical Tasks”
– “Device Management/Administration Tasks”
– “Switching/Layer 2 Tasks”
– “Node and Layer 3 Tasks”
– “Security Tasks”
– Bonus Tasks
I tried to picture myself in my own lab a year ago, and what I would have expected of ‘me’

As you may have gathered from what you have read so far my studies aren’t coming-along as well as I hoped they would, I‘m currently trawling through my OSPF notes and the number of questions I am adding to my ‘CCIE Quickfire’ workbook is verging on ridiculous!  The workbook worked nicely for “Spanning Tree Protocol” and “VLANs and VTP” but routing protocols have so many facts/nuances to learn the list of questions is almost limitless – it seems impossible to know it all inside-out à I’m just hoping the amount of time I’m putting into the workbook now will be worth it when I’ve used it as a learning-tool a few times.

I’ve spotted one or two excellent articles around the ‘blogosphere’ during the last couple of weeks, here are a few of them:

1) Have you ever wondered how you can stop those annoying “Are you sure” prompts popping-up when working on Cisco kit? à see How to stop the verification of file commands @ Blindhog
2) The first of two fantastic posts @ PacketLife.net
à OSPF Area Types
3) And the second
à A huge collection of Wireshark Packet Captures
4) What was the old CCIE exam really like
à find out here

Hopefully, I’ll have some ‘useful’ technical content for you in the near future instead of my weekly rambling
J

« Newer Posts - Older Posts »

Categories