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1500 questions
8
votes
1 answer
Unidirectional Packet Loss
Recently after upgrading several MetroE circuits (L2 connectivity) from 100Mbps to 1Gbps, I noticed that large file transfers fail between some sites; however, the transfer only fails in direction. For instance, consider the following example.
From…
Paul Garrett
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8
votes
2 answers
Moving internally allocated VLANs
A VLAN I need to use is allocated for internal usage (as per vlan internal allocation policy ascending). I can't (easily) move the traffic over to another VLAN for various practical reasons.
I was therefore wondering if there's a trivial way to…
Jan
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8
votes
3 answers
Can 40GBASE-LR4 be used for 4x10G?
I have a 40GBASE-SR4 QSFP transceiver which can be used for 4x10G SFP+ communications using a 40G QSFP+ to 4x10G SFP+ multi-mode optical spliter. I am looking for an LR (single-mode) equivalent of this SR transceiver, but can't find any.
I fear that…
Randomblue
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8
votes
2 answers
Where is Cisco Hardware dCEF's adjacency table stored?
For Cisco Hardware dCEF, based on some documents published on Cisco website, at the ingress line card/interface, conceptually it looks up the FIB with dst IP address, and gets a pointer to an adjacency table entry, where L2 rewrite information is…
wei
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8
votes
4 answers
How to signal a VPLS multihoming change to a L2 CE device
We have the following setup:
Two MX routers connect to the same L2 site. Loop protection / redundancy is done via VPLS multihoming. On the other end are two switches (EX4200 for example).
When the blue link fails the two switches and the rest of…
Sebastian Wiesinger
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8
votes
5 answers
Switchport mode access VLAN & switchport mode trunk on one interface
Googling around to see if this setup on one port is correct (it doesn't look right to me), I'm not really seeing a straightforward answer.
There is an interface with the following configuration:
!
interface GigabitEthernet1/0/3
description Uplink…
PenguinCoder
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8
votes
2 answers
Duplicate IP Address Prevention?
Yesterday a laptop crashed the network because the IP address of the computer was the same as the router. Computers in the network were reaching the laptop instead of the router.
Is there anyway to prevent this from happening?
We currently have a…
Patrick Dubois
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8
votes
3 answers
Can I announce the same block of /24 given to me by ARIN at two different locations?
The setting: Two locations I'm trying to connect. I have a /24 address block from ARIN
Both location have the Same ISP.
The Question:
Can I announce the same /24 address block at the HQ location to Lumen?
Can I announce the same /24 address block…
13months
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8
votes
6 answers
How Does A Layer 2 Switch Differentiate Between Different Networks?
I know that different IP-based networks can be connected to the same layer-2 switch. and I know each network's nodes can communicate just fine, however, no normal traffic can occur between two nodes on two different networks.
My understanding is…
Shadi
- 285
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8
votes
3 answers
BGP - Soft Reset Outbound & Verification
My understanding of the command:
clear ip bgp * soft out
is that the router on which the command is issued will re-advertise everything it knows about BGP to it's neighbors. As I see it, it's as if the two routers are creating a brand new…
BrianK
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8
votes
1 answer
What was the intended use for VLANs 1002, 1003, 1004, 1005? (fddi trcrf fddinet trbrf)
The output of show vlan brief includes VLANs 1002 - 1005:
1002 fddi-default active
1003 trcrf-default active
1004 fddinet-default active
1005 trbrf-default active…
jester
- 127
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8
votes
4 answers
Expanding an HP IRF topology
I'm examining options for a future expansion of our infrastructure. We rent space at a colo so we don't have a dedicated datacenter of our own. This means that our next major expansion will likely involve two discrete cages not immediately adjacent.…
Blue Warrior NFB
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8
votes
2 answers
Which VLANs are allowed on this trunk?
I'm getting some mixed signals when configuring a trunk on a Cisco switch and I'd like to know which VLANs are actually being allowed on it. The way I want it to be is that only VLANs 1,10,20,30,99 should be allowed. Have a look at the…
Axel Kennedal
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8
votes
2 answers
If TCP packets are pre acknowledged, what happens if packets are dropped?
On a VSat link with 800ms RTT latency and 10mbps bandwidth, that means 1MB bandwidth-delay product (data in flight).
According to this useful (but closed) Q/A, packets are injected on both sides of the TCP connection to acknowledge the packets…
Kind Contributor
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8
votes
2 answers
How is IEEE 802.1ad (aka VLAN Tagging, QinQ) valid, when the packets are too large?
Recently i've been dealing with MTU issues. And it all seems to stem from the fact that the ethernet adapter on newer computers default of a frame size of 1504 bytes:
>netsh interface ipv4 show subinterfaces
MTU MediaSenseState Bytes In …
Ian Boyd
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