Questions tagged [gre]

Generic Routing Encapsulation is a tunnelling protocol, used to carry network layer protocols through encapsulation inside others.

Filter by
Sorted by
Tagged with
0
votes
1answer
27 views

Why does GRE tunnel has lesser TxBS/RxBS than its physical interface?

Given for instance, interface Tunnel200 tunnel destination 110.153.1.1 There's a static route for 110.153.1.1, pointing to physical interface Gi0/0. Gi0/0 is only used for tunnel200. Under show ...
0
votes
0answers
31 views

IPSEC Over GRE and GRE Over IPSEC

Can you show me example configuration IPSEC Over GRE and GRE Over IPSEC in Cisco IOS. I founded only example configuration GRE OVER IPSEC
2
votes
0answers
33 views

Router on one side of a GRE tunnel not adding OSPF route through the tunnel whilst the router on the other side is

I have configured GRE tunnel between the Dublin and Carlow routers with the following commands: //Carlow int tunnel 0 ip address 172.16.12.1 255.255.255.252 tunnel source s0/0/0 tunnel destination 87....
0
votes
0answers
20 views

How to configure ZPF with Tunnel?

I am trying to configure ZPF in a Cisco 4331 router in Packet Tracer. I have a tunnel interface for GRE tunnel in this router. But I am not being able to assign this tunnel interface to any zone due ...
0
votes
0answers
29 views

Does multicast over tunnels (e.g., GRE) require IGMP/MLD?

When subscribing to a multicast group on a tunnel device such as a GRE tunnel, are you supposed to participate in IGMP/MLD over that tunnel in order to announce your membership in the multicast group? ...
1
vote
1answer
48 views

What is the purpose of the Set-Link-Info message in PPTP? The RFC seems to contradict itself in regard to this message

A PPTP connection transports payload data by wrapping it into PPP and then sending it over a previously negotiated Enhanced GRE link. As per PPTP RFC, the following holds true: The encapsulated PPP ...
0
votes
1answer
58 views

GRE Encapsulation

i am learning networks and tunneling and i have problems with understanding some things about GRE. The structure of tunneling below: [Transport Protocol][ensapsulationg protocol(GRE)][encapsulateed ...
-1
votes
1answer
95 views

GRE over IPSec Transport vs. Tunnel Mode

I have a misunderstanding, in this article, Figure 4-9, in Transport Mode, first header (IPsec Hdr), is correct? Should not be GRE IP Hdr? https://www.cisco.com/c/en/us/td/docs/solutions/Enterprise/...
2
votes
0answers
724 views

GRE over IPsec problem

I'm trying to build a GRE Tunnel with IPSec encryption between two routers, but I keep getting error message saying "%CRYPTO-4-RECVD_PKT_NOT_IPSEC: Rec'd packet not an IPSEC packet..." Immediately I ...
0
votes
1answer
647 views

qos inside vpn, possible or not ? I read yes and no

I am wondering if possible to do QOS (or similar action) inside vpn tunnel to a cloud server. the goal is to reserved bandwith for voip traffic. I read that you can with GRE and other people said, ...
4
votes
1answer
577 views

How IPsec tunnel mode work without GRE

IPsec tunnel mode encrypt a whole IP packet and sends it as the payload of another IP packet. I have always used GRE as the encapsulation layer when doing IPsec encryption. However, how could I have ...
1
vote
1answer
34 views

Can a VPN tunnel between routers be built with different tunnel protocol on both ends?

I have two routers and the tunnel between them is up and working well. Router1 has GRE/IP as the protocol on its tunnel interface, and as for Router2 the tunnel interface is working with IPSEC/IP. Can ...
1
vote
1answer
77 views

Gre Tunnel issue

I've encountered an abnormal behavior of my GRE Tunnel between two routers Cisco. When I ping the remote physical IP of the tunnel, I reach it without any loss. But when I ping the remote Tunnel IP, I ...
4
votes
1answer
497 views

Scaling VXLAN tunnels in openvswitch

As we're creating a cluster of tens of KVM host nodes we've chosen openvswitch as our virtual network infrastructure. So we need to make isolated virtual networks between VMs on demand. I've seen ...
4
votes
1answer
495 views

Use cases for GRE over IPSEC

I'm trying to understand use cases for GRE over IPSEC. In the diagram below, each site uses GRE to encapsulate multicasts associated with OSPF. (There is still a requirement to configure SAs between ...
2
votes
1answer
49 views

Two channels between two switches

Is there a way to provide two physically diverse channels between two switches? I'm using two Cisco Catalysis 3560s, and I want to have two separate channels between them, with different access ...
4
votes
1answer
194 views

Encrypt Gre tunnel traffic

I have a gre tunnel between vyatta and juniper srx . I would like to encrypt the gre tunnel traffic if its possible. thanks Pratik
1
vote
1answer
46 views

Network Security Tunnel

In the Tunnel Interface, when I edit the tunnel information, it shows: Attributes Values Tunnel Source IF10 Tunnel Destination 1.0.0.1 Tunnel Mode GRE What does IF10 ...
2
votes
2answers
1k views

GRE-IPsec Tunnel between Cisco Router and a Linux Router

I am trying to create a GRE/IPsec tunnel between Cisco router and a Linux Router. The tunnel is UP and active, but when I do a "show crypto session" on the Cisco router the Active SA's keep on ...
1
vote
2answers
593 views

TTL, GRE tunnel

I need some advise on the TTL. Currently my application vendor sets TTL to be with value 1 and he should increase it. He is thinking about value of 10, but I'm not sure that this is enough: Assuming ...
0
votes
1answer
123 views

Is it possible to append custom data to every packet of a request? [closed]

For an end-to-site VPN, i.e. where a device (VPN client) is responsible for encapsulating the GRE packet, is it possible to send some custom data along with the GRE packet beyond just the standard ...
1
vote
1answer
727 views

How to use ACL to deny sending packages to the GRE tunnel?

I need to do a small lab. The topology is shown on the image below: What I need to do, is make static routing so all routers can ping each neighbour's physical interface, configure a GRE tunnel ...
2
votes
1answer
390 views

PPP CHAP Authentication password requirement

What is the requirement for CHAP authentication on a PPP interface? I thought both routers had to have the same password defined, such as below. r1> username r2 password demo r2> username r1 ...
3
votes
2answers
682 views

OSPF on tunnel interfaces

Can I keep different tunnel interfaces in different OSPF areas. Keep in mind that the physical interface is going to be the same
3
votes
3answers
552 views

Layer 3 tunnel with Dynamic IP address

I want to ask whether it is possible to configure Layer 3 Tunnel with the two end points/interfaces have dynamic IP address? If the interface IP change, the tunnel will have to be re-negotiated, is ...
2
votes
1answer
92 views

Qos implementation

I want to implement Qos on a GRE tunnel and want to give priority to a destination IP 1.1.1.1 of a system from our site using WAN link. I will match the traffic through an ACL in class-map in which ...
1
vote
1answer
177 views

Secure communication between multiple sites over Internet

Does anyone know what would be the best practice to securely connect 2 or more branches with HQ over the Internet, and to allow communication between all of them (so anyone can contact anyone) if I ...
2
votes
1answer
921 views

MPLS over GRE tunnel with Linux iproute2 [closed]

I'm trying to encapsulate IP packets in MPLS, transported over a GRE tunnel between two Linux hosts (a and b). a has 10.199.0.1 on GRE tunnel interface foo4, while b has 10.199.0.2 on GRE tunnel ...
6
votes
2answers
8k views

What is the difference between L2TP vs GRE

Can anyone clearly explain that what is the difference between L2TP and GRE tunnel? Is L2TPv3 Any different I am trying to understand where these protocol are used and why we use L2TP instead of ...
3
votes
1answer
695 views

GRE over IPSec vs L2TP over IPSEC

Every single VPN provider offers L2TP over IPSec. What is the reason GRE over IPSec is never offered ? Is there any downfall ? It seems to be exactly the same.
2
votes
1answer
951 views

Different tunnel modes (protected with ipsec)

I’m doing a connection of 2 sites in ipv6 over an ipv4 network. I thought to do a tunnel between this 2 sites and protect it with IPsec. But I saw there are different types of tunnels (by default GRE):...
3
votes
2answers
567 views

Site-to-Site VPN tunnel configuration

I remember in uni that we implemented VPN tunnels always on the border routers and then use GRE tunnels to connect between two remote subnets. I was always told that VPN tunnels need to know the ...
2
votes
2answers
106 views

Cisco IPSec questions on loopback0 and phase 2

ip multicast-routing crypto isakmp policy 2 encr 3des hash md5 authentication pre-share crypto isakmp key 123 address 1.7.129.10 ! crypto ipsec transform-set remotevpn esp-3des esp-md5-hmac ! ...
1
vote
1answer
716 views

Is a GRE tunnel sensitive to packet loss?

I tested a GRE tunnel on a lousy link, and all traffic seems lagging and slow, but when I switch to a healthy link, everything run smoothly. Is a GRE tunnel, in general, very sensitive to packet loss?...
1
vote
1answer
856 views

Regarding front door vrf concept

While reading up on front-door vrf concept here, i am just wondering , what if we made the network statements more precise/specific or used different subnets altogether, we would never have our tunnel ...
1
vote
1answer
377 views

Regarding Gre tunnel encapsulation

Please consider the attached image below: A GRE tunnel is set up between R1 and R4. Tunnel source is R1 interface having the IP address 172.16.0.1/16 Tunnel destination is R4 interface having the IP ...
1
vote
1answer
988 views

Regarding Multicast over the internet

I was going through the use cases of GRE tunnel and see that it is also used to carry multicast traffic over the internet.I understand that multicast IP belongs to class D address which is a public IP ...
1
vote
0answers
3k views

Tunnelling difference over VXLAN vs NVGRE vs GENEVE [closed]

Any bullet points that are most imp points when it comes differences between these three tunnellings VXLAN/NVGRE/GENEVE in networks. Found some notes here, anything that you may like to add would be ...
0
votes
1answer
895 views

More Fragment flag and Frag Offset field after GRE fragmentation

If the length of a packet by attaching GRE-IP header results in bigger size than router MTU, what happen on More Fragment Flag and Frag Offset field of that packet?
2
votes
3answers
5k views

GRE over IPsec between Juniper SRX100 and Fortigate 100D

I need assistance configuring VPN setup between Fortigate and Juniper devices (GRE over IPSec). I have the topology as follows: What I need to do is create a route-based IPSec tunnel between the ...
2
votes
2answers
957 views

Packet flow in GRE Tunnel

In the below image what would be the ip address in the outer ip header when packet goes from R1 to R2. If the ip address in the outer header is 172.16.0.1 , how does it travels the internet as its not ...
2
votes
2answers
2k views

Why source and destination addresses should match in GRE tunnel?

In a GRE tunnel, when R1 (public IP 172.16.0.1, tunnel address 10.0.0.1) sends a packet to R3 (public IP 172.16.0.6, tunnel address 10.0.0.2) and R3 receives it, the following happens: A packet is ...
2
votes
1answer
155 views

How would “looping” in GRE occur according to RFC 2784

RFC 2784 mentions: Care should be taken when forwarding such a packet, since if the destination address of the payload packet is the encapsulator of the packet (i.e., the other end of the tunnel), ...
2
votes
1answer
84 views

Why specify the source tunnel address?

http://www.firewall.cx/cisco-technical-knowledgebase/cisco-routers/868-cisco-router-gre-ipsec.html Let me use the same example as in my previous question. R1(config)# interface Tunnel0 R1(config-if)#...
2
votes
1answer
3k views

Two GRE tunnels in one subnet

http://www.firewall.cx/cisco-technical-knowledgebase/cisco-routers/868-cisco-router-gre-ipsec.html In the example above, R1: R1(config)# interface Tunnel0 R1(config-if)# ip address 172.16.0.1 255....
2
votes
2answers
378 views

Splitting Data and Voice by creating GRE tunnel for Data, using overhead for Voice

A client: 3 sites with L2 links to our Data Centre. I create L3 links by providing IP's both sides. I want to create a GRE tunnel over each link with seperate IPs in order to route Data over these new ...
2
votes
2answers
705 views

Support GRE tunneling router or firewall

I am new member of Network Engineering site! These days I am interested in GRE tunneling. I know that GRE is developed by CISCO and many routers produced by CISCO and Juniper support GRE tunneling. ...
3
votes
1answer
4k views

What is the difference between ip nhrp nhs and ip nhrp map?

These two commands seems similar when I configure a DMVPN Spoke. What is the difference? interface Tunnel1 ip address 192.168.88.2 255.255.255.248 no ip redirects **ip nhrp map 192.168.88.1 10.0.1....
3
votes
0answers
997 views

GRE tunnel(or even any tunnelling technique) between Alcatel 7750 and a Cisco Router [closed]

has anyone on here been able to successfully create a GRE tunnel or any kinda of tunnelling mechanism between an Alcatel router and a Cisco router. I've been struggling with this and for a while and ...
1
vote
0answers
183 views

Overlay network with GRE without spanning tree [closed]

I need to create an overlay network with potential of hundreds of servers (each is an hypervisor and running a open vswitch). I'm going to use ovswitch and connect each server to all other servers ...