Gre header size. You can therefore set the GRE IP MTU to be 24 bytes less than ...

Gre header size. You can therefore set the GRE IP MTU to be 24 bytes less than the outgoing interface, or increase the underlay transport Because the firewall encapsulates the tunneled packet in a GRE packet, the additional 24 bytes of GRE header automatically result in a smaller Maximum Segment Size (MSS) in the maximum transmission unit (MTU). Your clean, repackaged packets could be blown apart before they're delivered. To accommodate additional header data introduced by encapsulation, you must adjust the GRE ヘッダー形式 図 3 は、IPv4ネットワークでのフィルターベーストンネリングに使用される可変サイズGREヘッダーのフォーマットを示しており、ビット0が最上位ビット、ビット15が最下位ビットを示しています。 This includes the addition of a new IP header in tunnel mode and optional encapsulation methods like GRE over IPSec, which introduces GRE overhead. Oct 6, 2023 · The need to use GRE header increases to provide aflow-level granularity that describes the utilization of bandwidth. Usually, it lowers the tunnel’s effective Maximum Transmission Unit (MTU). Introduction This guide describes Generic Routing Encapsulation (GRE) and its configuration. Once the entire packet is reach by the peer, the external IP and GRE headers are removed and the internal IP The website encountered an unexpected error. 4 byte GRE header and 20 bytes new IP header is added; this increases MTU size of the IP packet. GRE header The GRE header format is shown in Figure: GRE header and described in Table: GRE header descriptions. ) GRE does not have strong security mechanisms. With ipsec tunnel mode, you will have 2 ip header in the ipsec packet: an inner ip header, that contains the destination of the ip packet after leaving the ipsec tunnel, an an outer ip header, that contains the tunnel endpoint address. To create a GRE tunnel, a GRE overhead is added to an IP Packet of 1500 bytes (IP header, TCP header and data). What Is an MSS Announcement? This document describes the usage of the Generic Routing Encapsulation (GRE) header for Network Virtualization (NVGRE) in multi-tenant data centers. 1q encapsulation. GRE Header Fields This document does not change the GRE header format or any So GRE encapsulation happens first where a 4 byte GRE header + 20 byte IPv4 header is added to the received 1477 byte packet, giving you a 1501 byte packet. 2. Jun 20, 2019 · The underlay network transports the encapsulated GRE packets. May 17, 2023 · GRE copies the DF bit from the data IPv4 header to the GRE IPv4 header. RFC 2784 Generic Routing Encapsulation March 2000 3. Sep 3, 2024 · IPSec over GRE Generic Routing Encapsulation (GRE) protocol Internet Protocol Security (IPSec) GRE Tunnel Configuration IPSec Configuation Generic Routing Encapsulation GRE is a Tunneling Protocol and it was Originally developed by Cisco systems for creating virtual point-to-point links between cisco routers at remote points over the Internet. Jul 24, 2018 · Why do we need tunnel MTU to be 24 bytes lower (or more) than interface MTU? Because GRE will add 4 bytes GRE header and another 20 bytes IP header. Solution When the GRE tunnel is configured in FortiOS, it may be noticed that the GRE tunnel has an MTU of less than 1500. The dot1Q encapsulation counts up to four extra bytes. Jul 21, 2020 · The IPsec encapsulation header size depends on the mode; it's typically 50 bytes to 57 bytes, depending on the padding that is needed to create packets that are a multiple of 8 bytes. If tunnelendpoint and final destination of the packet are the same, we can use transport mode, where the inner ip Mar 31, 2025 · For point-to-point GRE tunnels, each tunnel interface requires a tunnel source IPv6 address and a tunnel destination IPv6 address when being configured. Everything else is pure header size, without any outer or inner protocols, e. We can also use GRE to tunnel routing protocols like RIP, OSPF, or EIGRP between HQ and branch sites. Network virtualization decouples a virtual network from the underlying physical network infrastructure by virtualizing network addresses. Farinacci, et al. Do not use the "Check gateway" option "arp" when a GRE tunnel is used as a route gateway. Nov 26, 2019 · GRE tunnel adds 24 bytes to the IP Packet. Nov 29, 2012 · GRE --generic routing encapsulation. RFC 1701 Compliant Receiver An implementation complying to this specification will The original IP headers plus the data are appended to the new IP header and the GRE header (New IP Header | GRE | Original IP header | TCP | Payload). GENEVE has a flexible option header format, which defines the length, the Aug 29, 2024 · A maximum segment size (MSS) measures payload size. All rights reserved. GRE functions as a Layer 3 tunnelling protocol of Virtual Private Networks (VPNs), and provides a tunnel for transparently transmitting VPN packets. The second is a GRE header with information about the protocol. A GRE header includes the number of encapsulations, version, passenger protocol type, checksum, and key. This document also introduces No, the GRE IP header is there in both cases. When you encapsulate with GRE/IPSec you need to make room for new IP headers (20 bytes), the GRE header (4 bytes) and optionally the IPSec header (56 bytes). GRE tunnel can forward only IP and IPv6 packets (ethernet type 800 and 86dd). This means if Examples GRE over IPv4, encapsulates IPv4. The don’t-fragment (DF) bit is not set in the outer IP header of GRE-encapsulated packets. It is a simple IP packet encapsulation protocol. Then, a Delivery header is prepended to the GRE header, which adds a Layer 2 Data Link Layer May 21, 2020 · The GRE header adds between 4 to 16 bytes of overhead, depending on which fields are used. May 17, 2019 · GRE and GRETAP GRE and GRETAP Generic Routing Encapsulation, also known as GRE, is defined in RFC 2784 GRE tunneling adds an additional GRE header between the inside and outside IP headers. 5. “MPLS” is the size of a single MPLS label (4 bytes). GRE tunnels are not secure because it RFC 1701 Generic Routing Encapsulation (GRE) October 1994 is set to 1, then the Address Family field should be checked to determine the semantics and use of the SRE Length, SRE Offset and Routing Information fields. MTU Impact: Performance may be impacted by the larger packet size caused by this extra overhead. "Encapsulating" means wrapping one data packet within another data packet, like putting a box inside another box. GRE Overhead = 8 (GRE bytes) + 20 (IP GRE Header) = 24 . All packets are encapsulated with an outer IPv6 header and a GRE header. This means if RFC 7676 GRE IPv6 October 2015 o GRE MTU (GMTU): The maximum transmission unit, i. 2 to 1. Allows the encapsulation of a wide variety of Layer 3 protocols including IP. Once all SREs have been processed, then the source route is complete, the GRE header Dec 5, 2025 · 2. This document explains a common reason for this problem, and offers several workarounds. This overhead is then removed by a receiving router. Rather, it dictates the maximum size of the “data” part of the packet. GRE is the most secure tunneling protocol. GRE is a mechanism for encapsulating any network layer protocol over any other network layer protocol. When using encapsulation protocols it is necessary to adjust the IP MTU and the TCP Maximum Segment Size to prevent fragmentation. GRE Header Fields This document does not change the GRE header format or any Header sizes for VXLAN, LISP, and WireGuard include UDP, and STT includes TCP, because these protocols never use any other L4 protocol. Apr 7, 2025 · The average size of the GRE header is 24 bytes and if the data with 1,500 bytes MTU and 1,460 MSS value is used and processed with GRE, the MTU and MSS limit will extend. Hence, the end-user will require more computing power to operate. Common characteristics between GRE and IPsec GRE and IPsec protocols share some similar characteristics, including the following: GRE functions as a Layer 3 tunnelling protocol of Virtual Private Networks (VPNs), and provides a tunnel for transparently transmitting VPN packets. But you will add two headers, and that could mean you violate MTU rules. Your entire packet including your original IP header is preserved within the payload, allowing for source-IP logging and policy actions based on source address. You can therefore set the GRE IP MTU to be 24 bytes less than the outgoing interface, or increase the underlay transport Jun 2, 2015 · 18. 1. Tunnels that provide a specific pathway across the shared WAN and encapsulate traffic with new packet headers to ensure delivery to specific destinations. The following sections describe correct interoperation with such implementations. If I send a keepalive from 1. Move through the GRE encapsulation process, and you won't change the size of your payload. 4. The packet is routed based on the inner IP header. There are, however, existing implementations of RFC 1701. For GRE keepalives, the sender prebuilds the keepalive response packet inside the original keepalive request packet so that the remote end only needs to do standard GRE decapsulation of the outer GRE IP header and then revert the inner IP GRE packet to the sender. May 17, 2023 · Der Router ist so konfiguriert, dass er mit dem tunnel path-mtu-discovery Befehl PMTUD auf GRE + IPv4-Tunnelpaketen durchführt, und das DF-Bit wird vom ursprünglichen IPv4-Header in den GRE-IPv4-Header kopiert. Developed by Cisco but later became industry standard. Additional headers, such as the Authentication Header (AH) or Encapsulating Security Payload (ESP) header and trailer, also contribute to increased packet size. The options allow you select what encryption settings are used and whether you are using a GRE tunnel. The GRE header looks like: Aug 10, 2005 · Sometimes when traffic goes through a generic routing encapsulation (GRE) tunnel, you can successfully use the ping command and Telnet, but you cannot download Internet pages or transfer files using File Transfer Protocol (FTP). e. 3k次，点赞15次，收藏23次。GRE协议原理；GRE Header封装格式；GRE配置简介；ERSPAN原理_gre报文 Mar 20, 2023 · A GRE header can be between 4 bytes and 16 bytes long, depending on which options are enabled, with a default of 4 bytes. Difference between VxLAN and NVGRE VxLAN and NVGRE both are network virtualization techniques but differ from each other concerning varius Jul 25, 2025 · On the other hand, in IPsec over GRE only the payload is encrypted within the GRE tunnel, leaving the GRE header and routing protocols unencrypted. 2 the internal GRE message is from 2. That means if you're doing IPSec over GRE you need to set aside 80 bytes for the encapsulation - so your MTU has to be 1420. g. The first pair of bytes (bits 0 through 15) contains the flags that indicate the presence of GRE options. The GMTU is equal to the PMTU associated with the path between the GRE ingress and the GRE egress, minus the GRE overhead. 総称ルーティングカプセル化（GRE）とは、直接ネットワーク接続を設定するためにデータパケットをカプセル化するためのプロトコルのことです。GREトンネルの仕組みについてご説明します。 Mar 21, 2020 · GRE is a tunneling protocol. So we only need to care about IPv4 and GRE, and we add IPv4 (20 bytes) and GRE (4 bytes). In GRE an IP Datagram is tunnelled i. GRE IPv6 Tunnel Protection GRE scores are essential in the holistic admissions process since only GRE tests provide a research-based, objective, directly comparable measure that institutions can use to fairly evaluate applicants from different backgrounds. The exact semantics for processing a SRE for each Address Family is defined in other documents. Sep 9, 2023 · GRE tunnel adds a 24 byte overhead (4-byte gre header + 20-byte IP). Combined with a management and control plane for the The website encountered an unexpected error. The GRE header alone adds at least 24 bytes of overhead. Jul 22, 2025 · Because the firewall encapsulates the tunneled packet in a GRE packet, the additional 24 bytes of GRE header automatically result in a smaller Maximum Segment Size (MSS) in the maximum transmission unit (MTU). MPLS-over-GRE (generic routing encapsulation) is used for Layer 3 routing between Contrail and MX Series routers. No, the GRE IP header is there in both cases. If your outbound physical interface is configured as ethernet, the frame size that will cross the wire is expected be 14 bytes more, 18 bytes if link is configured with 802. GRE allows routing of IP packets between private networks which are separated over public network like internet. 1, which is king of a bidirectional link testing. 3. Therefore, to prevent fragmentation and ensure that packets can traverse the tunnel without issues, you should set the IP MTU on the tunnel interface to be 24 bytes less than the IP MTU of the real outgoing interface. I need to understand the header format in detail. The limitation of NVGRE is that it is not compatible with traditional load balancing. Cloudflare sets up tunnel endpoints on global network servers inside your network namespace, and you set up tunnel endpoints on routers at your data center. Some of the issues associated with MTU size and fragmentation in IP tunneling and use of ICMP messages are outlined in Section 4. Dec 17, 2025 · MSS does not include the TCP header or the IP header. While the flexibility and extensibility for GENEVE incorporates the GRE, VXLAN, and GPE use-cases, new use-cases are being created on a daily basis. None of these encapsulation tunnelling methods require any change to hardware networking infrastructure, though some vendors offer hardware that can help assist in accelerating the efficiency of the solution. Network Virtualization decouples virtual networks and addresses from physical network infrastructure, providing isolation and concurrency between multiple virtual networks on the same physical network infrastructure. The act of encapsulation increases the header size of the packet (specifically 4 bytes GRE header and 20 byte IP header) therefore this GRE packet size will exceed the default Ethernet interface MTU of 1500 bytes. Tunneling provides a mechanism to transport packets of one Apr 19, 2020 · Hence, they can still transmit packet with size of 1500 bytes which when added with additional GRE/IPv4 headers will result to 1524 bytes which can't be sent through Ethernet medium and has to be Oct 9, 2024 · 文章浏览阅读3. So 1500 - (20+8+4) = 1468 bytes. ScopeFortiGate. Copyright ©2007 - 2026 Zscaler Inc. The GRE header is 4 bytes, and the outer IP header is 20 bytes, so we need take the MTU of our real interface (commonly 1500), and subtract 24 bytes. This header enables GRE to efficiently encapsulate multiple Layer 3 protocols. If you don’t change the IPv4 MSS Adjustment Size for the interface, the firewall reduces the MTU by 64 bytes by default (40 bytes of IP header + 24 bytes of GRE header). Generic Routing Encapsulation, or GRE, is a protocol for encapsulating data packets that use one routing protocol inside the packets of another protocol. In general, GRE allows a tunnel to be created using a certain protocol, which then hides the contents of another protocol carried within the tunnel. Once all SREs have been processed, then the source route is complete, the GRE header May 19, 2006 · Hi, I need to know whether a packet if traversing a GRE tunnel Ip over Gre over IP then, is the headers added to the original packet is arranged as per the attachment doc. GRE encapsulation attacks: definition and defense Feb 16, 2026 · Cloudflare WAN uses Generic Routing Encapsulation (GRE) and IPsec tunnels to transmit packets from Cloudflare's global network to your origin network. GRE Header: Positioned between the delivery header and payload, the GRE header defines protocol type, version, and flags. This adds 8 bytes to the overhead. Jan 22, 2024 · GRE tunnel adds a 24 byte overhead (4-byte gre header + 20-byte IP header). Common characteristics between GRE and IPsec GRE and IPsec protocols share some similar characteristics, including the following: De-encapsulation—A router operating as a tunnel remote router handles GRE packets as follows: When the destination router receives the IP packet from the tunnel interface, the outer IP header and GRE header are removed. Generic Routing Encapsulation (GRE) GRE is described by the IETF in the RFC 27841 and is very popular in the SD-WAN industry. GRE encapsulates a payload, that is, an inner packet that needs to be delivered to a destination Introduction Sometimes when traffic goes through a generic routing encapsulation (GRE) tunnel, you can successfully use the ping command and Telnet, but you cannot download Internet pages or transfer files using File Transfer Protocol (FTP). This would cause the router to fragment the tunnel traffic before sending it out the physical interface which is a very CPU-intensive operation. The IP MTU for traffic that needs to traverse the tunnel will then be 1468 - (18 +20 What is GRE? When a packet enters a GRE tunnel, it has an encapsulation process applied where the new IP header and GRE header are appended to the packet - after encapsulation, the addresses in the attached IP header are used for forwarding So GRE encapsulation happens first where a 4 byte GRE header + 20 byte IPv4 header is added to the received 1477 byte packet, giving you a 1501 byte packet. Mar 20, 2023 · A GRE header can be between 4 bytes and 16 bytes long, depending on which options are enabled, with a default of 4 bytes. If the DF bit is set in the GRE IPv4 header and the packet is "too large" after IPv4sec encryption for the IPv4 MTU on the physical outgoing interface, then IPv4sec drops the packet and notifies the GRE tunnel to reduce its IPv4 MTU size. As a result, the GRE header will never contain the Key, Sequence Number or Routing fields specified in RFC 1701. Feb 2, 2004 · From your config, I deduced that you are using a GRE tunnel. First, a GRE header is prepended to the payload packet, and the Ethertype for the protocol used in that packet is included in the GRE header. 4. So how do we fix this? May 15, 2006 · Actually, if you look at the information I provided, you can see that each hello contains its own response (a GRE message in a GRE message). GRE is stateless. Since this size exceeds the link MTU of 1500 MTU in this case, the encapsulated packet is fragmented. Standards Track [Page 3]RFC 2784 Generic Routing Encapsulation March 2000 3. 総称ルーティングカプセル化（GRE）とは、直接ネットワーク接続を設定するためにデータパケットをカプセル化するためのプロトコルのことです。GREトンネルの仕組みについてご説明します。 Jan 23, 2008 · GRE packets are formed by the addition of the original packets and the required GRE headers. If tunnelendpoint and final destination of the packet are the same, we can use transport mode, where the inner ip Apr 20, 2023 · GRE copies the DF bit from the data IPv4 header to the GRE IPv4 header. Outer IP header : This is 20 bytes long and has the local and remote end points of the GRE tunnel ip address. IPSec Overhead Calculator This is a tool to calculate the resulting packet size when it traverses an IPSec tunnel. Once the network traf Nov 6, 2020 · fragmentation or other less common features of the IP header, such as options and extension headers. Apr 2, 2025 · The article discusses the PMTU (path MTU) of the GRE Tunnel, identifying and using the fragmentation to recover the traffic over the tunnel. Its value is determined by the MTU size within the customer's network. Both RFC 2784 and RFC 1701 define the GRE Headers, and this two GRE Headers are different. Generic routing encapsulation (GRE) is a tunneling protocol developed by Cisco Systems that can encapsulate a wide variety of network layer protocols inside virtual point-to-point links or point-to-multipoint links over an Internet Protocol network. When the physical interface MTU is 1500 bytes, the maximum payload MTU through a GRE tunnel is 1476 bytes. Forwarding Decapsulated IPv4 Payload Packets When a tunnel endpoint decapsulates a GRE packet which has an IPv4 packet as the payload, the destination address in the IPv4 payload packet header MUST be used to forward the packet and the TTL of the Jun 22, 2017 · That header size is 24-bit for VXLAN and NVGRE, the latter being used mostly by Microsoft, while STT has a 64-bit header size. Forwarding Decapsulated IPv4 Payload Packets When a tunnel endpoint decapsulates a GRE packet which has an IPv4 packet as the payload, the destination address in the IPv4 payload packet header MUST be used to forward the packet and the TTL of the payload packet MUST be decremented. The GRE Header defined in the RFC 2784 has a size of 64 bits (8 bytes) where the last 32 bits, commonly not used are optional and only present if the first bit of the first 32 bits is set to 1. GRE encapsulation supports any OSI Layer 3 protocol. GRE adds two headers to each Layer 3 packet: GRE header : This is 4 bytes long and has the protocol type, version and a few other optional parameters. Careful planning on the interface MTU is necessary. Jun 10, 2009 · Introduction: Packet header: Basic GRE tunnel configuration: RFCs Related information: GRE is used to encapsulate an arbitrary layer protocol over another arbitrary layer protocol. 2 of [INTAREA-TUNNELS]. The base GRE header is 4 bytes long, but if optional fields are used, such as a checksum or key, the header size increases accordingly. Thanks in adv. Nov 3, 2025 · このドキュメントでは、Catalyst 9000シリーズスイッチの最大伝送ユニット(MTU)を理解してトラブルシューティングする方法について説明します。 RFC 1701 Generic Routing Encapsulation (GRE) October 1994 is set to 1, then the Address Family field should be checked to determine the semantics and use of the SRE Length, SRE Offset and Routing Information fields. Try again later. The term GRE tunnels in this document implies only unicast IPv4 GRE tunnel that supports IPv4 payload. 1 to 2. RFC 2784, `Generic Routing Encapsulation' (GRE), provides a mechanism for encapsulating a payload packet to send that packet over a network of a different type. What is GRE? Generic Routing Encapsulation (GRE) is a Cisco developed tunneling protocol. How Do GRE Tunnels Work? When a router encapsulates data packets, it modifies the packet’s header information (encapsulation) to include the remote endpoint’s IP address as the destination. GRE provides flow control · GRE header—Header that is added to the payload packet to change the payload packet to a GRE packet. The Checksum, Key, and Sequence Number header fields are all optional. DSCP, ECN, and TTL When encapsulating IP (including over Ethernet) packets in Geneve, Apr 18, 2025 · For GRE keepalives, the sender prebuilds the keepalive response packet inside the original keepalive request packet so that the remote end only needs to do standard GRE decapsulation of the outer GRE IP header and then revert the inner IP GRE packet to the sender. Which three statements are characteristics of generic routing encapsulation (GRE)? (Choose three. De-encapsulation—A router operating as a tunnel remote router handles GRE packets as follows: When the destination router receives the IP packet from the tunnel interface, the outer IP header and GRE header are removed. e encapsulated within another IP datagram. Dec 2, 2020 · Fast forward to 2020, GENEVE has been selected as the upcoming “standard” tunnel protocol. Together these pieces make up an additional 24 bytes for a total of 1524 bytes for the IP packet. Oct 20, 2021 · GRE (IP Protocol 47) (RFC 2784) adds 24 bytes (20 byte IPv4 header, 4 byte GRE header) 6in4 encapsulation (IP Protocol 41, RFC 4213) adds 20 bytes 3 days ago · Introduction GRE (Generic Routing Encapsulation) adds 24 bytes of overhead to each packet: a 20-byte outer IP header and a 4-byte GRE header. Added all together it gives you 68 and you can add in 14 bytes for the Ethernet header giving you 82 bytes total. RFC 7676 GRE IPv6 October 2015 o GRE MTU (GMTU): The maximum transmission unit, i. This is one of the most compelling but also most complex areas for GENEVE. The SDP Path MTU is calculated automatically by subtracting transport IP and GRE header bytes from the configured IP MTU of the outgoing interface. For a generic routing encapsulation (GRE) tunnel, enable fragmentation of GRE-encapsulated packets whose size exceeds the maximum transmission unit (MTU) value of a link that the packet passes through. Nov 7, 2025 · Overhead and MTU Overhead: GRE adds a minimum of 24 bytes of overhead (20 bytes for the outside IP header + 4 bytes for the GRE header) to every tunneled packet. Dec 5, 2025 · 2. We want tunnel MTU, parent interface MTU is 1500 Parent interface MTU is maximum size of IPv4 packets it can transmit, not counting Ethernet frame headers. EVPN-VXLAN is used for Layer 2 connectivity between virtual machines and top-of-rack (TOR) switches, for example, QFX5100 switches, within a Layer 2 domain. Care should be taken when forwarding such a packet, since May 6, 2021 · IPv4 unicast Generic Routing Encapsulation Tunnel (GRE) tunneling protocol provides a simple generic approach to transport packets of one protocol over another protocol by means of encapsulation. Using the GRE tunneling example in the previous section, because the size of total headers is 64, the TCP MSS value should be set to 1436 or lower, to ensure that fragmentation is not needed. Jun 9, 2015 · The second packet consists of an IP header (20 bytes), a GRE header (4 bytes), an inner IP header (20 bytes), and 24 bytes of payload (our overflow from packet 1). Service MTU indicates the maximum frame size that the customer can accept over the service (PW SAP). In that case, the data packet will be fragmented and packet delivery speed will be slow. These headers are 24-bytes in length and since these headers are added to the original frame, depending on the original size of the packet we may run into IP MTU problems. Regs Kas Dec 15, 2024 · GRE Tunnel provides point-to-point tunneling without encryption, while IPSec secures communication with encryption and authentication. , maximum packet size in octets, that can be conveyed over a GRE tunnel without fragmentation of any kind. GRE is one way to set up a direct point-to-point connection across a network, for This will change the maximum packet size that can pass over the tunnel. Even though the maximum IP datagram has been defined as 64K, most links enforce a RFC 2784 Generic Routing Encapsulation March 2000 3. With the increasing popularity of IPSec VPN deployments on the Internet, there is often a need to understand the exact IPSec and other tunnel encapsulation overhead in order to What is GRE? When a packet enters a GRE tunnel, it has an encapsulation process applied where the new IP header and GRE header are appended to the packet - after encapsulation, the addresses in the attached IP header are used for forwarding Apr 6, 2024 · GRE Packet structure The below picture shows the GRE encapsulation in action. The GRE header itself contains 4 bytes, which represent the minimum size of GRE header with no added options. Without correct MTU configuration, packets are fragmented at the tunnel entry point or silently dropped if DF bit is set. It may include optional fields, such as a checksum or key, for authentication. This lightweight design minimizes overhead, making GRE efficient for encapsulation tasks. In theory, GRE could encapsulate any Layer 3 protocol with a valid Ethernet type, unlike IPIP, which can only encapsulate IP. 2. As you are bridging, this is the maximum datagram size for your tunnel. Fragmentation is your enemy. Care should be taken when forwarding such a packet, since burdening the network control plane This document describes use of the Generic Routing Encapsulation (GRE) header [3] [4] for network virtualization. Use this guide to understand the MPLS technology and MPLS applications functions, and to configure MPLS and other feature modules deploying the MPLS applications. yrhvjm rzpb bcpxtm bqmshdkz ppu amma dhfzq udra epdtcw ynecrhc